/* ============================================================
   影伴英语 LingoLearn · 方案 C 强设计感风
   深色极光主题 / 纯 CSS / 零外部依赖
   ============================================================ */

:root {
  --bg: #05060f;
  --bg-2: #0a0a14;
  --blue: #2fa4e7;
  --cyan: #79d2f0;
  --purple: #a78bfa;
  --text: #e9eff8;
  --muted: #9aa7bd;
  --line: rgba(121, 210, 240, 0.14);
  --glass: rgba(15, 18, 34, 0.66);
  --radius: 20px;
  --font: "PingFang SC", "Microsoft YaHei", "Segoe UI", system-ui, -apple-system, sans-serif;
  --serif: Georgia, "Times New Roman", serif;
}

* { margin: 0; padding: 0; box-sizing: border-box; }

/* scroll-padding-top 不能省：导航是 fixed 68px，
   没有它时点锚点会把标题顶到导航底下 */
html {
  scroll-behavior: smooth;
  scroll-padding-top: 78px;
}

body {
  background: var(--bg);
  color: var(--text);
  font-family: var(--font);
  line-height: 1.7;
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
}

::selection { background: rgba(47, 164, 231, 0.35); color: #fff; }

img { max-width: 100%; display: block; }
a { color: inherit; text-decoration: none; }

/* 键盘可达性：深色底上浏览器默认焦点框几乎看不见 */
:focus-visible {
  outline: 2px solid var(--cyan);
  outline-offset: 3px;
  border-radius: 6px;
}

.container { width: min(1120px, calc(100% - 48px)); margin: 0 auto; }
.container-narrow { width: min(820px, calc(100% - 48px)); }

.grad {
  background: linear-gradient(100deg, var(--blue) 0%, var(--cyan) 55%, var(--purple) 110%);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}

/* ==================== 极光背景 ==================== */
.aurora {
  position: fixed;
  inset: 0;
  z-index: -1;
  overflow: hidden;
  background:
    radial-gradient(1200px 700px at 75% -10%, rgba(47, 164, 231, 0.10), transparent 60%),
    radial-gradient(900px 600px at 10% 110%, rgba(167, 139, 250, 0.08), transparent 60%),
    var(--bg);
}
.blob {
  position: absolute;
  border-radius: 50%;
  filter: blur(110px);
  opacity: 0.55;
  will-change: transform;
}
.blob-a {
  width: 560px; height: 560px;
  top: -180px; left: -120px;
  background: radial-gradient(circle, rgba(47, 164, 231, 0.32), transparent 65%);
  animation: drift-a 26s ease-in-out infinite alternate;
}
.blob-b {
  width: 640px; height: 640px;
  top: 8%; right: -220px;
  background: radial-gradient(circle, rgba(167, 139, 250, 0.26), transparent 65%);
  animation: drift-b 32s ease-in-out infinite alternate;
}
.blob-c {
  width: 520px; height: 520px;
  bottom: -200px; left: 28%;
  background: radial-gradient(circle, rgba(121, 210, 240, 0.20), transparent 65%);
  animation: drift-c 38s ease-in-out infinite alternate;
}
@keyframes drift-a { to { transform: translate(140px, 90px) scale(1.15); } }
@keyframes drift-b { to { transform: translate(-160px, 120px) scale(0.9); } }
@keyframes drift-c { to { transform: translate(120px, -100px) scale(1.1); } }

.grid-overlay {
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(rgba(121, 210, 240, 0.05) 1px, transparent 1px),
    linear-gradient(90deg, rgba(121, 210, 240, 0.05) 1px, transparent 1px);
  background-size: 72px 72px;
  -webkit-mask-image: radial-gradient(ellipse 90% 60% at 50% 0%, #000 30%, transparent 75%);
  mask-image: radial-gradient(ellipse 90% 60% at 50% 0%, #000 30%, transparent 75%);
}

