/* ==========================================================
   象棋奇兵 · 官方下载站
   设计思路：深色国风主基调 + 中国红/古铜金点缀
   ========================================================== */

/* ---------- 设计变量 ---------- */
:root {
  --bg: #14110d;
  --bg-2: #1a1611;
  --surface: #1f1a14;
  --surface-2: #2a231a;
  --border: rgba(212, 175, 55, 0.18);
  --border-strong: rgba(212, 175, 55, 0.35);

  --text: #f3eee4;
  --text-muted: #b8b0a1;
  --text-dim: #807868;

  --red: #c8102e;
  --red-deep: #8b0a1f;
  --gold: #d4af37;
  --gold-soft: #e6c870;

  --gradient-warm: linear-gradient(135deg, #c8102e 0%, #8b0a1f 100%);
  --gradient-gold: linear-gradient(135deg, #f3d97a 0%, #d4af37 60%, #9a7d1f 100%);
  --gradient-hero: radial-gradient(1200px 600px at 80% -10%, rgba(212, 175, 55, 0.18), transparent 60%),
                   radial-gradient(900px 500px at -10% 110%, rgba(200, 16, 46, 0.22), transparent 60%);

  --shadow-sm: 0 2px 6px rgba(0, 0, 0, 0.35);
  --shadow-md: 0 12px 30px rgba(0, 0, 0, 0.45);
  --shadow-lg: 0 30px 60px rgba(0, 0, 0, 0.55);

  --radius-sm: 10px;
  --radius-md: 16px;
  --radius-lg: 24px;

  --container: 1180px;
  --header-h: 72px;

  --ease: cubic-bezier(0.22, 1, 0.36, 1);
}

/* ---------- 基础重置 ---------- */
* { box-sizing: border-box; }
*::before, *::after { box-sizing: border-box; }

html { scroll-behavior: smooth; -webkit-text-size-adjust: 100%; }

body {
  margin: 0;
  font-family: "Noto Sans SC", -apple-system, BlinkMacSystemFont, "PingFang SC",
               "Microsoft YaHei", "Segoe UI", Arial, sans-serif;
  font-size: 16px;
  line-height: 1.7;
  color: var(--text);
  background: var(--bg);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  overflow-x: hidden;
}

img { max-width: 100%; display: block; }

a { color: inherit; text-decoration: none; transition: color .25s var(--ease); }
button { font-family: inherit; cursor: pointer; border: none; background: none; color: inherit; }

ul { list-style: none; padding: 0; margin: 0; }

h1, h2, h3, h4 {
  font-family: "Noto Serif SC", "Songti SC", "SimSun", serif;
  font-weight: 700;
  line-height: 1.25;
  letter-spacing: 0.02em;
  margin: 0 0 .6em;
  color: var(--text);
}

p { margin: 0 0 1em; color: var(--text-muted); }

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

/* ---------- 公共组件 ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 12px 22px;
  border-radius: 999px;
  font-weight: 600;
  font-size: 15px;
  letter-spacing: 0.02em;
  white-space: nowrap;
  transition: transform .25s var(--ease), box-shadow .25s var(--ease),
              background .25s var(--ease), color .25s var(--ease), border-color .25s var(--ease);
}
.btn:hover { transform: translateY(-2px); }
.btn:active { transform: translateY(0); }

.btn-primary {
  background: var(--gradient-warm);
  color: #fff;
  box-shadow: 0 10px 24px -10px rgba(200, 16, 46, 0.7);
}
.btn-primary:hover { box-shadow: 0 16px 30px -10px rgba(200, 16, 46, 0.9); }

.btn-ghost {
  background: transparent;
  border: 1px solid var(--border-strong);
  color: var(--gold-soft);
}
.btn-ghost:hover {
  background: rgba(212, 175, 55, 0.08);
  border-color: var(--gold);
}

.btn-lg {
  padding: 15px 30px;
  font-size: 16px;
}

.eyebrow,
.section-tag {
  display: inline-block;
  font-size: 13px;
  font-weight: 600;
  letter-spacing: 0.3em;
  text-transform: uppercase;
  color: var(--gold);
  margin-bottom: 14px;
  padding: 6px 14px;
  border: 1px solid var(--border-strong);
  border-radius: 999px;
  background: rgba(212, 175, 55, 0.06);
}

