:root {
  --bg: #ffffff;
  --fg: #1a1a1b;
  --muted: #787c7e;
  --line: #d3d6da;
  --line-strong: #878a8c;
  --tile-empty: #ffffff;
  --green: #6aaa64;
  --yellow: #c9b458;
  --gray: #787c7e;
  --key-bg: #d3d6da;
  --key-fg: #1a1a1b;
  --accent: #5a7bd8;
  --panel: #f6f7f8;
  --panel-line: #e3e5e8;
  --shadow: 0 1px 3px rgba(0,0,0,.12);
  --maxw: 1060px;
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #121213;
    --fg: #e9e9ea;
    --muted: #818384;
    --line: #3a3a3c;
    --line-strong: #565758;
    --tile-empty: #121213;
    --green: #538d4e;
    --yellow: #b59f3b;
    --gray: #3a3a3c;
    --key-bg: #818384;
    --key-fg: #ffffff;
    --accent: #7e9cff;
    --panel: #1c1c1e;
    --panel-line: #2c2c2e;
    --shadow: 0 1px 3px rgba(0,0,0,.5);
  }
}

* { box-sizing: border-box; }
html, body { margin: 0; }
body {
  background: var(--bg);
  color: var(--fg);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  line-height: 1.45;
  -webkit-font-smoothing: antialiased;
}

/* ---------- header ---------- */
.topbar {
  position: relative;
  text-align: center;
  padding: 22px 16px 14px;
  border-bottom: 1px solid var(--line);
}
.topbar h1 { margin: 0; padding: 0 12px; font-size: clamp(1.15rem, 3.4vw, 2rem); letter-spacing: .2px; }
.tagline { margin: 6px auto 0; max-width: 640px; color: var(--muted); font-size: .95rem; }
.tagline em { color: var(--fg); font-style: normal; font-weight: 600; }

/* ---------- mode tabs ---------- */
.modes {
  display: flex; flex-wrap: wrap; gap: 6px; justify-content: center;
  padding: 12px 10px; max-width: var(--maxw); margin: 0 auto;
}
.tab {
  border: 1px solid var(--line-strong); background: transparent; color: var(--fg);
  padding: 7px 13px; border-radius: 999px; cursor: pointer; font-size: .86rem;
  font-weight: 600; transition: background .12s, color .12s;
}
.tab:hover { background: var(--panel); }
.tab.active { background: var(--fg); color: var(--bg); border-color: var(--fg); }
.tab.special { border-style: dashed; }

main { max-width: var(--maxw); margin: 0 auto; padding: 4px 12px 40px; }

.mode-head { text-align: center; margin: 8px 0 14px; }
.mode-head h2 { margin: 0 0 4px; font-size: 1.5rem; }
.blurb, .mode-head .blurb { max-width: 620px; margin: 0 auto; color: var(--muted); font-size: .92rem; }
.blurb em { color: var(--fg); font-style: italic; }
.hint { color: var(--muted); font-weight: 400; font-size: .8em; }

/* ---------- layout ---------- */
.play-grid {
  display: grid; grid-template-columns: minmax(0, 1fr); gap: 26px;
  align-items: start; justify-items: center;
}
.play-grid.with-info { grid-template-columns: minmax(0,1fr) minmax(0, 380px); }
.board-col { width: 100%; max-width: 360px; }

