/* ===================================================
   MORSE CODE TRAINER — Design System & Styles
   =================================================== */

/* ---------- CSS Custom Properties ---------- */
:root {
    /* Palette */
    --bg-primary: #0a0e17;
    --bg-secondary: #111827;
    --bg-card: #1a2236;
    --bg-card-hover: #1f2a42;
    --bg-input: #0f1629;
    --border: #2a3654;
    --border-focus: #38bdf8;

    /* Text */
    --text-primary: #e2e8f0;
    --text-secondary: #94a3b8;
    --text-muted: #64748b;
    --text-accent: #38bdf8;

    /* Accent colors */
    --accent: #38bdf8;
    --accent-glow: rgba(56, 189, 248, 0.25);
    --accent-2: #818cf8;
    --green: #34d399;
    --green-glow: rgba(52, 211, 153, 0.2);
    --red: #f87171;
    --red-glow: rgba(248, 113, 113, 0.2);
    --amber: #fbbf24;
    --amber-glow: rgba(251, 191, 36, 0.2);

    /* Spacing */
    --space-xs: 0.25rem;
    --space-sm: 0.5rem;
    --space-md: 1rem;
    --space-lg: 1.5rem;
    --space-xl: 2rem;
    --space-2xl: 3rem;

    /* Radius */
    --radius-sm: 6px;
    --radius-md: 10px;
    --radius-lg: 16px;
    --radius-full: 9999px;

    /* Typography */
    --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    --font-mono: 'JetBrains Mono', 'Fira Code', 'Consolas', monospace;

    /* Transitions */
    --transition: 0.2s ease;
    --transition-slow: 0.4s ease;

    /* Shadows */
    --shadow-sm: 0 1px 3px rgba(0,0,0,0.3);
    --shadow-md: 0 4px 16px rgba(0,0,0,0.4);
    --shadow-lg: 0 8px 32px rgba(0,0,0,0.5);
    --shadow-glow: 0 0 30px var(--accent-glow);
}

/* ---------- Reset & Base ---------- */
*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    font-size: 16px;
    scroll-behavior: smooth;
    -webkit-font-smoothing: antialiased;
    overflow-x: hidden;
}

/* Custom Scrollbar */
::-webkit-scrollbar {
    width: 6px;
    height: 6px;
}

::-webkit-scrollbar-track {
    background: var(--bg-primary);
}

::-webkit-scrollbar-thumb {
    background: var(--border);
    border-radius: var(--radius-full);
}

::-webkit-scrollbar-thumb:hover {
    background: var(--accent);
}

/* For Firefox */
* {
    scrollbar-width: thin;
    scrollbar-color: var(--border) var(--bg-primary);
}

body {
    font-family: var(--font-sans);
    background: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.6;
    min-height: 100vh;
    overflow-x: hidden;
    overflow-y: auto;
    position: relative;
    -webkit-overflow-scrolling: touch;
}

/* Screen reader only */
.sr-only {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0,0,0,0);
    border: 0;
}

/* ---------- Animated Background ---------- */
.bg-grid {
    position: fixed;
    inset: 0;
    background-image:
        linear-gradient(rgba(56, 189, 248, 0.03) 1px, transparent 1px),
        linear-gradient(90deg, rgba(56, 189, 248, 0.03) 1px, transparent 1px);
    background-size: 60px 60px;
    pointer-events: none;
    z-index: 0;
}

.bg-glow {
    position: fixed;
    border-radius: 50%;
    filter: blur(120px);
    opacity: 0.4;
    pointer-events: none;
    z-index: 0;
    animation: float 20s ease-in-out infinite;
}

.bg-glow--1 {
    width: 500px;
    height: 500px;
    background: radial-gradient(circle, rgba(56,189,248,0.15), transparent 70%);
    top: -100px;
    right: -100px;
}

.bg-glow--2 {
    width: 400px;
    height: 400px;
    background: radial-gradient(circle, rgba(129,140,248,0.12), transparent 70%);
    bottom: -100px;
    left: -50px;
    animation-delay: -10s;
}

