/* ============================================================
   Brand 官网样式 - 设计语言参考 Plaud（白底/黑字/灰辅助/克制阴影）
   ============================================================ */

:root {
  --bg: #ffffff;
  --bg-alt: #f9fafb;
  --ink: #1f1f1f;
  --ink-strong: #1d2939;
  --ink-gray: #667085;
  --ink-light: #98a2b3;
  --line: #ebebeb;
  --card: #ffffff;
  --radius: 12px;
  --radius-sm: 10px;
  --shadow: 0 8px 24px rgba(29, 41, 57, .08);
  --shadow-hover: 0 12px 32px rgba(29, 41, 57, .12);
  --font: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC",
          "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
}

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

html { scroll-behavior: smooth; }

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

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

.container { max-width: 1120px; margin: 0 auto; padding: 0 24px; }

/* ---------- 按钮 ---------- */
.btn {
  display: inline-flex; align-items: center; justify-content: center;
  padding: 10px 24px; border-radius: var(--radius-sm);
  font-size: 15px; font-weight: 600; cursor: pointer;
  border: 1px solid transparent; transition: all .2s ease; white-space: nowrap;
}
.btn-lg { padding: 14px 32px; font-size: 16px; border-radius: var(--radius); }
.btn-dark { background: var(--ink-strong); color: #f9fafb; }
.btn-dark:hover { background: #344054; transform: translateY(-1px); box-shadow: var(--shadow); }
.btn-ghost { border-color: var(--line); color: var(--ink-strong); background: var(--bg); }
.btn-ghost:hover { border-color: var(--ink-strong); }
.btn-light { background: #ffffff; color: var(--ink-strong); }
.btn-light:hover { background: #f2f4f7; transform: translateY(-1px); }
.btn.disabled { background: #f2f4f7; color: var(--ink-light); cursor: not-allowed; pointer-events: none; }

/* ---------- 头部导航 ---------- */
.site-header {
  position: sticky; top: 0; z-index: 100;
  background: rgba(255, 255, 255, .92); backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--line);
}
.nav-wrap { display: flex; align-items: center; gap: 40px; height: 68px; }
.logo { display: flex; align-items: center; }
.nav { display: flex; gap: 32px; margin-left: auto; }
.nav-link { font-size: 15px; color: var(--ink-gray); font-weight: 500; transition: color .2s; }
.nav-link:hover { color: var(--ink-strong); }
.nav-link.active { color: var(--ink-strong); font-weight: 600; }
.btn-nav { margin-left: 8px; }

.nav-toggle { display: none; flex-direction: column; gap: 5px; background: none; border: 0; cursor: pointer; padding: 8px; }
.nav-toggle span { width: 22px; height: 2px; background: var(--ink-strong); border-radius: 2px; transition: all .2s; }

/* 语言切换 */
.lang-switch {
  margin-left: 16px; padding: 6px 14px; border: 1px solid var(--line); border-radius: 999px;
  font-size: 13px; font-weight: 600; color: var(--ink-strong); transition: all .2s;
}
.lang-switch:hover { border-color: var(--ink-strong); background: var(--bg-alt); }

/* ---------- Hero ---------- */
.hero { padding: 96px 0 72px; background:
  radial-gradient(ellipse 80% 60% at 70% -10%, #f2f4f7 0%, transparent 60%), var(--bg); }
.hero-inner { display: grid; grid-template-columns: 1.1fr .9fr; gap: 64px; align-items: center; }
.hero h1 { font-size: clamp(40px, 6vw, 64px); line-height: 1.15; font-weight: 700; letter-spacing: -0.02em; }
.hero-sub { font-size: 18px; color: var(--ink-gray); margin: 24px 0 36px; max-width: 30em; }
.hero-actions { display: flex; gap: 16px; flex-wrap: wrap; }
.hero-platforms { margin-top: 40px; color: var(--ink-light); font-size: 14px; display: flex; gap: 10px; align-items: center; }
.hero-platforms i { font-style: normal; color: var(--line); }

/* ---------- 产品视觉占位（纯 CSS mock） ---------- */
.mock-window { background: var(--card); border: 1px solid var(--line); border-radius: var(--radius); box-shadow: var(--shadow); overflow: hidden; }
.mock-window.small { max-width: 460px; }
.mock-titlebar { display: flex; gap: 8px; padding: 14px 16px; border-bottom: 1px solid var(--line); }
.mock-titlebar span { width: 10px; height: 10px; border-radius: 50%; background: #eaecf0; }
.mock-body { display: flex; min-height: 260px; }
.mock-sidebar { width: 88px; border-right: 1px solid var(--line); background: var(--bg-alt); }
.mock-main { flex: 1; padding: 24px; display: flex; flex-direction: column; gap: 14px; }
.mock-line { height: 12px; border-radius: 6px; background: #eaecf0; }
.mock-line.w45 { width: 45%; } .mock-line.w60 { width: 60%; }
.mock-line.w75 { width: 75%; } .mock-line.w80 { width: 80%; } .mock-line.w90 { width: 90%; }
.mock-block { height: 92px; border-radius: var(--radius-sm); background: linear-gradient(135deg, #f2f4f7, #e4e7ec); margin-top: 8px; }

