/* =========================================================
   FreeCAD 官方推广网站 — 主样式表
   配色取自 FreeCAD Logo：蓝 #418fde / 红 #ff585d / 深红 #cb333b
   风格：扁平 / 现代 / 专业
   ========================================================= */

/* ---------- 1. 设计令牌（CSS Variables） ---------- */
:root {
  /* 主色 */
  --c-primary: #418fde;        /* FreeCAD 蓝 */
  --c-primary-dark: #2f74b8;
  --c-primary-light: #e8f2fb;
  --c-accent: #ff585d;         /* FreeCAD 红 */
  --c-accent-dark: #cb333b;    /* FreeCAD 深红 */
  --c-accent-light: #ffe9ea;

  /* 中性色 */
  --c-text: #1f2933;
  --c-text-soft: #52606d;
  --c-text-muted: #7b8794;
  --c-border: #e4e7eb;
  --c-bg: #ffffff;
  --c-bg-soft: #f5f7fa;
  --c-bg-deep: #1a2b3c;

  /* 字体 */
  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC",
    "Hiragino Sans GB", "Microsoft YaHei", "Helvetica Neue", Arial, sans-serif;
  --font-mono: "SFMono-Regular", Consolas, "Liberation Mono", Menlo, monospace;

  /* 尺寸 */
  --container: 1200px;
  --radius: 10px;
  --radius-sm: 6px;
  --radius-lg: 18px;
  --shadow-sm: 0 1px 3px rgba(31, 41, 51, .06), 0 1px 2px rgba(31, 41, 51, .04);
  --shadow-md: 0 4px 12px rgba(31, 41, 51, .08), 0 2px 4px rgba(31, 41, 51, .04);
  --shadow-lg: 0 12px 32px rgba(31, 41, 51, .12), 0 4px 8px rgba(31, 41, 51, .06);
  --transition: .25s cubic-bezier(.4, 0, .2, 1);
}

/* ---------- 2. 基础重置 ---------- */
*, *::before, *::after { box-sizing: border-box; }
html { scroll-behavior: smooth; -webkit-text-size-adjust: 100%; }
body {
  margin: 0;
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.7;
  color: var(--c-text);
  background: var(--c-bg);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}
img { max-width: 100%; height: auto; display: block; }
a { color: var(--c-primary); text-decoration: none; transition: color var(--transition); }
a:hover { color: var(--c-primary-dark); }
ul, ol { margin: 0; padding: 0; list-style: none; }
h1, h2, h3, h4, h5, h6 { margin: 0 0 .5em; line-height: 1.25; font-weight: 700; color: var(--c-text); }
h1 { font-size: clamp(2rem, 4vw, 3.2rem); letter-spacing: -.02em; }
h2 { font-size: clamp(1.6rem, 2.8vw, 2.3rem); letter-spacing: -.01em; }
h3 { font-size: 1.25rem; }
p { margin: 0 0 1em; }

/* ---------- 3. 布局容器 ---------- */
.container {
  width: 100%;
  max-width: var(--container);
  margin: 0 auto;
  padding: 0 24px;
}
.section { padding: 80px 0; }
.section--soft { background: var(--c-bg-soft); }
.section--deep { background: var(--c-bg-deep); color: #fff; }
.section--deep h1, .section--deep h2, .section--deep h3 { color: #fff; }
.section--primary { background: linear-gradient(135deg, var(--c-primary) 0%, var(--c-primary-dark) 100%); color: #fff; }
.section--primary h1, .section--primary h2, .section--primary h3 { color: #fff; }

.section-head { text-align: center; max-width: 760px; margin: 0 auto 56px; }
.section-head .eyebrow {
  display: inline-block;
  font-size: .85rem;
  font-weight: 700;
  letter-spacing: .08em;
  text-transform: uppercase;
  color: var(--c-primary);
  background: var(--c-primary-light);
  padding: 4px 14px;
  border-radius: 999px;
  margin-bottom: 18px;
}
.section--deep .section-head .eyebrow,
.section--primary .section-head .eyebrow {
  color: #fff;
  background: rgba(255, 255, 255, .15);
}
.section-head p {
  font-size: 1.05rem;
  color: var(--c-text-soft);
  margin: 0;
}
.section--deep .section-head p,
.section--primary .section-head p { color: rgba(255, 255, 255, .85); }