@keyframes float {
    0%, 100% { transform: translate(0, 0); }
    33% { transform: translate(30px, -20px); }
    66% { transform: translate(-20px, 15px); }
}

/* ---------- App Container ---------- */
.app {
    position: relative;
    z-index: 1;
    max-width: 860px;
    margin: 0 auto;
    padding: var(--space-md) var(--space-md);
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

/* ---------- Header ---------- */
.header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: var(--space-md);
    flex-wrap: wrap;
    margin-bottom: var(--space-md);
}

.header__brand {
    display: flex;
    align-items: center;
    gap: var(--space-md);
}

.header__logo {
    display: flex;
    align-items: center;
    gap: 4px;
    padding: 10px;
    background: var(--bg-card);
    border-radius: var(--radius-md);
    border: 1px solid var(--border);
}

.header__dot {
    width: 8px;
    height: 8px;
    border-radius: 50%;
    background: var(--accent);
    animation: pulse-dot 2s ease-in-out infinite;
}

.header__dash {
    width: 22px;
    height: 8px;
    border-radius: 4px;
    background: var(--accent);
    animation: pulse-dot 2s ease-in-out infinite 0.3s;
}

@keyframes pulse-dot {
    0%, 100% { opacity: 0.5; }
    50% { opacity: 1; box-shadow: 0 0 8px var(--accent-glow); }
}

.header__title {
    font-size: 1.5rem;
    font-weight: 700;
    background: linear-gradient(135deg, var(--accent), var(--accent-2));
    background-clip: text;
    -webkit-background-clip: text;
    color: transparent;
    line-height: 1.2;
}

.header__subtitle {
    font-size: 0.75rem;
    color: var(--text-muted);
    font-weight: 500;
    letter-spacing: 0.5px;
}

/* Panel Localized Controls */
.panel__controls {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: var(--space-md);
    margin-bottom: var(--space-lg);
    padding-bottom: var(--space-lg);
    border-bottom: 1px solid var(--border);
}

.header__controls {
    display: flex;
    gap: var(--space-md);
    flex-wrap: wrap;
}

.speed-control, .freq-control {
    display: flex;
    align-items: center;
    gap: var(--space-sm);
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius-md);
    padding: var(--space-sm) var(--space-md);
    cursor: default;
}

.speed-control__label, .freq-control__label {
    font-size: 0.75rem;
    color: var(--text-muted);
    text-transform: uppercase;
    letter-spacing: 0.5px;
    font-weight: 600;
}

.speed-control__slider, .freq-control__slider {
    -webkit-appearance: none;
    appearance: none;
    width: 80px;
    height: 4px;
    border-radius: 2px;
    background: var(--border);
    outline: none;
    cursor: pointer;
}

.speed-control__slider::-webkit-slider-thumb,
.freq-control__slider::-webkit-slider-thumb {
    -webkit-appearance: none;
    appearance: none;
    width: 16px;
    height: 16px;
    border-radius: 50%;
    background: var(--accent);
    cursor: pointer;
    box-shadow: 0 0 6px var(--accent-glow);
    transition: transform var(--transition);
}

.speed-control__slider::-webkit-slider-thumb:hover,
.freq-control__slider::-webkit-slider-thumb:hover {
    transform: scale(1.2);
}

.speed-control__value, .freq-control__value {
    font-size: 0.8rem;
    font-family: var(--font-mono);
    color: var(--accent);
    min-width: 58px;
    text-align: right;
}

/* ---------- Tabs ---------- */
.tabs {
    display: flex;
    gap: 4px;
    background: var(--bg-secondary);
    border: 1px solid var(--border);
    border-radius: var(--radius-lg);
    padding: 4px;
    margin-bottom: var(--space-md);
}

.tab {
    flex: 1;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--space-sm);
    padding: var(--space-sm) var(--space-md);
    background: transparent;
    border: none;
    border-radius: var(--radius-md);
    color: var(--text-secondary);
    font-family: var(--font-sans);
    font-size: 0.9rem;
    font-weight: 500;
    cursor: pointer;
    transition: all var(--transition);
    position: relative;
}

