*, *::before, *::after { margin: 0; padding: 0; box-sizing: border-box; }

:root {
    --bg-primary: #0a0e17;
    --bg-secondary: #111827;
    --bg-panel: #1a2235;
    --border: #2a3550;
    --text-primary: #e2e8f0;
    --text-secondary: #94a3b8;
    --text-muted: #64748b;
    --accent: #06b6d4;
    --accent-dim: rgba(6, 182, 212, 0.15);
    --flag-yellow: #f59e0b;
    --flag-red: #ef4444;
    --success: #22c55e;
    --danger: #ef4444;
}

body {
    font-family: 'Inter', system-ui, sans-serif;
    background: var(--bg-primary);
    color: var(--text-primary);
    min-height: 100vh;
}

header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    flex-wrap: wrap;
    gap: 1rem;
    padding: 1rem 1.5rem;
    background: var(--bg-secondary);
    border-bottom: 1px solid var(--border);
}

.brand {
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

.brand h1 { font-size: 1.15rem; font-weight: 700; }
.brand h1 span.accent { color: var(--accent); }

.version-label {
    font-family: 'Share Tech Mono', monospace;
    font-size: 0.7rem;
    color: var(--text-muted);
    font-weight: 400;
}

.btn-back-hub {
    color: var(--text-secondary);
    text-decoration: none;
    font-size: 0.85rem;
    transition: color 0.2s;
}

.btn-back-hub:hover {
    color: var(--text-primary);
}

.mode-tabs { display: flex; gap: 0.35rem; flex-wrap: wrap; }

.mode-tab {
    padding: 0.45rem 0.85rem;
    background: var(--bg-panel);
    border: 1px solid var(--border);
    border-radius: 8px;
    color: var(--text-secondary);
    font-size: 0.78rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s;
}

.mode-tab:hover { border-color: var(--accent); color: var(--text-primary); }
.mode-tab.active {
    background: var(--accent-dim);
    border-color: var(--accent);
    color: var(--accent);
}

.container {
    max-width: 1100px;
    margin: 0 auto;
    padding: 1rem 1.5rem 2rem;
}

.panel {
    background: var(--bg-panel);
    border: 1px solid var(--border);
    border-radius: 12px;
    padding: 1.25rem;
    display: none;
}

.panel.active { display: block; }

/* Semaphore figure */
.semaphore-stage {
    display: flex;
    justify-content: center;
    align-items: center;
    padding: 2rem;
    background: var(--bg-secondary);
    border-radius: 12px;
    margin-bottom: 1rem;
    min-height: 300px;
}

.semaphore-figure {
    position: relative;
    width: 200px;
    height: 260px;
}

.figure-body {
    position: absolute;
    left: 50%;
    transform: translateX(-50%);
}

.figure-head {
    width: 36px;
    height: 36px;
    background: var(--accent);
    border-radius: 50%;
    position: absolute;
    top: 0;
    left: 50%;
    transform: translateX(-50%);
}

.figure-torso {
    width: 4px;
    height: 70px;
    background: var(--accent);
    position: absolute;
    top: 36px;
    left: 50%;
    transform: translateX(-50%);
    border-radius: 2px;
}

.figure-leg-l, .figure-leg-r {
    width: 4px;
    height: 55px;
    background: var(--accent);
    position: absolute;
    top: 106px;
    transform-origin: top center;
    border-radius: 2px;
}

.figure-leg-l { left: calc(50% - 12px); transform: rotate(15deg); }
.figure-leg-r { left: calc(50% + 8px); transform: rotate(-15deg); }

.figure-arm {
    width: 4px;
    height: 65px;
    position: absolute;
    top: 42px;
    transform-origin: top center;
    transition: transform 0.4s cubic-bezier(0.4, 0, 0.2, 1);
    border-radius: 2px;
}

.figure-arm-l {
    left: calc(50% - 2px);
    background: var(--accent);
}

.figure-arm-r {
    left: calc(50% - 2px);
    background: var(--accent);
}

.flag-element {
    width: 24px;
    height: 18px;
    position: absolute;
    bottom: -2px;
    border-radius: 2px;
}

.flag-element-l { background: var(--flag-yellow); right: -24px; }
.flag-element-r { background: var(--flag-red); left: -24px; }

/* Reference grid */
.ref-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(130px, 1fr));
    gap: 0.75rem;
}

.ref-card {
    background: var(--bg-secondary);
    border: 1px solid var(--border);
    border-radius: 10px;
    padding: 0.75rem;
    cursor: pointer;
    transition: border-color 0.2s, transform 0.15s;
    text-align: center;
}

.ref-card:hover {
    border-color: var(--accent);
    transform: translateY(-2px);
}

.ref-card .letter {
    font-family: 'Share Tech Mono', monospace;
    font-size: 1.4rem;
    color: var(--accent);
    font-weight: 700;
    margin-bottom: 0.25rem;
}

.ref-card .positions {
    font-size: 0.65rem;
    color: var(--text-muted);
    text-transform: uppercase;
    letter-spacing: 0.04em;
}

