/* ============================================
   快连官网 - 全局样式表
   纯CSS背景差异化 · 移动端适配 · 必应SEO友好
   ============================================ */

/* ---------- Reset & Base ---------- */
*,
*::before,
*::after { margin: 0; padding: 0; box-sizing: border-box; }

:root {
  --color-bg: #0a0e1a;
  --color-bg-alt: #0f1424;
  --color-bg-card: #141a2e;
  --color-primary: #2d7ff9;
  --color-primary-light: #5aa0ff;
  --color-accent: #00d4aa;
  --color-text: #e4e8f1;
  --color-text-muted: #8b94a7;
  --color-border: #1e2540;
  --color-success: #00d4aa;
  --color-warning: #ffb800;
  --color-danger: #ff4d6d;
  --radius: 12px;
  --radius-lg: 16px;
  --shadow: 0 4px 24px rgba(0,0,0,.25);
  --shadow-lg: 0 8px 40px rgba(0,0,0,.35);
  --max-width: 1160px;
  --transition: .25s ease;
}

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

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC",
    "Hiragino Sans GB", "Microsoft YaHei", "Helvetica Neue", Helvetica, Arial,
    sans-serif;
  background: var(--color-bg);
  color: var(--color-text);
  line-height: 1.75;
  font-size: 16px;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

a { color: var(--color-primary-light); text-decoration: none; transition: color var(--transition); }
a:hover { color: var(--color-accent); }

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

ul, ol { list-style: none; }

/* ---------- Layout ---------- */
.container { max-width: var(--max-width); margin: 0 auto; padding: 0 24px; }

section { padding: 64px 0; position: relative; }

/* ---------- Typography ---------- */
h1, h2, h3, h4 { font-weight: 700; line-height: 1.3; color: #fff; }
h1 { font-size: clamp(2rem, 5vw, 3.2rem); letter-spacing: -.02em; }
h2 { font-size: clamp(1.5rem, 3.5vw, 2.2rem); margin-bottom: 16px; }
h3 { font-size: 1.25rem; margin-bottom: 10px; }
h4 { font-size: 1.05rem; margin-bottom: 8px; }

p { margin-bottom: 14px; color: var(--color-text-muted); }

.section-tag {
  display: inline-block;
  font-size: .8rem;
  font-weight: 600;
  letter-spacing: .12em;
  text-transform: uppercase;
  color: var(--color-accent);
  background: rgba(0,212,170,.1);
  padding: 4px 14px;
  border-radius: 20px;
  margin-bottom: 14px;
}

.section-head { text-align: center; margin-bottom: 44px; }
.section-head p { max-width: 640px; margin: 0 auto; }

/* ---------- Buttons ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 13px 28px;
  border-radius: var(--radius);
  font-weight: 600;
  font-size: .95rem;
  cursor: pointer;
  border: none;
  transition: transform var(--transition), box-shadow var(--transition), background var(--transition);
  text-decoration: none;
  white-space: nowrap;
}
.btn-primary { background: linear-gradient(135deg, var(--color-primary), #1a6fd0); color: #fff; box-shadow: 0 4px 16px rgba(45,127,249,.35); }
.btn-primary:hover { transform: translateY(-2px); box-shadow: 0 6px 24px rgba(45,127,249,.5); color: #fff; }
.btn-accent { background: linear-gradient(135deg, var(--color-accent), #00b894); color: #04120e; }
.btn-accent:hover { transform: translateY(-2px); color: #04120e; }
.btn-outline { background: transparent; color: var(--color-text); border: 2px solid var(--color-border); }
.btn-outline:hover { border-color: var(--color-primary); color: #fff; }
.btn-sm { padding: 9px 18px; font-size: .85rem; }

/* ---------- Header ---------- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(10,14,26,.85);
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
  border-bottom: 1px solid var(--color-border);
}
.nav-wrap { display: flex; align-items: center; justify-content: space-between; height: 68px; }
.logo { font-size: 1.4rem; font-weight: 800; color: #fff; letter-spacing: -.02em; }
.logo span { color: var(--color-primary); }
.nav-links { display: flex; gap: 28px; align-items: center; }
.nav-links a { color: var(--color-text-muted); font-size: .92rem; font-weight: 500; }
.nav-links a:hover, .nav-links a.active { color: #fff; }
.nav-cta { display: flex; gap: 10px; align-items: center; }
.mobile-toggle { display: none; background: none; border: none; color: #fff; font-size: 1.5rem; cursor: pointer; }

