/* main.css — Aha 啊哈时刻 官网 (Doodle Style) */

:root {
  /* Pastel palette */
  --c-mint: #c5f0d8;
  --c-mint-bg: #ddf7e7;
  --c-pink: #ffd0d8;
  --c-pink-bg: #ffe4e9;
  --c-yellow: #fff2b8;
  --c-yellow-bg: #fff8d6;
  --c-purple: #e4d4ff;
  --c-purple-bg: #f0e7ff;
  --c-blue: #c8def5;
  --c-blue-bg: #dfecf8;
  --c-peach: #ffd9c4;
  --c-peach-bg: #ffe7d8;

  /* Brand */
  --c-accent: #fa5e4e;
  --c-accent-blue: #3558df;
  --c-accent-green: #2bb474;

  /* Neutrals */
  --c-text: #1a1d2e;
  --c-text-soft: #5a5e72;
  --c-muted: #8b8fa3;
  --c-border: #1a1d2e;
  --c-border-soft: #d8dae3;
  --c-bg: #f4f5f7;
  --c-bg-soft: #fafbfc;
  --c-white: #ffffff;

  --r-card: 14px;
  --r-pill: 999px;
  --shadow-card: 4px 4px 0 #1a1d2e;
  --shadow-card-hover: 6px 6px 0 #1a1d2e;
  --shadow-soft: 0 2px 8px rgba(26, 29, 46, .06);
  --container: 1200px;
  --font-sans: -apple-system, BlinkMacSystemFont, "PingFang SC", "Microsoft YaHei", "Helvetica Neue", Arial, sans-serif;
  --font-hand: "Comic Sans MS", "Marker Felt", "PingFang SC", system-ui, sans-serif;
}

/* ---------- Body ---------- */
body {
  background-color: var(--c-bg);
  background-image: radial-gradient(circle, #d0d3dc 1px, transparent 1px);
  background-size: 18px 18px;
  color: var(--c-text);
  font-family: var(--font-sans);
}

.container { width: 100%; max-width: var(--container); margin: 0 auto; padding: 0 24px; position: relative; }

section { padding: 100px 0; position: relative; overflow: hidden; }

/* ---------- Section header ---------- */
.section-header { text-align: center; margin-bottom: 64px; position: relative; }
.section-tag {
  display: inline-block; padding: 6px 16px; background: var(--c-yellow);
  border: 2px solid var(--c-border); border-radius: var(--r-pill);
  font-size: 13px; font-weight: 700; color: var(--c-text); margin-bottom: 20px;
  transform: rotate(-1.5deg);
}
.section-title {
  font-size: 44px; font-weight: 800; color: var(--c-text); line-height: 1.2;
  position: relative; display: inline-block;
}
.section-title .underline {
  position: relative; display: inline-block;
}
.section-title .underline::after {
  content: ''; position: absolute; left: 0; right: 0; bottom: -8px; height: 12px;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 200 12' preserveAspectRatio='none'%3E%3Cpath d='M2 8 Q 50 2, 100 6 T 198 8' stroke='%232bb474' stroke-width='4' fill='none' stroke-linecap='round'/%3E%3C/svg%3E");
  background-repeat: no-repeat; background-size: 100% 100%;
  clip-path: inset(0 0 0 0);
  pointer-events: none;
}
.section-title .underline:hover::after {
  animation: wave-draw 1s cubic-bezier(.55, .05, .25, 1);
}
@keyframes wave-draw {
  from { clip-path: inset(0 100% 0 0); }
  to { clip-path: inset(0 0 0 0); }
}
.section-title .underline.pink::after {
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 200 12' preserveAspectRatio='none'%3E%3Cpath d='M2 8 Q 50 2, 100 6 T 198 8' stroke='%23fa5e4e' stroke-width='4' fill='none' stroke-linecap='round'/%3E%3C/svg%3E");
}
.section-subtitle { margin-top: 20px; font-size: 16px; color: var(--c-text-soft); }

/* ---------- Doodle decorations ---------- */
.doodle { position: absolute; pointer-events: none; animation: doodle-twinkle 2.6s ease-in-out infinite; transform-origin: center; will-change: transform, opacity; }
.doodle-star { animation-name: doodle-spin-twinkle; animation-duration: 3.2s; }
.doodle-spark { animation-name: doodle-spin-twinkle; animation-duration: 2.4s; }
.doodle-plus { animation-name: doodle-pop; animation-duration: 1.8s; }
.doodle-circle { animation-name: doodle-pulse; animation-duration: 2.2s; }
.doodle-zigzag { animation-name: doodle-wiggle; animation-duration: 2.6s; }
.doodle-arrow { animation-name: doodle-wiggle; animation-duration: 3s; }

/* Stagger so they don't blink in sync */
.hero-doodle-1 { animation-delay: 0s; }
.hero-doodle-2 { animation-delay: .6s; }
.hero-doodle-3 { animation-delay: 1.2s; }
.hero-doodle-4 { animation-delay: 1.8s; }
.hero-doodle-5 { animation-delay: 2.4s; }
.doodle:nth-of-type(2n) { animation-delay: .4s; }
.doodle:nth-of-type(3n) { animation-delay: 1.1s; }

@keyframes doodle-twinkle {
  0%, 100% { opacity: .07; transform: scale(.9); }
  50% { opacity: .14; transform: scale(1.15); }
}
@keyframes doodle-spin-twinkle {
  0%   { opacity: .07; transform: scale(.85) rotate(0deg); }
  50%  { opacity: .14; transform: scale(1.2) rotate(180deg); }
  100% { opacity: .07; transform: scale(.85) rotate(360deg); }
}
@keyframes doodle-pop {
  0%, 100% { opacity: .07; transform: scale(.8) rotate(-10deg); }
  50%      { opacity: .14; transform: scale(1.25) rotate(10deg); }
}
@keyframes doodle-pulse {
  0%, 100% { opacity: .07; transform: scale(.9); }
  50%      { opacity: .14; transform: scale(1.3); }
}
@keyframes doodle-wiggle {
  0%, 100% { opacity: .07; transform: rotate(-6deg) translateY(0); }
  50%      { opacity: .14; transform: rotate(6deg) translateY(-4px); }
}
@media (prefers-reduced-motion: reduce) {
  .doodle, .doodle-star, .doodle-plus, .doodle-circle, .doodle-zigzag, .doodle-arrow, .doodle-spark,
  .doodle-fx, .doodle-pi, .doodle-sigma, .doodle-sqrt, .doodle-integral,
  .doodle-xsq, .doodle-lambda, .doodle-h2o, .doodle-co2, .doodle-letterA, .doodle-quote { animation: none !important; }
}

