:root{
  --paper:#faf9f6;
  --surface:#ffffff;
  --ink:#1b1b19;
  --muted:#6c6c66;
  --line:#e6e3dc;
  --accent:#2f6f5e;
  --accent-soft:#e8f1ed;
  --radius:14px;
  --maxw:1120px;
}
*{box-sizing:border-box;}
html{scroll-behavior:smooth;}
body{
  margin:0;
  font-family:-apple-system,BlinkMacSystemFont,"Segoe UI","PingFang SC","Microsoft YaHei",sans-serif;
  color:var(--ink);
  background:var(--paper);
  line-height:1.7;
  -webkit-font-smoothing:antialiased;
}
img{display:block;max-width:100%;height:auto;}
a{color:inherit;text-decoration:none;}

/* ---- nav ---- */
.nav{
  position:sticky;top:0;z-index:50;
  backdrop-filter:saturate(180%) blur(10px);
  background:rgba(250,249,246,.82);
  border-bottom:1px solid var(--line);
}
.nav-inner{
  max-width:var(--maxw);margin:0 auto;padding:14px 24px;
  display:flex;align-items:center;justify-content:space-between;gap:16px;
}
.brand{font-weight:600;letter-spacing:.04em;font-size:15px;}
.brand span{color:var(--accent);}
.nav-links{display:flex;gap:22px;font-size:13px;color:var(--muted);flex-wrap:wrap;}
.nav-links a:hover{color:var(--ink);}

/* ---- layout ---- */
.wrap{max-width:var(--maxw);margin:0 auto;padding:0 24px;}
section{padding:84px 0;border-bottom:1px solid var(--line);}
.kicker{
  font-size:12px;letter-spacing:.18em;text-transform:uppercase;
  color:var(--accent);font-weight:600;margin:0 0 10px;
}
/* ② 项目背景与 ③ 设计挑战 合成一个模块：去掉中间分割线、收紧凑间距 */
#about{border-bottom:0;padding-bottom:0;}
#challenge{padding-top:56px;}
h2.title{font-size:28px;line-height:1.25;margin:0 0 14px;font-weight:600;letter-spacing:.01em;}
.lead{font-size:16px;color:var(--muted);max-width:680px;margin:0 0 40px;}
.lead.sm{font-size:15px;margin-bottom:28px;}

/* ---- hero ---- */
.hero{
  position:relative;color:#fff;overflow:hidden;
  background:radial-gradient(1100px 560px at 78% 12%,rgba(47,111,94,.38),transparent 62%),#0b0b0a;
}
.hero-bg{
  position:absolute;inset:0;background-size:cover;background-position:center;
  opacity:.15;
}
.hero::after{
  content:"";position:absolute;inset:0;pointer-events:none;
  background:linear-gradient(100deg,rgba(8,9,8,.9) 0%,rgba(8,9,8,.45) 50%,rgba(8,9,8,.08) 100%);
}
.hero-inner{
  position:relative;z-index:1;max-width:var(--maxw);margin:0 auto;
  padding:96px 24px;display:grid;grid-template-columns:1.1fr .9fr;gap:48px;align-items:center;
}
.hero-copy .tag{
  display:inline-block;font-size:12px;letter-spacing:.16em;text-transform:uppercase;
  color:#9fe1cb;border:1px solid rgba(159,225,203,.4);padding:5px 12px;border-radius:999px;margin-bottom:22px;
}
.hero-copy h1{font-size:46px;line-height:1.1;margin:0 0 18px;font-weight:600;letter-spacing:.01em;}
.hero-copy p{font-size:17px;color:rgba(255,255,255,.82);max-width:460px;margin:0 0 14px;}
.hero-meta{display:flex;gap:28px;margin-top:30px;flex-wrap:wrap;}
.hero-meta div{font-size:13px;color:rgba(255,255,255,.7);}
.hero-meta b{display:block;font-size:18px;color:#fff;font-weight:600;margin-bottom:2px;}

/* device frame (real iPhone mockup image) */
.device{
  position:relative;width:100%;max-width:280px;margin:0 auto;
  aspect-ratio:1430/2961;
  filter:drop-shadow(0 30px 50px rgba(0,0,0,.35));
}
.device .screen{
  position:absolute;left:3.846%;right:3.846%;top:1.587%;bottom:1.554%;
  width:92.308%;height:96.859%;
  object-fit:cover;border-radius:6.5% / 3%;
}
.device .frame{position:absolute;inset:0;width:100%;height:100%;pointer-events:none;}
.hero .device{max-width:300px;}

/* phone grid (screenshots) */
.phones{
  display:grid;grid-template-columns:repeat(auto-fit,minmax(200px,1fr));
  gap:28px;align-items:start;
}
.phone-cap{text-align:center;margin-top:14px;font-size:13px;color:var(--muted);}
.phone-cap b{display:block;color:var(--ink);font-weight:600;font-size:14px;margin-bottom:2px;}
.phones.cols-5{grid-template-columns:repeat(5,1fr);gap:20px;}
@media (max-width:1000px){.phones.cols-5{grid-template-columns:repeat(3,1fr);}}
@media (max-width:640px){.phones.cols-5{grid-template-columns:repeat(2,1fr);gap:16px;}}