.section {
  padding: clamp(60px, 9vw, 120px) 0;
  position: relative;
}

.section-head {
  text-align: center;
  max-width: 720px;
  margin: 0 auto clamp(36px, 5vw, 60px);
}
.section-head .section-tag { margin: 0 0 16px; }

.section-title {
  font-size: clamp(28px, 4vw, 44px);
  margin: 0 0 12px;
  background: var(--gradient-gold);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
}

.section-desc {
  font-size: clamp(15px, 1.6vw, 17px);
  color: var(--text-muted);
}

/* ---------- 导航栏 ---------- */
.navbar {
  position: fixed;
  top: 0; left: 0; right: 0;
  height: var(--header-h);
  z-index: 100;
  background: rgba(20, 17, 13, 0.65);
  backdrop-filter: saturate(160%) blur(14px);
  -webkit-backdrop-filter: saturate(160%) blur(14px);
  border-bottom: 1px solid transparent;
  transition: background .3s var(--ease), border-color .3s var(--ease);
}
.navbar.is-scrolled {
  background: rgba(20, 17, 13, 0.85);
  border-bottom-color: var(--border);
}

.nav-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 100%;
}

.logo {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-family: "Noto Serif SC", serif;
  font-weight: 700;
  font-size: 20px;
  color: var(--text);
}
.logo-icon {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 36px; height: 36px;
  border-radius: 9px;
  background: var(--gradient-warm);
  color: #fff;
  font-size: 18px;
  font-weight: 700;
  box-shadow: 0 6px 14px -6px rgba(200, 16, 46, 0.8);
}
.logo-text { letter-spacing: 0.06em; }

.nav-menu {
  display: flex;
  align-items: center;
  gap: clamp(10px, 2vw, 36px);
}
.nav-menu ul {
  display: flex;
  gap: clamp(8px, 1.5vw, 28px);
}
.nav-menu a {
  font-size: 15px;
  font-weight: 500;
  color: var(--text-muted);
  position: relative;
  padding: 8px 4px;
}
.nav-menu a:hover { color: var(--gold-soft); }
.nav-menu a::after {
  content: "";
  position: absolute;
  left: 50%; bottom: 0;
  height: 2px; width: 0;
  background: var(--gold);
  transition: width .3s var(--ease), left .3s var(--ease);
}
.nav-menu a:hover::after { width: 100%; left: 0; }

.nav-cta { padding: 9px 18px; font-size: 14px; }

.nav-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  width: 40px;
  height: 40px;
  align-items: center;
  justify-content: center;
}
.nav-toggle span {
  display: block;
  width: 22px;
  height: 2px;
  background: var(--text);
  border-radius: 2px;
  transition: transform .3s var(--ease), opacity .3s var(--ease);
}
.nav-toggle.is-open span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
.nav-toggle.is-open span:nth-child(2) { opacity: 0; }
.nav-toggle.is-open span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }

/* ---------- Hero 首屏 ---------- */
.hero {
  position: relative;
  min-height: 100vh;
  padding: calc(var(--header-h) + 60px) 0 80px;
  display: flex;
  align-items: center;
  background: var(--gradient-hero), var(--bg);
  overflow: hidden;
}
.hero-bg {
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(rgba(212, 175, 55, 0.05) 1px, transparent 1px),
    linear-gradient(90deg, rgba(212, 175, 55, 0.05) 1px, transparent 1px);
  background-size: 48px 48px;
  mask-image: radial-gradient(ellipse at center, #000 30%, transparent 75%);
  -webkit-mask-image: radial-gradient(ellipse at center, #000 30%, transparent 75%);
  pointer-events: none;
}

.hero-inner {
  position: relative;
  display: grid;
  grid-template-columns: 1.05fr 0.95fr;
  gap: clamp(30px, 5vw, 70px);
  align-items: center;
}

.hero-text { animation: fadeUp 1s var(--ease) both; }

.hero-title {
  font-size: clamp(36px, 6vw, 64px);
  margin: 0 0 22px;
  letter-spacing: 0.04em;
}
.hero-title .accent {
  display: inline-block;
  margin-top: 8px;
  font-size: clamp(20px, 2.6vw, 28px);
  background: var(--gradient-gold);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
  font-weight: 500;
}

