/* ══════════════════════════════════════════
   Surf 品牌首页样式
   色板：科技蓝 #1A73E8 · 琥珀金 #C49A6C
        浪花白 #F5F6FA · 深邃灰 #2C2C2C
   ══════════════════════════════════════════ */

:root {
  --bg: #f5f6fa;
  --panel: #ffffff;
  --panel-2: #fafbfd;
  --border: #e6e9f0;
  --border-strong: #d5dae5;
  --text: #1a1a1a;
  --text-2: #3c4043;
  --text-3: #5f6368;
  --accent: #1a73e8;
  --accent-deep: #0f2a5c;
  --accent-soft: #e8f0fe;
  --gold: #c49a6c;
  --gold-ink: #a17c50;
  --gold-soft: #f7f0e7;
  --ok: #1e7a46;
  --radius: 14px;
  --shadow: 0 1px 2px rgba(16, 24, 40, 0.04), 0 1px 3px rgba(16, 24, 40, 0.06);
  --shadow-md: 0 4px 16px rgba(16, 24, 40, 0.07);
  --shadow-lg: 0 16px 44px rgba(16, 24, 40, 0.11);

  --font-serif: "Noto Serif SC", "Source Han Serif SC", "Songti SC", "STSong", SimSun, serif;
  --font-sans: "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", "Noto Sans SC",
    "Source Han Sans SC", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  --mono: ui-monospace, "SF Mono", Consolas, "Liberation Mono", monospace;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.75;
  -webkit-font-smoothing: antialiased;
}

a {
  color: inherit;
  text-decoration: none;
}

code {
  font-family: var(--mono);
  font-size: 0.9em;
  background: var(--accent-soft);
  color: var(--accent-deep);
  padding: 1px 6px;
  border-radius: 5px;
}

.wrap {
  max-width: 1160px;
  margin: 0 auto;
  padding: 0 24px;
}

.wrap.narrow {
  max-width: 820px;
}

.center {
  text-align: center;
}

/* ── 导航 ─────────────────────────────── */
.nav {
  position: sticky;
  top: 0;
  z-index: 50;
  background: rgba(255, 255, 255, 0.88);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--border);
}

.nav-inner {
  max-width: 1160px;
  margin: 0 auto;
  padding: 13px 24px;
  display: flex;
  align-items: center;
  gap: 28px;
}

.brand {
  display: flex;
  align-items: center;
  gap: 9px;
  flex: 0 0 auto;
}

.logo {
  width: 34px;
  height: 34px;
  border-radius: 10px;
  background: linear-gradient(135deg, #eaf1fd 0%, #fbf5ec 100%);
  border: 1px solid #dfe6f5;
  display: grid;
  place-items: center;
  flex: 0 0 34px;
}

.logo.small {
  width: 28px;
  height: 28px;
  flex: 0 0 28px;
  border-radius: 8px;
}

.brand-name {
  font-size: 19px;
  font-weight: 600;
  letter-spacing: 0.01em;
  color: var(--accent-deep);
}

.brand-sub {
  font-family: var(--font-serif);
  font-size: 12px;
  color: var(--gold-ink);
  border-left: 1px solid var(--border-strong);
  padding-left: 9px;
  margin-left: 1px;
}

.nav-links {
  display: flex;
  gap: 24px;
  flex: 1;
  font-size: 14.5px;
  color: var(--text-2);
}

.nav-links a {
  transition: color 0.15s;
}

.nav-links a:hover {
  color: var(--accent);
}

.btn-nav {
  flex: 0 0 auto;
  font-size: 14.5px;
  font-weight: 550;
  color: #fff;
  background: var(--accent);
  padding: 8px 18px;
  border-radius: 9px;
  transition: background 0.15s, transform 0.15s;
}

.btn-nav:hover {
  background: #1557b8;
  transform: translateY(-1px);
}

/* ── Hero ─────────────────────────────── */
.hero {
  padding: 72px 0 84px;
  background:
    radial-gradient(900px 420px at 12% -5%, rgba(26, 115, 232, 0.09), transparent 62%),
    radial-gradient(700px 380px at 92% 8%, rgba(196, 154, 108, 0.1), transparent 60%),
    var(--panel);
  border-bottom: 1px solid var(--border);
}

