/* =========================================================================
   STONEVAN —— 全站样式（简洁版）
   设计语言：超大标题 + 细字重 + 大留白 + 一屏一件事 + 滚动渐显
   品牌色：炭黑 #16171A / 矿脉金 #9C7A4A / 暖白 #FAF9F7
   ========================================================================= */
:root{
  --ink:#16171a; --ink2:#3a3c40; --gray:#73767c; --line:#e5e2dc;
  --paper:#faf9f7; --stone:#f2f1ed; --ore:#9c7a4a; --ore-lt:#c2a678;
  --sans:"Segoe UI",-apple-system,BlinkMacSystemFont,Arial,"Microsoft YaHei",sans-serif;
  --mono:"Bahnschrift",Consolas,"Cascadia Mono",monospace;
  --wrap:1320px;
}
*{box-sizing:border-box;margin:0;padding:0}
html{scroll-behavior:smooth}
body{font-family:var(--sans);background:var(--paper);color:var(--ink2);
  font-size:17px;line-height:1.6;-webkit-font-smoothing:antialiased}
img{max-width:100%;display:block}
a{color:inherit;text-decoration:none}
:focus-visible{outline:2px solid var(--ore);outline-offset:3px}
.wrap{max-width:var(--wrap);margin:0 auto;padding-inline:40px}

/* ---------- 排版：字重拉细、字距收紧、行高压到 1 以下 ---------- */
h1,h2{color:var(--ink);font-weight:300;letter-spacing:-.028em;line-height:.98;text-wrap:balance}
h1{font-size:clamp(44px,7.4vw,96px)}
h2{font-size:clamp(34px,5.4vw,70px)}
h3{color:var(--ink);font-weight:500;font-size:20px;letter-spacing:-.01em}
.eye{font-family:var(--mono);font-size:11.5px;font-weight:500;letter-spacing:.24em;
  text-transform:uppercase;color:var(--ore);margin-bottom:22px}
.lead{font-size:19px;color:var(--gray);max-width:48ch;line-height:1.62}
section{padding-block:clamp(78px,10vw,150px)}

/* ---------- 按钮 ---------- */
.btn{display:inline-flex;align-items:center;gap:11px;padding:17px 32px;
  background:var(--ink);color:#fff;font-size:14.5px;font-weight:500;
  border:1px solid var(--ink);cursor:pointer;font-family:var(--sans);
  transition:gap .2s,background .2s,color .2s}
.btn:hover{gap:18px;background:#000}
.btn.ghost{background:transparent;color:var(--ink)}
.btn.ghost:hover{background:var(--ink);color:#fff}
.btn.light{background:#fff;color:var(--ink);border-color:#fff}
.btn.light:hover{background:var(--ore-lt);border-color:var(--ore-lt)}
.tlink{display:inline-flex;align-items:center;gap:9px;font-size:14.5px;
  font-weight:500;color:var(--ink);transition:gap .2s,color .2s}
.tlink:hover{gap:15px;color:var(--ore)}
.row{display:flex;gap:16px;flex-wrap:wrap;align-items:center}

/* ---------- 导航 ---------- */
nav{position:sticky;top:0;z-index:60;background:rgba(250,249,247,.93);
  backdrop-filter:blur(14px);border-bottom:1px solid var(--line)}
nav .wrap{display:flex;align-items:center;justify-content:space-between;min-height:76px;gap:20px}
.logo{display:flex;flex-direction:column;line-height:1.02}
.logo b{font-family:var(--mono);font-size:21px;font-weight:700;letter-spacing:.14em;color:var(--ink)}
.logo i{font-family:var(--mono);font-size:8.5px;font-style:normal;letter-spacing:.34em;color:var(--ore)}
.menu{display:flex;gap:36px}
.menu a{font-size:14.5px;font-weight:500;color:var(--ink2);transition:color .18s}
.menu a:hover,.menu a.on{color:var(--ore)}
.nav-r{display:flex;align-items:center;gap:18px}
.nav-r .mail{font-size:13.5px;color:var(--gray)}
.burger{display:none;background:none;border:0;font-size:24px;color:var(--ink);cursor:pointer;line-height:1}

/* ---------- 页头（内页） ---------- */
.head{padding-block:clamp(54px,7vw,98px) 0}
.head h1{margin-bottom:22px;max-width:14ch}
.crumb{font-family:var(--mono);font-size:11.5px;letter-spacing:.14em;
  text-transform:uppercase;color:var(--gray);margin-bottom:26px}
.crumb a:hover{color:var(--ore)}

/* ---------- 数据条 ---------- */
.stats{border-block:1px solid var(--line);padding-block:clamp(46px,6vw,78px)}
.stats .g{display:grid;grid-template-columns:repeat(4,1fr);gap:40px 24px}
.stats .n{font-family:var(--mono);font-size:clamp(38px,5.2vw,66px);font-weight:600;
  color:var(--ink);line-height:1;letter-spacing:-.02em;font-variant-numeric:tabular-nums}
.stats .l{font-family:var(--mono);font-size:11.5px;letter-spacing:.18em;
  text-transform:uppercase;color:var(--gray);margin-top:14px}