.hero-sub {
  font-size: clamp(15px, 1.7vw, 18px);
  color: var(--text-muted);
  max-width: 540px;
  margin-bottom: 34px;
}

.hero-cta {
  display: flex;
  flex-wrap: wrap;
  gap: 14px;
  margin-bottom: 44px;
}

.hero-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 36px;
  border-top: 1px solid var(--border);
  padding-top: 24px;
}
.hero-meta li {
  font-size: 14px;
  color: var(--text-muted);
}
.hero-meta strong {
  display: block;
  font-family: "Noto Serif SC", serif;
  font-size: 26px;
  color: var(--gold-soft);
  margin-bottom: 2px;
  font-weight: 700;
}

.hero-media {
  position: relative;
  animation: fadeUp 1.2s var(--ease) both;
}
.hero-frame {
  position: relative;
  border-radius: var(--radius-lg);
  overflow: hidden;
  border: 1px solid var(--border-strong);
  box-shadow: var(--shadow-lg);
  transform: rotate(-1.5deg);
  transition: transform .6s var(--ease);
}
.hero-frame:hover { transform: rotate(0); }
.hero-frame img {
  width: 100%;
  aspect-ratio: 4 / 5;
  object-fit: cover;
}
.hero-decor {
  position: absolute;
  border-radius: 50%;
  filter: blur(60px);
  pointer-events: none;
}
.hero-decor-1 {
  width: 280px; height: 280px;
  background: rgba(200, 16, 46, 0.4);
  top: -60px; right: -60px;
}
.hero-decor-2 {
  width: 220px; height: 220px;
  background: rgba(212, 175, 55, 0.4);
  bottom: -50px; left: -50px;
}

/* ---------- 介绍板块 ---------- */
.section-intro {
  background: linear-gradient(180deg, var(--bg) 0%, var(--bg-2) 100%);
}
.intro-inner {
  display: grid;
  grid-template-columns: 1.1fr 0.9fr;
  gap: clamp(36px, 6vw, 90px);
  align-items: center;
}
.intro-text .section-title {
  text-align: left;
  background: none;
  -webkit-text-fill-color: var(--text);
  font-size: clamp(28px, 4vw, 42px);
}
.lead { font-size: 17px; color: var(--text); margin-bottom: 18px; }

.check-list {
  margin-top: 22px;
}
.check-list li {
  position: relative;
  padding-left: 32px;
  margin-bottom: 12px;
  color: var(--text-muted);
  font-size: 15px;
}
.check-list li::before {
  content: "✓";
  position: absolute;
  left: 0; top: 0;
  width: 22px; height: 22px;
  border-radius: 50%;
  background: var(--gradient-warm);
  color: #fff;
  font-size: 12px;
  font-weight: 700;
  display: flex;
  align-items: center;
  justify-content: center;
}

.intro-media {
  position: relative;
  display: flex;
  justify-content: center;
}
.intro-frame {
  position: relative;
  width: 100%;
  max-width: 460px;
  border-radius: var(--radius-lg);
  overflow: hidden;
  border: 1px solid var(--border-strong);
  box-shadow: var(--shadow-lg);
  transform: rotate(2deg);
  transition: transform .6s var(--ease);
}
.intro-frame:hover { transform: rotate(0); }
.intro-frame img {
  width: 100%;
  aspect-ratio: 4 / 5;
  object-fit: cover;
}
.intro-badge {
  position: absolute;
  top: 22px; right: 22px;
  background: var(--gradient-gold);
  color: #1a1611;
  padding: 8px 16px;
  border-radius: 999px;
  font-weight: 700;
  font-size: 13px;
  display: inline-flex;
  align-items: center;
  gap: 6px;
  box-shadow: var(--shadow-md);
}

/* ---------- 特点板块 ---------- */
.section-features {
  background: var(--bg-2);
  position: relative;
}
.section-features::before {
  content: "";
  position: absolute; inset: 0;
  background: radial-gradient(800px 400px at 50% 0%, rgba(212, 175, 55, 0.08), transparent 70%);
  pointer-events: none;
}