.doodle-star {
  width: 36px; height: 36px;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 32 32' fill='none' stroke='%23ffc940' stroke-width='2.5' stroke-linecap='round'%3E%3Cpath d='M16 4 L18 14 L28 16 L18 18 L16 28 L14 18 L4 16 L14 14 Z'/%3E%3C/svg%3E");
  background-size: contain; background-repeat: no-repeat;
}
.doodle-plus {
  width: 24px; height: 24px;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24' fill='none' stroke='%232bb474' stroke-width='3' stroke-linecap='round'%3E%3Cline x1='12' y1='4' x2='12' y2='20'/%3E%3Cline x1='4' y1='12' x2='20' y2='12'/%3E%3C/svg%3E");
  background-size: contain; background-repeat: no-repeat;
}
.doodle-circle {
  width: 32px; height: 32px;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 32 32' fill='none' stroke='%23ffb0bd' stroke-width='2.5'%3E%3Ccircle cx='16' cy='16' r='12'/%3E%3C/svg%3E");
  background-size: contain; background-repeat: no-repeat;
}
.doodle-zigzag {
  width: 50px; height: 30px;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 50 30' fill='none' stroke='%233558df' stroke-width='3' stroke-linecap='round' stroke-linejoin='round'%3E%3Cpath d='M2 22 L12 8 L22 22 L32 8 L42 22'/%3E%3C/svg%3E");
  background-size: contain; background-repeat: no-repeat;
}
.doodle-arrow {
  width: 60px; height: 40px;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 60 40' fill='none' stroke='%231a1d2e' stroke-width='2.5' stroke-linecap='round' stroke-linejoin='round'%3E%3Cpath d='M2 20 Q 30 5, 50 25'/%3E%3Cpath d='M50 25 L 42 18'/%3E%3Cpath d='M50 25 L 56 17'/%3E%3C/svg%3E");
  background-size: contain; background-repeat: no-repeat;
}
.doodle-spark {
  width: 28px; height: 28px;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 28 28' fill='none' stroke='%23ffc940' stroke-width='2.5' stroke-linecap='round'%3E%3Cpath d='M14 2 L14 10'/%3E%3Cpath d='M14 18 L14 26'/%3E%3Cpath d='M2 14 L10 14'/%3E%3Cpath d='M18 14 L26 14'/%3E%3C/svg%3E");
  background-size: contain; background-repeat: no-repeat;
}
/* 标题下划线同款波浪短线 — 绿/红两色 */
.doodle-line {
  width: 80px; height: 14px;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 80 14' preserveAspectRatio='none'%3E%3Cpath d='M2 10 Q 20 2, 40 8 T 78 10' stroke='%232bb474' stroke-width='4' fill='none' stroke-linecap='round'/%3E%3C/svg%3E");
  background-size: contain; background-repeat: no-repeat;
}
.doodle-line.pink {
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 80 14' preserveAspectRatio='none'%3E%3Cpath d='M2 10 Q 20 2, 40 8 T 78 10' stroke='%23fa5e4e' stroke-width='4' fill='none' stroke-linecap='round'/%3E%3C/svg%3E");
}
.doodle-line { animation-name: doodle-wiggle; animation-duration: 3.2s; }
/* Themed doodles aligned with core message: 答疑 + 学习 + 顿悟 */
.doodle-pencil {
  width: 56px; height: 56px;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 56 56' fill='none' stroke='%231a1d2e' stroke-width='2.5' stroke-linejoin='round' stroke-linecap='round'%3E%3Cpath d='M8 48 L 14 42 L 40 16 L 46 22 L 20 48 Z' fill='%23fff2b8'/%3E%3Cpath d='M40 16 L 44 12 L 50 18 L 46 22 Z' fill='%23ffd0d8'/%3E%3Cpath d='M8 48 L 14 42 L 18 46 L 14 50 Z' fill='%231a1d2e'/%3E%3C/svg%3E");
  background-size: contain; background-repeat: no-repeat;
}
.doodle-eraser {
  width: 48px; height: 32px;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 48 32' fill='none' stroke='%231a1d2e' stroke-width='2.4' stroke-linejoin='round'%3E%3Crect x='4' y='6' width='40' height='20' rx='3' fill='%23ffd0d8'/%3E%3Cline x1='18' y1='6' x2='18' y2='26'/%3E%3C/svg%3E");
  background-size: contain; background-repeat: no-repeat;
}
.doodle-compass {
  width: 50px; height: 50px;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 50 50' fill='none' stroke='%231a1d2e' stroke-width='2.4' stroke-linejoin='round' stroke-linecap='round'%3E%3Ccircle cx='25' cy='10' r='4' fill='%23c5f0d8'/%3E%3Cpath d='M25 14 L 12 44'/%3E%3Cpath d='M25 14 L 38 44'/%3E%3Cpath d='M16 36 Q 25 32 34 36' stroke-dasharray='3 3'/%3E%3C/svg%3E");
  background-size: contain; background-repeat: no-repeat;
}
.doodle-bulb {
  width: 40px; height: 48px;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 40 48' fill='none' stroke='%231a1d2e' stroke-width='2.4' stroke-linejoin='round' stroke-linecap='round'%3E%3Cpath d='M20 6 C 12 6 6 12 6 20 C 6 25 9 27 11 30 V 34 H 29 V 30 C 31 27 34 25 34 20 C 34 12 28 6 20 6 Z' fill='%23fff2b8'/%3E%3Cline x1='13' y1='38' x2='27' y2='38'/%3E%3Cline x1='15' y1='42' x2='25' y2='42'/%3E%3Cline x1='20' y1='1' x2='20' y2='3' stroke='%23fa5e4e'/%3E%3Cline x1='6' y1='4' x2='8' y2='6' stroke='%23fa5e4e'/%3E%3Cline x1='34' y1='4' x2='32' y2='6' stroke='%23fa5e4e'/%3E%3C/svg%3E");
  background-size: contain; background-repeat: no-repeat;
}
.doodle-book {
  width: 56px; height: 44px;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 56 44' fill='none' stroke='%231a1d2e' stroke-width='2.4' stroke-linejoin='round'%3E%3Cpath d='M28 10 C 24 6 14 6 6 8 V 38 C 14 36 24 36 28 40 C 32 36 42 36 50 38 V 8 C 42 6 32 6 28 10 Z' fill='%23c8def5'/%3E%3Cline x1='28' y1='10' x2='28' y2='40'/%3E%3C/svg%3E");
  background-size: contain; background-repeat: no-repeat;
}
.doodle-ruler {
  width: 60px; height: 22px;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 60 22' fill='none' stroke='%231a1d2e' stroke-width='2.2' stroke-linejoin='round'%3E%3Crect x='2' y='4' width='56' height='14' rx='2' fill='%23e4d4ff'/%3E%3Cline x1='10' y1='4' x2='10' y2='10'/%3E%3Cline x1='18' y1='4' x2='18' y2='8'/%3E%3Cline x1='26' y1='4' x2='26' y2='10'/%3E%3Cline x1='34' y1='4' x2='34' y2='8'/%3E%3Cline x1='42' y1='4' x2='42' y2='10'/%3E%3Cline x1='50' y1='4' x2='50' y2='8'/%3E%3C/svg%3E");
  background-size: contain; background-repeat: no-repeat;
}
.doodle-chat {
  width: 48px; height: 42px;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 48 42' fill='none' stroke='%231a1d2e' stroke-width='2.4' stroke-linejoin='round'%3E%3Cpath d='M6 6 H 42 A 4 4 0 0 1 46 10 V 26 A 4 4 0 0 1 42 30 H 22 L 14 38 V 30 H 6 A 4 4 0 0 1 2 26 V 10 A 4 4 0 0 1 6 6 Z' fill='%23ffd9c4'/%3E%3Ccircle cx='16' cy='18' r='1.6' fill='%231a1d2e'/%3E%3Ccircle cx='24' cy='18' r='1.6' fill='%231a1d2e'/%3E%3Ccircle cx='32' cy='18' r='1.6' fill='%231a1d2e'/%3E%3C/svg%3E");
  background-size: contain; background-repeat: no-repeat;
}
.doodle-checkmark {
  width: 36px; height: 36px;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 36 36' fill='none' stroke='%232bb474' stroke-width='4' stroke-linejoin='round' stroke-linecap='round'%3E%3Cpath d='M6 18 L 14 26 L 30 8'/%3E%3C/svg%3E");
  background-size: contain; background-repeat: no-repeat;
}
.doodle-pencil { animation-name: doodle-wiggle; animation-duration: 3.4s; }
.doodle-eraser { animation-name: doodle-pop; animation-duration: 2.8s; }
.doodle-compass { animation-name: doodle-spin-twinkle; animation-duration: 4s; }
.doodle-bulb { animation-name: doodle-pop; animation-duration: 2s; }
.doodle-book { animation-name: doodle-twinkle; animation-duration: 3s; }
.doodle-ruler { animation-name: doodle-wiggle; animation-duration: 3.2s; }
.doodle-chat { animation-name: doodle-twinkle; animation-duration: 2.6s; }
.doodle-checkmark { animation-name: doodle-pop; animation-duration: 1.8s; }

