*{box-sizing:border-box}
body{
  font-family:'Inter',system-ui,-apple-system,Segoe UI,Roboto,Ubuntu,'Helvetica Neue',Arial;
  background: radial-gradient(circle at 20% -10%, #0ea5e9 0%, transparent 25%), 
              radial-gradient(circle at 120% 20%, #22d3ee 0%, transparent 30%),
              linear-gradient(#0b1020,#060913);
  color:#e2e8f0;margin:0;padding:0
}
.wrapper{max-width:860px;margin:48px auto;background:rgba(13,18,34,.85);
  padding:36px 28px;border-radius:22px;box-shadow:0 8px 40px rgba(2,132,199,.25)}
h1{text-align:center;font-size:2rem;color:#7dd3fc;margin:0 0 10px}
.subtitle{text-align:center;color:#a3b2c7;margin:0 0 24px}
.os-list{display:flex;flex-wrap:wrap;justify-content:center;gap:12px;margin-bottom:20px}
.os-btn{background:linear-gradient(90deg,#06b6d4,#0ea5e9);color:#fff;border:none;padding:10px 18px;border-radius:9999px;cursor:pointer;font-weight:700;letter-spacing:.2px;transition:all .25s}
.os-btn:hover{transform:translateY(-3px);box-shadow:0 8px 18px rgba(14,165,233,.35)}
.guide-box{background:#121a2a;border:1px solid #1f2a44;border-radius:16px;padding:22px;margin-top:18px;box-shadow:inset 0 0 0 1px rgba(125,211,252,.06)}
.mt-20{margin-top:28px}
.placeholder{text-align:center;color:#97a6ba}
.section-title{margin:0 0 10px;color:#7dd3fc}
.guide-step{margin:10px 0;padding-left:12px;border-left:3px solid #38bdf8}
.copy-box{display:inline-block;background:#0b1020;padding:8px 10px;border-radius:8px;color:#93c5fd;font-family:ui-monospace,SFMono-Regular,Menlo,monospace;border:1px solid rgba(125,211,252,.25);text-decoration:none}
.copy-row{display:flex;flex-wrap:wrap;gap:10px;margin:12px 0}
.tip{background:#0a1322;border-left:3px solid #22c55e;padding:10px;border-radius:8px;margin:10px 0;color:#b7c8dd}
.warn{background:#1a0f14;border-left:3px solid #f59e0b;padding:10px;border-radius:8px;margin:10px 0;color:#f8d7a1}
kbd{background:#0b1020;border:1px solid #25324a;border-bottom-width:3px;border-radius:6px;padding:2px 6px;font-family:ui-monospace,SFMono-Regular,Menlo,monospace;color:#e2e8f0}
footer{text-align:center;margin-top:26px;font-size:.9rem;color:#7a8aa1}
footer a{color:#7dd3fc;text-decoration:none}
footer a:hover{text-decoration:underline}

/* Accordion */
.acc{margin:10px 0;border:1px solid #23314d;border-radius:10px;overflow:hidden}
.acc-h{background:#0f1627;cursor:pointer;display:flex;justify-content:space-between;align-items:center;padding:12px 14px}
.acc-h b{color:#e2e8f0}
.acc-c{display:none;padding:12px 14px;background:#101728}
.acc.open .acc-c{display:block}
.acc.open .acc-h{background:#0c1322}