/* Telegram中文版 仿官网样式（视觉母版 https://telegram.org：navbar-tg 蓝条 + plane logo + 卡片 + 多列 footer）。
   主色变量由 BaseLayout 内联 :root 注入（--brand #179cde 等），此处只做版式。 */
*{box-sizing:border-box;margin:0;padding:0}
:root{--ink:#1a1a1a;--muted:#707579;--line:#e7eaef;--bg:#fff;--soft:#f4f8fb}
html{scroll-behavior:smooth}
body{font-family:'Roboto',-apple-system,'Segoe UI','Microsoft YaHei',sans-serif;color:var(--ink);background:var(--bg);line-height:1.62;-webkit-font-smoothing:antialiased}
.wrap{max-width:1100px;margin:0 auto;padding:0 20px}
a{color:var(--brand-dark);text-decoration:none}
a:hover{text-decoration:underline}
img{max-width:100%;height:auto;display:block}
h1,h2,h3,h4{line-height:1.25;color:#0f172a}
p{margin:.5em 0}

/* ===== navbar（仿 navbar-tg 蓝条） ===== */
.site-hd{background:var(--brand);color:#fff;position:sticky;top:0;z-index:30;box-shadow:0 1px 0 rgba(0,0,0,.06)}
.site-hd .bar{display:flex;align-items:center;gap:18px;height:58px}
.brand{display:flex;align-items:center;gap:9px;color:#fff}
.brand:hover{text-decoration:none;opacity:.92}
.brand img{width:32px;height:32px;border-radius:50%;background:#fff}
.logo-text{font-weight:600;font-size:18px;letter-spacing:.2px}
.nav{display:flex;gap:20px;margin-left:8px;flex:1;flex-wrap:wrap}
.nav a{color:rgba(255,255,255,.92);font-size:15px}
.nav a:hover{color:#fff;text-decoration:none}
.btn{display:inline-block;padding:8px 20px;border-radius:22px;background:#fff;color:var(--brand-dark);font-weight:600;font-size:15px;white-space:nowrap}
.btn:hover{text-decoration:none;background:var(--brand-glow);color:var(--brand-dark)}
.btn-lg{padding:13px 30px;font-size:17px}
.btn-solid{background:var(--brand);color:#fff}
.btn-solid:hover{background:var(--brand-dark);color:#fff}

/* ===== hero ===== */
.hero{background:linear-gradient(180deg,var(--brand-light) 0%,#fff 78%);padding:46px 0 30px;border-bottom:1px solid var(--line)}
.hero .wrap{display:grid;grid-template-columns:1fr 1fr;gap:36px;align-items:center}
.hero-narrow .wrap{grid-template-columns:1.05fr .95fr}
.hero h1{font-size:34px;letter-spacing:-.4px;margin-bottom:10px}
.hero .lead{font-size:18px;color:#3a4550;margin-bottom:18px}
.hero .cta{display:flex;gap:12px;flex-wrap:wrap;margin-top:6px}
.hero-media{position:relative}
.hero-media picture,.hero-media img{border-radius:14px;width:100%}
.breadcrumb{font-size:13px;color:var(--muted);margin-bottom:12px}
.breadcrumb a{color:var(--muted)}
.kpis{display:flex;gap:26px;margin-top:18px;flex-wrap:wrap}
.kpis div{font-size:13px;color:var(--muted)}
.kpis b{display:block;font-size:22px;color:var(--brand-dark);font-weight:700}

/* ===== sections ===== */
.section{padding:38px 0}
.section.alt{background:var(--soft)}
.section h2{font-size:25px;margin-bottom:6px}
.section h3{font-size:19px;margin:20px 0 4px}
.eyebrow{color:var(--brand-dark);font-weight:600;font-size:14px;text-transform:uppercase;letter-spacing:.6px}
.answer{font-size:16px;color:#2b3640;background:var(--soft);border-left:3px solid var(--brand);padding:10px 14px;border-radius:0 8px 8px 0;margin:8px 0 12px}
.section.alt .answer{background:#fff}
.prose{max-width:820px}
.prose p{color:#39434d}
.prose ul{margin:.6em 0 .6em 1.3em;color:#39434d}
.prose li{margin:.3em 0}
.subgrid{display:grid;grid-template-columns:1fr 1fr;gap:10px 30px}
@media(max-width:760px){.subgrid{grid-template-columns:1fr}}

/* ===== feature cards（仿 "Why Telegram?" 卡片栅格） ===== */
.cards{display:grid;grid-template-columns:repeat(3,1fr);gap:22px;margin-top:24px}
.card{background:#fff;border:1px solid var(--line);border-radius:14px;padding:22px;transition:.15s;text-align:center}
.card:hover{box-shadow:0 8px 26px rgba(23,156,222,.12);transform:translateY(-2px)}
.card .ic{width:58px;height:58px;margin:0 auto 12px;display:flex;align-items:center;justify-content:center;background:var(--brand-light);border-radius:16px}
.card h3{font-size:18px;margin-bottom:4px}
.card p{color:var(--muted);font-size:14.5px}
@media(max-width:860px){.cards{grid-template-columns:repeat(2,1fr)}}
@media(max-width:560px){.cards{grid-template-columns:1fr}}