/* ---------- 4. 按钮 ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 12px 26px;
  font-size: 1rem;
  font-weight: 600;
  font-family: inherit;
  line-height: 1.2;
  border: 1px solid transparent;
  border-radius: var(--radius);
  cursor: pointer;
  transition: all var(--transition);
  text-align: center;
  white-space: nowrap;
  text-decoration: none;
}
.btn--primary {
  background: var(--c-primary);
  color: #fff;
  box-shadow: 0 4px 12px rgba(65, 143, 222, .3);
}
.btn--primary:hover {
  background: var(--c-primary-dark);
  color: #fff;
  transform: translateY(-2px);
  box-shadow: 0 8px 20px rgba(65, 143, 222, .4);
}
.btn--accent {
  background: var(--c-accent);
  color: #fff;
  box-shadow: 0 4px 12px rgba(255, 88, 93, .3);
}
.btn--accent:hover {
  background: var(--c-accent-dark);
  color: #fff;
  transform: translateY(-2px);
  box-shadow: 0 8px 20px rgba(255, 88, 93, .4);
}
.btn--ghost {
  background: transparent;
  color: var(--c-text);
  border-color: var(--c-border);
}
.btn--ghost:hover {
  background: var(--c-bg-soft);
  border-color: var(--c-primary);
  color: var(--c-primary);
}
.btn--white {
  background: #fff;
  color: var(--c-primary);
  box-shadow: var(--shadow-md);
}
.btn--white:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-lg);
  color: var(--c-primary-dark);
}
.btn--lg { padding: 16px 36px; font-size: 1.1rem; }
.btn--block { width: 100%; }

/* ---------- 5. 顶部导航 ---------- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(255, 255, 255, .95);
  backdrop-filter: saturate(180%) blur(12px);
  -webkit-backdrop-filter: saturate(180%) blur(12px);
  border-bottom: 1px solid var(--c-border);
}
.nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 68px;
}
.nav__brand {
  display: flex;
  align-items: center;
  gap: 10px;
  font-weight: 800;
  font-size: 1.25rem;
  color: var(--c-text);
}
.nav__brand img { height: 36px; width: auto; }
.nav__brand:hover { color: var(--c-primary); }
.nav__menu {
  display: flex;
  align-items: center;
  gap: 4px;
}
.nav__link {
  display: inline-block;
  padding: 8px 14px;
  font-size: .95rem;
  font-weight: 500;
  color: var(--c-text-soft);
  border-radius: var(--radius-sm);
  transition: all var(--transition);
}
.nav__link:hover { color: var(--c-primary); background: var(--c-primary-light); }
.nav__link.is-active { color: var(--c-primary); font-weight: 600; }
.nav__cta { margin-left: 12px; }
.nav__toggle {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  padding: 8px;
  color: var(--c-text);
}
.nav__toggle svg { width: 26px; height: 26px; }

@media (max-width: 960px) {
  .nav__menu {
    position: fixed;
    top: 68px;
    left: 0;
    right: 0;
    flex-direction: column;
    align-items: stretch;
    gap: 0;
    background: #fff;
    border-top: 1px solid var(--c-border);
    box-shadow: var(--shadow-lg);
    padding: 12px 24px 24px;
    transform: translateY(-12px);
    opacity: 0;
    visibility: hidden;
    transition: all var(--transition);
  }
  .nav__menu.is-open { transform: translateY(0); opacity: 1; visibility: visible; }
  .nav__link { padding: 12px 14px; border-radius: var(--radius-sm); }
  .nav__cta { margin: 12px 0 0; }
  .nav__toggle { display: inline-flex; }
}