/* ==================== 导航 ==================== */
.nav {
  position: fixed;
  top: 0; left: 0; right: 0;
  z-index: 100;
  transition: background 0.35s, border-color 0.35s, box-shadow 0.35s;
  border-bottom: 1px solid transparent;
}
.nav.scrolled {
  background: rgba(5, 6, 15, 0.72);
  backdrop-filter: blur(18px);
  -webkit-backdrop-filter: blur(18px);
  border-bottom-color: var(--line);
}
.nav-inner {
  width: min(1200px, calc(100% - 48px));
  margin: 0 auto;
  height: 68px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}
.nav-brand { display: flex; align-items: center; gap: 12px; }
.nav-logo { width: 34px; height: 34px; border-radius: 9px; }
.nav-name { font-size: 16px; letter-spacing: 0.02em; color: var(--muted); }
.nav-name b { color: var(--text); font-weight: 700; }
.nav-links { display: flex; align-items: center; gap: 30px; font-size: 14.5px; }
.nav-links a { color: var(--muted); transition: color 0.25s; }
.nav-links a:hover { color: var(--text); }
.nav-cta {
  padding: 8px 18px;
  border-radius: 999px;
  color: var(--text) !important;
  background: linear-gradient(100deg, rgba(47, 164, 231, 0.22), rgba(167, 139, 250, 0.22));
  border: 1px solid rgba(121, 210, 240, 0.35);
}
.nav-burger {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: 0;
  cursor: pointer;
  padding: 8px;
}
.nav-burger span {
  display: block;
  width: 22px; height: 2px;
  background: var(--text);
  border-radius: 2px;
  transition: transform 0.3s, opacity 0.3s;
}
.nav-burger.open span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
.nav-burger.open span:nth-child(2) { opacity: 0; }
.nav-burger.open span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }

/* ==================== Hero ==================== */
.hero {
  position: relative;
  padding-top: 108px;
  display: flex;
  flex-direction: column;
}
.hero-inner {
  width: min(1440px, calc(100% - 48px));
  margin: 0 auto;
  text-align: center;
  flex: 1;
}
.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: 9px;
  font-size: 14.5px;
  color: var(--cyan);
  padding: 9px 20px;
  border-radius: 999px;
  border: 1px solid rgba(121, 210, 240, 0.28);
  background: rgba(47, 164, 231, 0.08);
  backdrop-filter: blur(8px);
  margin-bottom: 22px;
}
.hero-badge .dot {
  width: 7px; height: 7px;
  border-radius: 50%;
  background: var(--cyan);
  box-shadow: 0 0 12px var(--cyan);
  animation: pulse 2.2s ease-in-out infinite;
}
@keyframes pulse { 50% { opacity: 0.35; } }

.hero-title {
  font-size: clamp(56px, 8.6vw, 128px);
  line-height: 1.12;
  font-weight: 800;
  letter-spacing: -0.02em;
}
.hero-en {
  margin-top: 16px;
  font-family: var(--serif);
  font-style: italic;
  font-size: clamp(22px, 2.8vw, 34px);
  letter-spacing: 0.04em;
  background: linear-gradient(95deg, var(--cyan), var(--purple));
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}
.hero-sub {
  margin: 20px auto 0;
  max-width: 860px;
  color: var(--muted);
  font-size: 19px;
}
.hero-cta {
  margin-top: 34px;
  display: flex;
  justify-content: center;
  gap: 20px;
  flex-wrap: wrap;
}
.hero-cta .btn {
  padding: 16px 42px;
  font-size: 17px;
}

/* ==================== 按钮 ==================== */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 14px 34px;
  border-radius: 999px;
  font-size: 15.5px;
  font-weight: 600;
  letter-spacing: 0.02em;
  transition: transform 0.25s, box-shadow 0.25s, background 0.25s;
  cursor: pointer;
}
.btn-glow {
  color: #04121d;
  background: linear-gradient(100deg, var(--blue), var(--cyan));
  box-shadow:
    0 0 24px rgba(47, 164, 231, 0.45),
    0 0 80px rgba(47, 164, 231, 0.22);
}
.btn-glow:hover {
  transform: translateY(-2px);
  box-shadow:
    0 0 32px rgba(47, 164, 231, 0.65),
    0 0 110px rgba(47, 164, 231, 0.35);
}
.btn-ghost {
  color: var(--text);
  border: 1px solid rgba(121, 210, 240, 0.3);
  background: rgba(121, 210, 240, 0.06);
  backdrop-filter: blur(8px);
}
.btn-ghost:hover {
  transform: translateY(-2px);
  background: rgba(121, 210, 240, 0.12);
  box-shadow: 0 0 30px rgba(121, 210, 240, 0.18);
}
.btn-block { width: 100%; }