/* ---------- Footer ---------- */
.site-footer {
  background: #060912;
  padding: 48px 0 28px;
  border-top: 1px solid var(--color-border);
  margin-top: 0;
}
.footer-grid { display: grid; grid-template-columns: 2fr 1fr 1fr 1fr; gap: 36px; margin-bottom: 32px; }
.footer-brand p { font-size: .88rem; max-width: 320px; }
.footer-col h4 { font-size: .9rem; color: #fff; margin-bottom: 14px; }
.footer-col ul li { margin-bottom: 8px; }
.footer-col ul li a { font-size: .88rem; color: var(--color-text-muted); }
.footer-col ul li a:hover { color: var(--color-primary-light); }
.footer-bottom {
  border-top: 1px solid var(--color-border);
  padding-top: 20px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: .82rem;
  color: var(--color-text-muted);
  flex-wrap: wrap;
  gap: 10px;
}
.footer-bottom .update-date { color: var(--color-accent); font-weight: 500; }

/* ============================================
   BACKGROUND VARIANTS — 纯CSS板块背景差异化
   ============================================ */

/* 1. 纯色深底 */
.bg-solid { background: var(--color-bg); }

/* 2. 径向光晕底 */
.bg-radial {
  background: var(--color-bg);
  overflow: hidden;
}
.bg-radial::before {
  content: "";
  position: absolute;
  top: -200px; right: -160px;
  width: 560px; height: 560px;
  background: radial-gradient(circle, rgba(45,127,249,.18) 0%, transparent 70%);
  pointer-events: none;
}
.bg-radial::after {
  content: "";
  position: absolute;
  bottom: -180px; left: -140px;
  width: 480px; height: 480px;
  background: radial-gradient(circle, rgba(0,212,170,.10) 0%, transparent 70%);
  pointer-events: none;
}

/* 3. 细网格纹理底 */
.bg-grid {
  background-color: var(--color-bg-alt);
  background-image:
    linear-gradient(rgba(45,127,249,.045) 1px, transparent 1px),
    linear-gradient(90deg, rgba(45,127,249,.045) 1px, transparent 1px);
  background-size: 44px 44px;
}

/* 4. 顶部分隔渐变 */
.bg-topgrad {
  background: var(--color-bg);
  position: relative;
}
.bg-topgrad::before {
  content: "";
  position: absolute;
  top: 0; left: 0; right: 0;
  height: 3px;
  background: linear-gradient(90deg, var(--color-primary), var(--color-accent));
}

/* 5. 微差深色底 */
.bg-slight { background: #0c1120; }

/* ---------- Hero ---------- */
.hero { padding: 88px 0 72px; text-align: center; }
.hero h1 { max-width: 820px; margin: 0 auto 20px; }
.hero h1 .hl { color: var(--color-primary-light); }
.hero p.lead { font-size: 1.1rem; max-width: 660px; margin: 0 auto 30px; color: var(--color-text-muted); }
.hero-cta { display: flex; gap: 14px; justify-content: center; flex-wrap: wrap; margin-bottom: 40px; }
.hero-stats { display: flex; gap: 40px; justify-content: center; flex-wrap: wrap; margin-top: 20px; }
.hero-stat .num { font-size: 2rem; font-weight: 800; color: var(--color-accent); }
.hero-stat .lbl { font-size: .82rem; color: var(--color-text-muted); }

/* ---------- Quick Start (3 steps) ---------- */
.quick-steps { display: grid; grid-template-columns: repeat(3, 1fr); gap: 22px; margin-top: 32px; }
.step-card {
  background: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: 28px 24px;
  position: relative;
  transition: transform var(--transition), border-color var(--transition);
}
.step-card:hover { transform: translateY(-4px); border-color: var(--color-primary); }
.step-num {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 40px; height: 40px;
  border-radius: 10px;
  background: linear-gradient(135deg, var(--color-primary), var(--color-accent));
  color: #fff;
  font-weight: 800;
  font-size: 1.1rem;
  margin-bottom: 16px;
}
.step-card h3 { font-size: 1.08rem; }
.step-card p { font-size: .9rem; margin-bottom: 0; }

/* ---------- Scenes ---------- */
.scene-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 22px; }
.scene-card {
  background: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: 26px 22px;
  transition: transform var(--transition);
}
.scene-card:hover { transform: translateY(-4px); }
.scene-icon { font-size: 2rem; margin-bottom: 12px; }
.scene-card h3 { font-size: 1.05rem; }
.scene-card p { font-size: .88rem; margin-bottom: 0; }