.tab:hover {
    color: var(--text-primary);
    background: rgba(56,189,248,0.05);
}

.tab--active {
    background: var(--bg-card);
    color: var(--accent);
    box-shadow: var(--shadow-sm);
}

.tab__icon {
    width: 18px;
    height: 18px;
    flex-shrink: 0;
}

/* ---------- Content Panels ---------- */
.content {
    flex: 1;
}

.panel {
    display: none;
    animation: fadeIn 0.3s ease;
}

.panel--active {
    display: block;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(8px); }
    to { opacity: 1; transform: translateY(0); }
}

.panel__header {
    margin-bottom: var(--space-md);
}

.panel__title {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: var(--space-xs);
}

.panel__desc {
    font-size: 0.875rem;
    color: var(--text-secondary);
    line-height: 1.5;
}

.panel__desc code {
    background: var(--bg-card);
    padding: 2px 6px;
    border-radius: 4px;
    font-family: var(--font-mono);
    font-size: 0.85em;
    color: var(--accent);
}

/* ---------- Form Elements ---------- */
.field-label {
    display: block;
    font-size: 0.8rem;
    font-weight: 600;
    color: var(--text-secondary);
    text-transform: uppercase;
    letter-spacing: 0.5px;
    margin-bottom: var(--space-sm);
}

.textarea, .input {
    width: 100%;
    padding: var(--space-md);
    background: var(--bg-input);
    border: 1px solid var(--border);
    border-radius: var(--radius-md);
    color: var(--text-primary);
    font-family: var(--font-sans);
    font-size: 1rem;
    line-height: 1.6;
    resize: vertical;
    transition: border-color var(--transition), box-shadow var(--transition);
    outline: none;
}

.textarea:focus, .input:focus {
    border-color: var(--border-focus);
    box-shadow: 0 0 0 3px var(--accent-glow);
}

.textarea--mono {
    font-family: var(--font-mono);
    letter-spacing: 2px;
    font-size: 1.1rem;
}

.input--lg {
    font-size: 1.2rem;
    padding: var(--space-md) var(--space-lg);
    text-align: center;
    font-family: var(--font-mono);
    letter-spacing: 3px;
    text-transform: uppercase;
}

/* ---------- Buttons ---------- */
.btn {
    display: inline-flex;
    align-items: center;
    gap: var(--space-sm);
    padding: 10px 18px;
    border: 1px solid transparent;
    border-radius: var(--radius-md);
    font-family: var(--font-sans);
    font-size: 0.875rem;
    font-weight: 500;
    cursor: pointer;
    transition: all var(--transition);
    white-space: nowrap;
    outline: none;
}

.btn svg {
    width: 16px;
    height: 16px;
    flex-shrink: 0;
}

.btn:disabled {
    opacity: 0.4;
    cursor: not-allowed;
}

.btn--primary {
    background: linear-gradient(135deg, #0ea5e9, #38bdf8);
    color: #0a0e17;
    font-weight: 600;
    box-shadow: 0 2px 10px rgba(14,165,233,0.3);
}

.btn--primary:hover:not(:disabled) {
    box-shadow: 0 4px 20px rgba(14,165,233,0.5);
    transform: translateY(-1px);
}

.btn--accent {
    background: linear-gradient(135deg, var(--green), #6ee7b7);
    color: #0a0e17;
    font-weight: 600;
    box-shadow: 0 2px 10px var(--green-glow);
}

.btn--accent:hover:not(:disabled) {
    box-shadow: 0 4px 20px var(--green-glow);
    transform: translateY(-1px);
}

.btn--ghost {
    background: var(--bg-card);
    border-color: var(--border);
    color: var(--text-secondary);
}

.btn--ghost:hover:not(:disabled) {
    border-color: var(--accent);
    color: var(--text-primary);
    background: var(--bg-card-hover);
}