/* ---------- 6. Hero ---------- */
.hero {
  position: relative;
  padding: 96px 0 80px;
  background:
    radial-gradient(circle at 15% 20%, rgba(65, 143, 222, .12) 0%, transparent 50%),
    radial-gradient(circle at 85% 80%, rgba(255, 88, 93, .10) 0%, transparent 50%),
    linear-gradient(180deg, #f8fbff 0%, #ffffff 100%);
  overflow: hidden;
}
.hero__grid {
  display: grid;
  grid-template-columns: 1.05fr 1fr;
  gap: 60px;
  align-items: center;
}
.hero__title {
  font-size: clamp(2.2rem, 4.5vw, 3.4rem);
  line-height: 1.15;
  margin-bottom: 20px;
  letter-spacing: -.02em;
}
.hero__title .hl { color: var(--c-primary); }
.hero__title .hl-accent { color: var(--c-accent); }
.hero__lead {
  font-size: 1.15rem;
  color: var(--c-text-soft);
  margin-bottom: 32px;
  max-width: 560px;
}
.hero__actions { display: flex; gap: 14px; flex-wrap: wrap; margin-bottom: 36px; }
.hero__meta {
  display: flex;
  gap: 28px;
  flex-wrap: wrap;
  font-size: .9rem;
  color: var(--c-text-muted);
}
.hero__meta strong { color: var(--c-text); font-size: 1.4rem; font-weight: 700; display: block; }

/* Hero 视觉：纯 CSS + SVG 等距立方体 */
.hero__visual {
  position: relative;
  aspect-ratio: 1 / 1;
  display: flex;
  align-items: center;
  justify-content: center;
}
.hero__visual svg { width: 100%; height: 100%; }
.hero__badge {
  position: absolute;
  background: #fff;
  border-radius: var(--radius);
  padding: 10px 14px;
  box-shadow: var(--shadow-md);
  font-size: .85rem;
  font-weight: 600;
  display: flex;
  align-items: center;
  gap: 8px;
}
.hero__badge--1 { top: 10%; left: 0; color: var(--c-primary); }
.hero__badge--2 { bottom: 14%; right: 4%; color: var(--c-accent); }
.hero__badge--3 { top: 50%; right: -10px; color: var(--c-accent-dark); }
.hero__badge .dot { width: 8px; height: 8px; border-radius: 50%; background: currentColor; }

@media (max-width: 880px) {
  .hero__grid { grid-template-columns: 1fr; gap: 40px; }
  .hero__visual { max-width: 460px; margin: 0 auto; }
}

/* ---------- 7. 通用网格 ---------- */
.grid { display: grid; gap: 24px; }
.grid--2 { grid-template-columns: repeat(2, 1fr); }
.grid--3 { grid-template-columns: repeat(3, 1fr); }
.grid--4 { grid-template-columns: repeat(4, 1fr); }
@media (max-width: 960px) {
  .grid--3, .grid--4 { grid-template-columns: repeat(2, 1fr); }
}
@media (max-width: 640px) {
  .grid--2, .grid--3, .grid--4 { grid-template-columns: 1fr; }
}

/* ---------- 8. 卡片 ---------- */
.card {
  background: #fff;
  border: 1px solid var(--c-border);
  border-radius: var(--radius-lg);
  padding: 28px;
  transition: all var(--transition);
}
.card:hover {
  border-color: var(--c-primary);
  box-shadow: var(--shadow-md);
  transform: translateY(-4px);
}
.card__icon {
  width: 56px;
  height: 56px;
  border-radius: 14px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 26px;
  margin-bottom: 18px;
  background: var(--c-primary-light);
  color: var(--c-primary);
}
.card__icon--accent { background: var(--c-accent-light); color: var(--c-accent); }
.card__icon--dark { background: rgba(26, 43, 60, .08); color: var(--c-bg-deep); }
.card h3 { margin-bottom: 10px; }
.card p { margin: 0; color: var(--c-text-soft); font-size: .95rem; }

/* 特性大卡 */
.feature-card {
  display: flex;
  flex-direction: column;
  gap: 14px;
  background: #fff;
  border: 1px solid var(--c-border);
  border-radius: var(--radius-lg);
  padding: 32px;
  transition: all var(--transition);
  height: 100%;
}
.feature-card:hover {
  border-color: var(--c-primary);
  box-shadow: var(--shadow-lg);
  transform: translateY(-4px);
}
.feature-card__num {
  font-family: var(--font-mono);
  font-size: .9rem;
  font-weight: 700;
  color: var(--c-primary);
  letter-spacing: .08em;
}
.feature-card__title { font-size: 1.3rem; margin-bottom: 6px; }
.feature-card__desc { color: var(--c-text-soft); margin: 0; flex: 1; }
.feature-card__tag {
  display: inline-block;
  font-size: .75rem;
  font-weight: 600;
  padding: 4px 10px;
  border-radius: 999px;
  background: var(--c-primary-light);
  color: var(--c-primary);
}