.hero-inner {
  max-width: 1160px;
  margin: 0 auto;
  padding: 0 24px;
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 56px;
  align-items: center;
}

.eyebrow {
  display: inline-block;
  font-family: var(--font-serif);
  font-size: 13px;
  letter-spacing: 0.14em;
  color: var(--gold-ink);
  background: var(--gold-soft);
  padding: 4px 13px;
  border-radius: 999px;
  margin: 0 0 20px;
}

.hero h1 {
  font-family: var(--font-serif);
  font-size: 50px;
  line-height: 1.24;
  font-weight: 700;
  letter-spacing: -0.01em;
  margin: 0 0 14px;
  color: var(--text);
}

.hero h1 .hl {
  color: var(--accent);
}

.hero-slogan {
  font-family: var(--font-serif);
  font-size: 19px;
  letter-spacing: 0.09em;
  color: var(--gold-ink);
  margin: 0 0 22px;
}

.hero-desc {
  font-size: 16.5px;
  line-height: 1.85;
  color: var(--text-2);
  margin: 0 0 30px;
  max-width: 520px;
}

.hero-desc strong {
  color: var(--text);
  font-weight: 600;
}

.hero-actions {
  display: flex;
  gap: 13px;
  flex-wrap: wrap;
  margin-bottom: 20px;
}

.btn-primary {
  display: inline-block;
  font-size: 16px;
  font-weight: 550;
  color: #fff;
  background: var(--accent);
  padding: 12px 26px;
  border-radius: 10px;
  box-shadow: 0 4px 14px rgba(26, 115, 232, 0.26);
  transition: all 0.16s;
}

.btn-primary:hover {
  background: #1557b8;
  transform: translateY(-2px);
  box-shadow: 0 7px 20px rgba(26, 115, 232, 0.32);
}

.btn-primary.big {
  font-size: 17px;
  padding: 14px 34px;
  margin-top: 8px;
}

.btn-ghost {
  display: inline-block;
  font-size: 16px;
  font-weight: 500;
  color: var(--text-2);
  background: var(--panel);
  border: 1px solid var(--border-strong);
  padding: 12px 24px;
  border-radius: 10px;
  transition: all 0.16s;
}

.btn-ghost:hover {
  border-color: var(--accent);
  color: var(--accent);
  background: var(--accent-soft);
}

.hero-note {
  font-size: 13.5px;
  color: var(--text-3);
  margin: 0;
}

/* Hero 视觉：浏览器模拟窗口 */
.browser-mock {
  background: var(--panel);
  border: 1px solid var(--border-strong);
  border-radius: 13px;
  overflow: hidden;
  box-shadow: var(--shadow-lg);
}

.mock-bar {
  display: flex;
  align-items: center;
  gap: 7px;
  padding: 11px 14px;
  background: var(--panel-2);
  border-bottom: 1px solid var(--border);
}

.dot-r,
.dot-y,
.dot-g {
  width: 10px;
  height: 10px;
  border-radius: 50%;
  flex: 0 0 10px;
}

.dot-r {
  background: #ff5f57;
}
.dot-y {
  background: #febc2e;
}
.dot-g {
  background: #28c840;
}

.mock-url {
  margin-left: 10px;
  font-size: 12.5px;
  color: var(--text-3);
  font-family: var(--mono);
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.mock-body {
  padding: 18px 16px 20px;
}

.mock-line {
  display: flex;
  align-items: flex-start;
  gap: 11px;
  padding: 9px 0;
  border-bottom: 1px dashed var(--border);
}

.mock-line:last-of-type {
  border-bottom: none;
}

.mock-step {
  flex: 0 0 22px;
  height: 22px;
  border-radius: 6px;
  background: var(--accent-soft);
  color: var(--accent);
  font-size: 12px;
  font-weight: 700;
  display: grid;
  place-items: center;
}

.mock-step.ok {
  background: #e7f4ec;
  color: var(--ok);
}

.mock-thought {
  font-size: 14.5px;
  color: var(--text-2);
  line-height: 1.6;
}