/* ==================== 跑马灯 ==================== */
.marquee {
  margin-top: 70px;
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
  padding: 22px 0;
  overflow: hidden;
  background: rgba(10, 10, 20, 0.4);
  backdrop-filter: blur(6px);
  -webkit-mask-image: linear-gradient(90deg, transparent, #000 8%, #000 92%, transparent);
  mask-image: linear-gradient(90deg, transparent, #000 8%, #000 92%, transparent);
}
.marquee-track {
  display: flex;
  width: max-content;
  animation: mq 30s linear infinite;
}
.marquee:hover .marquee-track { animation-play-state: paused; }
@keyframes mq { to { transform: translateX(-50%); } }
.mq-group {
  display: flex;
  align-items: center;
  gap: 44px;
  padding-right: 44px;
}
.mq-group span {
  font-size: clamp(20px, 2.6vw, 32px);
  font-weight: 800;
  letter-spacing: 0.06em;
  white-space: nowrap;
  background: linear-gradient(100deg, var(--blue), var(--cyan));
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}
.mq-group span:nth-child(4n + 3) {
  background: none;
  color: transparent;
  -webkit-text-stroke: 1px rgba(233, 239, 248, 0.4);
}
.mq-group i {
  font-style: normal;
  color: var(--purple);
  font-size: 14px;
}

/* ==================== 通用 Section ==================== */
.section { padding: 60px 0 40px; }
.sec-head { text-align: center; margin-bottom: 64px; }
.sec-kicker {
  font-size: 13px;
  letter-spacing: 0.35em;
  color: var(--cyan);
  font-weight: 700;
  margin-bottom: 16px;
}
.sec-title {
  font-size: clamp(34px, 4.6vw, 52px);
  font-weight: 800;
  letter-spacing: -0.01em;
  line-height: 1.25;
}
.sec-sub { margin-top: 18px; color: var(--muted); font-size: 16.5px; }

/* ==================== 玻璃卡片（Bento 通用） ==================== */
.card {
  position: relative;
  border-radius: var(--radius);
  border: 1px solid transparent;
  background:
    linear-gradient(var(--glass), var(--glass)) padding-box,
    linear-gradient(135deg, rgba(47, 164, 231, 0.45), rgba(167, 139, 250, 0.28) 50%, rgba(121, 210, 240, 0.35)) border-box;
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  overflow: hidden;
  transition: transform 0.35s ease, box-shadow 0.35s ease;
}
.card::before {
  content: "";
  position: absolute;
  inset: 0;
  border-radius: inherit;
  background: radial-gradient(520px circle at var(--mx, 50%) var(--my, 50%), rgba(47, 164, 231, 0.15), transparent 45%);
  opacity: 0;
  transition: opacity 0.35s;
  pointer-events: none;
}
.card:hover {
  transform: translateY(-6px);
  box-shadow:
    0 18px 50px rgba(0, 0, 0, 0.45),
    0 0 46px rgba(47, 164, 231, 0.16);
}
.card:hover::before { opacity: 1; }

/* ==================== Bento 网格 ==================== */
.bento {
  display: grid;
  grid-template-columns: repeat(6, 1fr);
  gap: 20px;
}
.bento .card { padding: 30px; grid-column: span 2; }
.bento .card-wide { grid-column: span 4; }
.bento .card h3 {
  font-size: 21px;
  font-weight: 700;
  margin: 20px 0 10px;
}
.bento .card p { color: var(--muted); font-size: 14.8px; }
.card-num {
  position: absolute;
  top: 14px; right: 22px;
  font-size: 82px;
  font-weight: 800;
  line-height: 1;
  background: linear-gradient(135deg, rgba(121, 210, 240, 0.30), rgba(167, 139, 250, 0.22));
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
  pointer-events: none;
}

/* 大卡内的装饰字幕条 */
.card-deco {
  margin-top: 26px;
  display: flex;
  flex-direction: column;
  gap: 10px;
  max-width: 420px;
}
.deco-bar {
  height: 10px;
  border-radius: 6px;
  background: rgba(233, 239, 248, 0.08);
  border: 1px solid rgba(121, 210, 240, 0.10);
}
.deco-bar:nth-child(1) { width: 62%; }
.deco-bar:nth-child(3) { width: 44%; }
.deco-bar.on {
  width: 86%;
  background: linear-gradient(90deg, rgba(47, 164, 231, 0.55), rgba(121, 210, 240, 0.35));
  border-color: rgba(121, 210, 240, 0.45);
  box-shadow: 0 0 22px rgba(47, 164, 231, 0.35);
}