/* ---------- Subject doodles (学科符号装饰，每个仅出现一次) ---------- */
/* 共用：粗体衬线 + 单色描边风，避免花哨；尺寸统一 */
.doodle-sub {
  background-size: contain; background-repeat: no-repeat;
}
.doodle-fx {
  width: 72px; height: 48px;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 72 48' overflow='visible'%3E%3Ctext x='8' y='34' font-family='Georgia,Cambria,serif' font-style='italic' font-size='30' font-weight='700' fill='%23fa5e4e'%3Ef(x)%3C/text%3E%3C/svg%3E");
}
.doodle-pi {
  width: 44px; height: 48px;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 44 48' overflow='visible'%3E%3Ctext x='6' y='38' font-family='Georgia,Cambria,serif' font-style='italic' font-size='34' font-weight='700' fill='%232bb474'%3E%CF%80%3C/text%3E%3C/svg%3E");
}
.doodle-sigma {
  width: 46px; height: 48px;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 46 48' overflow='visible'%3E%3Ctext x='6' y='38' font-family='Georgia,Cambria,serif' font-size='34' font-weight='700' fill='%233558df'%3E%CE%A3%3C/text%3E%3C/svg%3E");
}
.doodle-sqrt {
  width: 64px; height: 48px;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 64 48' overflow='visible'%3E%3Cpath d='M6 28 L 14 28 L 20 40 L 30 10 L 60 10' stroke='%23fa5e4e' stroke-width='3' fill='none' stroke-linecap='round' stroke-linejoin='round'/%3E%3C/svg%3E");
}
.doodle-integral {
  width: 36px; height: 60px;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 36 60' overflow='visible'%3E%3Ctext x='4' y='48' font-family='Georgia,Cambria,serif' font-style='italic' font-size='44' font-weight='700' fill='%232bb474'%3E%E2%88%AB%3C/text%3E%3C/svg%3E");
}
.doodle-xsq {
  width: 60px; height: 48px;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 60 48' overflow='visible'%3E%3Ctext x='6' y='38' font-family='Georgia,Cambria,serif' font-style='italic' font-size='32' font-weight='700' fill='%231a1d2e'%3Ex%3C/text%3E%3Ctext x='28' y='22' font-family='Georgia,Cambria,serif' font-size='20' font-weight='700' fill='%23fa5e4e'%3E2%3C/text%3E%3C/svg%3E");
}
.doodle-lambda {
  width: 44px; height: 48px;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 44 48' overflow='visible'%3E%3Ctext x='6' y='38' font-family='Georgia,Cambria,serif' font-style='italic' font-size='34' font-weight='700' fill='%233558df'%3E%CE%BB%3C/text%3E%3C/svg%3E");
}
.doodle-h2o {
  width: 68px; height: 40px;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 68 40' overflow='visible'%3E%3Ctext x='6' y='30' font-family='Georgia,Cambria,serif' font-size='24' font-weight='700' fill='%233558df'%3EH%3C/text%3E%3Ctext x='24' y='34' font-family='Georgia,Cambria,serif' font-size='16' font-weight='700' fill='%23fa5e4e'%3E2%3C/text%3E%3Ctext x='38' y='30' font-family='Georgia,Cambria,serif' font-size='24' font-weight='700' fill='%233558df'%3EO%3C/text%3E%3C/svg%3E");
}
.doodle-co2 {
  width: 72px; height: 40px;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 72 40' overflow='visible'%3E%3Ctext x='6' y='30' font-family='Georgia,Cambria,serif' font-size='24' font-weight='700' fill='%232bb474'%3ECO%3C/text%3E%3Ctext x='44' y='34' font-family='Georgia,Cambria,serif' font-size='16' font-weight='700' fill='%23fa5e4e'%3E2%3C/text%3E%3C/svg%3E");
}
.doodle-letterA {
  width: 44px; height: 48px;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 44 48' overflow='visible'%3E%3Ctext x='6' y='38' font-family='Georgia,Cambria,serif' font-size='34' font-weight='800' fill='%23fa5e4e'%3EA%3C/text%3E%3C/svg%3E");
}
.doodle-quote {
  width: 56px; height: 48px;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 56 48' overflow='visible'%3E%3Ctext x='6' y='36' font-family='Georgia,Cambria,serif' font-size='34' font-weight='700' fill='%231a1d2e'%3E%E2%80%9C%E2%80%9D%3C/text%3E%3C/svg%3E");
}
.doodle-fx, .doodle-pi, .doodle-sigma, .doodle-sqrt, .doodle-integral,
.doodle-xsq, .doodle-lambda, .doodle-h2o, .doodle-co2,
.doodle-letterA, .doodle-quote {
  background-size: contain; background-repeat: no-repeat;
  opacity: .1;                        /* 基础透明度，避免动画延迟期间从 1 闪到 .1 */
  animation-fill-mode: both;          /* 延迟期间也应用 0% 关键帧 */
  animation-timing-function: ease-in-out;
}
/* 学科符号：每个符号独立动画，错开节奏与运动方式 */
.doodle-fx       { animation-name: sub-float-y;   animation-duration: 4.2s; animation-delay: 0s;   }
.doodle-pi       { animation-name: sub-spin;      animation-duration: 9s;   animation-delay: .4s;  animation-timing-function: linear; }
.doodle-sigma    { animation-name: sub-pulse;     animation-duration: 3.6s; animation-delay: .9s;  }
.doodle-sqrt     { animation-name: sub-sway;      animation-duration: 5s;   animation-delay: 1.4s; }
.doodle-integral { animation-name: sub-drift-x;   animation-duration: 4.6s; animation-delay: 1.8s; }
.doodle-xsq      { animation-name: sub-pop-tilt;  animation-duration: 3.8s; animation-delay: 2.3s; }
.doodle-lambda   { animation-name: sub-tilt;      animation-duration: 4.4s; animation-delay: .2s;  }
.doodle-h2o      { animation-name: sub-bob;       animation-duration: 5.2s; animation-delay: 1.1s; }
.doodle-co2      { animation-name: sub-rise;      animation-duration: 4.8s; animation-delay: 2s;   }
.doodle-letterA  { animation-name: sub-heartbeat; animation-duration: 3.2s; animation-delay: .7s;  }
.doodle-quote    { animation-name: sub-fade;      animation-duration: 3.6s; animation-delay: 1.5s; }

/* 各 keyframe — opacity 全部锁在 .22 ↔ .32，差异在 transform */
@keyframes sub-float-y { /* fx：上下浮动 */
  0%, 100% { opacity: .07; transform: translateY(-4px); }
  50%      { opacity: .13; transform: translateY(4px); }
}
@keyframes sub-spin { /* π：缓慢匀速旋转 */
  0%   { opacity: .08; transform: rotate(0deg); }
  50%  { opacity: .13; transform: rotate(180deg); }
  100% { opacity: .08; transform: rotate(360deg); }
}
@keyframes sub-pulse { /* Σ：纯缩放呼吸 */
  0%, 100% { opacity: .07; transform: scale(.92); }
  50%      { opacity: .13; transform: scale(1.1); }
}
@keyframes sub-sway { /* √：左右倾斜 */
  0%, 100% { opacity: .07; transform: rotate(-6deg); }
  50%      { opacity: .13; transform: rotate(6deg); }
}
@keyframes sub-drift-x { /* ∫：水平漂移 */
  0%, 100% { opacity: .07; transform: translateX(-5px); }
  50%      { opacity: .13; transform: translateX(5px); }
}
@keyframes sub-pop-tilt { /* x²：缩放 + 反向小角度 */
  0%, 100% { opacity: .07; transform: scale(.9) rotate(-5deg); }
  50%      { opacity: .13; transform: scale(1.08) rotate(5deg); }
}
@keyframes sub-tilt { /* λ：单纯左右摇摆 */
  0%, 100% { opacity: .07; transform: rotate(8deg); }
  50%      { opacity: .13; transform: rotate(-8deg); }
}
@keyframes sub-bob { /* H₂O：对角线漂浮 */
  0%, 100% { opacity: .07; transform: translate(-3px, -3px); }
  50%      { opacity: .13; transform: translate(3px, 3px); }
}
@keyframes sub-rise { /* CO₂：上升下降 */
  0%, 100% { opacity: .07; transform: translateY(6px); }
  50%      { opacity: .13; transform: translateY(-6px); }
}
@keyframes sub-heartbeat { /* A：心跳式 */
  0%, 60%, 100% { opacity: .07; transform: scale(1); }
  20%           { opacity: .14; transform: scale(1.12); }
  35%           { opacity: .09; transform: scale(.96); }
}
@keyframes sub-fade { /* "" ：纯透明度，无位移 */
  0%, 100% { opacity: .05; transform: scale(1); }
  50%      { opacity: .14; transform: scale(1); }
}

