:root {
  --bg: #f6f3ee;
  --panel: #ffffff;
  --text: #1f1b17;
  --muted: #6b6259;
  --border: #d9d1c5;
  --accent: #1565C0;
  --accent-text: #ffffff;
  --good: #1B7F3A;
  --bad: #C62828;
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #17140f;
    --panel: #221e18;
    --text: #f2ede6;
    --muted: #a89e92;
    --border: #3a342c;
    --accent: #4f8fe0;
    --accent-text: #0e0c09;
    --good: #4cc47a;
    --bad: #ff6b6b;
  }
}
/* Colorblind mode: blue vs red-orange stays distinct for red-green color blindness */
body.cb { --good: #005AB5; --bad: #DC3220; }
@media (prefers-color-scheme: dark) { body.cb { --good: #5fa8ff; --bad: #ff6a4d; } }

* { box-sizing: border-box; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: Inter, system-ui, -apple-system, "Segoe UI", Helvetica, Arial, sans-serif;
}
main { max-width: 1600px; margin: 0 auto; padding: 24px 16px 48px; }
h1 { font-size: 1.6rem; margin: 0 0 4px; }
.sub { color: var(--muted); margin: 0 0 20px; }

.panel {
  background: var(--panel); border: 1px solid var(--border);
  border-radius: 12px; padding: 14px 16px; margin-bottom: 20px;
}
.controls { display: flex; flex-wrap: wrap; gap: 16px 28px; }
fieldset { border: 0; margin: 0; padding: 0; min-width: 0; }
legend, .label { font-size: .75rem; font-weight: 700; letter-spacing: .06em;
                 text-transform: uppercase; color: var(--muted); margin-bottom: 6px; }

/* Radio groups styled as segmented buttons (still real radios) */
.seg { display: inline-flex; flex-wrap: wrap; border: 1px solid var(--border); border-radius: 8px; overflow: hidden; }
.seg input { position: absolute; opacity: 0; pointer-events: none; }
.seg label {
  padding: 8px 14px; cursor: pointer; font-size: .9rem; font-weight: 600;
  border-right: 1px solid var(--border); user-select: none;
}
.seg label:last-of-type { border-right: 0; }
.seg label:hover { background: color-mix(in srgb, var(--accent) 10%, transparent); }
.seg input:checked + label { background: var(--accent); color: var(--accent-text); }
.seg input:focus-visible + label { outline: 3px solid var(--accent); outline-offset: -3px; }

.switch { display: inline-flex; align-items: center; gap: 10px; cursor: pointer;
          font-size: .9rem; font-weight: 600; padding: 7px 0; user-select: none; }
.switch input { position: absolute; opacity: 0; pointer-events: none; }
.switch .track { width: 40px; height: 22px; border-radius: 11px; background: var(--border);
                 position: relative; transition: background .15s; flex: none; }
.switch .track::after { content: ""; position: absolute; top: 3px; left: 3px; width: 16px; height: 16px;
                        border-radius: 50%; background: #fff; box-shadow: 0 1px 2px rgba(0,0,0,.3); transition: transform .15s; }
.switch input:checked + .track { background: var(--accent); }
.switch input:checked + .track::after { transform: translateX(18px); }
.switch input:focus-visible + .track { outline: 3px solid var(--accent); outline-offset: 2px; }

/* Exercise header */
.ex-head { display: flex; flex-wrap: wrap; align-items: center; justify-content: space-between; gap: 12px; margin-bottom: 14px; }
.tabs { display: flex; gap: 6px; flex-wrap: wrap; }
.tab { border: 1px solid var(--border); background: transparent; color: var(--text); border-radius: 999px;
       padding: 6px 14px; font: inherit; font-size: .85rem; font-weight: 700; cursor: pointer; }
.tab[aria-selected="true"] { background: var(--accent); border-color: var(--accent); color: var(--accent-text); }
.tab:disabled { opacity: .45; cursor: default; }
.score { display: flex; gap: 18px; font-size: .9rem; color: var(--muted); }
.score b { color: var(--text); font-size: 1.05rem; }

.prompt { font-size: 1.35rem; font-weight: 600; margin: 4px 0 14px; line-height: 2.1; }
.prompt .chip { vertical-align: middle; margin: 0 4px; line-height: 1.3; }
.chip { display: inline-flex; align-items: center; border-radius: 999px; font-weight: 800; overflow: hidden;
        border: 2px solid rgba(0,0,0,.15); }
.chip span { padding: 4px 14px; }
.chip.string { background: var(--text); color: var(--bg); padding: 4px 14px; }

.board-wrap { overflow-x: auto; border-radius: 8px; }
#board { display: block; width: 100%; height: auto; min-width: 640px; user-select: none; -webkit-user-select: none; }
#board .cell { cursor: pointer; }
#board .cell rect { fill: transparent; }
#board .cell .ghost { opacity: 0; transition: opacity .1s; }
#board .cell:hover .ghost { opacity: .55; }
#board.locked .cell { cursor: default; }
#board.locked .cell:hover .ghost { opacity: 0; }