.features-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}
.feature-card {
  position: relative;
  padding: 34px 28px;
  border-radius: var(--radius-md);
  background: var(--surface);
  border: 1px solid var(--border);
  transition: transform .4s var(--ease), border-color .4s var(--ease),
              box-shadow .4s var(--ease);
}
.feature-card:hover {
  transform: translateY(-6px);
  border-color: var(--border-strong);
  box-shadow: var(--shadow-md);
}
.feature-card::before {
  content: "";
  position: absolute;
  inset: 0;
  border-radius: var(--radius-md);
  background: linear-gradient(180deg, rgba(212, 175, 55, 0.08), transparent 50%);
  opacity: 0;
  transition: opacity .4s var(--ease);
  pointer-events: none;
}
.feature-card:hover::before { opacity: 1; }

.feature-icon {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 56px; height: 56px;
  font-size: 28px;
  border-radius: 14px;
  background: linear-gradient(135deg, rgba(200, 16, 46, 0.18), rgba(212, 175, 55, 0.14));
  border: 1px solid var(--border-strong);
  margin-bottom: 18px;
}
.feature-card h3 {
  font-size: 20px;
  margin: 0 0 10px;
  color: var(--gold-soft);
}
.feature-card p {
  font-size: 14.5px;
  color: var(--text-muted);
  margin: 0;
}

/* ---------- 评价板块 ---------- */
.section-reviews {
  background: linear-gradient(180deg, var(--bg-2) 0%, var(--bg) 100%);
}

.reviews-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 22px;
  margin-bottom: 50px;
}
.review-card {
  margin: 0;
  padding: 28px 24px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  transition: transform .4s var(--ease), border-color .4s var(--ease);
  display: flex;
  flex-direction: column;
}
.review-card:hover {
  transform: translateY(-4px);
  border-color: var(--border-strong);
}
.review-card-featured {
  background: linear-gradient(180deg, rgba(200, 16, 46, 0.12), var(--surface) 70%);
  border-color: rgba(200, 16, 46, 0.4);
}
.stars {
  color: var(--gold);
  font-size: 16px;
  letter-spacing: 3px;
  margin-bottom: 14px;
}
.review-card blockquote {
  margin: 0 0 22px;
  font-size: 14.5px;
  color: var(--text-muted);
  line-height: 1.7;
  flex: 1;
  font-style: normal;
}
.review-card figcaption {
  display: flex;
  align-items: center;
  gap: 12px;
  border-top: 1px solid var(--border);
  padding-top: 16px;
}
.avatar {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 42px; height: 42px;
  border-radius: 50%;
  background: var(--gradient-warm);
  color: #fff;
  font-family: "Noto Serif SC", serif;
  font-weight: 700;
  font-size: 16px;
  flex-shrink: 0;
}
.review-card figcaption strong {
  display: block;
  color: var(--text);
  font-size: 15px;
}
.review-card figcaption small {
  color: var(--text-dim);
  font-size: 12.5px;
}

.reviews-summary {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 22px;
  padding: 26px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  max-width: 520px;
  margin: 0 auto;
}
.rating-big {
  font-family: "Noto Serif SC", serif;
  font-size: 48px;
  font-weight: 900;
  line-height: 1;
  color: var(--gold);
}
.rating-big span {
  font-size: 18px;
  color: var(--text-dim);
  font-weight: 500;
}
.rating-meta .stars { margin-bottom: 6px; }
.rating-meta p {
  margin: 0;
  font-size: 14px;
  color: var(--text-muted);
}

/* ---------- 下载帮助板块 ---------- */
.section-help { background: var(--bg-2); }

.help-grid {
  display: grid;
  grid-template-columns: 1.6fr 1fr;
  gap: 36px;
  margin-bottom: 60px;
}

.help-steps {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 20px;
}
.step-card {
  padding: 30px 24px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  transition: transform .35s var(--ease), border-color .35s var(--ease);
}
.step-card:hover { transform: translateY(-4px); border-color: var(--border-strong); }
.step-num {
  font-family: "Noto Serif SC", serif;
  font-size: 38px;
  font-weight: 900;
  background: var(--gradient-gold);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
  line-height: 1;
  margin-bottom: 14px;
}
.step-card h3 {
  font-size: 19px;
  margin: 0 0 8px;
  color: var(--text);
}
.step-card p {
  margin: 0;
  font-size: 14.5px;
}