.btn--sm {
    padding: 6px 14px;
    font-size: 0.8rem;
}

.btn--toggle {
    background: var(--bg-card);
    border-color: var(--border);
    color: var(--text-secondary);
}

.btn--toggle--active {
    background: rgba(56, 189, 248, 0.15);
    border-color: var(--accent);
    color: var(--accent);
}

.btn-group {
    display: flex;
    flex-wrap: wrap;
    gap: 6px;
}

/* ---------- Encoder / Decoder ---------- */
.encoder, .decoder {
    display: flex;
    flex-direction: column;
    gap: var(--space-lg);
}

.encoder__actions, .decoder__actions {
    display: flex;
    flex-wrap: wrap;
    gap: var(--space-sm);
    margin-top: var(--space-sm);
}

.morse-output, .text-output {
    min-height: 80px;
    padding: var(--space-md);
    background: var(--bg-input);
    border: 1px solid var(--border);
    border-radius: var(--radius-md);
    font-family: var(--font-mono);
    font-size: 1.2rem;
    letter-spacing: 3px;
    line-height: 2;
    word-break: break-all;
    color: var(--accent);
    position: relative;
}

.text-output {
    font-family: var(--font-sans);
    font-size: 1.1rem;
    letter-spacing: 1px;
    color: var(--text-primary);
}

.morse-output__placeholder, .text-output__placeholder {
    color: var(--text-muted);
    font-family: var(--font-sans);
    font-size: 0.9rem;
    letter-spacing: normal;
}

.morse-output .dot {
    color: var(--green);
}

.morse-output .dash {
    color: var(--accent);
}

.morse-output .separator {
    color: var(--text-muted);
    margin: 0 2px;
}

.morse-output .word-break {
    color: var(--amber);
    margin: 0 6px;
}

/* ---------- Signal Lamp ---------- */
.signal-lamp {
    width: 12px;
    height: 12px;
    border-radius: 50%;
    background: var(--text-muted);
    margin: var(--space-sm) auto 0;
    transition: all 0.05s;
    opacity: 0.3;
}

.signal-lamp--lg {
    width: 24px;
    height: 24px;
}

.signal-lamp--on {
    background: var(--accent);
    opacity: 1;
    box-shadow: 0 0 20px var(--accent-glow), 0 0 60px var(--accent-glow);
}

/* ---------- Trainer ---------- */
.trainer {
    display: flex;
    flex-direction: column;
    gap: var(--space-lg);
}

.trainer__difficulty {
    display: flex;
    align-items: center;
    gap: var(--space-md);
    flex-wrap: wrap;
}

.trainer__challenge {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--space-md);
}

.challenge-card {
    width: 100%;
    text-align: center;
    padding: var(--space-2xl) var(--space-lg);
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius-lg);
    position: relative;
    overflow: hidden;
}

.challenge-card::before {
    content: '';
    position: absolute;
    inset: 0;
    background: linear-gradient(135deg, rgba(56,189,248,0.03), rgba(129,140,248,0.03));
    pointer-events: none;
}

.challenge-card__morse {
    font-family: var(--font-mono);
    font-size: 1.8rem;
    letter-spacing: 6px;
    color: var(--accent);
    margin-bottom: var(--space-md);
    word-break: break-all;
    line-height: 1.8;
}

.challenge-card__visual {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 6px;
    flex-wrap: wrap;
    min-height: 20px;
}

.visual-dot {
    width: 12px;
    height: 12px;
    border-radius: 50%;
    background: var(--green);
    display: inline-block;
    animation: popIn 0.3s ease;
}

.visual-dash {
    width: 36px;
    height: 12px;
    border-radius: 6px;
    background: var(--accent);
    display: inline-block;
    animation: popIn 0.3s ease;
}

.visual-space {
    width: 16px;
    display: inline-block;
}

.visual-word-space {
    width: 32px;
    display: inline-block;
}

@keyframes popIn {
    from { transform: scale(0); opacity: 0; }
    to { transform: scale(1); opacity: 1; }
}