/* ---------- Buttons ---------- */
.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 8px;
  padding: 14px 28px; border-radius: var(--r-pill); font-size: 15px; font-weight: 700;
  border: 2px solid var(--c-border); cursor: pointer; white-space: nowrap;
  transition: transform .15s ease, box-shadow .15s ease;
  box-shadow: 3px 3px 0 var(--c-border);
}
.btn:hover { transform: translate(-2px, -2px); box-shadow: 5px 5px 0 var(--c-border); }
.btn:active { transform: translate(0, 0); box-shadow: 2px 2px 0 var(--c-border); }
.btn-primary { background: var(--c-mint); color: var(--c-text); }
.btn-secondary { background: var(--c-white); color: var(--c-text); }
.btn-accent { background: var(--c-pink); color: var(--c-text); }
.btn-sm { padding: 9px 18px; font-size: 14px; box-shadow: 2px 2px 0 var(--c-border); }
.btn-sm:hover { box-shadow: 4px 4px 0 var(--c-border); }

/* ---------- Pastel pill tags ---------- */
.pill {
  display: inline-flex; align-items: center; padding: 4px 12px;
  border: 1.5px solid var(--c-border); border-radius: var(--r-pill);
  font-size: 12px; font-weight: 600; color: var(--c-text);
  background: var(--c-white);
}
.pill.mint { background: var(--c-mint); }
.pill.pink { background: var(--c-pink); }
.pill.yellow { background: var(--c-yellow); }
.pill.purple { background: var(--c-purple); }
.pill.blue { background: var(--c-blue); }
.pill.peach { background: var(--c-peach); }

/* ---------- Doodle card ---------- */
.dcard {
  background: var(--c-white); border: 2px solid var(--c-border);
  border-radius: var(--r-card); padding: 24px;
  box-shadow: var(--shadow-card); transition: transform .2s ease, box-shadow .2s ease;
}
.dcard:hover { transform: translate(-2px, -2px); box-shadow: var(--shadow-card-hover); }

/* ---------- Header ---------- */
.site-header {
  position: sticky; top: 0; z-index: 100;
  background: rgba(244, 245, 247, .85); backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 2px solid transparent; transition: border-color .2s ease;
}
.site-header.scrolled { border-bottom-color: var(--c-border); background: rgba(244, 245, 247, .95); }

.nav { display: flex; align-items: center; justify-content: space-between; height: 76px; }
.nav-logo { display: flex; align-items: center; gap: 14px; font-size: 22px; font-weight: 800; color: var(--c-text); }
.nav-logo .logo-mark {
  width: 44px; height: 44px; border: 2px solid var(--c-border); border-radius: 12px;
  background: var(--c-mint); display: flex; align-items: center; justify-content: center;
  box-shadow: 2px 2px 0 var(--c-border);
  position: relative; flex-shrink: 0; padding: 4px;
  transition: transform .25s ease, box-shadow .25s ease, background-color .25s ease;
  transform-origin: center;
}
.nav-logo:hover .logo-mark {
  transform: rotate(-6deg) scale(1.08) translate(-1px, -1px);
  box-shadow: 4px 4px 0 var(--c-border);
  background: var(--c-yellow);
}
.nav-logo:hover .logo-mark svg { animation: logo-bulb-pulse .6s ease;
}
@keyframes logo-bulb-pulse {
  0%   { transform: scale(1) rotate(0); }
  40%  { transform: scale(1.12) rotate(8deg); }
  70%  { transform: scale(.96) rotate(-4deg); }
  100% { transform: scale(1) rotate(0); }
}
.nav-logo .logo-mark svg { width: 100%; height: 100%; }
.nav-logo .logo-mark::before,
.nav-logo .logo-mark::after { content: none; }
.nav-logo span:not(.logo-mark) { position: relative; }
.nav-logo .brand-und {
  position: relative;
}
.nav-logo .brand-und::after {
  content: ''; position: absolute; left: 0; right: 0; bottom: -4px; height: 6px;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 100 6' preserveAspectRatio='none'%3E%3Cpath d='M2 4 Q 30 1, 50 3 T 98 4' stroke='%232bb474' stroke-width='3' fill='none' stroke-linecap='round'/%3E%3C/svg%3E");
  background-repeat: no-repeat; background-size: 100% 100%;
  clip-path: inset(0 0 0 0);
  pointer-events: none;
}
.nav-logo:hover .brand-und::after {
  animation: wave-draw 1s cubic-bezier(.55, .05, .25, 1);
}

.nav-links { display: flex; align-items: center; gap: 28px; }
.nav-links a {
  font-size: 14px; color: var(--c-text); font-weight: 600; padding: 6px 12px; border-radius: var(--r-pill);
  transition: background .2s ease, transform .15s ease;
}
.nav-links a:hover { background: var(--c-yellow); transform: rotate(-1deg); }
.nav-links a.active { background: var(--c-mint); }

.nav-cta { display: flex; align-items: center; gap: 12px; }
.nav-toggle { display: none; width: 40px; height: 40px; border: 2px solid var(--c-border); border-radius: 10px; background: var(--c-white); align-items: center; justify-content: center; box-shadow: 2px 2px 0 var(--c-border); }
.nav-toggle span { width: 18px; height: 2px; background: var(--c-text); position: relative; transition: all .25s ease; }
.nav-toggle span::before, .nav-toggle span::after { content: ''; position: absolute; left: 0; width: 18px; height: 2px; background: var(--c-text); transition: all .25s ease; }
.nav-toggle span::before { top: -6px; } .nav-toggle span::after { top: 6px; }
.nav.open .nav-toggle span { background: transparent; }
.nav.open .nav-toggle span::before { transform: translateY(6px) rotate(45deg); }
.nav.open .nav-toggle span::after { transform: translateY(-6px) rotate(-45deg); }

/* ---------- Hero ---------- */
.hero { padding: 80px 0 100px; position: relative; overflow: hidden; }
.hero-grid { display: grid; grid-template-columns: 1.15fr 1fr; gap: 56px; align-items: center; }

.hero-eyebrow {
  display: inline-flex; align-items: center; gap: 8px; padding: 6px 16px;
  background: var(--c-pink); border: 2px solid var(--c-border); border-radius: var(--r-pill);
  font-size: 13px; font-weight: 700; color: var(--c-text); margin-bottom: 28px;
  transform: rotate(-1deg); box-shadow: 2px 2px 0 var(--c-border);
  transition: transform .35s cubic-bezier(.34,1.56,.64,1), box-shadow .35s ease, border-color .35s ease, background-color .35s ease;
  cursor: default;
}
.hero-eyebrow:hover {
  transform: rotate(0deg) translate(-2px, -2px) scale(1.04);
  background: var(--c-yellow);
  border-color: var(--c-accent-green);
  box-shadow: 4px 4px 0 var(--c-accent-green);
}
.hero-eyebrow:hover .dot { background: var(--c-accent-green); }
.hero-eyebrow .dot { width: 8px; height: 8px; border-radius: 50%; background: var(--c-accent); animation: pulse 1.6s ease-in-out infinite; transition: background-color .35s ease; }
@keyframes pulse { 0%,100%{transform:scale(1)} 50%{transform:scale(1.3)} }

.hero-title { font-size: 64px; line-height: 1.1; font-weight: 800; color: var(--c-text); letter-spacing: -.02em; }
.hero-title .accent {
  position: relative; display: inline-block;
}
.hero-title .accent::after {
  content: ''; position: absolute; left: -4px; right: -4px; bottom: -4px; height: 18px;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 200 18' preserveAspectRatio='none'%3E%3Cpath d='M3 12 Q 50 2, 100 9 T 197 12' stroke='%232bb474' stroke-width='6' fill='none' stroke-linecap='round'/%3E%3C/svg%3E");
  background-repeat: no-repeat; background-size: 100% 100%; z-index: -1;
  clip-path: inset(0 0 0 0);
  pointer-events: none;
}
.hero-title .accent:hover::after {
  animation: wave-draw 1s cubic-bezier(.55, .05, .25, 1);
}
.hero-title .accent2 {
  position: relative; display: inline-block; background: var(--c-yellow);
  padding: 0 8px; border-radius: 6px; transform: rotate(-2deg);
}
.hero-subtitle { margin-top: 28px; font-size: 18px; color: var(--c-text-soft); max-width: 500px; line-height: 1.7; }

