/* AST POWERBANK — prototype stylesheet (口径17 原型 V1) */
:root{
  --ink:#0e1116;
  --ink-2:#1a2029;
  --muted:#6b7684;
  --line:#e6e9ee;
  --bg:#ffffff;
  --bg-soft:#f5f7fa;
  --accent:#1f6feb;
  --accent-2:#0b4bc4;
  --ok:#0f9d58;
  --radius:14px;
  --max:1180px;
}
*{box-sizing:border-box}
html,body{margin:0;padding:0}
body{
  font-family:-apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,"Helvetica Neue",Arial,"Noto Sans",sans-serif;
  color:var(--ink);background:var(--bg);line-height:1.62;-webkit-font-smoothing:antialiased;
}
img{max-width:100%;height:auto;display:block;object-fit:contain}
a{color:inherit;text-decoration:none}
.wrap{max-width:var(--max);margin:0 auto;padding:0 24px}
.btn{display:inline-block;padding:13px 26px;border-radius:999px;font-weight:600;font-size:15px;transition:.2s;border:1px solid transparent}
.btn-primary{background:var(--accent);color:#fff}
.btn-primary:hover{background:var(--accent-2)}
.btn-ghost{border-color:#cfd6e0;color:var(--ink)}
.btn-ghost:hover{border-color:var(--ink)}

/* header */
header{position:sticky;top:0;z-index:50;background:rgba(255,255,255,.92);backdrop-filter:blur(10px);border-bottom:1px solid var(--line)}
.nav{display:flex;align-items:center;justify-content:space-between;height:68px}
.brand{display:flex;align-items:center;gap:10px;font-weight:800;letter-spacing:.06em;font-size:15px}
.brand .dot{width:10px;height:10px;border-radius:3px;background:var(--accent)}
.nav ul{display:flex;gap:26px;list-style:none;margin:0;padding:0;font-size:14.5px;font-weight:500}
.nav ul a:hover{color:var(--accent)}

/* hero */
.hero{padding:96px 0 80px;background:linear-gradient(180deg,#f7f9fc 0%,#fff 100%)}
.hero-grid{display:grid;grid-template-columns:1.05fr .95fr;gap:56px;align-items:center}
.eyebrow{display:inline-block;font-size:12.5px;letter-spacing:.14em;text-transform:uppercase;color:var(--accent);font-weight:700;margin-bottom:18px}
h1{font-size:clamp(34px,4.6vw,58px);line-height:1.08;margin:0 0 20px;letter-spacing:-.02em;font-weight:800}
.lead{font-size:18px;color:var(--muted);margin:0 0 32px;max-width:34em}
.hero-cta{display:flex;gap:14px;flex-wrap:wrap}
.hero-img{position:relative}
.hero-img img{width:100%;height:auto;object-fit:contain}

/* trust bar */
.trust{border-top:1px solid var(--line);border-bottom:1px solid var(--line);background:#fff}
.trust .wrap{display:grid;grid-template-columns:repeat(4,1fr);gap:0}
.trust div{padding:26px 18px;text-align:center;border-right:1px solid var(--line)}
.trust div:last-child{border-right:0}
.trust b{display:block;font-size:21px;letter-spacing:-.01em}
.trust span{font-size:12.8px;color:var(--muted);letter-spacing:.02em}

/* sections */
section{padding:84px 0}
.section-head{max-width:640px;margin-bottom:44px}
.section-head h2{font-size:clamp(26px,3vw,36px);margin:0 0 12px;letter-spacing:-.015em}
.section-head p{margin:0;color:var(--muted);font-size:16.5px}
.soft{background:var(--bg-soft)}