.download-card {
  padding: 32px 28px;
  background: linear-gradient(180deg, var(--surface-2), var(--surface));
  border: 1px solid var(--border-strong);
  border-radius: var(--radius-md);
  position: relative;
}
.download-card h3 {
  font-size: 22px;
  margin: 0 0 6px;
  color: var(--gold-soft);
}
.download-card p {
  font-size: 14px;
  color: var(--text-muted);
  margin: 0 0 22px;
}
.download-list {
  display: flex;
  flex-direction: column;
  gap: 12px;
  margin-bottom: 22px;
}
.dl-btn {
  display: flex;
  align-items: center;
  gap: 14px;
  padding: 14px 18px;
  background: rgba(255, 255, 255, 0.03);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  transition: all .3s var(--ease);
}
.dl-btn:hover {
  background: rgba(212, 175, 55, 0.1);
  border-color: var(--gold);
  transform: translateX(2px);
}
.dl-icon {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 38px; height: 38px;
  border-radius: 10px;
  background: rgba(212, 175, 55, 0.12);
  font-size: 20px;
  flex-shrink: 0;
}
.dl-text { display: flex; flex-direction: column; line-height: 1.2; }
.dl-text small { font-size: 11px; color: var(--text-dim); letter-spacing: 0.1em; }
.dl-text strong { font-size: 15px; color: var(--text); font-weight: 600; }

.dl-tip {
  margin: 0;
  font-size: 12.5px;
  color: var(--text-dim);
  text-align: center;
  padding-top: 16px;
  border-top: 1px dashed var(--border);
}

/* FAQ */
.faq-title {
  text-align: center;
  font-size: 26px;
  margin: 0 0 28px;
  color: var(--gold-soft);
}
.faq-list {
  max-width: 820px;
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  gap: 12px;
}
.faq-item {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  overflow: hidden;
  transition: border-color .3s var(--ease);
}
.faq-item:hover { border-color: var(--border-strong); }
.faq-item summary {
  padding: 18px 22px;
  cursor: pointer;
  font-weight: 600;
  font-size: 15.5px;
  color: var(--text);
  list-style: none;
  position: relative;
  padding-right: 50px;
}
.faq-item summary::-webkit-details-marker { display: none; }
.faq-item summary::after {
  content: "+";
  position: absolute;
  right: 22px; top: 50%;
  transform: translateY(-50%);
  color: var(--gold);
  font-size: 22px;
  font-weight: 300;
  transition: transform .3s var(--ease);
}
.faq-item[open] summary::after { transform: translateY(-50%) rotate(45deg); }
.faq-item p {
  padding: 0 22px 20px;
  margin: 0;
  font-size: 14.5px;
  color: var(--text-muted);
}

/* ---------- 页脚 ---------- */
.footer {
  background: #0e0c09;
  border-top: 1px solid var(--border);
  padding: 50px 0 28px;
}
.footer-inner {
  display: grid;
  grid-template-columns: auto 1fr auto;
  align-items: center;
  gap: 30px;
}
.footer-brand p {
  margin: 8px 0 0;
  font-size: 13px;
  color: var(--text-dim);
}
.footer-nav ul {
  display: flex;
  justify-content: center;
  gap: 24px;
}
.footer-nav a {
  font-size: 14px;
  color: var(--text-muted);
}
.footer-nav a:hover { color: var(--gold-soft); }
.copyright {
  margin: 0;
  font-size: 12.5px;
  color: var(--text-dim);
  text-align: right;
}

/* ---------- 入场动画 ---------- */
.reveal {
  opacity: 0;
  transform: translateY(28px);
  transition: opacity .8s var(--ease), transform .8s var(--ease);
}
.reveal.is-visible {
  opacity: 1;
  transform: translateY(0);
}

@keyframes fadeUp {
  from { opacity: 0; transform: translateY(30px); }
  to   { opacity: 1; transform: translateY(0); }
}