/* ---------- 深色故事块 ---------- */
.story{background:var(--ink);color:#fff}
.story .g{display:grid;grid-template-columns:1fr 1.15fr;gap:clamp(40px,6vw,90px);align-items:center}
.story h2{color:#fff;margin-bottom:24px;max-width:13ch}
.story .lead{color:#a8a49c;margin-bottom:32px}
.story ul{list-style:none;margin-bottom:38px}
.story li{padding-left:28px;position:relative;margin-bottom:14px;font-size:15.5px;color:#e2ded7}
.story li::before{content:"✓";position:absolute;left:0;color:var(--ore-lt);font-weight:600}
.story .pic img{width:100%;aspect-ratio:4/3;object-fit:cover}
.story .meta{display:flex;gap:34px;margin-top:24px;flex-wrap:wrap}
.story .meta div{display:flex;align-items:baseline;gap:8px}
.story .meta b{font-family:var(--mono);font-size:26px;font-weight:600;color:#fff;letter-spacing:-.01em}
.story .meta span{font-family:var(--mono);font-size:10.5px;letter-spacing:.16em;
  text-transform:uppercase;color:#8d8a84}

/* ---------- 图文交替块 ---------- */
.alt{display:grid;grid-template-columns:1fr 1.1fr;gap:clamp(36px,5.5vw,84px);align-items:center}
.alt.flip{grid-template-columns:1.1fr 1fr}
.alt.flip .txt{order:2}
.alt img{width:100%;aspect-ratio:4/3;object-fit:cover}
.alt h2{margin-bottom:20px;max-width:14ch}
.alt .lead{margin-bottom:28px}

/* ---------- 三栏 ---------- */
.trio{display:grid;grid-template-columns:repeat(3,1fr);gap:clamp(28px,4vw,56px)}
.trio .step{font-family:var(--mono);font-size:11.5px;letter-spacing:.2em;
  text-transform:uppercase;color:var(--ore);margin-bottom:14px}
.trio h3{margin-bottom:10px}
.trio p{font-size:15.5px;color:var(--gray)}

/* ---------- 结尾 ---------- */
.end{text-align:center}
.end h2{margin-bottom:22px;max-width:16ch;margin-inline:auto}
.end .lead{margin:0 auto 38px}
.end .row{justify-content:center}

/* ---------- 页脚 ---------- */
footer{background:var(--ink);color:#8d9095;padding-block:60px 32px;font-size:14px}
footer .g{display:grid;grid-template-columns:1.8fr 1fr 1fr 1fr;gap:40px;padding-bottom:44px}
footer h4{color:#fff;font-size:12.5px;font-weight:500;margin-bottom:16px;
  font-family:var(--mono);letter-spacing:.14em;text-transform:uppercase}
footer ul{list-style:none}
footer li{margin-bottom:10px}
footer a:hover{color:var(--ore-lt)}
footer .logo b{color:#fff}
footer .about{margin-top:16px;max-width:36ch;line-height:1.7}
footer .bot{border-top:1px solid #2b2d30;padding-top:24px;font-size:12.5px;color:#6d7075;
  display:flex;justify-content:space-between;gap:16px;flex-wrap:wrap}

/* =========================================================================
   滚动渐显 —— 初始隐藏由 JS 添加，JS 不跑时内容照常可见
   ========================================================================= */
.pre{opacity:0;transform:translateY(32px)}
.in{opacity:1;transform:none;
  transition:opacity .78s cubic-bezier(.22,.72,.3,1) var(--d,0ms),
             transform .78s cubic-bezier(.22,.72,.3,1) var(--d,0ms)}
@media (prefers-reduced-motion:reduce){ .pre{opacity:1;transform:none} .in{transition:none} }

/* =========================================================================
   响应式
   ========================================================================= */
@media (max-width:1000px){
  .wrap{padding-inline:26px}
  .story .g,.alt,.alt.flip{grid-template-columns:1fr}
  .alt.flip .txt{order:0}
  .trio{grid-template-columns:1fr}
  .stats .g{grid-template-columns:repeat(2,1fr)}
  footer .g{grid-template-columns:1fr 1fr}
  .burger{display:block}
  .menu{display:none;position:absolute;top:76px;left:0;right:0;background:var(--paper);
    flex-direction:column;gap:0;padding:8px 26px 20px;border-bottom:1px solid var(--line)}
  .menu.open{display:flex}
  .menu a{padding:14px 0;border-bottom:1px solid var(--line)}
  .nav-r .mail{display:none}
}
@media (max-width:640px){
  footer .g{grid-template-columns:1fr}
}