/* ---------- Inline Download ---------- */
.download-inline {
  text-align: center;
  background: linear-gradient(135deg, rgba(45,127,249,.08), rgba(0,212,170,.06));
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: 44px 28px;
  margin: 20px 0;
}
.download-inline h2 { margin-bottom: 10px; }
.download-inline p { max-width: 560px; margin: 0 auto 22px; }
.platform-pills { display: flex; gap: 10px; justify-content: center; flex-wrap: wrap; margin-top: 18px; }
.platform-pill {
  display: inline-flex; align-items: center; gap: 6px;
  background: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-radius: 30px;
  padding: 8px 16px;
  font-size: .85rem;
  color: var(--color-text-muted);
}

/* ---------- Features deep ---------- */
.feature-block { margin-bottom: 36px; }
.feature-block:last-child { margin-bottom: 0; }
.feature-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 32px;
  align-items: center;
  margin-bottom: 32px;
}
.feature-row:nth-child(even) .feature-text { order: 2; }
.feature-text h3 { font-size: 1.3rem; margin-bottom: 12px; }
.feature-text ul { padding-left: 0; }
.feature-text ul li {
  position: relative;
  padding-left: 22px;
  margin-bottom: 10px;
  color: var(--color-text-muted);
  font-size: .93rem;
}
.feature-text ul li::before {
  content: "✓";
  position: absolute;
  left: 0; top: 0;
  color: var(--color-accent);
  font-weight: 700;
}
.feature-img {
  border-radius: var(--radius-lg);
  overflow: hidden;
  border: 1px solid var(--color-border);
  background: var(--color-bg-card);
  aspect-ratio: 16/10;
  display: flex;
  align-items: center;
  justify-content: center;
}
.feature-img img { width: 100%; height: 100%; object-fit: cover; }

/* ---------- Reviews & Data ---------- */
.reviews-grid { display: grid; grid-template-columns: repeat(2, 1fr); gap: 20px; margin-bottom: 36px; }
.review-card {
  background: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: 24px;
}
.review-stars { color: var(--color-warning); font-size: 1.05rem; margin-bottom: 10px; letter-spacing: 2px; }
.review-text { font-size: .92rem; color: var(--color-text); margin-bottom: 14px; font-style: normal; }
.review-author { display: flex; align-items: center; gap: 10px; }
.review-avatar {
  width: 38px; height: 38px;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--color-primary), var(--color-accent));
  display: flex; align-items: center; justify-content: center;
  font-weight: 700; color: #fff; font-size: .9rem;
}
.review-name { font-size: .9rem; font-weight: 600; color: #fff; }
.review-tag { font-size: .78rem; color: var(--color-text-muted); }

.data-board { display: grid; grid-template-columns: repeat(4, 1fr); gap: 18px; }
.data-item {
  background: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 22px 16px;
  text-align: center;
}
.data-num { font-size: 2rem; font-weight: 800; color: var(--color-primary-light); line-height: 1.1; }
.data-lbl { font-size: .82rem; color: var(--color-text-muted); margin-top: 6px; }

/* ---------- News ---------- */
.news-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 22px; }
.news-card {
  background: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  overflow: hidden;
  transition: transform var(--transition), border-color var(--transition);
  display: flex;
  flex-direction: column;
}
.news-card:hover { transform: translateY(-4px); border-color: var(--color-primary); }
.news-img { aspect-ratio: 16/9; overflow: hidden; background: #1a2038; }
.news-img img { width: 100%; height: 100%; object-fit: cover; }
.news-body { padding: 18px 20px; flex: 1; display: flex; flex-direction: column; }
.news-date { font-size: .78rem; color: var(--color-text-muted); margin-bottom: 8px; }
.news-card h3 { font-size: 1.02rem; margin-bottom: 8px; line-height: 1.4; }
.news-card h3 a { color: #fff; }
.news-card h3 a:hover { color: var(--color-primary-light); }
.news-excerpt { font-size: .85rem; color: var(--color-text-muted); margin-bottom: 14px; flex: 1; }
.news-more { font-size: .85rem; font-weight: 600; color: var(--color-primary-light); }

/* ---------- FAQ ---------- */
.faq-grid { display: grid; grid-template-columns: repeat(2, 1fr); gap: 20px; }
.faq-card {
  background: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: 24px;
}
.faq-card h3 { font-size: 1.05rem; margin-bottom: 14px; color: #fff; }
.faq-card ol { padding-left: 0; counter-reset: none; }
.faq-card ol li {
  position: relative;
  padding-left: 26px;
  margin-bottom: 8px;
  color: var(--color-text-muted);
  font-size: .88rem;
  line-height: 1.65;
  counter-increment: faqstep;
}
.faq-card ol li::before {
  content: counter(faqstep);
  position: absolute;
  left: 0; top: 2px;
  width: 18px; height: 18px;
  border-radius: 50%;
  background: var(--color-primary);
  color: #fff;
  font-size: .72rem;
  font-weight: 700;
  display: flex; align-items: center; justify-content: center;
}