/* ---------- 9. 使用场景卡片 ---------- */
.usecase {
  position: relative;
  border-radius: var(--radius-lg);
  overflow: hidden;
  background: #fff;
  border: 1px solid var(--c-border);
  transition: all var(--transition);
  min-height: 280px;
  display: flex;
  flex-direction: column;
}
.usecase:hover { transform: translateY(-4px); box-shadow: var(--shadow-lg); }
.usecase__banner {
  height: 140px;
  position: relative;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 3rem;
  color: #fff;
}
.usecase__banner--blue { background: linear-gradient(135deg, #418fde 0%, #2f74b8 100%); }
.usecase__banner--red { background: linear-gradient(135deg, #ff585d 0%, #cb333b 100%); }
.usecase__banner--dark { background: linear-gradient(135deg, #1a2b3c 0%, #2c4358 100%); }
.usecase__banner--mix { background: linear-gradient(135deg, #418fde 0%, #ff585d 100%); }
.usecase__body { padding: 22px 24px 26px; flex: 1; display: flex; flex-direction: column; }
.usecase__title { font-size: 1.15rem; margin-bottom: 8px; }
.usecase__desc { color: var(--c-text-soft); font-size: .92rem; margin: 0 0 14px; flex: 1; }
.usecase__tags { display: flex; flex-wrap: wrap; gap: 6px; }
.usecase__tag {
  font-size: .72rem;
  font-weight: 600;
  padding: 3px 9px;
  border-radius: 999px;
  background: var(--c-bg-soft);
  color: var(--c-text-soft);
}

/* ---------- 10. 用户评价 ---------- */
.testimonial {
  background: #fff;
  border: 1px solid var(--c-border);
  border-radius: var(--radius-lg);
  padding: 32px;
  position: relative;
  height: 100%;
  display: flex;
  flex-direction: column;
}
.testimonial::before {
  content: """;
  position: absolute;
  top: 16px;
  right: 28px;
  font-size: 5rem;
  font-family: Georgia, serif;
  color: var(--c-primary-light);
  line-height: 1;
}
.testimonial__text {
  font-size: 1.02rem;
  line-height: 1.7;
  color: var(--c-text);
  margin: 0 0 22px;
  flex: 1;
  position: relative;
  z-index: 1;
}
.testimonial__author {
  display: flex;
  align-items: center;
  gap: 12px;
}
.testimonial__avatar {
  width: 48px;
  height: 48px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  color: #fff;
  font-size: 1.1rem;
  flex-shrink: 0;
}
.testimonial__avatar--1 { background: linear-gradient(135deg, #418fde, #2f74b8); }
.testimonial__avatar--2 { background: linear-gradient(135deg, #ff585d, #cb333b); }
.testimonial__avatar--3 { background: linear-gradient(135deg, #1a2b3c, #2c4358); }
.testimonial__avatar--4 { background: linear-gradient(135deg, #418fde, #ff585d); }
.testimonial__name { font-weight: 600; font-size: .95rem; }
.testimonial__role { color: var(--c-text-muted); font-size: .82rem; }
.testimonial__rating { color: #f5a623; font-size: .9rem; letter-spacing: 2px; margin-bottom: 10px; }

/* ---------- 11. 数据统计 ---------- */
.stats {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 24px;
  text-align: center;
}
.stats__item .num {
  font-size: clamp(2rem, 4vw, 2.8rem);
  font-weight: 800;
  color: var(--c-primary);
  line-height: 1.1;
  letter-spacing: -.02em;
}
.stats__item .num--accent { color: var(--c-accent); }
.stats__item .num--white { color: #fff; }
.stats__item .label {
  margin-top: 6px;
  color: var(--c-text-soft);
  font-size: .92rem;
}
.section--deep .stats__item .label,
.section--primary .stats__item .label { color: rgba(255, 255, 255, .85); }
@media (max-width: 640px) {
  .stats { grid-template-columns: repeat(2, 1fr); gap: 32px 16px; }
}

