:root{
  --bg:#0f172a; /* slate-900 */
  --fg:#e2e8f0; /* slate-200 */
  --muted:#94a3b8; /* slate-400 */
  --accent:#22d3ee; /* cyan-400 */
  --card:#111827; /* gray-900 */
  --btn:#1f2937; /* gray-800 */
}
*{box-sizing:border-box}
html,body{margin:0;padding:0;background:var(--bg);color:var(--fg);font-family:ui-sans-serif,system-ui,-apple-system,"Segoe UI",Roboto,"Noto Sans","Helvetica Neue",Arial,"Apple Color Emoji","Segoe UI Emoji"}
.container{max-width:960px;margin:40px auto;padding:24px}
.card{background:linear-gradient(180deg,rgba(255,255,255,0.04),rgba(255,255,255,0.02));border:1px solid rgba(255,255,255,0.08);border-radius:16px;box-shadow:0 10px 30px rgba(0,0,0,.4);padding:24px}
h1{font-size:32px;margin:0 0 8px 0;letter-spacing:0.3px}
.sub{color:var(--muted);margin-bottom:20px}
.controls{display:flex;gap:12px;flex-wrap:wrap;margin-bottom:16px}
input[type="number"]{background:var(--card);color:var(--fg);border:1px solid rgba(255,255,255,0.08);border-radius:12px;padding:12px 14px;outline:none;min-width:180px}
button{background:var(--btn);color:var(--fg);border:1px solid rgba(255,255,255,0.12);border-radius:12px;padding:12px 16px;cursor:pointer;transition:transform .08s ease, border-color .2s ease}
button:hover{border-color:var(--accent)}
button:active{transform:translateY(1px)}
.output{white-space:pre-wrap;line-height:1.8;background:rgba(0,0,0,.35);border:1px dashed rgba(255,255,255,.15);padding:18px;border-radius:12px;min-height:220px}
.footer{margin-top:12px;display:flex;gap:10px;flex-wrap:wrap;align-items:center}
.small{font-size:12px;color:var(--muted)}
.tag{font-size:12px;border:1px solid rgba(255,255,255,0.12);padding:6px 8px;border-radius:999px}
a{color:var(--accent);text-decoration:none}
.toast{position:fixed;right:16px;bottom:16px;background:var(--card);padding:10px 14px;border-radius:12px;border:1px solid rgba(255,255,255,0.1);opacity:0;transform:translateY(6px);transition:all .2s ease}
.toast.show{opacity:1;transform:none}