.actions { display: flex; flex-wrap: wrap; align-items: center; gap: 10px; margin-top: 12px; }
.actions .spacer { flex: 1; }
.btn { border: 1px solid var(--border); background: var(--panel); color: var(--text); border-radius: 8px;
       padding: 9px 16px; font: inherit; font-size: .9rem; font-weight: 700; cursor: pointer; }
.btn:hover { background: color-mix(in srgb, var(--accent) 10%, var(--panel)); }
.btn.primary { background: var(--accent); border-color: var(--accent); color: var(--accent-text); }
.btn.primary:hover { filter: brightness(1.08); }
.btn:disabled { opacity: .45; cursor: default; filter: none; }
.btn[aria-pressed="true"] { border-color: var(--accent); box-shadow: inset 0 0 0 1px var(--accent); }
.btn:focus-visible, .tab:focus-visible { outline: 3px solid var(--accent); outline-offset: 2px; }

.feedback { min-height: 1.6em; margin-top: 12px; font-weight: 700; font-size: 1.05rem; }
.feedback.good { color: var(--good); }
.feedback.bad { color: var(--bad); }
.legend { display: flex; flex-wrap: wrap; gap: 16px; font-size: .85rem; color: var(--muted); margin-top: 4px; }
[hidden] { display: none !important; }
.legend svg { vertical-align: middle; margin-right: 4px; }
.hint { color: var(--muted); font-size: .85rem; }

/* Difficulty help tooltip */
.row { display: flex; align-items: center; gap: 8px; }
.tip { position: relative; display: inline-flex; }
.tip > button {
  width: 24px; height: 24px; border-radius: 50%; border: 1.5px solid var(--muted); background: transparent;
  color: var(--muted); font: inherit; font-size: .8rem; font-weight: 800; cursor: pointer; padding: 0; line-height: 1;
}
.tip > button:hover, .tip.open > button { border-color: var(--accent); color: var(--accent); }
.tip > button:focus-visible { outline: 3px solid var(--accent); outline-offset: 2px; }
.tip-pop {
  position: absolute; z-index: 10; top: calc(100% + 8px); left: var(--tip-left, -140px);
  width: min(300px, 80vw); padding: 10px 12px; border-radius: 8px;
  background: var(--text); color: var(--bg); font-size: .85rem; font-weight: 500; line-height: 1.45;
  box-shadow: 0 6px 20px rgba(0,0,0,.2); visibility: hidden; opacity: 0; transition: opacity .12s;
}
.tip-pop::before { content: ""; position: absolute; top: -6px; left: var(--tip-arrow, 146px); transform: translateX(-50%);
  border: 6px solid transparent; border-top: 0; border-bottom-color: var(--text); }
.tip:hover .tip-pop, .tip:focus-within .tip-pop, .tip.open .tip-pop { visibility: visible; opacity: 1; }
/* --tip-left / --tip-arrow are set by JS so the bubble always stays on screen */

/* Total Recall answer buttons */
.answers { display: grid; grid-template-columns: repeat(7, minmax(0, 1fr)); gap: 8px; margin-top: 14px; }
.answers.chromatic { grid-template-columns: repeat(6, minmax(0, 1fr)); }
@media (max-width: 640px) { .answers, .answers.chromatic { grid-template-columns: repeat(4, minmax(0, 1fr)); } }
.answer {
  position: relative; display: flex; align-items: center; justify-content: center;
  padding: 10px 6px; border: 2px solid var(--border); border-radius: 10px; background: var(--panel);
  font: inherit; font-size: 1.05rem; cursor: pointer; min-height: 52px;
}
.answer:hover:not(:disabled) { border-color: var(--accent); transform: translateY(-1px); }
.answer:focus-visible { outline: 3px solid var(--accent); outline-offset: 2px; }
.answer:disabled { cursor: default; }
.answer .chip span { padding: 4px 12px; }
.answer.is-right { border-color: var(--good); box-shadow: 0 0 0 2px var(--good); }
.answer.is-wrong { border-color: var(--bad); box-shadow: 0 0 0 2px var(--bad); }
.answer.is-dim { opacity: .4; }
.answer .mark { position: absolute; top: -9px; right: -9px; width: 22px; height: 22px; border-radius: 50%;
  display: grid; place-items: center; font-size: .8rem; font-weight: 800; color: #fff; }
.answer.is-right .mark { background: var(--good); }
.answer.is-wrong .mark { background: var(--bad); }

/* Pulsing ring around the Total Recall target */
@keyframes pulse { 0% { stroke-opacity: .9; } 50% { stroke-opacity: .25; } 100% { stroke-opacity: .9; } }
#board .pulse { animation: pulse 1.4s ease-in-out infinite; }
@media (prefers-reduced-motion: reduce) { #board .pulse { animation: none; } }