.hero-cta { margin-top: 40px; display: flex; flex-wrap: wrap; gap: 16px; }
.hero-trust { margin-top: 36px; display: flex; flex-wrap: wrap; align-items: center; gap: 16px; }
.hero-trust .pill { box-shadow: 2px 2px 0 var(--c-border); transition: transform .25s ease, box-shadow .25s ease, border-color .25s ease, color .25s ease; cursor: default; }
.hero-trust .pill:nth-child(odd):hover {
  transform: rotate(-1.5deg) translate(-1px, -1px);
  border-color: var(--c-accent-green);
  box-shadow: 4px 4px 0 var(--c-accent-green);
  color: var(--c-accent-green);
}
.hero-trust .pill:nth-child(even):hover {
  transform: rotate(1.5deg) translate(-1px, -1px);
  border-color: var(--c-accent-green);
  box-shadow: 4px 4px 0 var(--c-accent-green);
  color: var(--c-accent-green);
}

/* Hero doodles — 横纵坐标都错开，避免基线对齐感 */
.hero-doodle-1 { top: 24px;  left: 14%;  transform: rotate(-14deg); }
.hero-doodle-2 { top: 32%;   left: 2%;   transform: rotate(10deg); }
.hero-doodle-3 { bottom: 8px; left: 26%; transform: rotate(-4deg); }
.hero-doodle-4 { top: 14%;   right: 30%; transform: rotate(14deg); }
.hero-doodle-5 { top: 70%;   right: 6%;  transform: rotate(-8deg); }

/* Hero visual */
.hero-visual { position: relative; display: flex; justify-content: center; }
.hero-card {
  position: relative; background: var(--c-white); border: 2.5px solid var(--c-border);
  border-radius: 20px; padding: 24px; box-shadow: 6px 6px 0 var(--c-border);
  width: 400px; max-width: 100%;
}
.hero-card .hc-header { display: flex; align-items: center; gap: 12px; margin-bottom: 18px; }
.hero-card .hc-ava {
  width: 44px; height: 44px; border: 2px solid var(--c-border); border-radius: 50%;
  background: var(--c-mint); display: flex; align-items: center; justify-content: center;
  font-weight: 800; font-size: 16px; box-shadow: 2px 2px 0 var(--c-border);
}
.hero-card .hc-info strong { display: block; font-size: 15px; font-weight: 700; }
.hero-card .hc-info span { font-size: 12px; color: var(--c-muted); }
.hero-card .hc-online { margin-left: auto; padding: 4px 10px; background: var(--c-mint); border: 1.5px solid var(--c-border); border-radius: var(--r-pill); font-size: 11px; font-weight: 700; }

.hc-msg {
  padding: 10px 14px; border: 2px solid var(--c-border); border-radius: 14px;
  font-size: 13px; line-height: 1.5; max-width: 78%; margin-bottom: 10px;
}
.hc-msg.left { background: var(--c-bg-soft); border-bottom-left-radius: 4px; }
.hc-msg.right { background: var(--c-pink-bg); border-bottom-right-radius: 4px; margin-left: auto; }
.hc-msg.image { padding: 6px; max-width: 60%; background: var(--c-blue-bg); }
.hc-msg.image .img-ph { height: 70px; border: 2px dashed var(--c-border); border-radius: 8px; display: flex; align-items: center; justify-content: center; gap: 6px; font-size: 11px; color: var(--c-text-soft); }
.img-ph-ic { width: 18px; height: 18px; display: inline-flex; }
.img-ph-ic svg { width: 100%; height: 100%; }
.hc3-ic { width: 16px; height: 16px; display: inline-flex; vertical-align: -3px; margin-right: 4px; }
.hc3-ic svg { width: 100%; height: 100%; }
.fc-ic { width: 14px; height: 14px; display: inline-flex; vertical-align: -2px; margin-right: 6px; }
.fc-ic svg { width: 100%; height: 100%; }
.hc-typing { display: inline-flex; gap: 4px; padding: 12px 14px; }
.hc-typing span { width: 6px; height: 6px; border-radius: 50%; background: var(--c-muted); animation: typing 1.4s infinite both; }
.hc-typing span:nth-child(2){animation-delay:.2s} .hc-typing span:nth-child(3){animation-delay:.4s}
@keyframes typing { 0%,80%,100%{transform:scale(.6);opacity:.4} 40%{transform:scale(1);opacity:1} }

.hero-card .hc-deco {
  position: absolute; top: -16px; left: -18px;
  background: var(--c-yellow); border: 2px solid var(--c-border); border-radius: var(--r-pill);
  padding: 6px 12px; font-size: 11px; font-weight: 700;
  box-shadow: 2px 2px 0 var(--c-border);
  transform: rotate(-4deg);
  transition: transform .25s ease, box-shadow .25s ease, border-color .25s ease;
}
.hero-card .hc-deco:hover {
  transform: rotate(-1.5deg) translate(-1px, -1px);
  box-shadow: 4px 4px 0 var(--c-accent-green);
  border-color: var(--c-accent-green);
}

.hero-card-2 {
  position: absolute; bottom: -22px; right: -28px;
  padding: 10px 16px 10px 12px;
  background: var(--c-mint-bg); border: 2px solid var(--c-border); border-radius: var(--r-pill);
  box-shadow: 3px 3px 0 var(--c-border);
  display: flex; align-items: center; gap: 10px;
  transform: rotate(-3deg);
  transition: transform .25s ease, box-shadow .25s ease, border-color .25s ease;
}
.hero-card-2:hover {
  transform: rotate(-1.5deg) translate(-1px, -1px);
  box-shadow: 4px 4px 0 var(--c-accent-green);
  border-color: var(--c-accent-green);
}
.hero-card-2 .hc2-ic {
  width: 28px; height: 28px; flex-shrink: 0;
  background: var(--c-accent-green); border: 2px solid var(--c-border); border-radius: 50%;
  display: flex; align-items: center; justify-content: center;
  box-shadow: 1px 1px 0 var(--c-border);
}
.hero-card-2 .hc2-ic svg { width: 16px; height: 16px; }
.hero-card-2 .hc2-text { display: flex; flex-direction: column; line-height: 1.15; }
.hero-card-2 .hc2-text strong { font-size: 13px; font-weight: 800; color: var(--c-text); }
.hero-card-2 .hc2-text span { font-size: 11px; color: var(--c-text-soft); font-weight: 600; margin-top: 3px; }
.hero-card-2 .hc2-text em { color: var(--c-accent); font-weight: 800; font-style: normal; font-size: 12px; }

.hero-card-3 {
  position: absolute; top: -20px; right: -30px; padding: 10px 14px;
  background: var(--c-purple); border: 2px solid var(--c-border); border-radius: var(--r-card);
  box-shadow: 3px 3px 0 var(--c-border);
  font-size: 12px; font-weight: 700;
  transform: rotate(4deg);
  transition: transform .25s ease, box-shadow .25s ease, border-color .25s ease;
}
.hero-card-3:hover {
  transform: rotate(1.5deg) translate(-1px, -1px);
  box-shadow: 4px 4px 0 var(--c-accent-green);
  border-color: var(--c-accent-green);
}

/* ---------- Interactive card hover (selected state) ----------
   按设计：默认平直，hover/选中时奇偶倾斜不同角度 + 绿色描边 + 标题变绿。 */
.mb-item,
.income-card,
.contact-item,
.qrcode,
.faq-item,
.teacher-steps li {
  transition:
    transform .4s cubic-bezier(.34,1.56,.64,1),
    box-shadow .3s ease,
    border-color .3s ease,
    color .3s ease;
}
.mb-item:hover,
.income-card:hover,
.contact-item:hover,
.qrcode:hover,
.faq-item:hover,
.teacher-steps li:hover {
  border-color: var(--c-accent-green) !important;
  box-shadow: 6px 6px 0 var(--c-accent-green) !important;
}
/* 奇偶倾斜方向不同 — 柔和弹性 */
.mb-item:nth-child(odd):hover,
.income-card:nth-child(odd):hover,
.contact-item:nth-child(odd):hover,
.qrcode:nth-child(odd):hover,
.faq-item:nth-child(odd):hover,
.teacher-steps li:nth-child(odd):hover {
  transform: rotate(-1deg) translateY(-5px) scale(1.02) !important;
}
.mb-item:nth-child(even):hover,
.income-card:nth-child(even):hover,
.contact-item:nth-child(even):hover,
.qrcode:nth-child(even):hover,
.faq-item:nth-child(even):hover,
.teacher-steps li:nth-child(even):hover {
  transform: rotate(1deg) translateY(-5px) scale(1.02) !important;
}
/* hover 时标题/数字变绿 */
.mb-item:hover h5,
.contact-item:hover .val,
.qrcode:hover .qr-name {
  color: var(--c-accent-green);
}
.faq-item:hover .faq-q { color: var(--c-accent-green); }