/* image gallery (landscape / mixed) */
.gallery{display:grid;grid-template-columns:repeat(auto-fit,minmax(320px,1fr));gap:24px;}
.gallery .shot{
  background:var(--surface);border:1px solid var(--line);border-radius:var(--radius);
  overflow:hidden;box-shadow:0 12px 30px -18px rgba(0,0,0,.25);
}
.gallery .shot img{width:100%;height:auto;}
.shot-cap{padding:14px 16px;font-size:13px;color:var(--muted);}
.shot-cap b{color:var(--ink);font-weight:600;font-size:14px;display:block;margin-bottom:2px;}

/* two-up portrait (house renders, dark band) */
.duo{display:grid;grid-template-columns:1fr 1fr;gap:24px;}
.duo .shot{background:transparent;border:0;border-radius:12px;overflow:hidden;box-shadow:none;}
.duo .shot img{width:100%;height:auto;}

/* floors: 2 floors per row (base vs lit each) — keeps images smaller */
.floors{display:grid;grid-template-columns:1fr 1fr;gap:48px 30px;margin-top:8px;}
.floor-tag{
  display:flex;align-items:baseline;gap:14px;flex-wrap:wrap;
  margin:0 0 12px;color:#fff;font-size:14px;font-weight:600;letter-spacing:.02em;
}
.floor-tag span{font-size:12px;font-weight:400;color:rgba(255,255,255,.45);letter-spacing:.03em;}
.floor .duo{gap:12px;}

/* dark showcase band */
.section-dark{background:#000;color:#fff;border-bottom:1px solid #000;}
.section-dark .kicker{color:#9fe1cb;}
.section-dark h2.title{color:#fff;}
.section-dark .lead,.section-dark .lead.sm{color:rgba(255,255,255,.65);}
.section-dark .phone-cap{color:rgba(255,255,255,.6);}
.section-dark .phone-cap b{color:#fff;}

/* split layout: stacked shots + phone */
.split{display:grid;grid-template-columns:1.7fr 1fr;gap:28px;align-items:start;}
.split .stack{display:grid;gap:24px;}
@media (max-width:860px){.split{grid-template-columns:1fr;}}

/* butler gif grid */
.gif-grid{display:grid;grid-template-columns:repeat(4,1fr);gap:18px;}
.gif-cell{background:var(--surface);border:1px solid var(--line);border-radius:var(--radius);overflow:hidden;text-align:center;}
.gif-cell img{width:100%;height:auto;aspect-ratio:1/1;object-fit:cover;}
.gif-cell .name{padding:10px;font-size:13px;color:var(--muted);}

/* two-col text */
.two-col{display:grid;grid-template-columns:1fr 1fr;gap:36px;}
.card{background:var(--surface);border:1px solid var(--line);border-radius:var(--radius);padding:26px;}
.card h3{margin:0 0 10px;font-size:17px;font-weight:600;}
.card p{margin:0;color:var(--muted);font-size:14px;}

/* design notes */
.notes{display:grid;grid-template-columns:repeat(auto-fit,minmax(160px,1fr));gap:16px;margin-top:8px;}
.note{background:var(--accent-soft);border-radius:12px;padding:18px;}
.note b{display:block;font-size:14px;margin-bottom:4px;color:var(--accent);}
.note span{font-size:13px;color:var(--muted);}

/* footer / outro */
.outro{background:#0d0d0c;color:#fff;text-align:center;padding:90px 24px;border:0;}
.outro h2{font-size:30px;margin:0 0 14px;font-weight:600;}
.outro p{color:rgba(255,255,255,.72);max-width:560px;margin:0 auto 30px;font-size:15px;}
.btn{
  display:inline-block;padding:13px 28px;border-radius:999px;
  border:1px solid rgba(255,255,255,.35);color:#fff;font-size:14px;
  transition:background .2s,border-color .2s;
}
.btn:hover{background:rgba(255,255,255,.1);border-color:#fff;}

/* lightbox */
#lightbox{
  position:fixed;inset:0;z-index:100;display:none;
  background:rgba(10,10,9,.92);align-items:center;justify-content:center;padding:40px;cursor:zoom-out;
}
#lightbox.open{display:flex;}
#lightbox img{max-width:92vw;max-height:88vh;border-radius:10px;box-shadow:0 30px 80px rgba(0,0,0,.6);}
.zoom{cursor:zoom-in;}

/* responsive */
@media (max-width:860px){
  .hero-inner{grid-template-columns:1fr;padding:72px 24px 88px;}
  .hero-copy h1{font-size:36px;}
  .two-col,.duo{grid-template-columns:1fr;}
  .floors{grid-template-columns:1fr;}
  .gif-grid{grid-template-columns:repeat(2,1fr);}
  section{padding:60px 0;}
  h2.title{font-size:24px;}
}

/* ← 返回作品集（2026-10-21 古要求加，固定左上，浅色页配色） */
.back-home{
  position:fixed;top:22px;left:26px;z-index:60;
  display:inline-flex;align-items:center;height:42px;padding:0 22px;
  border:1px solid var(--line);border-radius:999px;
  font-size:14px;color:var(--ink);letter-spacing:.04em;text-decoration:none;
  background:rgba(255,255,255,.85);backdrop-filter:blur(8px);-webkit-backdrop-filter:blur(8px);
  transition:border-color .2s,background .2s;
}
.back-home:hover{border-color:var(--accent);background:#fff}