/* product cards */
.cards{display:grid;grid-template-columns:repeat(4,1fr);gap:22px}
.card{border:1px solid var(--line);border-radius:var(--radius);padding:26px 22px;background:#fff;transition:.22s;display:flex;flex-direction:column}
.card:hover{transform:translateY(-4px);box-shadow:0 18px 40px rgba(14,17,22,.09);border-color:#d6dce6}
.card .thumb{height:150px;display:flex;align-items:center;justify-content:center;margin-bottom:18px}
.card .thumb img{max-height:150px;object-fit:contain}
.card h3{margin:0 0 4px;font-size:19px;letter-spacing:-.01em}
.card .cap{color:var(--accent);font-weight:700;font-size:14px;margin-bottom:10px}
.card p{margin:0 0 18px;color:var(--muted);font-size:14.2px;flex:1}
.card .more{font-size:14px;font-weight:600;color:var(--ink)}
.card .more:hover{color:var(--accent)}

/* use cases */
.uses{display:grid;grid-template-columns:repeat(4,1fr);gap:20px}
.use{border-radius:var(--radius);padding:28px 22px;background:#fff;border:1px solid var(--line)}
.use .ico{font-size:22px;margin-bottom:14px}
.use h4{margin:0 0 8px;font-size:16.5px}
.use p{margin:0;color:var(--muted);font-size:14px}

/* why */
.why{display:grid;grid-template-columns:repeat(2,1fr);gap:18px 34px}
.why div{padding:20px 0;border-bottom:1px solid var(--line)}
.why b{display:block;margin-bottom:4px;font-size:16px}
.why span{color:var(--muted);font-size:14.5px}

/* cta band */
.band{background:var(--ink);color:#fff}
.band .wrap{display:flex;align-items:center;justify-content:space-between;gap:32px;padding:64px 24px}
.band h2{margin:0 0 8px;font-size:clamp(24px,2.6vw,32px)}
.band p{margin:0;color:#a8b3c1}
.band .btn-primary{background:#fff;color:var(--ink)}
.band .btn-primary:hover{background:#e8edf5}

/* product page */
.pdp{padding:64px 0 20px}
.pdp-grid{display:grid;grid-template-columns:1.1fr .9fr;gap:56px;align-items:center}
.spec{width:100%;border-collapse:collapse;margin-top:18px;font-size:14.5px}
.spec th,.spec td{text-align:left;padding:12px 4px;border-bottom:1px solid var(--line);vertical-align:top}
.spec th{width:42%;color:var(--muted);font-weight:500}
.pill{display:inline-block;font-size:12px;font-weight:700;letter-spacing:.06em;text-transform:uppercase;color:var(--accent);background:#eaf1fe;padding:5px 11px;border-radius:999px;margin-bottom:14px}

/* footer */
footer{background:#0b0e13;color:#8d99a8;padding:56px 0 34px;font-size:14px}
footer .cols{display:grid;grid-template-columns:1.4fr 1fr 1fr 1fr;gap:32px;margin-bottom:36px}
footer h5{color:#fff;font-size:13px;letter-spacing:.1em;text-transform:uppercase;margin:0 0 14px}
footer a:hover{color:#fff}
footer ul{list-style:none;margin:0;padding:0;display:grid;gap:9px}
footer .copy{border-top:1px solid #1b2029;padding-top:22px;font-size:12.8px;color:#6b7684}

/* responsive */
@media(max-width:960px){
  .hero-grid,.pdp-grid{grid-template-columns:1fr;gap:36px}
  .cards,.uses{grid-template-columns:repeat(2,1fr)}
  .trust .wrap{grid-template-columns:repeat(2,1fr)}
  .trust div:nth-child(2){border-right:0}
  .why{grid-template-columns:1fr}
  .nav ul{display:none}
  footer .cols{grid-template-columns:1fr 1fr}
  .band .wrap{flex-direction:column;align-items:flex-start}
}
@media(max-width:560px){
  .cards,.uses,footer .cols{grid-template-columns:1fr}
  section{padding:60px 0}
}