/* ---------- Pain Points ---------- */
.card-grid { display: grid; gap: 24px; }
.card-grid--4 { grid-template-columns: repeat(4, 1fr); }
.card-grid--3 { grid-template-columns: repeat(3, 1fr); }

/* Unified card component */
.uni-card {
  background: var(--c-white); border: 2px solid var(--c-border); border-radius: var(--r-card);
  padding: 28px 22px; box-shadow: 4px 4px 0 var(--c-border);
  display: flex; flex-direction: column; align-items: center; text-align: center; gap: 10px;
  transition: transform .4s cubic-bezier(.34,1.56,.64,1), box-shadow .3s ease, border-color .3s ease;
}
.uni-card:hover {
  border-color: var(--c-accent-green);
  box-shadow: 6px 6px 0 var(--c-accent-green);
}
.uni-card:nth-child(odd):hover { transform: rotate(-1deg) translateY(-5px) scale(1.02); }
.uni-card:nth-child(even):hover { transform: rotate(1deg) translateY(-5px) scale(1.02); }
.uni-card-icon {
  width: 56px; height: 56px; border: 2px solid var(--c-border); border-radius: 16px;
  display: flex; align-items: center; justify-content: center;
  box-shadow: 2px 2px 0 var(--c-border); background: var(--c-white);
}
.uni-card-icon svg { width: 36px; height: 36px; }
.uni-card-name { font-size: 15px; font-weight: 800; }
.uni-card:hover .uni-card-name { color: var(--c-accent-green); }
.uni-card-label { font-size: 13px; color: var(--c-muted); line-height: 1.6; }

/* Pain icon colors */
.card-grid--4 .uni-card:nth-child(1) .uni-card-icon { background: var(--c-pink); }
.card-grid--4 .uni-card:nth-child(2) .uni-card-icon { background: var(--c-yellow); }
.card-grid--4 .uni-card:nth-child(3) .uni-card-icon { background: var(--c-mint); }
.card-grid--4 .uni-card:nth-child(4) .uni-card-icon { background: var(--c-purple); }

/* Flow variant */
.uni-card--flow { padding: 28px 22px; }
.uni-card--flow:nth-child(1) { background: var(--c-pink-bg); }
.uni-card--flow:nth-child(2) { background: var(--c-yellow-bg); }
.uni-card--flow:nth-child(3) { background: var(--c-blue-bg); }
.uni-card--flow:nth-child(4) { background: var(--c-mint-bg); }
.uni-card--flow .flow-num {
  width: 44px; height: 44px; border-radius: 50%; border: 2.5px solid var(--c-text);
  display: flex; align-items: center; justify-content: center;
  font-size: 20px; font-weight: 800; margin-bottom: 6px;
}

/* Voice variant */
.uni-card--voice { align-items: flex-start; text-align: left; }
.uni-card--voice:nth-child(1) { background: var(--c-yellow-bg); }
.uni-card--voice:nth-child(2) { background: var(--c-pink-bg); }
.uni-card--voice:nth-child(3) { background: var(--c-blue-bg); }
.uni-card-quote { font-size: 15px; line-height: 1.8; min-height: 100px; position: relative; }
.uni-card-quote::after { content: '\201D'; position: absolute; top: -8px; right: 0; font-size: 48px; color: var(--c-border); font-family: Georgia, serif; }
.uni-card-meta { display: flex; align-items: center; gap: 12px; margin-top: 12px; padding-top: 14px; border-top: 2px dashed var(--c-border-soft); width: 100%; }
.uni-card-ava {
  width: 40px; height: 40px; border-radius: 50%; border: 2px solid var(--c-border);
  display: flex; align-items: center; justify-content: center;
  font-weight: 800; font-size: 14px; background: var(--c-white); flex-shrink: 0;
}
.uni-card--voice .uni-card-name { font-size: 14px; }
.uni-card--voice .uni-card-label { font-size: 12px; }
.uni-card--voice:hover .uni-card-quote { color: var(--c-accent-green); }

/* Security icon colors */
.card-grid--3 .uni-card:nth-child(1) .uni-card-icon { background: var(--c-mint); }
.card-grid--3 .uni-card:nth-child(2) .uni-card-icon { background: var(--c-pink); }
.card-grid--3 .uni-card:nth-child(3) .uni-card-icon { background: var(--c-blue); }

/* ---------- Trust bar / Stats ---------- */
.trust-bar { padding: 72px 0; background: transparent; border: none; }
.trust-cards { display: grid; grid-template-columns: repeat(4, 1fr); gap: 24px; }
.trust-card {
  background: var(--c-white); border: 2px solid var(--c-border); border-radius: var(--r-card);
  padding: 28px 22px 24px; text-align: center; box-shadow: 4px 4px 0 var(--c-border);
  display: flex; flex-direction: column; align-items: center; gap: 10px;
  transition: transform .4s cubic-bezier(.34,1.56,.64,1), box-shadow .3s ease, border-color .3s ease;
}
.trust-card:nth-child(1) { background: var(--c-mint-bg); }
.trust-card:nth-child(2) { background: var(--c-pink-bg); }
.trust-card:nth-child(3) { background: var(--c-yellow-bg); }
.trust-card:nth-child(4) { background: var(--c-blue-bg); }
.trust-card:hover {
  border-color: var(--c-accent-green);
  box-shadow: 6px 6px 0 var(--c-accent-green);
}
.trust-card:nth-child(odd):hover { transform: rotate(-1deg) translateY(-5px) scale(1.02); }
.trust-card:nth-child(even):hover { transform: rotate(1deg) translateY(-5px) scale(1.02); }
.trust-card:hover .trust-card-num { color: var(--c-accent-green); }
.trust-card-icon {
  width: 56px; height: 56px; border: 2px solid var(--c-border); border-radius: 16px;
  display: flex; align-items: center; justify-content: center;
  box-shadow: 2px 2px 0 var(--c-border); background: var(--c-white);
}
.trust-card-icon svg { width: 36px; height: 36px; }
.trust-card-num {
  font-size: 44px; font-weight: 800; color: var(--c-text); line-height: 1;
  transition: color .3s ease;
}
.trust-card-name { font-size: 15px; font-weight: 800; margin-bottom: 4px; }
.trust-card-label { font-size: 12px; color: var(--c-muted); }

/* ---------- Features ---------- */
.feature-block { display: grid; grid-template-columns: 1fr 1.1fr; gap: 64px; align-items: center; margin-bottom: 100px; position: relative; }
.feature-block:last-child { margin-bottom: 0; }
.feature-block.reverse { grid-template-columns: 1.1fr 1fr; }
.feature-block.reverse .feature-text { order: 2; }
.feature-block.reverse .feature-visual { order: 1; }

.feature-badge {
  display: inline-block; padding: 6px 16px; border: 2px solid var(--c-border);
  border-radius: var(--r-pill); font-size: 12px; font-weight: 700;
  margin-bottom: 16px; box-shadow: 2px 2px 0 var(--c-border);
  cursor: default;
  transition: transform .25s ease, box-shadow .25s ease, border-color .25s ease, color .25s ease;
}
.feature-badge.mint { background: var(--c-mint); }
.feature-badge.pink { background: var(--c-pink); }
.feature-badge:hover {
  transform: rotate(-1.5deg) translate(-1px, -1px);
  box-shadow: 4px 4px 0 var(--c-accent-green);
  border-color: var(--c-accent-green);
}

.section-tag {
  cursor: default;
  transform: rotate(-1.5deg);
  transition: transform .25s ease, box-shadow .25s ease, border-color .25s ease, color .25s ease;
}
.section-tag:hover {
  transform: rotate(-3deg) translate(-1px, -1px);
  box-shadow: 4px 4px 0 var(--c-accent-green);
  border-color: var(--c-accent-green);
}