/* ==================== CSS 小图标 ==================== */
.fi {
  position: relative;
  width: 48px; height: 48px;
  border-radius: 14px;
  background: linear-gradient(135deg, rgba(47, 164, 231, 0.16), rgba(167, 139, 250, 0.12));
  border: 1px solid rgba(121, 210, 240, 0.28);
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
}
.fi i, .fi b { display: block; position: absolute; }

/* 01 逐句精读：三条字幕行 */
.fi-sub { flex-direction: column; gap: 6px; align-items: flex-start; padding-left: 12px; }
.fi-sub i { position: static; height: 3.5px; border-radius: 3px; background: rgba(233, 239, 248, 0.3); }
.fi-sub i:nth-child(1) { width: 16px; }
.fi-sub i:nth-child(2) { width: 25px; background: linear-gradient(90deg, var(--blue), var(--cyan)); box-shadow: 0 0 8px rgba(47, 164, 231, 0.6); }
.fi-sub i:nth-child(3) { width: 20px; }

/* 02 点词查义：文字行 + 释义气泡 */
.fi-word i:nth-child(1) { left: 10px; bottom: 13px; width: 28px; height: 3.5px; border-radius: 3px; background: rgba(233, 239, 248, 0.3); }
.fi-word i:nth-child(2) { left: 10px; bottom: 20px; width: 18px; height: 3.5px; border-radius: 3px; background: linear-gradient(90deg, var(--blue), var(--cyan)); }
.fi-word b {
  top: 7px; right: 7px;
  width: 16px; height: 12px;
  border-radius: 4px;
  background: rgba(167, 139, 250, 0.25);
  border: 1px solid rgba(167, 139, 250, 0.6);
}

/* 03 跟读打分：声波纹 */
.fi-mic { gap: 3px; }
.fi-mic i { position: static; width: 3.5px; border-radius: 3px; background: linear-gradient(180deg, var(--cyan), var(--blue)); }
.fi-mic i:nth-child(1) { height: 10px; }
.fi-mic i:nth-child(2) { height: 18px; }
.fi-mic i:nth-child(3) { height: 26px; box-shadow: 0 0 8px rgba(47, 164, 231, 0.6); }
.fi-mic i:nth-child(4) { height: 14px; }
.fi-mic i:nth-child(5) { height: 8px; }

/* 04 AI 陪看：对话气泡 */
.fi-ai i:nth-child(1) {
  top: 9px; left: 8px;
  width: 21px; height: 13px;
  border-radius: 6px;
  background: linear-gradient(120deg, rgba(47, 164, 231, 0.55), rgba(121, 210, 240, 0.35));
}
.fi-ai i:nth-child(2) {
  bottom: 9px; right: 8px;
  width: 17px; height: 11px;
  border-radius: 5px;
  background: rgba(167, 139, 250, 0.3);
  border: 1px solid rgba(167, 139, 250, 0.55);
}

/* 05 生词本：书 */
.fi-book i:nth-child(1) {
  left: 12px; top: 10px;
  width: 24px; height: 28px;
  border-radius: 4px;
  border: 2px solid rgba(121, 210, 240, 0.55);
  background: rgba(47, 164, 231, 0.10);
}
.fi-book i:nth-child(2) {
  left: 22px; top: 10px;
  width: 4px; height: 28px;
  background: linear-gradient(180deg, var(--purple), transparent);
  border-radius: 2px;
}

/* 06 实时字幕：录制点 + 字幕行 */
.fi-live i {
  left: 11px; bottom: 12px;
  width: 26px; height: 4px;
  border-radius: 3px;
  background: linear-gradient(90deg, var(--blue), var(--cyan));
}
.fi-live b {
  top: 10px; left: 11px;
  width: 8px; height: 8px;
  border-radius: 50%;
  background: var(--purple);
  box-shadow: 0 0 10px var(--purple);
  animation: pulse 1.8s ease-in-out infinite;
}

/* 07 网络视频：播放钮 */
.fi-play i {
  width: 26px; height: 26px;
  border-radius: 50%;
  border: 1.6px solid rgba(121, 210, 240, 0.65);
  position: relative;
}
.fi-play i::after {
  content: "";
  position: absolute;
  top: 50%; left: 54%;
  transform: translate(-50%, -50%);
  border-left: 9px solid var(--cyan);
  border-top: 6px solid transparent;
  border-bottom: 6px solid transparent;
}