.mock-line.final .mock-thought {
  color: var(--ok);
  font-weight: 550;
}

.mock-elements {
  margin-top: 14px;
  padding-top: 14px;
  border-top: 1px solid var(--border);
  display: flex;
  flex-wrap: wrap;
  gap: 7px;
}

.el {
  font-family: var(--mono);
  font-size: 11.5px;
  color: var(--accent);
  background: var(--accent-soft);
  padding: 3px 9px;
  border-radius: 6px;
}

.el.dim {
  color: var(--text-3);
  background: var(--panel-2);
}

/* ── 通用区块 ─────────────────────────── */
.section {
  padding: 78px 0;
}

.section.alt {
  background: var(--panel);
  border-top: 1px solid var(--border);
  border-bottom: 1px solid var(--border);
}

.sec-head {
  margin-bottom: 46px;
  max-width: 700px;
}

.sec-eyebrow {
  font-family: var(--font-serif);
  font-size: 13px;
  letter-spacing: 0.14em;
  color: var(--gold-ink);
  margin: 0 0 10px;
}

.sec-head h2 {
  font-family: var(--font-serif);
  font-size: 34px;
  line-height: 1.4;
  font-weight: 700;
  margin: 0 0 14px;
  letter-spacing: -0.005em;
}

.sec-desc {
  font-size: 16px;
  color: var(--text-2);
  line-height: 1.85;
  margin: 0;
}

/* ── 功能模块 ─────────────────────────── */
.module-grid {
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  gap: 16px;
}

.module-card {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 22px 18px;
  box-shadow: var(--shadow);
  transition: all 0.18s;
}

.module-card:hover {
  transform: translateY(-3px);
  box-shadow: var(--shadow-md);
  border-color: #c7d8f7;
}

.mod-icon {
  font-size: 25px;
  color: var(--accent);
  margin-bottom: 11px;
  line-height: 1;
}

.module-card h3 {
  font-size: 17px;
  font-weight: 650;
  margin: 0 0 4px;
  color: var(--accent-deep);
  letter-spacing: 0.01em;
}

.mod-role {
  font-family: var(--font-serif);
  font-size: 13px;
  color: var(--gold-ink);
  margin: 0 0 11px;
}

.mod-desc {
  font-size: 14px;
  color: var(--text-2);
  line-height: 1.75;
  margin: 0;
}

/* ── 应用场景 ─────────────────────────── */
.scene-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 18px;
}

.scene-card {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 24px 22px;
  transition: all 0.18s;
}

.scene-card:hover {
  background: var(--panel);
  border-color: #c7d8f7;
  box-shadow: var(--shadow-md);
}

.scene-card h4 {
  font-size: 17.5px;
  font-weight: 620;
  margin: 0 0 10px;
  color: var(--text);
}

.scene-card p {
  font-size: 14.5px;
  color: var(--text-2);
  line-height: 1.8;
  margin: 0 0 12px;
}

.scene-eg {
  font-family: var(--mono);
  font-size: 12.5px !important;
  color: var(--accent) !important;
  background: var(--accent-soft);
  padding: 8px 11px;
  border-radius: 7px;
  margin: 0 !important;
  line-height: 1.6 !important;
}

/* ── 为什么是 Surf ────────────────────── */
.why-list {
  display: flex;
  flex-direction: column;
  gap: 22px;
}

.why-item {
  display: flex;
  gap: 24px;
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 26px 28px;
  box-shadow: var(--shadow);
}

.why-num {
  font-family: var(--font-serif);
  font-size: 30px;
  font-weight: 700;
  color: var(--gold);
  flex: 0 0 auto;
  line-height: 1.2;
}

.why-item h3 {
  font-size: 19px;
  font-weight: 620;
  margin: 0 0 9px;
  color: var(--text);
}

.why-item p {
  font-size: 15.5px;
  color: var(--text-2);
  line-height: 1.85;
  margin: 0;
}

/* ── 对比表 ───────────────────────────── */
.table-wrap {
  overflow-x: auto;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--panel);
  box-shadow: var(--shadow);
}

.cmp-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 15px;
  min-width: 660px;
}