/* ---------- Trust ---------- */
.trust-bar {
  display: flex;
  gap: 36px;
  justify-content: center;
  flex-wrap: wrap;
  margin-top: 24px;
}
.trust-item { text-align: center; }
.trust-item .ti-icon { font-size: 2rem; margin-bottom: 6px; }
.trust-item .ti-lbl { font-size: .88rem; color: var(--color-text-muted); }

/* ---------- Download Page ---------- */
.dl-selfcheck {
  background: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: 28px;
  margin-bottom: 32px;
}
.dl-selfcheck h3 { margin-bottom: 14px; }
.selfcheck-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 14px; }
.selfcheck-item {
  display: flex; align-items: center; gap: 10px;
  font-size: .9rem; color: var(--color-text-muted);
}
.selfcheck-dot { width: 10px; height: 10px; border-radius: 50%; background: var(--color-success); flex-shrink: 0; }

.dl-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 20px; margin-bottom: 36px; }
.dl-card {
  background: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: 26px 22px;
  text-align: center;
  transition: transform var(--transition);
}
.dl-card:hover { transform: translateY(-4px); border-color: var(--color-primary); }
.dl-icon { font-size: 2.4rem; margin-bottom: 12px; }
.dl-card h3 { font-size: 1.1rem; }
.dl-card p { font-size: .85rem; margin-bottom: 16px; }
.dl-meta { font-size: .78rem; color: var(--color-text-muted); margin-top: 10px; }

.dl-steps { counter-reset: dlstep; }
.dl-steps .step-item {
  display: flex; gap: 16px; margin-bottom: 20px;
  background: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 20px;
}
.dl-steps .step-item .step-badge {
  flex-shrink: 0;
  width: 36px; height: 36px;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--color-primary), var(--color-accent));
  color: #fff; font-weight: 700; font-size: .95rem;
  display: flex; align-items: center; justify-content: center;
}
.dl-steps .step-body h4 { font-size: 1rem; margin-bottom: 6px; }
.dl-steps .step-body p { font-size: .88rem; margin-bottom: 4px; }
.dl-steps .step-body .note { font-size: .82rem; color: var(--color-warning); }

.version-table { width: 100%; border-collapse: collapse; margin-top: 16px; font-size: .88rem; }
.version-table th, .version-table td { padding: 12px 14px; text-align: left; border-bottom: 1px solid var(--color-border); }
.version-table th { color: var(--color-text-muted); font-weight: 600; font-size: .82rem; text-transform: uppercase; letter-spacing: .05em; }
.version-table td { color: var(--color-text); }

/* ---------- Tutorial Page ---------- */
.tut-section-block { margin-bottom: 40px; }
.tut-section-block h2 { font-size: 1.5rem; margin-bottom: 18px; }
.tut-step {
  background: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 22px 24px;
  margin-bottom: 16px;
  border-left: 4px solid var(--color-primary);
}
.tut-step h4 { font-size: 1.02rem; margin-bottom: 8px; }
.tut-step p { font-size: .9rem; margin-bottom: 4px; }
.tut-step .note { font-size: .84rem; color: var(--color-warning); }
.tut-step .result { font-size: .84rem; color: var(--color-success); }

.warn-box {
  background: rgba(255,184,0,.06);
  border: 1px solid rgba(255,184,0,.3);
  border-radius: var(--radius);
  padding: 18px 22px;
  margin: 20px 0;
}
.warn-box h4 { color: var(--color-warning); margin-bottom: 8px; }
.warn-box p { font-size: .88rem; margin-bottom: 0; }

/* ---------- FAQ Page ---------- */
.faq-cat { margin-bottom: 40px; }
.faq-cat h2 { font-size: 1.4rem; margin-bottom: 16px; padding-bottom: 10px; border-bottom: 1px solid var(--color-border); }
.faq-item {
  background: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 22px 24px;
  margin-bottom: 14px;
}
.faq-item h3 { font-size: 1.05rem; margin-bottom: 12px; color: #fff; }
.faq-item ol li { font-size: .9rem; margin-bottom: 8px; color: var(--color-text-muted); line-height: 1.7; }