.mock-phone { width: 240px; margin: 0 auto; background: var(--card); border: 1px solid var(--line); border-radius: 32px; box-shadow: var(--shadow); padding: 12px; }
.mock-notch { width: 80px; height: 6px; border-radius: 3px; background: #eaecf0; margin: 6px auto 16px; }
.mock-screen { display: flex; flex-direction: column; gap: 14px; padding: 4px 8px 16px; }

/* ---------- 区块通用 ---------- */
.section { padding: 88px 0; }
.section-alt { background: var(--bg-alt); }
.section-head { text-align: center; max-width: 560px; margin: 0 auto 56px; }
.section-head h2 { font-size: 32px; font-weight: 700; letter-spacing: -0.01em; }
.section-head p { color: var(--ink-gray); margin-top: 12px; }

.page-head { padding: 72px 0 8px; text-align: center; }
.page-head h1 { font-size: 40px; font-weight: 700; letter-spacing: -0.01em; }
.page-head p { color: var(--ink-gray); margin-top: 12px; font-size: 17px; }

/* ---------- 卡片网格 ---------- */
.grid { display: grid; gap: 24px; }
.grid-3 { grid-template-columns: repeat(3, 1fr); }
.card {
  background: var(--card); border: 1px solid var(--line); border-radius: var(--radius);
  padding: 32px; transition: all .2s ease;
}
.card:hover { border-color: #d0d5dd; box-shadow: var(--shadow-hover); transform: translateY(-2px); }
.card-icon {
  width: 48px; height: 48px; border-radius: var(--radius-sm); background: var(--bg-alt);
  display: flex; align-items: center; justify-content: center; font-size: 22px; margin-bottom: 20px;
}
.card h3 { font-size: 19px; font-weight: 600; margin-bottom: 10px; }
.card p { color: var(--ink-gray); font-size: 15px; }

/* ---------- 数据统计 ---------- */
.stats { display: grid; grid-template-columns: repeat(4, 1fr); gap: 24px; text-align: center; }
.stat strong { font-size: 40px; font-weight: 700; color: var(--ink-strong); display: block; letter-spacing: -0.02em; }
.stat span { color: var(--ink-gray); font-size: 14px; }

/* ---------- 分栏 ---------- */
.split { display: grid; grid-template-columns: 1fr 1fr; gap: 64px; align-items: center; }
.split h2 { font-size: 32px; font-weight: 700; line-height: 1.3; letter-spacing: -0.01em; }
.split > .split-text > p { color: var(--ink-gray); margin: 20px 0; }
.check-list { margin: 8px 0 28px; display: flex; flex-direction: column; gap: 12px; }
.check-list li { padding-left: 28px; position: relative; color: var(--ink); font-size: 15px; }
.check-list li::before {
  content: ""; position: absolute; left: 0; top: 4px; width: 18px; height: 18px; border-radius: 50%;
  background: var(--bg-alt) url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 12 12'%3E%3Cpath d='M2 6.5L4.5 9 10 3.5' stroke='%231d2939' stroke-width='1.8' fill='none' stroke-linecap='round' stroke-linejoin='round'/%3E%3C/svg%3E") center no-repeat;
}

/* ---------- 功能行（产品页） ---------- */
.feature-row { display: grid; grid-template-columns: 1fr 1fr; gap: 64px; align-items: center; margin-bottom: 88px; }
.feature-row:last-child { margin-bottom: 0; }
.feature-row.reverse .feature-media { order: 2; }
.feature-tag {
  display: inline-block; font-size: 13px; font-weight: 600; color: var(--ink-strong);
  background: var(--bg-alt); border-radius: 999px; padding: 4px 14px; margin-bottom: 16px;
}
.feature-text h2 { font-size: 30px; font-weight: 700; margin-bottom: 8px; }
.feature-text > p { color: var(--ink-gray); margin: 12px 0 8px; }

/* ---------- 价值观卡 / 时间线（关于页） ---------- */
.value-cards { display: flex; flex-direction: column; gap: 16px; }
.value-card {
  background: var(--card); border: 1px solid var(--line); border-radius: var(--radius);
  padding: 24px 28px; display: flex; align-items: baseline; gap: 20px;
}
.value-card strong { font-size: 18px; min-width: 3em; }
.value-card span { color: var(--ink-gray); font-size: 15px; }

