:root {
    --bg: #0e0e10;
    --panel: #1c1c1e;
    --panel-2: #2c2c2e;
    --border: #3a3a3c;
    --text: #e5e5ea;
    --muted: #8e8e93;
    --accent: #0a84ff;
    --green: #32d74b;
    --red: #ff453a;
    --orange: #ff9f0a;
    --purple: #bf5af2;
    --court: #7a5230;
    --court-line: #e8d5b7;
}

* { box-sizing: border-box; -webkit-tap-highlight-color: transparent; }

html, body { height: 100%; }

body {
    margin: 0;
    background: var(--bg);
    color: var(--text);
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    line-height: 1.4;
    -webkit-text-size-adjust: 100%;
}

.site-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 12px;
    padding: 14px 18px;
    padding-top: max(14px, env(safe-area-inset-top));
    background: var(--panel);
    border-bottom: 1px solid var(--border);
    position: sticky;
    top: 0;
    z-index: 10;
}

.brand {
    color: var(--text);
    text-decoration: none;
    font-weight: 700;
    font-size: 17px;
}

.scorebar { display: flex; gap: 8px; align-items: center; }

.score-pill {
    background: var(--panel-2);
    border: 1px solid var(--border);
    border-radius: 999px;
    padding: 4px 12px;
    font-size: 14px;
    color: var(--muted);
    font-variant-numeric: tabular-nums;
}
.score-pill b { color: var(--text); }

.container {
    max-width: 560px;
    margin: 0 auto;
    padding: 18px;
    padding-bottom: max(24px, env(safe-area-inset-bottom));
}

.screen { animation: fade 0.18s ease; }
@keyframes fade { from { opacity: 0; transform: translateY(4px); } to { opacity: 1; transform: none; } }

h1 { font-size: 24px; margin: 8px 0 8px; }
.sub { color: var(--muted); font-size: 15px; margin: 0 0 22px; }
.hint { color: var(--muted); font-size: 13px; margin-top: 18px; }

/* ---------- Buttons ---------- */
.btn {
    display: block;
    width: 100%;
    min-height: 52px;
    border: 1px solid var(--border);
    border-radius: 12px;
    background: var(--panel-2);
    color: var(--text);
    font-size: 17px;
    font-weight: 600;
    cursor: pointer;
    padding: 12px 16px;
    transition: transform 0.06s, border-color 0.15s, background 0.15s;
}
.btn:active { transform: scale(0.985); }
.btn.primary { background: var(--accent); border-color: var(--accent); color: #fff; }
.btn.next { margin-top: 14px; background: var(--accent); border-color: var(--accent); color: #fff; }

/* ---------- Diagram ---------- */
.diagram-card {
    background: var(--panel);
    border: 1px solid var(--border);
    border-radius: 14px;
    padding: 10px;
    margin-bottom: 16px;
}
.diagram { display: block; width: 100%; height: auto; }

/* ---------- Choices ---------- */
.prompt { font-size: 17px; font-weight: 600; margin: 0 0 12px; text-align: center; }

.choices { display: grid; gap: 10px; }

.choice {
    display: flex;
    align-items: center;
    gap: 10px;
    width: 100%;
    min-height: 54px;
    text-align: left;
    background: var(--panel);
    border: 1px solid var(--border);
    border-radius: 12px;
    color: var(--text);
    font-size: 16px;
    padding: 12px 16px;
    cursor: pointer;
    transition: transform 0.06s, border-color 0.15s, background 0.15s;
}
.choice:active { transform: scale(0.99); }
.choice .kbd {
    flex: 0 0 26px;
    height: 26px;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: 7px;
    background: var(--panel-2);
    border: 1px solid var(--border);
    font-size: 13px;
    font-weight: 700;
    color: var(--muted);
}
.choice.correct { border-color: var(--green); background: rgba(50, 215, 75, 0.12); }
.choice.correct .kbd { border-color: var(--green); color: var(--green); }
.choice.wrong { border-color: var(--red); background: rgba(255, 69, 58, 0.12); }
.choice.wrong .kbd { border-color: var(--red); color: var(--red); }
.choice:disabled { cursor: default; opacity: 0.85; }
.choice.dim { opacity: 0.4; }

/* ---------- Feedback ---------- */
.feedback {
    margin-top: 16px;
    padding: 14px 16px;
    border-radius: 12px;
    border: 1px solid var(--border);
    background: var(--panel);
    font-size: 15px;
}
.feedback.good { border-color: var(--green); }
.feedback.bad { border-color: var(--red); }
.feedback .fb-title { font-weight: 700; margin-bottom: 6px; }
.feedback.good .fb-title { color: var(--green); }
.feedback.bad .fb-title { color: var(--red); }
.feedback .fb-desc { color: var(--muted); }

.watch-link {
    display: block;
    text-align: center;
    margin-top: 16px;
    color: var(--accent);
    text-decoration: none;
    font-size: 14px;
}
.watch-link:hover { text-decoration: underline; }

.final-msg { font-size: 16px; margin: 4px 0 20px; }
.final-msg.good { color: var(--green); }
.final-msg.bad { color: var(--orange); }