/* --- internal structure video slots --- */
.video-slot{padding:8px 0 0}
.video-frame{position:relative;aspect-ratio:16/9;border-radius:14px;overflow:hidden;background:#0f1720;border:1px solid #e6ebf2}
.video-frame iframe,.video-frame video{position:absolute;inset:0;width:100%;height:100%;border:0}
.video-placeholder,.video-poster{position:absolute;inset:0;display:flex;flex-direction:column;align-items:center;justify-content:center;gap:14px;border:0;width:100%;background:#0f1720 center/cover no-repeat;color:#cbd6e2;cursor:default;font:inherit}
button.video-poster{cursor:pointer}
button.video-poster:hover .video-play{transform:scale(1.06)}
.video-badge{position:absolute;top:16px;left:16px;font-size:12px;letter-spacing:.08em;text-transform:uppercase;color:#9fb0c3;border:1px solid #2b3a4a;border-radius:999px;padding:5px 10px}
.video-play{width:64px;height:64px;border-radius:50%;background:#fff;color:#0f1720;display:flex;align-items:center;justify-content:center;font-size:22px;transition:transform .15s ease}
.video-note{margin:0;font-size:13px;color:#8fa1b5}

/* kit figure */
.kit-grid{display:grid;grid-template-columns:1.35fr .65fr;gap:24px;margin-top:32px;align-items:start}
.kit-grid figure,.kit-dims{margin:0}
.kit-grid img,.kit-dims img{width:100%;height:auto;display:block;object-fit:contain;border:1px solid var(--line);border-radius:var(--radius);background:#fff}
.kit-batt img{max-height:430px;margin:0 auto}
.kit-grid figcaption,.kit-dims figcaption{margin-top:10px;font-size:13.5px;color:var(--muted);line-height:1.5}
.kit-dims{margin-top:24px}
@media (max-width:900px){.kit-grid{grid-template-columns:1fr}.kit-batt img{max-height:none}}
/* responsive image cards — never stretch */
.hero-img.is-wide img{aspect-ratio:16/9;object-fit:contain;width:100%;height:auto;background:#fff;border:1px solid var(--line);border-radius:var(--radius);padding:10px}
.kit-main img{aspect-ratio:16/9;object-fit:contain;background:#fff}
.kit-batt img{aspect-ratio:1/1;object-fit:contain;background:#fff;max-height:none}
.kit-dims img{object-fit:contain;background:#fff;max-width:960px;margin:0 auto}
.kit-grid img,.kit-dims img{padding:10px}
@media (max-width:900px){.kit-dims img{max-width:100%}}
/* hero image card — contain, never crop or stretch */
.hero-img.is-card img{width:100%;height:auto;max-height:min(58vh,520px);object-fit:contain;background:#fff;border:1px solid var(--line);border-radius:16px;padding:12px}
@media(max-width:960px){.hero-img.is-card img{max-height:none}}
/* product card thumbs — fit inside, no letterbox jump */
.card .thumb{display:flex;align-items:center;justify-content:center;height:170px}
.card .thumb img{max-height:100%;width:auto;object-fit:contain}
/* placeholder thumb (awaiting product photo) */
.card .thumb .ph{width:100%;height:150px;display:flex;flex-direction:column;align-items:center;justify-content:center;gap:4px;background:#f5f7fa;border:1px dashed #cfd8e3;border-radius:10px;color:#8b96a5;font-size:13px;text-align:center}
.card .thumb .ph span{font-size:12px;color:#a6b0bd}

/* langbar v2 */
.langbar{display:inline-flex;align-items:center;gap:3px;margin-left:18px;padding:3px;border:1px solid #dfe6ef;border-radius:999px;background:#fff;white-space:nowrap}
.langbar a{display:inline-block;padding:5px 12px;border-radius:999px;font-size:13.5px;font-weight:800;letter-spacing:.02em;color:#40506a;text-decoration:none}
.langbar a:hover{background:#eef4ff;color:#0f62fe}
.langbar a.on{background:#0f62fe;color:#fff}
.langbar a.on:hover{background:#0b4fd4;color:#fff}
.langbar .soon{font-size:11.5px;font-weight:700;color:#a6b0bd;padding:0 7px 0 4px}
@media(max-width:1080px){.langbar{margin-left:10px}}
@media(max-width:820px){.langbar{margin-left:0;order:5}.langbar .soon{display:none}.langbar a{padding:5px 10px;font-size:13px}}