.timeline { max-width: 640px; margin: 0 auto; }
.tl-item { display: flex; gap: 24px; position: relative; padding-bottom: 40px; }
.tl-item:last-child { padding-bottom: 0; }
.tl-item::before { content: ""; position: absolute; left: 7px; top: 20px; bottom: 0; width: 2px; background: var(--line); }
.tl-item:last-child::before { display: none; }
.tl-dot { width: 16px; height: 16px; border-radius: 50%; background: var(--ink-strong); border: 3px solid #fff; box-shadow: 0 0 0 1px var(--line); flex-shrink: 0; margin-top: 4px; }
.tl-body time { font-size: 13px; color: var(--ink-light); font-weight: 600; letter-spacing: .04em; }
.tl-body h3 { font-size: 18px; font-weight: 600; margin: 4px 0; }
.tl-body p { color: var(--ink-gray); font-size: 15px; }

/* ---------- CTA ---------- */
.section-cta { padding: 88px 0; }
.cta-box {
  background: var(--ink-strong); border-radius: 20px; text-align: center;
  padding: 72px 32px; color: #fff;
}
.cta-box h2 { font-size: 34px; font-weight: 700; letter-spacing: -0.01em; }
.cta-box p { color: rgba(255, 255, 255, .72); margin: 14px 0 32px; }

/* ---------- 下载页 ---------- */
.dl-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(320px, 1fr)); gap: 24px; margin-bottom: 56px; }

.dl-card {
  background: var(--card); border: 1px solid var(--line); border-radius: var(--radius);
  padding: 28px; display: flex; flex-direction: column; gap: 16px; transition: all .2s ease; position: relative;
}
.dl-card:hover { border-color: #d0d5dd; box-shadow: var(--shadow-hover); }
.dl-card.current { border-color: var(--ink-strong); box-shadow: var(--shadow); }
.dl-card .current-badge {
  position: absolute; top: -12px; right: 20px; background: var(--ink-strong); color: #fff;
  font-size: 12px; font-weight: 600; padding: 3px 12px; border-radius: 999px;
}
.dl-head { display: flex; align-items: center; gap: 14px; }
.dl-platform-icon { width: 44px; height: 44px; border-radius: var(--radius-sm); background: var(--bg-alt); display: flex; align-items: center; justify-content: center; }
.dl-platform-icon svg { width: 24px; height: 24px; }
.dl-head h3 { font-size: 18px; font-weight: 600; }
.dl-head p { font-size: 13px; color: var(--ink-gray); }
.dl-meta { display: flex; gap: 16px; font-size: 13px; color: var(--ink-gray); flex-wrap: wrap; }
.dl-meta b { color: var(--ink); font-weight: 600; }
.dl-btn { margin-top: 4px; }
.dl-channels { border-top: 1px dashed var(--line); padding-top: 14px; display: flex; flex-direction: column; gap: 8px; }
.dl-channels summary { font-size: 13px; color: var(--ink-gray); cursor: pointer; user-select: none; }
.dl-channels summary:hover { color: var(--ink-strong); }
.dl-channel { display: flex; justify-content: space-between; align-items: center; font-size: 14px; padding: 6px 0; }
.dl-channel a { color: var(--ink-strong); font-weight: 500; border-bottom: 1px solid transparent; }
.dl-channel a:hover { border-bottom-color: var(--ink-strong); }
.dl-channel .soon { color: var(--ink-light); font-size: 13px; }
.dl-detail-toggle { font-size: 13px; color: var(--ink-gray); cursor: pointer; user-select: none; }
.dl-detail { font-size: 13px; color: var(--ink-gray); border-top: 1px dashed var(--line); padding-top: 12px; }
.dl-detail code { background: var(--bg-alt); padding: 2px 8px; border-radius: 6px; font-size: 12px; word-break: break-all; color: var(--ink); }
.dl-detail .changelog { margin: 8px 0 4px; }
.dl-detail .changelog li { padding-left: 14px; position: relative; }
.dl-detail .changelog li::before { content: "·"; position: absolute; left: 2px; }

.dl-note { background: var(--bg-alt); border-radius: var(--radius); padding: 28px 32px; }
.dl-note h3 { font-size: 16px; font-weight: 600; margin-bottom: 12px; }
.dl-note ul { display: flex; flex-direction: column; gap: 8px; }
.dl-note li { font-size: 14px; color: var(--ink-gray); padding-left: 16px; position: relative; }
.dl-note li::before { content: "·"; position: absolute; left: 2px; color: var(--ink-strong); font-weight: 700; }