/* Proximity Mine */
.step { display: inline-grid; place-items: center; width: 1.6em; height: 1.6em; border-radius: 50%;
        background: var(--accent); color: var(--accent-text); font-size: .8em; font-weight: 800; vertical-align: middle; margin-right: 4px; }
.answers.intervals { grid-template-columns: repeat(4, minmax(0, 1fr)); }
@media (max-width: 640px) { .answers.intervals { grid-template-columns: repeat(2, minmax(0, 1fr)); } }
.answer.iv { flex-direction: column; gap: 2px; color: var(--text); }
.iv-name { font-weight: 800; font-size: .95rem; }
.iv-sub { font-size: .75rem; color: var(--muted); font-weight: 600; }

/* How to play guide */
.btn.small { padding: 6px 12px; font-size: .85rem; }
.ex-head .score { margin-left: auto; }
.guide { border: 1px solid var(--border); border-radius: 10px; padding: 4px 16px 14px; margin: 0 0 16px;
         background: color-mix(in srgb, var(--accent) 5%, var(--panel)); }
.guide h2 { font-size: .8rem; letter-spacing: .06em; text-transform: uppercase; color: var(--muted); margin: 14px 0 8px; }
.g-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(260px, 1fr)); gap: 10px; align-items: start; }
.g-item { background: var(--panel); border: 1px solid var(--border); border-radius: 8px; padding: 10px 12px; }
.g-item.current { border-color: var(--accent); box-shadow: 0 0 0 1px var(--accent); }
.g-item h3 { margin: 0 0 4px; font-size: 1rem; }
.g-item p { margin: 0; font-size: .88rem; line-height: 1.5; }
.g-item .now { font-size: .7rem; font-weight: 700; color: var(--accent-text); background: var(--accent);
               border-radius: 999px; padding: 1px 8px; vertical-align: middle; }
.cheat { margin-top: 8px; font-size: .88rem; }
.cheat summary { cursor: pointer; font-weight: 700; color: var(--accent); }
.cheat p { margin: 6px 0; }
.iv-table { border-collapse: collapse; width: 100%; font-size: .85rem; }
.iv-table th, .iv-table td { text-align: left; padding: 3px 8px; border-bottom: 1px solid var(--border); }
.iv-table th { color: var(--muted); font-weight: 700; }

/* Proximity Mine */
.answers .btn.skip { grid-column: 1 / -1; justify-self: end; }

/* Playground tab sits apart from the exercises */
.ex-tools { display: flex; align-items: center; gap: 8px; margin-left: auto; }
.tab-play { border-style: dashed; }
.tab-play[aria-selected="true"] { border-style: solid; }
.play-title { font-weight: 800; margin-right: 18px; padding-right: 18px; border-right: 2px solid var(--border); }
.prompt .muted { color: var(--muted); font-size: .8em; font-weight: 600; }
.chord { margin-right: 10px; }
.chord-sym { display: inline-block; margin-left: 6px; padding: 0 10px; border-radius: 999px; font-weight: 800;
             background: var(--accent); color: var(--accent-text); font-size: .85em; line-height: 1.6; vertical-align: middle; }
.g-item .builds { display: block; margin-top: 10px; }

/* Random mode */
.tab-random { border-color: var(--accent); }
.random-pick { display: flex; flex-wrap: wrap; align-items: center; gap: 8px 12px; margin: -4px 0 14px;
               padding: 10px 12px; border: 1px dashed var(--border); border-radius: 10px; }
.random-pick .label { margin: 0; }
.random-pick .toggles { display: flex; flex-wrap: wrap; gap: 6px; }
.toggle { position: relative; cursor: pointer; user-select: none; }
.toggle input { position: absolute; opacity: 0; pointer-events: none; }
.toggle span { display: inline-flex; align-items: center; gap: 6px; padding: 5px 12px; border-radius: 999px;
               border: 1.5px solid var(--border); font-size: .85rem; font-weight: 700; color: var(--muted); }
.toggle span::before { content: ""; width: 14px; height: 14px; border-radius: 4px; border: 1.5px solid currentColor; }
.toggle input:checked + span { border-color: var(--accent); color: var(--text); background: color-mix(in srgb, var(--accent) 12%, var(--panel)); }
.toggle input:checked + span::before { content: "✓"; display: grid; place-items: center; font-size: 11px; line-height: 1;
               background: var(--accent); color: var(--accent-text); border-color: var(--accent); }
.toggle input:focus-visible + span { outline: 3px solid var(--accent); outline-offset: 2px; }
.pick-note { font-size: .8rem; color: var(--muted); }
.pick-note.warn { color: var(--bad); font-weight: 700; }
.ex-badge { display: inline-block; font-size: .7rem; font-weight: 800; letter-spacing: .05em; text-transform: uppercase;
            color: var(--accent); border: 1.5px solid var(--accent); border-radius: 999px; padding: 0 10px;
            line-height: 1.8; vertical-align: middle; margin-right: 10px; }