.cmp-table th,
.cmp-table td {
  padding: 14px 16px;
  text-align: center;
  border-bottom: 1px solid var(--border);
}

.cmp-table th:first-child,
.cmp-table td:first-child {
  text-align: left;
  font-weight: 550;
  color: var(--text);
}

.cmp-table thead th {
  background: var(--panel-2);
  font-size: 14px;
  font-weight: 600;
  color: var(--text-2);
  border-bottom: 1px solid var(--border-strong);
}

.cmp-table tbody tr:last-child td {
  border-bottom: none;
}

.cmp-table tbody tr:hover {
  background: var(--panel-2);
}

.cmp-table .hi {
  background: var(--accent-soft);
  color: var(--accent-deep);
  font-weight: 650;
}

.cmp-table thead .hi {
  background: #d9e6fd;
  color: var(--accent-deep);
  font-weight: 700;
}

.table-note {
  font-size: 13px;
  color: var(--text-3);
  margin: 14px 0 0;
}

/* ── 工作原理 ─────────────────────────── */
.flow {
  display: flex;
  align-items: stretch;
  gap: 12px;
  margin-bottom: 34px;
}

.flow-step {
  flex: 1;
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 22px 18px;
  text-align: center;
  box-shadow: var(--shadow);
}

.flow-num {
  width: 32px;
  height: 32px;
  margin: 0 auto 12px;
  border-radius: 9px;
  background: var(--accent);
  color: #fff;
  font-size: 15px;
  font-weight: 700;
  display: grid;
  place-items: center;
}

.flow-step h4 {
  font-size: 17px;
  font-weight: 620;
  margin: 0 0 8px;
}

.flow-step p {
  font-size: 14px;
  color: var(--text-2);
  line-height: 1.75;
  margin: 0;
}

.flow-arrow {
  display: grid;
  place-items: center;
  color: var(--border-strong);
  font-size: 20px;
  flex: 0 0 auto;
}

.safety-note {
  background: var(--gold-soft);
  border: 1px solid #ecdcc8;
  border-radius: var(--radius);
  padding: 18px 22px;
  font-size: 15px;
  line-height: 1.85;
  color: var(--text-2);
}

.safety-note strong {
  color: var(--gold-ink);
}

/* ── FAQ ──────────────────────────────── */
.faq-list {
  display: flex;
  flex-direction: column;
  gap: 11px;
}

.faq-item {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
  box-shadow: var(--shadow);
}

.faq-item summary {
  cursor: pointer;
  padding: 17px 22px;
  font-size: 16.5px;
  font-weight: 550;
  color: var(--text);
  list-style: none;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 14px;
  transition: background 0.15s;
}

.faq-item summary::-webkit-details-marker {
  display: none;
}

.faq-item summary::after {
  content: "＋";
  color: var(--accent);
  font-size: 19px;
  font-weight: 400;
  flex: 0 0 auto;
}

.faq-item[open] summary::after {
  content: "－";
}

.faq-item summary:hover {
  background: var(--panel-2);
}

.faq-item p {
  padding: 0 22px;
  font-size: 15px;
  color: var(--text-2);
  line-height: 1.9;
  margin: 0 0 14px;
}

.faq-item p:first-of-type {
  padding-top: 4px;
}

/* ── 结尾 CTA ─────────────────────────── */
.cta {
  padding: 84px 0;
  background:
    radial-gradient(700px 320px at 50% 0%, rgba(26, 115, 232, 0.1), transparent 65%),
    var(--panel);
  border-top: 1px solid var(--border);
}

.cta h2 {
  font-family: var(--font-serif);
  font-size: 36px;
  font-weight: 700;
  margin: 0 0 14px;
  letter-spacing: -0.005em;
}

.cta p {
  font-size: 16.5px;
  color: var(--text-2);
  line-height: 1.85;
  margin: 0 0 22px;
}

.cta-note {
  font-size: 13.5px !important;
  color: var(--text-3) !important;
  margin: 18px 0 0 !important;
}

/* ── 页脚 ─────────────────────────────── */
.footer {
  padding: 38px 0;
  background: var(--accent-deep);
  color: #c9d6ea;
}