/* ---------- 12. 下载区域 ---------- */
.dl-platforms { display: grid; grid-template-columns: repeat(3, 1fr); gap: 22px; }
@media (max-width: 880px) { .dl-platforms { grid-template-columns: 1fr; } }
.dl-card {
  background: #fff;
  border: 1px solid var(--c-border);
  border-radius: var(--radius-lg);
  padding: 30px 28px;
  text-align: center;
  transition: all var(--transition);
}
.dl-card:hover { border-color: var(--c-primary); box-shadow: var(--shadow-md); transform: translateY(-3px); }
.dl-card__icon {
  width: 64px;
  height: 64px;
  margin: 0 auto 16px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 30px;
  border-radius: 16px;
  background: var(--c-primary-light);
  color: var(--c-primary);
}
.dl-card__icon--mac { background: var(--c-accent-light); color: var(--c-accent); }
.dl-card__icon--linux { background: rgba(26, 43, 60, .08); color: var(--c-bg-deep); }
.dl-card__name { font-size: 1.2rem; margin-bottom: 4px; }
.dl-card__ver { font-size: .82rem; color: var(--c-text-muted); margin-bottom: 18px; }
.dl-card__req { font-size: .82rem; color: var(--c-text-muted); margin-top: 14px; padding-top: 14px; border-top: 1px dashed var(--c-border); }

.sysreq-table { width: 100%; border-collapse: collapse; }
.sysreq-table th, .sysreq-table td {
  padding: 14px 16px;
  text-align: left;
  border-bottom: 1px solid var(--c-border);
  font-size: .92rem;
}
.sysreq-table th { background: var(--c-bg-soft); font-weight: 600; color: var(--c-text); }
.sysreq-table td:first-child { font-weight: 600; color: var(--c-text); }
.sysreq-table tr:last-child td { border-bottom: none; }

/* ---------- 13. 学习资源 ---------- */
.learn-card {
  display: flex;
  gap: 18px;
  padding: 22px;
  background: #fff;
  border: 1px solid var(--c-border);
  border-radius: var(--radius);
  transition: all var(--transition);
  height: 100%;
}
.learn-card:hover { border-color: var(--c-primary); box-shadow: var(--shadow-sm); }
.learn-card__icon {
  flex-shrink: 0;
  width: 48px;
  height: 48px;
  border-radius: 12px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 22px;
  background: var(--c-primary-light);
  color: var(--c-primary);
}
.learn-card__body h4 { margin: 0 0 6px; font-size: 1.05rem; }
.learn-card__body p { margin: 0; font-size: .88rem; color: var(--c-text-soft); }
.learn-card__body .meta { font-size: .78rem; color: var(--c-text-muted); margin-top: 6px; }

/* ---------- 14. 步骤时间线 ---------- */
.steps { display: grid; grid-template-columns: repeat(4, 1fr); gap: 24px; counter-reset: step; }
@media (max-width: 880px) { .steps { grid-template-columns: repeat(2, 1fr); } }
@media (max-width: 480px) { .steps { grid-template-columns: 1fr; } }
.step {
  position: relative;
  padding: 24px;
  background: #fff;
  border: 1px solid var(--c-border);
  border-radius: var(--radius-lg);
  counter-increment: step;
}
.step::before {
  content: counter(step, decimal-leading-zero);
  display: inline-block;
  font-family: var(--font-mono);
  font-size: .85rem;
  font-weight: 700;
  color: var(--c-primary);
  background: var(--c-primary-light);
  padding: 4px 10px;
  border-radius: 999px;
  margin-bottom: 12px;
}
.step h4 { margin: 0 0 6px; }
.step p { margin: 0; font-size: .9rem; color: var(--c-text-soft); }

/* ---------- 15. 通用页面 Banner ---------- */
.page-hero {
  background:
    radial-gradient(circle at 80% 20%, rgba(65, 143, 222, .15) 0%, transparent 50%),
    radial-gradient(circle at 20% 80%, rgba(255, 88, 93, .10) 0%, transparent 50%),
    linear-gradient(180deg, #f8fbff 0%, #ffffff 100%);
  padding: 72px 0 56px;
  text-align: center;
}
.page-hero__crumb {
  font-size: .85rem;
  color: var(--c-text-muted);
  margin-bottom: 14px;
}
.page-hero__crumb a { color: var(--c-text-muted); }
.page-hero__crumb a:hover { color: var(--c-primary); }
.page-hero__title { margin-bottom: 14px; }
.page-hero__lead { font-size: 1.1rem; color: var(--c-text-soft); max-width: 720px; margin: 0 auto; }