/* ==========================================================
   响应式断点
   ========================================================== */

/* ---------- 平板 (≤ 980px) ---------- */
@media (max-width: 980px) {
  :root { --header-h: 64px; }

  /* 导航：汉堡菜单 */
  .nav-toggle { display: flex; }
  .nav-menu {
    position: fixed;
    inset: var(--header-h) 0 0 0;
    flex-direction: column;
    align-items: stretch;
    background: rgba(20, 17, 13, 0.98);
    backdrop-filter: blur(12px);
    padding: 24px;
    gap: 18px;
    transform: translateX(100%);
    transition: transform .35s var(--ease);
    overflow-y: auto;
  }
  .nav-menu.is-open {
    transform: translateX(0);
    box-shadow: -20px 0 40px rgba(0, 0, 0, 0.4);
  }
  .nav-menu ul {
    flex-direction: column;
    gap: 4px;
  }
  .nav-menu ul a {
    display: block;
    font-size: 17px;
    padding: 14px 8px;
    border-bottom: 1px solid var(--border);
  }
  .nav-menu ul a::after { display: none; }
  .nav-cta {
    margin-top: 18px;
    align-self: flex-start;
    padding: 13px 24px;
  }

  /* Hero 单列 */
  .hero-inner {
    grid-template-columns: 1fr;
    text-align: left;
  }
  .hero-media {
    max-width: 460px;
    margin: 0 auto;
    order: -1;
  }
  .hero-frame { transform: rotate(0); }
  .hero-meta { gap: 24px; }
  .hero-meta strong { font-size: 22px; }

  /* 介绍 */
  .intro-inner {
    grid-template-columns: 1fr;
    gap: 40px;
  }
  .intro-frame {
    transform: rotate(0);
    max-width: 420px;
    margin: 0 auto;
  }

  /* 特点：2 列 */
  .features-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  /* 评价：2 列 */
  .reviews-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  /* 下载帮助 */
  .help-grid {
    grid-template-columns: 1fr;
  }
  .help-steps { grid-template-columns: repeat(3, 1fr); }
}

/* ---------- 手机 (≤ 640px) ---------- */
@media (max-width: 640px) {
  .container { padding-inline: 18px; }
  .section { padding: 64px 0; }

  /* 导航 */
  .logo-text { font-size: 18px; }
  .logo-icon { width: 34px; height: 34px; font-size: 16px; }

  /* Hero */
  .hero {
    padding-top: calc(var(--header-h) + 36px);
    min-height: auto;
  }
  .hero-cta { flex-direction: column; align-items: stretch; }
  .hero-cta .btn { width: 100%; }
  .hero-meta {
    gap: 18px;
    flex-wrap: wrap;
  }
  .hero-meta li { font-size: 13px; }
  .hero-meta strong { font-size: 20px; }

  /* 介绍 */
  .intro-badge { font-size: 11.5px; padding: 6px 12px; top: 14px; right: 14px; }

  /* 特点：单列 */
  .features-grid { grid-template-columns: 1fr; }
  .feature-card { padding: 26px 22px; }

  /* 评价：单列 */
  .reviews-grid { grid-template-columns: 1fr; }
  .reviews-summary {
    flex-direction: column;
    text-align: center;
    gap: 12px;
  }
  .rating-big { font-size: 42px; }

  /* 帮助 */
  .help-steps { grid-template-columns: 1fr; }
  .download-card { padding: 24px 20px; }

  /* FAQ */
  .faq-item summary {
    font-size: 15px;
    padding: 16px 18px;
    padding-right: 44px;
  }
  .faq-item p { padding: 0 18px 18px; }

  /* 页脚 */
  .footer-inner {
    grid-template-columns: 1fr;
    text-align: center;
    gap: 22px;
  }
  .footer-brand, .footer-nav, .copyright { text-align: center; justify-content: center; }
}

/* ---------- 大屏优化 (≥ 1280px) ---------- */
@media (min-width: 1280px) {
  .features-grid { gap: 28px; }
  .reviews-grid { gap: 24px; }
}

/* ---------- 减弱动效偏好 ---------- */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    transition-duration: 0.01ms !important;
  }
  html { scroll-behavior: auto; }
}