/* ===== download / platform cards ===== */
.platforms{display:grid;grid-template-columns:repeat(4,1fr);gap:18px;margin-top:22px}
.plat{display:flex;flex-direction:column;align-items:center;gap:10px;padding:24px 16px;border:1px solid var(--line);border-radius:16px;background:#fff;text-align:center}
.plat img,.plat svg{width:54px;height:54px}
.plat h3{font-size:17px}
.plat p{font-size:13.5px;color:var(--muted);min-height:38px}
.plat .btn{margin-top:4px}
@media(max-width:860px){.platforms{grid-template-columns:repeat(2,1fr)}}
@media(max-width:480px){.platforms{grid-template-columns:1fr}}

/* showcase image strip */
.showcase{margin:22px 0}
.showcase img{border-radius:14px;border:1px solid var(--line);width:100%}
.figcap{font-size:13px;color:var(--muted);text-align:center;margin-top:8px}

/* steps */
.steps{counter-reset:s;display:grid;gap:14px;margin-top:18px}
.step{display:flex;gap:14px;align-items:flex-start}
.step .n{flex:none;counter-increment:s;width:30px;height:30px;border-radius:50%;background:var(--brand);color:#fff;display:flex;align-items:center;justify-content:center;font-weight:700;font-size:15px}
.step .n::before{content:counter(s)}
.step h4{font-size:16px;margin-bottom:2px}
.step p{color:var(--muted);font-size:14.5px;margin:0}

/* sources + related */
.sources{font-size:13.5px;color:var(--muted);margin-top:26px;padding-top:14px;border-top:1px dashed var(--line)}
.sources a{color:var(--brand-dark)}
.related{display:flex;gap:14px;flex-wrap:wrap;font-size:14px;margin-top:14px}

/* FAQ accordion */
.faq{margin-top:20px;max-width:880px}
.faq details{border:1px solid var(--line);border-radius:10px;margin-bottom:10px;background:#fff;overflow:hidden}
.faq summary{cursor:pointer;padding:14px 18px;font-weight:600;font-size:16px;list-style:none;position:relative}
.faq summary::-webkit-details-marker{display:none}
.faq summary::after{content:'+';position:absolute;right:18px;color:var(--brand);font-size:20px;font-weight:400}
.faq details[open] summary::after{content:'\2212'}
.faq details[open] summary{color:var(--brand-dark)}
.faq .a{padding:0 18px 16px;color:#39434d;font-size:15px}

/* tool */
.tool{background:#fff;border:1px solid var(--line);border-radius:16px;padding:24px;margin-top:20px;max-width:720px}
.tool label{display:block;font-weight:600;margin:14px 0 6px;font-size:15px}
.tool select,.tool input{width:100%;padding:11px 13px;border:1px solid var(--line);border-radius:10px;font-size:15px;background:var(--soft)}
.tool .out{margin-top:20px;padding:18px;border-radius:12px;background:var(--brand-light);border:1px solid var(--brand-glow)}
.tool .out b{color:var(--brand-dark);font-size:26px}
.tool table{width:100%;border-collapse:collapse;margin-top:18px;font-size:14px}
.tool th,.tool td{border:1px solid var(--line);padding:9px 11px;text-align:left}
.tool th{background:var(--soft)}

/* ===== footer（仿 telegram.org 多列 footer） ===== */
.site-ft{background:#fff;border-top:1px solid var(--line);margin-top:10px;padding:38px 0 46px}
.ftgrid{display:grid;grid-template-columns:1.6fr 1fr 1fr 1fr;gap:26px}
.ftbrand{display:flex;gap:12px;align-items:flex-start}
.ftbrand strong{font-size:17px}
.fttag{color:var(--muted);font-size:13.5px;margin-top:4px;max-width:240px}
.ftmark svg{display:block;border-radius:50%}
.ftcol h5{font-size:14px;margin-bottom:10px;color:#0f172a}
.ftcol ul{list-style:none}
.ftcol li{margin:7px 0}
.ftcol a{color:var(--muted);font-size:14px}
.ftcol a:hover{color:var(--brand-dark)}
.ftrelated{display:none}
@media(max-width:820px){
  .ftgrid{grid-template-columns:1fr 1fr}
  .hero .wrap{grid-template-columns:1fr}
  .hero-media{order:-1}
  .hero h1{font-size:28px}
}
@media(max-width:520px){.ftgrid{grid-template-columns:1fr}.nav{display:none}}