.trainer__answer {
    display: flex;
    flex-direction: column;
    gap: var(--space-sm);
}

.trainer__answer-actions {
    display: flex;
    flex-wrap: wrap;
    gap: var(--space-sm);
}

/* Score cards */
.trainer__score {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: var(--space-sm);
}

.score-card {
    text-align: center;
    padding: var(--space-md);
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius-md);
}

.score-card__label {
    display: block;
    font-size: 0.7rem;
    text-transform: uppercase;
    letter-spacing: 1px;
    color: var(--text-muted);
    margin-bottom: 4px;
}

.score-card__value {
    font-family: var(--font-mono);
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--text-primary);
}

.score-card__value--correct { color: var(--green); }
.score-card__value--wrong { color: var(--red); }
.score-card__value--streak { color: var(--amber); }

/* Feedback */
.trainer__feedback {
    text-align: center;
    font-size: 1rem;
    font-weight: 500;
    padding: var(--space-md);
    border-radius: var(--radius-md);
    min-height: 48px;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all var(--transition);
}

.trainer__feedback--correct {
    background: var(--green-glow);
    color: var(--green);
    border: 1px solid rgba(52, 211, 153, 0.3);
}

.trainer__feedback--wrong {
    background: var(--red-glow);
    color: var(--red);
    border: 1px solid rgba(248, 113, 113, 0.3);
}

.trainer__feedback--reveal {
    background: var(--amber-glow);
    color: var(--amber);
    border: 1px solid rgba(251, 191, 36, 0.3);
}

/* ---------- Audio Decoder ---------- */
.audio-decoder {
    display: flex;
    flex-direction: column;
    gap: var(--space-lg);
}

.audio-decoder__controls {
    display: flex;
    gap: var(--space-md);
    flex-wrap: wrap;
}

.audio-control {
    display: flex;
    align-items: center;
    gap: var(--space-sm);
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius-md);
    padding: var(--space-sm) var(--space-md);
    cursor: default;
    flex: 1;
    min-width: 200px;
}

.audio-control__label {
    font-size: 0.75rem;
    color: var(--text-muted);
    text-transform: uppercase;
    letter-spacing: 0.5px;
    font-weight: 600;
    white-space: nowrap;
}

.audio-control__slider {
    -webkit-appearance: none;
    appearance: none;
    flex: 1;
    height: 4px;
    border-radius: 2px;
    background: var(--border);
    outline: none;
    cursor: pointer;
}

.audio-control__slider::-webkit-slider-thumb {
    -webkit-appearance: none;
    appearance: none;
    width: 16px;
    height: 16px;
    border-radius: 50%;
    background: var(--accent);
    cursor: pointer;
    box-shadow: 0 0 6px var(--accent-glow);
    transition: transform var(--transition);
}

.audio-control__slider::-webkit-slider-thumb:hover {
    transform: scale(1.2);
}

.audio-control__value {
    font-size: 0.8rem;
    font-family: var(--font-mono);
    color: var(--accent);
    min-width: 50px;
    text-align: right;
}

.audio-decoder__actions {
    display: flex;
    flex-wrap: wrap;
    gap: var(--space-sm);
}

.btn--lg-icon svg {
    width: 20px;
    height: 20px;
}

.audio-decoder__visualizer {
    display: flex;
    flex-direction: column;
    gap: var(--space-sm);
}

.waveform-canvas {
    width: 100%;
    height: 120px;
    background: var(--bg-input);
    border: 1px solid var(--border);
    border-radius: var(--radius-md);
    display: block;
}

.audio-decoder__indicators {
    display: flex;
    align-items: center;
    gap: var(--space-md);
}

.audio-decoder__indicators .signal-lamp {
    margin: 0;
    flex-shrink: 0;
}

.audio-decoder__status {
    font-size: 0.85rem;
    font-weight: 500;
    color: var(--text-secondary);
}

.audio-decoder__magnitude {
    font-size: 0.8rem;
    font-family: var(--font-mono);
    color: var(--text-muted);
    margin-left: auto;
}