/* ---------- 联系页 ---------- */
.contact-grid { max-width: 900px; }
.contact-cards { display: grid; grid-template-columns: repeat(2, 1fr); gap: 24px; }
.contact-card {
  background: var(--card); border: 1px solid var(--line); border-radius: var(--radius);
  padding: 32px; transition: all .2s ease;
}
.contact-card:hover { border-color: #d0d5dd; box-shadow: var(--shadow-hover); }
.contact-card h3 { font-size: 18px; font-weight: 600; margin-bottom: 6px; }
.contact-card > p { color: var(--ink-gray); font-size: 14px; margin-bottom: 16px; }
.contact-link { font-weight: 600; color: var(--ink-strong); font-size: 15px; }
.contact-link:hover { text-decoration: underline; }
.contact-link.muted { color: var(--ink-light); font-weight: 400; }
.qr-placeholder {
  width: 140px; height: 140px; border: 1px dashed #d0d5dd; border-radius: var(--radius-sm);
  display: flex; align-items: center; justify-content: center; text-align: center;
  color: var(--ink-light); font-size: 13px; background: var(--bg-alt);
}

/* ---------- 页脚 ---------- */
.site-footer { background: var(--bg-alt); border-top: 1px solid var(--line); padding: 56px 0 0; margin-top: 40px; }
.footer-grid { display: grid; grid-template-columns: 2fr 1fr 1fr 1fr; gap: 40px; padding-bottom: 48px; }
.footer-brand img { margin-bottom: 12px; }
.footer-slogan { color: var(--ink-gray); font-size: 14px; }
.footer-col h4 { font-size: 14px; font-weight: 600; margin-bottom: 16px; color: var(--ink-strong); }
.footer-col a { display: block; font-size: 14px; color: var(--ink-gray); margin-bottom: 10px; transition: color .2s; }
.footer-col a:hover { color: var(--ink-strong); }
.footer-bottom {
  border-top: 1px solid var(--line); padding: 20px 0;
  display: flex; justify-content: space-between; align-items: center; flex-wrap: wrap; gap: 8px;
}
.footer-bottom p, .footer-bottom a { font-size: 13px; color: var(--ink-light); }
.footer-bottom a:hover { color: var(--ink-strong); }

/* ---------- 404 ---------- */
.center-page { min-height: 100vh; display: flex; align-items: center; justify-content: center; }
.error-box { text-align: center; }
.error-box h1 { font-size: 88px; font-weight: 700; color: var(--ink-strong); letter-spacing: -0.04em; }
.error-box p { color: var(--ink-gray); margin: 12px 0 28px; }

/* ---------- 入场动画 ---------- */
.reveal { opacity: 0; transform: translateY(24px); transition: opacity .6s ease, transform .6s ease; }
.reveal.visible { opacity: 1; transform: none; }
@media (prefers-reduced-motion: reduce) {
  .reveal { opacity: 1; transform: none; transition: none; }
}

/* ---------- 响应式 ---------- */
@media (max-width: 960px) {
  .hero-inner, .split, .feature-row { grid-template-columns: 1fr; gap: 40px; }
  .feature-row.reverse .feature-media { order: 0; }
  .hero-visual { order: -1; }
  .grid-3 { grid-template-columns: 1fr 1fr; }
  .stats { grid-template-columns: repeat(2, 1fr); gap: 40px; }
  .footer-grid { grid-template-columns: 1fr 1fr; }
}

@media (max-width: 640px) {
  .section { padding: 64px 0; }
  .hero { padding: 56px 0 48px; }
  .grid-3 { grid-template-columns: 1fr; }
  .contact-cards { grid-template-columns: 1fr; }
  .stats { grid-template-columns: repeat(2, 1fr); }
  .footer-grid { grid-template-columns: 1fr; gap: 28px; }
  .footer-bottom { flex-direction: column; text-align: center; }

  /* 移动端导航抽屉 */
  .nav {
    position: fixed; top: 68px; left: 0; right: 0;
    background: #fff; border-bottom: 1px solid var(--line);
    flex-direction: column; gap: 0; padding: 8px 24px 16px;
    transform: translateY(-8px); opacity: 0; pointer-events: none;
    transition: all .25s ease; margin-left: 0;
  }
  .nav.open { transform: none; opacity: 1; pointer-events: auto; }
  .nav-link { padding: 12px 0; font-size: 16px; }
  .btn-nav { display: none; }
  .nav-toggle { display: flex; margin-left: auto; }
  .nav-toggle.active span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
  .nav-toggle.active span:nth-child(2) { opacity: 0; }
  .nav-toggle.active span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }
}