/* ---------- board ---------- */
.board { display: grid; grid-template-rows: repeat(var(--rows, 6), 1fr); gap: 5px; margin: 0 auto 12px; width: min(330px, 86vw); }
.row { display: grid; grid-template-columns: repeat(5, 1fr); gap: 5px; }
.tile {
  aspect-ratio: 1 / 1; display: grid; place-items: center;
  font-weight: 700; font-size: clamp(1.3rem, 7vw, 2rem); text-transform: uppercase;
  border: 2px solid var(--line); color: var(--fg); background: var(--tile-empty);
  user-select: none;
}
.tile.filled { border-color: var(--line-strong); animation: pop .1s ease; }
.tile.green { background: var(--green); border-color: var(--green); color: #fff; }
.tile.yellow { background: var(--yellow); border-color: var(--yellow); color: #fff; }
.tile.gray { background: var(--gray); border-color: var(--gray); color: #fff; }
.tile.reveal { animation: flip .5s ease forwards; }
@keyframes pop { 0% { transform: scale(.9);} 100%{ transform: scale(1);} }
@keyframes flip { 0%{transform:rotateX(0);} 50%{transform:rotateX(90deg);} 100%{transform:rotateX(0);} }

.message { text-align: center; min-height: 24px; font-weight: 600; font-size: .95rem; }
.message.win { color: var(--green); }
.message.lose { color: #c0392b; }

/* ---------- keyboard ---------- */
.keyboard { display: flex; flex-direction: column; gap: 6px; margin: 10px auto 0; width: min(460px, 96vw); }
.krow { display: flex; gap: 5px; justify-content: center; }
.key {
  flex: 1 1 0; min-width: 0; height: 50px; border: none; border-radius: 5px;
  background: var(--key-bg); color: var(--key-fg); font-weight: 700; font-size: .8rem;
  text-transform: uppercase; cursor: pointer; display: grid; place-items: center;
}
.key.wide { flex: 1.5 1 0; font-size: .68rem; }
.kspacer { flex: .5 1 0; }
.key.green { background: var(--green); color: #fff; }
.key.yellow { background: var(--yellow); color: #fff; }
.key.gray { background: var(--gray); color: #fff; }
.key:active { transform: translateY(1px); }

.controls { display: flex; align-items: center; justify-content: center; gap: 16px; margin-top: 16px; flex-wrap: wrap; }
.btn {
  background: var(--fg); color: var(--bg); border: none; padding: 9px 16px;
  border-radius: 7px; font-weight: 700; cursor: pointer; font-size: .88rem;
}
.btn.ghost { background: transparent; color: var(--fg); border: 1px solid var(--line-strong); }
.overlay-toggle { display: flex; align-items: center; gap: 7px; font-size: .85rem; color: var(--muted); cursor: pointer; }

/* ---------- info column ---------- */
.info-col {
  width: 100%; background: var(--panel); border: 1px solid var(--panel-line);
  border-radius: 12px; padding: 16px 16px 18px; box-shadow: var(--shadow);
}
.info-col h3 { margin: 0 0 12px; font-size: 1.05rem; }
.meters { display: flex; gap: 12px; margin-bottom: 12px; }
.meter { flex: 1; background: var(--bg); border: 1px solid var(--panel-line); border-radius: 9px; padding: 10px 12px; }
.meter-label { font-size: .72rem; text-transform: uppercase; letter-spacing: .04em; color: var(--muted); }
.meter-value { font-size: 1.5rem; font-weight: 800; }
.meter-value span { font-variant-numeric: tabular-nums; }
.meter-sub { font-size: .78rem; color: var(--muted); }

.guess-coach { background: var(--bg); border: 1px solid var(--panel-line); border-radius: 9px; padding: 10px 12px; margin-bottom: 12px; }
.coach-row { display: flex; justify-content: space-between; gap: 10px; font-size: .86rem; padding: 2px 0; }
.coach-k { color: var(--muted); white-space: nowrap; }
.coach-v { text-align: right; }
.coach-v b { font-variant-numeric: tabular-nums; }

.trace { width: 100%; border-collapse: collapse; font-size: .82rem; font-variant-numeric: tabular-nums; }
.trace th, .trace td { text-align: right; padding: 5px 6px; border-bottom: 1px solid var(--panel-line); }
.trace th:nth-child(2), .trace td:nth-child(2) { text-align: left; text-transform: uppercase; letter-spacing: .08em; font-weight: 700; }
.trace th:first-child, .trace td:first-child { text-align: center; color: var(--muted); }
.trace .bar-cell { width: 92px; }
.bar { height: 9px; border-radius: 5px; background: var(--accent); display: inline-block; vertical-align: middle; }
.thumb-pos { color: var(--green); }
.thumb-neg { color: #c0392b; }

