:root {
  --bg: #0d1117; --card: #161d29; --ink: #e8edf6; --dim: #8b98ad;
  --gold: #f2b94b; --green: #37c978; --accent: #4c8dff; --red: #ff5d5d;
}
* { box-sizing: border-box; -webkit-tap-highlight-color: transparent; }
body { margin: 0; background: var(--bg); color: var(--ink);
  font: 16px/1.45 system-ui, -apple-system, sans-serif;
  max-width: 480px; margin-inline: auto; padding: 0 16px 40px; }
header { text-align: center; padding-top: 22px; }
h1 { margin: 0; letter-spacing: 6px; font-size: 28px; }
.sub { color: var(--dim); font-size: 13px; margin-bottom: 14px; }
nav { display: flex; gap: 8px; justify-content: center; align-items: center; }
nav button, .tabs button { background: var(--card); color: var(--dim); border: 1px solid #2a3446;
  border-radius: 999px; padding: 7px 16px; font-size: 14px; cursor: pointer; }
nav button.on, .tabs button.on { color: var(--ink); border-color: var(--accent); }
#streak { margin-left: 6px; font-size: 14px; color: var(--gold); }
.tabs { display: flex; gap: 8px; justify-content: center; margin: 18px 0 10px; }
.target-row { text-align: center; margin: 10px 0 6px; }
.target-label { color: var(--dim); font-size: 12px; letter-spacing: 3px; margin-right: 10px; }
#target { font-size: 42px; font-weight: 800; color: var(--gold); }
#solved-mark { font-size: 22px; margin-left: 8px; }
#chips { display: flex; flex-wrap: wrap; gap: 10px; justify-content: center; margin: 18px 0; min-height: 120px; }
.chip { background: var(--card); border: 2px solid #2a3446; border-radius: 14px; color: var(--ink);
  min-width: 64px; padding: 14px 10px; font-size: 24px; font-weight: 700; text-align: center;
  cursor: pointer; transition: transform .08s, border-color .12s; }
.chip:active { transform: scale(0.94); }
.chip.sel { border-color: var(--accent); color: var(--accent); }
.chip.used { display: none; }
.chip.pop { animation: pop .25s; }
@keyframes pop { 0% { transform: scale(.6); } 70% { transform: scale(1.12); } 100% { transform: scale(1); } }
.ops { display: flex; gap: 10px; justify-content: center; }
.ops button { width: 58px; height: 58px; font-size: 26px; border-radius: 50%;
  background: var(--card); color: var(--ink); border: 2px solid #2a3446; cursor: pointer; }
.ops button.sel { border-color: var(--gold); color: var(--gold); }
.controls { display: flex; gap: 12px; justify-content: center; margin-top: 16px; }
.controls button { background: none; border: none; color: var(--dim); font-size: 14px; cursor: pointer; }
#win { text-align: center; background: var(--card); border-radius: 16px; padding: 18px; margin-top: 18px; }
#win-stars { font-size: 30px; letter-spacing: 6px; }
#win-text { color: var(--dim); margin: 6px 0 12px; }
#win button { background: var(--accent); border: none; color: white; padding: 10px 18px;
  border-radius: 10px; font-size: 15px; cursor: pointer; margin: 0 5px; }
#win #next-diff { background: var(--card); border: 1px solid #2a3446; color: var(--ink); }
#view-archive h2 { text-align: center; }
#archive-list { display: flex; flex-direction: column; gap: 8px; }
.arch-row { display: flex; justify-content: space-between; align-items: center;
  background: var(--card); border-radius: 12px; padding: 12px 16px; cursor: pointer; }
.arch-row.locked { opacity: .55; }
.arch-row .stars { color: var(--gold); }
#paywall { text-align: center; background: linear-gradient(160deg, #1a2333, #161d29);
  border: 1px solid #2a3446; border-radius: 16px; padding: 20px; margin-top: 16px; }
#buy { background: var(--green); border: none; color: #04220f; font-weight: 800;
  padding: 13px 26px; font-size: 17px; border-radius: 12px; cursor: pointer; }
footer { text-align: center; color: var(--dim); font-size: 12px; margin-top: 26px; }
.hidden { display: none !important; }
.muted { color: var(--dim); } .small { font-size: 12px; }
#toast { position: fixed; bottom: 24px; left: 50%; transform: translateX(-50%);
  background: var(--ink); color: var(--bg); padding: 10px 18px; border-radius: 10px; font-weight: 600; }