/* ---------- 16. FAQ ---------- */
.faq { max-width: 820px; margin: 0 auto; }
.faq__item {
  border-bottom: 1px solid var(--c-border);
}
.faq__q {
  width: 100%;
  text-align: left;
  background: none;
  border: none;
  padding: 18px 0;
  font-size: 1.05rem;
  font-weight: 600;
  color: var(--c-text);
  cursor: pointer;
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 16px;
  font-family: inherit;
}
.faq__q:hover { color: var(--c-primary); }
.faq__q .icon { font-size: 1.4rem; color: var(--c-primary); transition: transform var(--transition); flex-shrink: 0; }
.faq__item.is-open .faq__q .icon { transform: rotate(45deg); }
.faq__a {
  max-height: 0;
  overflow: hidden;
  transition: max-height var(--transition);
  color: var(--c-text-soft);
}
.faq__a-inner { padding: 0 0 18px; line-height: 1.7; }
.faq__item.is-open .faq__a { max-height: 600px; }

/* ---------- 17. CTA Banner ---------- */
.cta-banner {
  background: linear-gradient(135deg, var(--c-primary) 0%, var(--c-primary-dark) 100%);
  border-radius: var(--radius-lg);
  padding: 56px 48px;
  color: #fff;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 32px;
  flex-wrap: wrap;
  box-shadow: var(--shadow-lg);
}
.cta-banner h2 { color: #fff; margin: 0 0 8px; }
.cta-banner p { margin: 0; color: rgba(255, 255, 255, .9); }
.cta-banner__actions { display: flex; gap: 14px; flex-wrap: wrap; }
@media (max-width: 720px) {
  .cta-banner { padding: 36px 24px; flex-direction: column; text-align: center; align-items: stretch; }
}

/* ---------- 18. 页脚 ---------- */
.site-footer {
  background: var(--c-bg-deep);
  color: rgba(255, 255, 255, .75);
  padding: 64px 0 24px;
}
.footer-grid {
  display: grid;
  grid-template-columns: 1.4fr repeat(4, 1fr);
  gap: 36px;
  margin-bottom: 40px;
}
@media (max-width: 880px) { .footer-grid { grid-template-columns: 1fr 1fr; } }
@media (max-width: 480px) { .footer-grid { grid-template-columns: 1fr; } }
.footer-brand img { height: 38px; margin-bottom: 14px; }
.footer-brand p { font-size: .9rem; line-height: 1.6; margin: 0 0 16px; }
.footer-col h5 {
  color: #fff;
  font-size: .95rem;
  font-weight: 700;
  margin-bottom: 16px;
  letter-spacing: .02em;
}
.footer-col ul li { margin-bottom: 10px; }
.footer-col a {
  color: rgba(255, 255, 255, .7);
  font-size: .9rem;
}
.footer-col a:hover { color: #fff; }
.footer-social { display: flex; gap: 10px; margin-top: 16px; }
.footer-social a {
  width: 36px; height: 36px;
  border-radius: 50%;
  background: rgba(255, 255, 255, .1);
  display: flex; align-items: center; justify-content: center;
  color: #fff;
  font-size: 16px;
  transition: all var(--transition);
}
.footer-social a:hover { background: var(--c-primary); transform: translateY(-2px); }
.footer-bottom {
  padding-top: 24px;
  border-top: 1px solid rgba(255, 255, 255, .1);
  display: flex;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 12px;
  font-size: .82rem;
  color: rgba(255, 255, 255, .55);
}
.footer-bottom a { color: rgba(255, 255, 255, .55); }
.footer-bottom a:hover { color: #fff; }