/* ---------- lab ---------- */
.lab-form { display: flex; gap: 8px; align-items: center; justify-content: center; flex-wrap: wrap; margin-bottom: 16px; }
.lab-form input {
  font-size: 1rem; padding: 9px 12px; border: 1px solid var(--line-strong);
  border-radius: 7px; background: var(--bg); color: var(--fg); text-transform: uppercase;
  letter-spacing: .1em; width: 240px; font-weight: 700;
}
.lab-form input::placeholder { letter-spacing: normal; text-transform: none; font-weight: 500; }
.lab-form input.err { border-color: #c0392b; }
.lab-tip { color: var(--muted); font-size: .82rem; width: 100%; text-align: center; }
.lab-tip code { background: var(--panel); padding: 1px 5px; border-radius: 4px; }
.lab-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(220px, 1fr)); gap: 14px; }
.lab-card { background: var(--panel); border: 1px solid var(--panel-line); border-radius: 11px; padding: 12px 13px; box-shadow: var(--shadow); }
.lab-card h4 { margin: 0 0 2px; font-size: 1rem; display: flex; justify-content: space-between; align-items: baseline; }
.lab-card .lc-bits { font-size: .78rem; color: var(--muted); font-weight: 600; }
.lab-card .lc-status { font-size: .76rem; color: var(--muted); margin-bottom: 8px; }
.lab-card.solved { outline: 2px solid var(--green); }
.lab-mini { display: grid; gap: 3px; margin-bottom: 8px; }
.lab-mini .row { gap: 3px; }
.lab-mini .tile { font-size: .8rem; border-width: 1px; aspect-ratio: 1/1; }
.lab-bars { display: flex; flex-direction: column; gap: 4px; }
.lab-bar-row { display: flex; align-items: center; gap: 6px; font-size: .72rem; }
.lab-bar-row .lbl { width: 40px; text-transform: uppercase; letter-spacing: .06em; color: var(--muted); }
.lab-bar-row .barwrap { flex: 1; background: var(--bg); border-radius: 5px; height: 12px; overflow: hidden; border: 1px solid var(--panel-line); }
.lab-bar-row .bar { height: 100%; border-radius: 0; }
.lab-bar-row .val { width: 58px; text-align: right; font-variant-numeric: tabular-nums; }

/* ---------- mystery ---------- */
.verdict { margin-top: 14px; padding: 12px 14px; border-radius: 10px; background: var(--bg); border: 1px solid var(--panel-line); font-size: .9rem; }
.verdict h4 { margin: 0 0 6px; font-size: 1.05rem; }
.verdict.win h4 { color: var(--green); }

.foot { border-top: 1px solid var(--line); text-align: center; padding: 18px 14px; color: var(--muted); font-size: .82rem; }
.foot a { color: var(--accent); }

@media (max-width: 860px) {
  .play-grid.with-info { grid-template-columns: minmax(0,1fr); }
  .info-col { max-width: 460px; }
}

@media (max-width: 520px) {
  .topbar { padding: 16px 12px 12px; }
  .topbar h1 { font-size: 1.1rem; }
  .tagline { font-size: .82rem; }
  main { padding: 4px 10px 32px; }

  /* keyboard: respect the page gutters and keep keys from looking stretched */
  .keyboard { width: 100%; gap: 5px; }
  .krow { gap: 4px; }
  .key { height: 44px; font-size: .76rem; border-radius: 4px; }
  .key.wide { font-size: .58rem; }

  .board { width: min(330px, 88vw); }
  .controls { gap: 12px; }
}