.footer-inner {
  display: flex;
  align-items: center;
  gap: 26px;
  flex-wrap: wrap;
}

.footer-brand {
  display: flex;
  align-items: center;
  gap: 11px;
}

.footer-brand .logo {
  background: rgba(255, 255, 255, 0.1);
  border-color: rgba(255, 255, 255, 0.16);
}

.footer-name {
  font-size: 16px;
  font-weight: 600;
  color: #fff;
  margin: 0;
}

.footer-slogan {
  font-family: var(--font-serif);
  font-size: 12.5px;
  color: var(--gold);
  margin: 1px 0 0;
  letter-spacing: 0.06em;
}

.footer-links {
  display: flex;
  gap: 22px;
  font-size: 14.5px;
}

.footer-links a:hover {
  color: #fff;
}

.footer-copy {
  font-size: 13px;
  color: #8fa3c4;
  margin: 0;
  width: 100%;
  padding-top: 18px;
  border-top: 1px solid rgba(255, 255, 255, 0.1);
}

/* ── 响应式 ───────────────────────────── */
@media (max-width: 980px) {
  .hero-inner {
    grid-template-columns: 1fr;
    gap: 40px;
  }
  .hero h1 {
    font-size: 38px;
  }
  .module-grid {
    grid-template-columns: repeat(2, 1fr);
  }
  .scene-grid {
    grid-template-columns: repeat(2, 1fr);
  }
  .flow {
    flex-wrap: wrap;
  }
  .flow-step {
    flex: 1 1 40%;
  }
  .flow-arrow {
    display: none;
  }
  .nav-links {
    display: none;
  }
}

@media (max-width: 620px) {
  .hero {
    padding: 48px 0 56px;
  }
  .hero h1 {
    font-size: 31px;
  }
  .sec-head h2 {
    font-size: 26px;
  }
  .cta h2 {
    font-size: 27px;
  }
  .module-grid,
  .scene-grid {
    grid-template-columns: 1fr;
  }
  .why-item {
    flex-direction: column;
    gap: 12px;
  }
}

/* ── 语言切换器（右上角）───────────────── */
.lang-switcher {
  position: relative;
  display: inline-block;
  font-size: 14px;
  line-height: 1;
}

.lang-current {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  background: var(--panel-2);
  border: 1px solid var(--border);
  border-radius: 999px;
  padding: 6px 13px;
  font-family: inherit;
  font-size: 13.5px;
  color: var(--text-2);
  cursor: pointer;
  transition: border-color 0.15s, background 0.15s, color 0.15s;
  white-space: nowrap;
}

.lang-current:hover {
  border-color: var(--border-strong);
  color: var(--text);
}

.lang-current svg {
  color: var(--text-3);
  flex: 0 0 auto;
}

.lang-current[aria-expanded="true"] {
  border-color: var(--accent);
  color: var(--accent);
}

.lang-dropdown {
  position: absolute;
  top: calc(100% + 8px);
  right: 0;
  min-width: 158px;
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 12px;
  box-shadow: 0 12px 32px rgba(16, 24, 40, 0.12);
  padding: 6px;
  z-index: 200;
  display: flex;
  flex-direction: column;
  gap: 2px;
  animation: langPop 0.14s ease-out;
}

.lang-dropdown[hidden] {
  display: none;
}

@keyframes langPop {
  from { opacity: 0; transform: translateY(-4px); }
  to { opacity: 1; transform: none; }
}

.lang-option {
  display: flex;
  align-items: center;
  justify-content: space-between;
  width: 100%;
  text-align: left;
  background: none;
  border: none;
  border-radius: 8px;
  padding: 9px 12px;
  font-family: inherit;
  font-size: 14px;
  color: var(--text-2);
  cursor: pointer;
  transition: background 0.12s, color 0.12s;
}

.lang-option:hover {
  background: var(--accent-soft);
  color: var(--accent);
}

.lang-option.active {
  background: var(--accent-soft);
  color: var(--accent);
  font-weight: 600;
}

.lang-option.active::after {
  content: "✓";
  font-size: 12px;
  color: var(--accent);
}