/* 08 学习统计：柱状图 */
.fi-chart i { bottom: 12px; width: 4.5px; border-radius: 3px 3px 0 0; background: linear-gradient(180deg, var(--cyan), rgba(47, 164, 231, 0.4)); }
.fi-chart i:nth-child(1) { left: 11px; height: 9px; }
.fi-chart i:nth-child(2) { left: 18px; height: 15px; }
.fi-chart i:nth-child(3) { left: 25px; height: 21px; }
.fi-chart i:nth-child(4) { left: 32px; height: 27px; background: linear-gradient(180deg, var(--purple), rgba(167, 139, 250, 0.35)); }
.fi-chart b { left: 9px; bottom: 10px; width: 30px; height: 1.6px; background: rgba(233, 239, 248, 0.3); }

/* ==================== 三步使用 ==================== */
.steps {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 20px;
  position: relative;
}
.step { padding: 34px 30px; }
.step-num {
  display: block;
  font-size: 46px;
  font-weight: 800;
  line-height: 1;
  margin-bottom: 18px;
  background: linear-gradient(120deg, var(--blue), var(--purple));
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}
.step h3 { font-size: 20px; margin-bottom: 10px; }
.step p { color: var(--muted); font-size: 14.8px; }

/* ==================== 下载 ==================== */
.dl-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 22px;
  max-width: 520px;
  margin: 0 auto;
}
.dl-card { padding: 40px 36px; text-align: center; }
.dl-card h3 { font-size: 24px; font-weight: 700; }
.dl-tag {
  position: absolute;
  top: 18px; right: 18px;
  font-size: 12.5px;
  font-weight: 700;
  letter-spacing: 0.1em;
  color: #04121d;
  padding: 4px 14px;
  border-radius: 999px;
  background: linear-gradient(100deg, var(--blue), var(--cyan));
  box-shadow: 0 0 18px rgba(47, 164, 231, 0.5);
}
.dl-size {
  margin: 10px 0 16px;
  font-size: 15px;
  font-weight: 700;
  background: linear-gradient(100deg, var(--cyan), var(--purple));
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}
.dl-desc { color: var(--muted); font-size: 14.8px; margin-bottom: 28px; min-height: 75px; }
.dl-mac {
  margin: 26px auto 0;
  max-width: 520px;
  text-align: center;
  font-size: 14px;
  color: var(--muted);
  padding: 12px 18px;
  border: 1px dashed rgba(122, 162, 255, 0.35);
  border-radius: 12px;
}

/* ==================== 真实界面截图 ==================== */
.shot-section { padding-top: 30px; padding-bottom: 50px; }
.shot-wrap {
  width: min(1360px, calc(100% - 64px));
  margin: 0 auto;
  perspective: 1400px;
}
.shot-frame {
  border-radius: 18px;
  overflow: hidden;
  border: 1px solid rgba(122, 162, 255, 0.22);
  box-shadow: 0 30px 80px rgba(3, 10, 24, 0.65), 0 0 60px rgba(47, 164, 231, 0.12);
  transform-style: preserve-3d;
  transition: transform 0.18s ease-out;
  will-change: transform;
}
.shot-frame img { display: block; width: 100%; height: auto; }

/* ==================== 授权 ==================== */
.lic-card {
  display: flex;
  align-items: center;
  gap: 48px;
  padding: 46px 50px;
  max-width: 960px;
  margin: 0 auto;
}
.lic-steps { flex: 1; }
.lic-step {
  display: flex;
  align-items: center;
  gap: 16px;
  padding: 13px 0;
}
.lic-step p { color: var(--muted); font-size: 15.5px; }
.lic-step b { color: var(--text); }
.lic-num {
  flex-shrink: 0;
  width: 34px; height: 34px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 15px;
  font-weight: 800;
  color: var(--cyan);
  background: rgba(47, 164, 231, 0.10);
  border: 1px solid rgba(121, 210, 240, 0.4);
}
.lic-note {
  margin-top: 18px;
  font-size: 13.5px;
  color: rgba(154, 167, 189, 0.75);
  border-top: 1px dashed rgba(121, 210, 240, 0.18);
  padding-top: 16px;
}
.lic-qr { text-align: center; flex-shrink: 0; }
.lic-qr img {
  width: 220px;
  border-radius: 16px;
  border: 1px solid rgba(121, 210, 240, 0.3);
  box-shadow: 0 0 40px rgba(47, 164, 231, 0.18);
  background: #fff;
  padding: 8px;
}
.lic-qr p { margin-top: 14px; font-size: 14px; color: var(--muted); }