/* ---------- Features Page ---------- */
.scenario-card {
  background: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: 26px;
  margin-bottom: 20px;
}
.scenario-card h3 { font-size: 1.15rem; margin-bottom: 10px; }
.scenario-card p { font-size: .9rem; }
.scenario-card .tag-row { display: flex; gap: 8px; flex-wrap: wrap; margin-top: 12px; }
.scenario-card .tag { background: rgba(45,127,249,.12); color: var(--color-primary-light); font-size: .78rem; padding: 4px 12px; border-radius: 20px; }

.compare-table { width: 100%; border-collapse: collapse; margin-top: 20px; font-size: .88rem; }
.compare-table th, .compare-table td { padding: 14px; text-align: center; border-bottom: 1px solid var(--color-border); }
.compare-table th { background: rgba(45,127,249,.06); color: #fff; font-weight: 600; }
.compare-table td { color: var(--color-text-muted); }
.compare-table td:first-child { text-align: left; color: var(--color-text); font-weight: 500; }
.compare-table .check { color: var(--color-success); font-weight: 700; }
.compare-table .cross { color: var(--color-danger); }

/* ---------- Changelog Page ---------- */
.log-version { margin-bottom: 36px; }
.log-version h2 { font-size: 1.4rem; margin-bottom: 6px; }
.log-date { font-size: .85rem; color: var(--color-text-muted); margin-bottom: 14px; }
.log-list { padding-left: 20px; }
.log-list li { margin-bottom: 8px; color: var(--color-text-muted); font-size: .9rem; line-height: 1.7; }
.log-list li::marker { color: var(--color-accent); }

/* ---------- News Detail ---------- */
.news-detail-wrap { max-width: 760px; margin: 0 auto; padding: 48px 0; }
.news-detail-wrap .news-detail-meta { font-size: .85rem; color: var(--color-text-muted); margin-bottom: 16px; }
.news-detail-wrap h1 { font-size: clamp(1.6rem, 4vw, 2.4rem); margin-bottom: 20px; }
.news-detail-wrap .news-detail-img { border-radius: var(--radius-lg); overflow: hidden; margin-bottom: 28px; aspect-ratio: 16/9; }
.news-detail-wrap .news-detail-img img { width: 100%; height: 100%; object-fit: cover; }
.news-detail-wrap h2 { font-size: 1.3rem; margin-top: 28px; margin-bottom: 12px; }
.news-detail-wrap p { font-size: 1rem; line-height: 1.85; }
.news-detail-wrap ol { padding-left: 22px; margin-bottom: 16px; }
.news-detail-wrap ol li { margin-bottom: 10px; color: var(--color-text-muted); font-size: .95rem; line-height: 1.75; }
.news-detail-wrap .related-links { background: var(--color-bg-card); border: 1px solid var(--color-border); border-radius: var(--radius); padding: 20px 24px; margin-top: 36px; }
.news-detail-wrap .related-links h3 { font-size: 1rem; margin-bottom: 10px; }
.news-detail-wrap .related-links ul li { margin-bottom: 8px; }
.news-detail-wrap .related-links ul li a { font-size: .9rem; }

/* ---------- Breadcrumb ---------- */
.breadcrumb { font-size: .85rem; color: var(--color-text-muted); margin-bottom: 18px; }
.breadcrumb a { color: var(--color-text-muted); }
.breadcrumb a:hover { color: var(--color-primary-light); }
.breadcrumb span { margin: 0 6px; }

/* ---------- Responsive ---------- */
@media (max-width: 900px) {
  .quick-steps, .scene-grid, .news-grid, .reviews-grid, .dl-grid { grid-template-columns: repeat(2, 1fr); }
  .feature-row { grid-template-columns: 1fr; }
  .feature-row:nth-child(even) .feature-text { order: 0; }
  .data-board { grid-template-columns: repeat(2, 1fr); }
  .footer-grid { grid-template-columns: 1fr 1fr; }
}
@media (max-width: 640px) {
  section { padding: 44px 0; }
  .nav-links { display: none; position: absolute; top: 68px; left: 0; right: 0; background: var(--color-bg-alt); flex-direction: column; padding: 20px; border-bottom: 1px solid var(--color-border); gap: 16px; }
  .nav-links.open { display: flex; }
  .mobile-toggle { display: block; }
  .quick-steps, .scene-grid, .news-grid, .reviews-grid, .dl-grid, .faq-grid, .selfcheck-grid { grid-template-columns: 1fr; }
  .data-board { grid-template-columns: repeat(2, 1fr); }
  .footer-grid { grid-template-columns: 1fr; }
  .hero-stats { gap: 24px; }
  .container { padding: 0 16px; }
}