/* Site 1 Root — Classic Telegram Blue, Centered Corporate */
:root {
  --primary: #2AABEE;
  --primary-dark: #1E96D1;
  --secondary: #229ED9;
  --bg: #F4F8FB;
  --surface: #FFFFFF;
  --text: #1A2B3C;
  --muted: #5A6F82;
  --border: #D6E4EF;
  --success: #31B545;
  --radius: 12px;
  --shadow: 0 4px 20px rgba(42, 171, 238, 0.12);
  --font: "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
}
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; }
body { font-family: var(--font); color: var(--text); background: var(--bg); line-height: 1.7; font-size: 16px; }
img, svg { display: block; max-width: 100%; }
a { color: var(--primary); text-decoration: none; }
a:hover { color: var(--primary-dark); }
.container { width: min(1120px, 92%); margin: 0 auto; }

/* Nav — fixed top bar */
.site-header { position: sticky; top: 0; z-index: 100; background: rgba(255,255,255,0.96); border-bottom: 1px solid var(--border); backdrop-filter: blur(8px); }
.nav-inner { display: flex; align-items: center; justify-content: space-between; height: 64px; }
.logo { display: flex; align-items: center; gap: 10px; font-weight: 700; font-size: 1.15rem; color: var(--text); }
.logo svg { width: 32px; height: 32px; }
.nav-links { display: flex; gap: 8px; list-style: none; }
.nav-links a { display: block; padding: 8px 16px; border-radius: 8px; color: var(--muted); font-weight: 500; transition: background 0.2s, color 0.2s; }
.nav-links a:hover { background: #E8F6FD; color: var(--primary); }
.nav-links a.active { background: var(--primary); color: #fff; }
.nav-links a.active:hover { color: #fff; background: var(--primary-dark); }

/* Buttons */
.btn { display: inline-flex; align-items: center; justify-content: center; gap: 8px; padding: 12px 24px; border: none; border-radius: 10px; font-size: 1rem; font-weight: 600; cursor: pointer; transition: background 0.2s, transform 0.15s; font-family: inherit; }
.btn:disabled { opacity: 0.7; cursor: wait; }
.btn-primary { background: var(--primary); color: #fff; }
.btn-primary:hover:not(:disabled) { background: var(--primary-dark); }
.btn-lg { padding: 16px 32px; font-size: 1.1rem; }
.btn-outline { background: transparent; border: 2px solid var(--primary); color: var(--primary); }
.btn-outline:hover:not(:disabled) { background: #E8F6FD; }
.btn-block { width: 100%; }
.btn svg { width: 20px; height: 20px; }

@keyframes spin { from { transform: rotate(0deg); } to { transform: rotate(360deg); } }

/* Hero — centered */
.hero { text-align: center; padding: 80px 0 64px; background: linear-gradient(180deg, #E3F4FC 0%, var(--bg) 100%); }
.hero-badge { display: inline-block; padding: 6px 14px; background: #fff; border: 1px solid var(--border); border-radius: 20px; font-size: 0.85rem; color: var(--primary); margin-bottom: 20px; font-weight: 600; }
.hero h1 { font-size: clamp(1.8rem, 4vw, 2.6rem); line-height: 1.3; margin-bottom: 16px; color: var(--text); }
.hero-desc { font-size: 1.1rem; color: var(--muted); max-width: 640px; margin: 0 auto 28px; }
.hero-actions { display: flex; flex-wrap: wrap; gap: 12px; justify-content: center; }
.hero-copy { max-width: 720px; margin: 0 auto; }
.hero-visual { margin-top: 48px; display: flex; justify-content: center; }
.hero-visual svg { width: min(280px, 70vw); height: auto; }

/* Sections */
.section { padding: 64px 0; }
.section-alt { background: var(--surface); }
.section-title { text-align: center; font-size: 1.75rem; margin-bottom: 12px; }
.section-sub { text-align: center; color: var(--muted); max-width: 620px; margin: 0 auto 40px; }