/* 抖动 keyframes 已迁移到 mb-item 风格的 hover 倾斜：保留为兼容（未引用） */
@media (prefers-reduced-motion: reduce) {
  .feature-badge:hover, .section-tag:hover { transform: none; }
}
.feature-text h3 { font-size: 36px; font-weight: 800; line-height: 1.2; margin-bottom: 18px; }
.feature-text h3 .hl { background: var(--c-yellow); padding: 0 6px; border-radius: 4px; }
.feature-desc { font-size: 16px; color: var(--c-text-soft); line-height: 1.7; margin-bottom: 24px; }
.feature-points { display: grid; gap: 12px; margin-bottom: 28px; }
.feature-points li { display: flex; align-items: flex-start; gap: 12px; font-size: 15px; color: var(--c-text); }
.feature-points li::before {
  content: ''; flex-shrink: 0; width: 22px; height: 22px; border-radius: 50%;
  background: var(--c-mint); border: 2px solid var(--c-border); margin-top: 1px;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24' fill='none' stroke='%231a1d2e' stroke-width='3' stroke-linecap='round' stroke-linejoin='round'%3E%3Cpolyline points='20 6 9 17 4 12'/%3E%3C/svg%3E");
  background-repeat: no-repeat; background-position: center; background-size: 14px;
}

/* Feature visual: chat mock */
.feature-mock {
  background: var(--c-white); border: 2.5px solid var(--c-border); border-radius: 20px;
  padding: 22px; box-shadow: 6px 6px 0 var(--c-border); position: relative;
}
.fm-header { display: flex; align-items: center; gap: 10px; margin-bottom: 16px; padding-bottom: 14px; border-bottom: 2px dashed var(--c-border-soft); }
.fm-ava {
  width: 40px; height: 40px; border: 2px solid var(--c-border); border-radius: 50%;
  background: var(--c-blue); display: flex; align-items: center; justify-content: center;
  font-weight: 800; font-size: 14px; box-shadow: 2px 2px 0 var(--c-border);
}
.fm-info strong { display: block; font-size: 14px; }
.fm-info span { font-size: 11px; color: var(--c-muted); }
.fm-status { margin-left: auto; padding: 4px 10px; background: var(--c-mint); border: 1.5px solid var(--c-border); border-radius: var(--r-pill); font-size: 11px; font-weight: 700; }

.fm-msg { padding: 10px 14px; border: 2px solid var(--c-border); border-radius: 14px; font-size: 13px; max-width: 78%; margin-bottom: 10px; line-height: 1.5; }
.fm-msg.left { background: var(--c-bg-soft); border-bottom-left-radius: 4px; }
.fm-msg.right { background: var(--c-pink); border-bottom-right-radius: 4px; margin-left: auto; }
.fm-board {
  margin-top: 8px; padding: 12px; background: var(--c-bg-soft); border: 2px solid var(--c-border);
  border-radius: 12px; height: 90px; position: relative;
}
.fm-board::after { content: '老师在讲解中...'; position: absolute; bottom: 6px; right: 10px; font-size: 11px; color: var(--c-muted); }
.fm-board svg { width: 100%; height: 60px; }

/* Feature visual: mistakes mock */
.mb-window { background: var(--c-white); border: 2.5px solid var(--c-border); border-radius: 20px; padding: 22px; box-shadow: 6px 6px 0 var(--c-border); }
.mb-header { display: flex; align-items: center; gap: 10px; margin-bottom: 18px; }
.mb-header h4 { font-size: 18px; font-weight: 800; }
.mb-header-icon { width: 26px; height: 26px; display: inline-flex; }
.mb-header-icon svg { width: 100%; height: 100%; }
.mb-filters { display: flex; gap: 8px; margin-bottom: 16px; flex-wrap: wrap; }
.mb-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 12px; }
.mb-item {
  background: var(--c-bg-soft); border: 2px solid var(--c-border); border-radius: 12px;
  padding: 12px; box-shadow: 2px 2px 0 var(--c-border);
}
.mb-thumb {
  height: 60px; border: 2px dashed var(--c-border); border-radius: 8px;
  display: flex; align-items: center; justify-content: center;
  font-size: 11px; color: var(--c-muted); margin-bottom: 8px;
}
.mb-item:nth-child(1) .mb-thumb { background: var(--c-pink-bg); }
.mb-item:nth-child(2) .mb-thumb { background: var(--c-yellow-bg); }
.mb-item:nth-child(3) .mb-thumb { background: var(--c-blue-bg); }
.mb-item:nth-child(4) .mb-thumb { background: var(--c-purple-bg); }
.mb-item h5 { font-size: 12px; font-weight: 700; margin-bottom: 6px; }
.mb-item .mb-tags { display: flex; gap: 4px; flex-wrap: wrap; }
.mb-item .pill { font-size: 10px; padding: 2px 8px; }

/* ---------- Teacher ---------- */
.teacher-grid { display: grid; grid-template-columns: 1.1fr 1fr; gap: 64px; align-items: center; }
.teacher-text h2 { font-size: 40px; font-weight: 800; margin-bottom: 18px; line-height: 1.2; }
.teacher-text h2 .hl { background: var(--c-mint); padding: 0 8px; border-radius: 6px; transform: rotate(-1deg); display: inline-block; }
.teacher-text .lead { font-size: 16px; color: var(--c-text-soft); margin-bottom: 28px; line-height: 1.7; }
.teacher-steps { display: grid; grid-template-columns: 1fr 1fr; gap: 14px; margin-bottom: 28px; }
.teacher-steps li {
  background: var(--c-white); border: 2px solid var(--c-border); border-radius: 12px;
  padding: 14px; font-size: 14px; box-shadow: 2px 2px 0 var(--c-border);
  display: flex; gap: 10px; align-items: center;
}
.teacher-steps li:nth-child(1) strong { background: var(--c-yellow); }
.teacher-steps li:nth-child(2) strong { background: var(--c-mint); }
.teacher-steps li:nth-child(3) strong { background: var(--c-pink); }
.teacher-steps li:nth-child(4) strong { background: var(--c-purple); }
.teacher-steps li strong {
  width: 32px; height: 32px; flex-shrink: 0; background: var(--c-yellow);
  border: 1.5px solid var(--c-border); border-radius: 50%;
  display: flex; align-items: center; justify-content: center; font-weight: 800; font-size: 13px;
}

.income-list { display: grid; gap: 16px; }
.income-card {
  display: flex; align-items: center; gap: 16px; padding: 18px;
  background: var(--c-white); border: 2px solid var(--c-border); border-radius: var(--r-card);
  box-shadow: 4px 4px 0 var(--c-border); transition: transform .15s ease, box-shadow .15s ease;
}
.income-card:hover { transform: translate(-2px, -2px); box-shadow: 6px 6px 0 var(--c-border); }
.income-card .role {
  width: 56px; height: 56px; flex-shrink: 0; border: 2px solid var(--c-border); border-radius: 14px;
  display: flex; align-items: center; justify-content: center;
  box-shadow: 2px 2px 0 var(--c-border);
}
.income-card .role svg { width: 38px; height: 38px; }
.income-card:nth-child(1) .role { background: var(--c-mint); }
.income-card:nth-child(2) .role { background: var(--c-yellow); }
.income-card:nth-child(3) .role { background: var(--c-pink); }
.income-card .info { flex: 1; }
.income-card .info strong { display: block; font-size: 15px; font-weight: 800; margin-bottom: 4px; }
.income-card .info span { font-size: 12px; color: var(--c-muted); }
.income-card .amount { font-size: 22px; font-weight: 800; color: var(--c-accent); white-space: nowrap; }