/* ---------- 19. 下载弹窗 ---------- */
.modal-overlay {
  position: fixed;
  inset: 0;
  background: rgba(26, 43, 60, .6);
  backdrop-filter: blur(6px);
  -webkit-backdrop-filter: blur(6px);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 1000;
  opacity: 0;
  visibility: hidden;
  transition: all var(--transition);
  padding: 24px;
}
.modal-overlay.is-open { opacity: 1; visibility: visible; }
.modal {
  background: #fff;
  border-radius: var(--radius-lg);
  max-width: 720px;
  width: 100%;
  max-height: 90vh;
  overflow-y: auto;
  box-shadow: var(--shadow-lg);
  transform: translateY(20px) scale(.98);
  transition: transform var(--transition);
}
.modal-overlay.is-open .modal { transform: translateY(0) scale(1); }
.modal__header {
  position: relative;
  padding: 28px 32px 16px;
  text-align: center;
  border-bottom: 1px solid var(--c-border);
}
.modal__title { font-size: 1.4rem; margin: 0 0 6px; }
.modal__sub { color: var(--c-text-soft); font-size: .92rem; margin: 0; }
.modal__close {
  position: absolute;
  top: 18px;
  right: 18px;
  width: 36px;
  height: 36px;
  border-radius: 50%;
  border: none;
  background: var(--c-bg-soft);
  color: var(--c-text);
  font-size: 1.4rem;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all var(--transition);
}
.modal__close:hover { background: var(--c-accent); color: #fff; transform: rotate(90deg); }
.modal__body { padding: 28px 32px 32px; }
.qr-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 24px; }
@media (max-width: 560px) { .qr-grid { grid-template-columns: 1fr; } }
.qr-item {
  text-align: center;
  padding: 22px 18px;
  border: 1px solid var(--c-border);
  border-radius: var(--radius);
  transition: all var(--transition);
}
.qr-item:hover { border-color: var(--c-primary); box-shadow: var(--shadow-sm); }
.qr-item img {
  width: 180px;
  height: 180px;
  margin: 0 auto 14px;
  display: block;
}
.qr-item__name { font-weight: 700; font-size: 1.05rem; margin-bottom: 4px; }
.qr-item__hint { font-size: .82rem; color: var(--c-text-muted); margin: 0 0 12px; }
.qr-item__platform {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-size: .8rem;
  font-weight: 600;
  padding: 4px 10px;
  border-radius: 999px;
  background: var(--c-primary-light);
  color: var(--c-primary);
}
.qr-item__platform--mac { background: var(--c-accent-light); color: var(--c-accent); }
.modal__tips {
  margin-top: 24px;
  padding: 16px 18px;
  background: var(--c-bg-soft);
  border-radius: var(--radius);
  font-size: .85rem;
  color: var(--c-text-soft);
  line-height: 1.7;
}
.modal__tips strong { color: var(--c-text); }

/* ---------- 20. 工具类 ---------- */
.text-center { text-align: center; }
.text-primary { color: var(--c-primary); }
.text-accent { color: var(--c-accent); }
.mt-0 { margin-top: 0; }
.mb-0 { margin-bottom: 0; }
.mt-2 { margin-top: 16px; }
.mb-2 { margin-bottom: 16px; }
.mt-4 { margin-top: 32px; }
.mb-4 { margin-bottom: 32px; }
.flex { display: flex; }
.flex-wrap { flex-wrap: wrap; }
.gap-2 { gap: 16px; }
.items-center { align-items: center; }
.justify-between { justify-content: space-between; }
.hidden { display: none !important; }

/* ---------- 21. 内容区块辅助 ---------- */
.prose { max-width: 820px; margin: 0 auto; }
.prose h2 { margin-top: 1.5em; margin-bottom: .6em; }
.prose h3 { margin-top: 1.4em; margin-bottom: .5em; }
.prose p { color: var(--c-text-soft); line-height: 1.85; }
.prose ul { list-style: disc; padding-left: 1.4em; margin-bottom: 1em; }
.prose ul li { color: var(--c-text-soft); margin-bottom: 6px; }
.prose strong { color: var(--c-text); }

/* 平台徽标列表 */
.platform-list { display: flex; gap: 8px; flex-wrap: wrap; }
.platform-list span {
  font-size: .78rem;
  font-weight: 600;
  padding: 4px 10px;
  border-radius: 6px;
  background: var(--c-bg-soft);
  color: var(--c-text-soft);
}

/* 信息条 */
.info-bar {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 12px 18px;
  background: var(--c-primary-light);
  border-left: 4px solid var(--c-primary);
  border-radius: var(--radius-sm);
  color: var(--c-text);
  font-size: .92rem;
}
.info-bar--accent { background: var(--c-accent-light); border-left-color: var(--c-accent); }