/* Feature cards — 3 col grid */
.feature-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 24px; }
.feature-card { background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); padding: 28px 24px; box-shadow: var(--shadow); }
.feature-card .icon { width: 48px; height: 48px; background: #E8F6FD; border-radius: 12px; display: flex; align-items: center; justify-content: center; margin-bottom: 16px; }
.feature-card .icon svg { width: 28px; height: 28px; color: var(--primary); }
.feature-card h3 { font-size: 1.15rem; margin-bottom: 10px; }
.feature-card p { color: var(--muted); font-size: 0.95rem; }

/* Platform download */
.platform-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 20px; }
.platform-card { background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); padding: 24px; text-align: center; }
.platform-card .plat-icon { width: 56px; height: 56px; margin: 0 auto 14px; color: var(--primary); }
.platform-card h3 { font-size: 1.1rem; margin-bottom: 8px; }
.platform-card p { color: var(--muted); font-size: 0.9rem; margin-bottom: 16px; }

/* Deep features */
.deep-block { display: grid; grid-template-columns: 1fr 1fr; gap: 40px; align-items: center; margin-bottom: 48px; }
.deep-block:nth-child(even) { direction: rtl; }
.deep-block:nth-child(even) > * { direction: ltr; }
.deep-block .deep-text h3 { font-size: 1.35rem; margin-bottom: 12px; }
.deep-block .deep-text p { color: var(--muted); margin-bottom: 10px; }
.deep-visual { background: #E8F6FD; border-radius: var(--radius); padding: 40px; display: flex; align-items: center; justify-content: center; }
.deep-visual svg { width: 120px; height: 120px; color: var(--primary); }

/* Reviews */
.review-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 20px; }
.review-card { background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); padding: 24px; }
.review-head { display: flex; align-items: center; gap: 12px; margin-bottom: 12px; }
.avatar { width: 44px; height: 44px; border-radius: 50%; background: var(--primary); color: #fff; display: flex; align-items: center; justify-content: center; font-weight: 700; }
.stars { color: #F5A623; font-size: 0.9rem; letter-spacing: 2px; }
.review-card p { color: var(--muted); font-size: 0.95rem; }

/* Stats */
.stats-row { display: grid; grid-template-columns: repeat(4, 1fr); gap: 20px; text-align: center; }
.stat-item { background: var(--primary); color: #fff; border-radius: var(--radius); padding: 28px 16px; }
.stat-item .num { font-size: 2rem; font-weight: 700; display: block; margin-bottom: 6px; }
.stat-item .label { font-size: 0.9rem; opacity: 0.9; }

/* Comparison table */
.compare-table { width: 100%; border-collapse: collapse; background: var(--surface); border-radius: var(--radius); overflow: hidden; box-shadow: var(--shadow); }
.compare-table th, .compare-table td { padding: 14px 18px; text-align: left; border-bottom: 1px solid var(--border); }
.compare-table th { background: var(--primary); color: #fff; font-weight: 600; }
.compare-table tr:last-child td { border-bottom: none; }
.compare-table td:first-child { font-weight: 600; }
.yes { color: var(--success); font-weight: 600; }
.no { color: #C0392B; }

/* FAQ accordion — CSS only */
.faq-list { max-width: 800px; margin: 0 auto; }
.faq-item { background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); margin-bottom: 12px; overflow: hidden; }
.faq-item details summary { padding: 18px 24px; cursor: pointer; font-weight: 600; list-style: none; display: flex; justify-content: space-between; align-items: center; }
.faq-item details summary::-webkit-details-marker { display: none; }
.faq-item details summary::after { content: "+"; font-size: 1.4rem; color: var(--primary); transition: transform 0.2s; }
.faq-item details[open] summary::after { content: "−"; }
.faq-item details .faq-body { padding: 0 24px 18px; color: var(--muted); }