/* ==================== FAQ ==================== */
.faq-list { display: flex; flex-direction: column; gap: 14px; }
.faq-item {
  border-radius: 16px;
  border: 1px solid transparent;
  background:
    linear-gradient(var(--glass), var(--glass)) padding-box,
    linear-gradient(135deg, rgba(47, 164, 231, 0.3), rgba(167, 139, 250, 0.2)) border-box;
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
  transition: box-shadow 0.3s;
}
.faq-item[open] { box-shadow: 0 0 34px rgba(47, 164, 231, 0.12); }
.faq-item summary {
  list-style: none;
  cursor: pointer;
  padding: 20px 26px;
  font-size: 16px;
  font-weight: 600;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
}
.faq-item summary::-webkit-details-marker { display: none; }
.faq-item summary::after {
  content: "+";
  font-size: 22px;
  font-weight: 400;
  color: var(--cyan);
  transition: transform 0.3s;
  flex-shrink: 0;
}
.faq-item[open] summary::after { transform: rotate(45deg); }
.faq-item p {
  padding: 0 26px 22px;
  color: var(--muted);
  font-size: 14.8px;
}

/* ==================== 页脚 ==================== */
.footer {
  margin-top: 130px;
  border-top: 1px solid var(--line);
  padding: 48px 0 56px;
  background: rgba(5, 6, 15, 0.6);
}
.footer-inner {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 16px;
  text-align: center;
  color: var(--muted);
  font-size: 14.5px;
}
.footer-logo { width: 44px; height: 44px; border-radius: 12px; }
.footer .beian { font-size: 13px; opacity: .65; }
.footer .beian a { color: inherit; }
.footer .beian a:hover { color: var(--blue, #56ccf2); }

/* ==================== 响应式 ==================== */
@media (max-width: 1024px) {
  .bento { grid-template-columns: repeat(2, 1fr); }
  .bento .card,
  .bento .card-wide { grid-column: span 1; }
  .bento .card-wide { grid-column: span 2; }
}

@media (max-width: 720px) {
  .nav-links {
    position: fixed;
    top: 68px; left: 0; right: 0;
    flex-direction: column;
    align-items: stretch;
    gap: 0;
    background: rgba(5, 6, 15, 0.92);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border-bottom: 1px solid var(--line);
    padding: 12px 24px 22px;
    transform: translateY(-130%);
    /* 收起时必须真正拿掉可交互性：只靠 translate 移出视口的话，
       链接仍可被 Tab 聚焦，键盘用户会"掉进"看不见的菜单。
       visibility 用 0s + 延迟切换，而不是参与过渡插值 ——
       后者靠浏览器对 visible 的特殊插值规则，没必要绕这一道。 */
    visibility: hidden;
    transition: transform 0.35s ease, visibility 0s linear 0.35s;
  }
  .nav-links.open {
    transform: translateY(0);
    visibility: visible;
    transition: transform 0.35s ease, visibility 0s;
  }
  .nav-links a { padding: 14px 4px; border-bottom: 1px solid rgba(121, 210, 240, 0.08); }
  .nav-cta { text-align: center; margin-top: 14px; border-bottom: none !important; }
  .nav-burger { display: flex; }

  .hero { padding-top: 130px; min-height: auto; }
  .hero-title { font-size: clamp(42px, 12vw, 56px); }
  .br-pc { display: none; }
  .marquee { margin-top: 70px; }

  .section { padding: 90px 0 20px; }
  .bento { grid-template-columns: 1fr; }
  .bento .card,
  .bento .card-wide { grid-column: span 1; }
  .card-num { font-size: 64px; }

  .steps { grid-template-columns: 1fr; }
  .dl-grid { grid-template-columns: 1fr; }
  .dl-desc { min-height: 0; }

  .lic-card { flex-direction: column; padding: 36px 28px; gap: 36px; }
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
  html { scroll-behavior: auto; }
}