.ref-card .mini-figure {
    display: flex;
    justify-content: center;
    margin: 0.5rem 0 0.25rem;
}

/* Quiz panels */
.quiz-stage {
    display: flex;
    justify-content: center;
    align-items: center;
    padding: 2rem;
    background: var(--bg-secondary);
    border-radius: 12px;
    margin-bottom: 1rem;
    min-height: 280px;
}

.quiz-prompt {
    font-size: 1.1rem;
    color: var(--text-secondary);
    margin-bottom: 1rem;
    text-align: center;
}

.quiz-prompt strong {
    color: var(--accent);
    font-size: 1.4rem;
}

.choices {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(56px, 1fr));
    gap: 0.5rem;
    margin-bottom: 1rem;
}

.choice-btn {
    padding: 0.65rem;
    background: var(--bg-secondary);
    border: 2px solid var(--border);
    border-radius: 8px;
    font-family: 'Share Tech Mono', monospace;
    font-size: 1.1rem;
    font-weight: 700;
    color: var(--text-primary);
    cursor: pointer;
    transition: all 0.15s;
}

.choice-btn:hover { border-color: var(--accent); }
.choice-btn.correct { border-color: var(--success); background: rgba(34,197,94,0.15); }
.choice-btn.wrong { border-color: var(--danger); background: rgba(239,68,68,0.15); }

.score-bar {
    display: flex;
    flex-wrap: wrap;
    gap: 1.25rem;
    margin: 1rem 0;
    font-size: 0.9rem;
    color: var(--text-secondary);
}

.score-bar strong { color: var(--accent); }

.timer-display {
    font-family: 'Share Tech Mono', monospace;
    font-size: 2rem;
    color: var(--accent);
    text-align: center;
    margin-bottom: 0.5rem;
}

.btn-row { display: flex; flex-wrap: wrap; gap: 0.5rem; justify-content: center; }

.btn {
    padding: 0.5rem 1rem;
    border-radius: 8px;
    border: 1px solid var(--border);
    background: var(--bg-secondary);
    color: var(--text-primary);
    font-weight: 600;
    font-size: 0.85rem;
    cursor: pointer;
}

.btn:hover { border-color: var(--accent); }

.btn-primary {
    background: var(--accent-dim);
    border-color: var(--accent);
    color: var(--accent);
}

.btn:disabled { opacity: 0.5; cursor: not-allowed; }

.feedback {
    text-align: center;
    padding: 0.5rem;
    margin-top: 0.5rem;
    border-radius: 6px;
    font-size: 0.9rem;
}

.feedback.ok { background: rgba(34,197,94,0.15); color: var(--success); }
.feedback.err { background: rgba(239,68,68,0.15); color: var(--danger); }

.hidden { display: none !important; }

/* Sender panel */
.sender-input {
    width: 100%;
    font-family: 'Share Tech Mono', monospace;
    font-size: 1.1rem;
    padding: 0.75rem;
    background: var(--bg-secondary);
    border: 2px solid var(--border);
    border-radius: 8px;
    color: var(--text-primary);
    margin-bottom: 1rem;
    text-transform: uppercase;
}

.sender-input:focus { outline: 2px solid var(--accent); }

.speed-control {
    display: flex;
    align-items: center;
    gap: 1rem;
    margin-bottom: 1rem;
}

.speed-control label {
    font-size: 0.75rem;
    text-transform: uppercase;
    letter-spacing: 0.06em;
    color: var(--text-muted);
}

.speed-control input[type="range"] { width: 160px; }

.sent-display {
    font-family: 'Share Tech Mono', monospace;
    padding: 0.75rem;
    background: var(--bg-secondary);
    border: 1px solid var(--border);
    border-radius: 8px;
    min-height: 2.5rem;
    color: var(--accent);
    font-size: 1.1rem;
    letter-spacing: 0.15em;
    margin-bottom: 1rem;
    text-align: center;
}

.filter-tabs {
    display: flex;
    gap: 0.35rem;
    margin-bottom: 1rem;
    flex-wrap: wrap;
}

.filter-tab {
    padding: 0.35rem 0.75rem;
    font-size: 0.75rem;
    border-radius: 6px;
    border: 1px solid var(--border);
    background: transparent;
    color: var(--text-muted);
    cursor: pointer;
}

.filter-tab.active {
    border-color: var(--accent);
    color: var(--accent);
    background: var(--accent-dim);
}

/* Spell-out exercise */
.spell-input {
    width: 100%;
    max-width: 300px;
    margin: 0 auto 1rem;
    display: block;
    padding: 0.75rem;
    font-family: 'Share Tech Mono', monospace;
    font-size: 1.25rem;
    text-align: center;
    text-transform: uppercase;
    background: var(--bg-secondary);
    border: 2px solid var(--border);
    border-radius: 8px;
    color: var(--text-primary);
}

.spell-input:focus { outline: 2px solid var(--accent); }

@media (max-width: 600px) {
    header { flex-direction: column; align-items: flex-start; }
    .mode-tabs { width: 100%; }
    .ref-grid { grid-template-columns: repeat(auto-fill, minmax(100px, 1fr)); }
}