/* Download page */
.dl-hero { background: linear-gradient(135deg, #1E96D1, #2AABEE); color: #fff; padding: 64px 0; text-align: center; }
.dl-hero h1 { font-size: clamp(1.6rem, 3.5vw, 2.4rem); margin-bottom: 12px; }
.dl-hero p { opacity: 0.95; margin-bottom: 24px; max-width: 560px; margin-left: auto; margin-right: auto; }
.dl-meta { display: flex; gap: 24px; justify-content: center; flex-wrap: wrap; margin-top: 16px; font-size: 0.95rem; opacity: 0.9; }
.dl-platforms { display: grid; grid-template-columns: repeat(3, 1fr); gap: 24px; }
.dl-card { background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); padding: 28px; box-shadow: var(--shadow); }
.dl-card h3 { margin-bottom: 8px; display: flex; align-items: center; gap: 10px; }
.dl-card h3 svg { width: 28px; height: 28px; color: var(--primary); }
.dl-card .meta { color: var(--muted); font-size: 0.9rem; margin-bottom: 16px; }
.steps { counter-reset: step; list-style: none; }
.steps li { position: relative; padding: 20px 20px 20px 64px; background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); margin-bottom: 14px; }
.steps li::before { counter-increment: step; content: counter(step); position: absolute; left: 18px; top: 20px; width: 32px; height: 32px; background: var(--primary); color: #fff; border-radius: 50%; display: flex; align-items: center; justify-content: center; font-weight: 700; font-size: 0.9rem; line-height: 32px; text-align: center; }
.steps li h3 { margin-bottom: 6px; font-size: 1.05rem; }
.steps li p { color: var(--muted); font-size: 0.95rem; }
.req-table { width: 100%; border-collapse: collapse; background: var(--surface); border-radius: var(--radius); overflow: hidden; }
.req-table th, .req-table td { padding: 12px 16px; border-bottom: 1px solid var(--border); text-align: left; }
.req-table th { background: #E8F6FD; }
.changelog { list-style: none; }
.changelog li { background: var(--surface); border-left: 4px solid var(--primary); padding: 18px 20px; margin-bottom: 12px; border-radius: 0 var(--radius) var(--radius) 0; }
.changelog .ver { font-weight: 700; color: var(--primary); }
.changelog .date { color: var(--muted); font-size: 0.9rem; margin-left: 12px; }
.security-box { background: #E8F8EC; border: 1px solid #B8E0C2; border-radius: var(--radius); padding: 28px; }
.security-box h2 { color: var(--success); margin-bottom: 12px; }

/* zh-cn article */
.article-hero { padding: 56px 0 32px; background: linear-gradient(180deg, #E3F4FC, var(--bg)); }
.article-hero h1 { font-size: clamp(1.5rem, 3vw, 2.2rem); margin-bottom: 14px; }
.article-body { max-width: 760px; margin: 0 auto; }
.article-body h2 { font-size: 1.4rem; margin: 36px 0 14px; }
.article-body h3 { font-size: 1.15rem; margin: 24px 0 10px; }
.article-body p { color: var(--muted); margin-bottom: 14px; }
.article-body ul { margin: 0 0 16px 1.4em; color: var(--muted); }
.cta-banner { background: var(--primary); color: #fff; text-align: center; padding: 48px 24px; border-radius: var(--radius); margin: 48px 0; }
.cta-banner h2 { color: #fff; margin-bottom: 12px; }
.cta-banner p { opacity: 0.95; margin-bottom: 20px; }
.cta-banner .btn { background: #fff; color: var(--primary); }
.cta-banner .btn:hover { background: #E8F6FD; }

/* Footer */
.site-footer { background: #1A2B3C; color: #B8C9D8; padding: 40px 0 28px; margin-top: 48px; }
.site-footer p { font-size: 0.9rem; margin-bottom: 8px; text-align: center; }
.footer-safe { color: #7DD3A8; font-weight: 500; }

@media (max-width: 960px) {
  .feature-grid, .review-grid, .dl-platforms { grid-template-columns: 1fr 1fr; }
  .platform-grid, .stats-row { grid-template-columns: 1fr 1fr; }
  .deep-block, .deep-block:nth-child(even) { grid-template-columns: 1fr; direction: ltr; }
}
@media (max-width: 640px) {
  .nav-links { gap: 2px; }
  .nav-links a { padding: 6px 10px; font-size: 0.85rem; }
  .feature-grid, .review-grid, .platform-grid, .stats-row, .dl-platforms { grid-template-columns: 1fr; }
  .hero { padding: 48px 0 40px; }
}