/* ---------- FAQ ---------- */
.faq-list { max-width: 820px; margin: 0 auto; display: grid; gap: 14px; }
.faq-item {
  background: var(--c-white); border: 2px solid var(--c-border); border-radius: var(--r-card);
  overflow: hidden; box-shadow: 3px 3px 0 var(--c-border); transition: transform .15s, box-shadow .15s;
}
.faq-item:hover { transform: translate(-1px, -1px); box-shadow: 4px 4px 0 var(--c-border); }
.faq-item.open {
  background: var(--c-yellow-bg);
  border-color: var(--c-accent-green);
  box-shadow: 4px 4px 0 var(--c-accent-green);
}
.faq-item.open .faq-q { color: var(--c-accent-green); }
.faq-item.open:nth-child(odd) { transform: rotate(-1.5deg) translate(-1px, -1px); }
.faq-item.open:nth-child(even) { transform: rotate(1.5deg) translate(-1px, -1px); }
.faq-q { width: 100%; text-align: left; padding: 20px 24px; font-size: 16px; font-weight: 700; display: flex; align-items: center; justify-content: space-between; gap: 16px; }
.faq-q .arrow {
  width: 30px; height: 30px; border: 2px solid var(--c-border); border-radius: 50%;
  background: var(--c-white); display: flex; align-items: center; justify-content: center;
  font-size: 12px; transition: all .25s ease; flex-shrink: 0;
}
.faq-item.open .faq-q .arrow { transform: rotate(180deg); background: var(--c-mint); }
.faq-a { max-height: 0; overflow: hidden; padding: 0 24px; font-size: 14px; color: var(--c-text-soft); line-height: 1.7; transition: all .3s ease; }
.faq-item.open .faq-a { max-height: 320px; padding: 0 24px 20px; }

/* ---------- Contact ---------- */
.contact-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 56px; align-items: center; }
.contact-list { display: grid; gap: 16px; }
.contact-item {
  display: flex; align-items: center; gap: 16px; padding: 20px;
  background: var(--c-white); border: 2px solid var(--c-border); border-radius: var(--r-card);
  box-shadow: 3px 3px 0 var(--c-border); transition: transform .15s, box-shadow .15s;
}
.contact-item:hover { transform: translate(-2px, -2px); box-shadow: 5px 5px 0 var(--c-border); }
.contact-item .ic {
  width: 48px; height: 48px; border: 2px solid var(--c-border); border-radius: 12px;
  display: flex; align-items: center; justify-content: center;
  flex-shrink: 0; box-shadow: 2px 2px 0 var(--c-border); padding: 10px;
}
.contact-item .ic svg { width: 100%; height: 100%; }
.contact-item:nth-child(1) .ic { background: var(--c-mint); }
.contact-item:nth-child(2) .ic { background: var(--c-pink); }
.contact-item:nth-child(3) .ic { background: var(--c-yellow); }
.contact-item .label { font-size: 12px; color: var(--c-muted); margin-bottom: 4px; }
.contact-item .val { font-size: 18px; font-weight: 800; color: var(--c-text); }

.qrcodes { display: grid; grid-template-columns: 1fr 1fr; gap: 20px; }
.qrcode {
  background: var(--c-white); border: 2px solid var(--c-border); border-radius: var(--r-card);
  padding: 22px; text-align: center; box-shadow: 4px 4px 0 var(--c-border);
}
.qr-img {
  width: 140px; height: 140px; margin: 0 auto 14px; border: 2px solid var(--c-border);
  border-radius: 10px; background: repeating-linear-gradient(45deg, #1a1d2e 0 4px, #fff 4px 8px); position: relative;
}
.qr-img::before, .qr-img::after { content: ''; position: absolute; width: 28px; height: 28px; border: 4px solid #1a1d2e; background: #fff; border-radius: 4px; }
.qr-img::before { top: 6px; left: 6px; } .qr-img::after { top: 6px; right: 6px; }
.qrcode .qr-name { font-size: 15px; font-weight: 800; margin-bottom: 4px; }
.qrcode .qr-label { font-size: 12px; color: var(--c-muted); }

/* 联动：hover 任一张时，另一张反向轻微倾斜（跷跷板效果） */
.qrcode:hover ~ .qrcode {
  transform: rotate(1.5deg) translate(1px, 1px) !important;
}
.qrcodes:has(.qrcode:nth-child(2):hover) .qrcode:nth-child(1) {
  transform: rotate(-1.5deg) translate(1px, 1px) !important;
}

/* ---------- Footer ---------- */
.site-footer { background: var(--c-text); color: rgba(255, 255, 255, .75); padding: 64px 0 24px; font-size: 14px; border-top: 2px solid var(--c-border); }
.footer-grid { display: grid; grid-template-columns: 1.6fr 1fr 1fr 1.2fr; gap: 48px; padding-bottom: 36px; border-bottom: 1px dashed rgba(255,255,255,.2); }
.footer-brand h4 { font-size: 22px; color: #fff; margin-bottom: 14px; font-weight: 800; }
.footer-brand p { line-height: 1.7; opacity: .65; font-size: 14px; }
.footer-col h5 { font-size: 14px; color: #fff; margin-bottom: 18px; font-weight: 700; }
.footer-col ul li { margin-bottom: 12px; }
.footer-col ul li a { opacity: .7; transition: opacity .2s; }
.footer-col ul li a:hover { opacity: 1; }
.footer-bottom { padding-top: 24px; display: flex; flex-wrap: wrap; align-items: center; justify-content: space-between; gap: 14px; font-size: 13px; opacity: .65; }
.footer-bottom a:hover { color: #fff; opacity: 1; }
.footer-bottom .pipe { margin: 0 8px; opacity: .4; }

/* ---------- Animations ---------- */
.reveal {
  opacity: 0;
  transform: translateY(36px);
}
.reveal.visible {
  animation: reveal-in .7s cubic-bezier(.22, .61, .36, 1) var(--reveal-delay, 0s) both;
}
@keyframes reveal-in {
  to { opacity: 1; transform: translateY(0); }
}

/* 同组卡片错峰上浮（stagger） */
.trust-cards > .reveal:nth-child(2) { --reveal-delay: .1s; }
.trust-cards > .reveal:nth-child(3) { --reveal-delay: .2s; }
.trust-cards > .reveal:nth-child(4) { --reveal-delay: .3s; }

@media (prefers-reduced-motion: reduce) {
  .reveal { transition: none; transform: none; opacity: 1; animation: none; }
}

/* ---------- Responsive ---------- */
@media (max-width: 1024px) {
  .hero-title { font-size: 48px; }
  .hero-grid { gap: 48px; }
  .card-grid--4, .card-grid--3, .trust-cards { grid-template-columns: repeat(2, 1fr); }
  .feature-block, .feature-block.reverse { grid-template-columns: 1fr; gap: 48px; }
  .feature-block.reverse .feature-text, .feature-block.reverse .feature-visual { order: unset; }
}

@media (max-width: 768px) {
  section { padding: 64px 0; }
  .section-title { font-size: 30px; }
  .hero { padding: 48px 0 64px; }
  .hero-grid, .teacher-grid, .contact-grid { grid-template-columns: 1fr; gap: 56px; }
  .hero-title { font-size: 36px; }
  .feature-text h3, .teacher-text h2 { font-size: 26px; }
  .nav-links {
    position: absolute; top: 76px; left: 0; right: 0; background: var(--c-white);
    flex-direction: column; align-items: stretch; gap: 0; padding: 12px 24px;
    border-top: 2px solid var(--c-border); border-bottom: 2px solid var(--c-border);
    transform: translateY(-12px); opacity: 0; pointer-events: none; transition: all .3s ease;
  }
  .nav-links a { padding: 14px 0; border-bottom: 1px dashed var(--c-border-soft); border-radius: 0; }
  .nav-links a:last-child { border-bottom: 0; }
  .nav.open .nav-links { transform: translateY(0); opacity: 1; pointer-events: auto; }
  .nav-toggle { display: inline-flex; }
  .nav-cta .btn-secondary { display: none; }
  .teacher-steps { grid-template-columns: 1fr; }
  .footer-grid { grid-template-columns: 1fr 1fr; gap: 32px; }
  .footer-bottom { justify-content: center; text-align: center; }
  .qrcodes { grid-template-columns: 1fr; }
  .income-card { flex-wrap: wrap; }
  .income-card .amount { width: 100%; text-align: right; }
  .doodle { display: none; }
  .hero-card-2, .hero-card-3 { display: none; }
}

@media (max-width: 480px) {
  .container { padding: 0 18px; }
  .card-grid--4, .card-grid--3, .trust-cards { grid-template-columns: 1fr; }
  .hero-title { font-size: 32px; }
  .trust-card-num { font-size: 36px; }
  .footer-grid { grid-template-columns: 1fr; }
  .mb-grid { grid-template-columns: 1fr; }
}