.audio-decoder__morse-group,
.audio-decoder__text-group {
    display: flex;
    flex-direction: column;
}

.audio-decoder__copy-actions {
    display: flex;
    gap: var(--space-sm);
    margin-top: var(--space-sm);
    flex-wrap: wrap;
}

.audio-decoder__status--listening {
    color: var(--green);
}

/* ---------- Contest Trainer ---------- */
.contest {
    display: flex;
    flex-direction: column;
    gap: var(--space-lg);
}

.contest__type {
    display: flex;
    align-items: center;
    gap: var(--space-md);
    flex-wrap: wrap;
}

.contest__exchange {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--space-md);
}

.contest__qso-label {
    font-size: 0.75rem;
    text-transform: uppercase;
    letter-spacing: 1px;
    color: var(--text-muted);
    margin-bottom: var(--space-sm);
}

.contest__log-entry {
    display: flex;
    flex-direction: column;
    gap: var(--space-md);
}

.contest__fields {
    display: grid;
    grid-template-columns: 2fr 1fr 1fr;
    gap: var(--space-sm);
}

.contest__field .input {
    text-transform: uppercase;
    font-family: var(--font-mono);
    letter-spacing: 1px;
}

.contest__actions {
    display: flex;
    flex-wrap: wrap;
    gap: var(--space-sm);
}

.contest__log-table-wrapper {
    margin-top: var(--space-sm);
}

.contest__log-table-scroll {
    max-height: 280px;
    overflow-y: auto;
    border: 1px solid var(--border);
    border-radius: var(--radius-md);
}

.contest__log-table {
    width: 100%;
    border-collapse: collapse;
    font-size: 0.85rem;
}

.contest__log-table thead {
    position: sticky;
    top: 0;
    z-index: 1;
}

.contest__log-table th {
    background: var(--bg-card);
    color: var(--text-muted);
    font-size: 0.7rem;
    padding: var(--space-xs) var(--space-sm);
    text-align: left;
    text-transform: uppercase;
    font-weight: 600;
    border-bottom: 2px solid var(--border);
}

.contest__log-table td {
    padding: var(--space-xs) var(--space-sm);
    border-bottom: 1px solid var(--border);
    color: var(--text-secondary);
}

/* ---------- Settings Panel ---------- */
.settings {
    display: flex;
    flex-direction: column;
    gap: var(--space-lg);
}

.settings__section {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius-lg);
    padding: var(--space-lg);
}

.settings__title {
    font-size: 1rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: var(--space-md);
    display: flex;
    align-items: center;
    gap: var(--space-sm);
}

.settings__grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: var(--space-md);
}

.settings__control {
    display: flex;
    flex-direction: column;
    gap: var(--space-xs);
}

.settings__label-group {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.settings__help {
    font-size: 0.75rem;
    color: var(--text-muted);
    line-height: 1.4;
}

/* --- Results/Correct/Wrong colors --- */
.result--correct { color: var(--green); font-weight: 600; }
.result--wrong { color: var(--red); font-weight: 600; }

.contest__log-table th {
    background: var(--bg-card);
    color: var(--text-muted);
    font-size: 0.7rem;
    padding: var(--space-xs) var(--space-sm);
    text-align: left;
    text-transform: uppercase;
    font-weight: 600;
    border-bottom: 2px solid var(--border);
}

.contest__log-table td {
    padding: 8px 12px;
    border-bottom: 1px solid rgba(42, 54, 84, 0.5);
    font-family: var(--font-mono);
    color: var(--text-primary);
}

.contest__log-table tr:hover td {
    background: var(--bg-card-hover);
}

.contest__log-table .result--correct {
    color: var(--green);
    font-weight: 600;
}

.contest__log-table .result--wrong {
    color: var(--red);
    font-weight: 600;
}

.contest__settings {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: var(--space-md);
    background: rgba(15, 23, 42, 0.4);
    padding: var(--space-md);
    border-radius: var(--radius-lg);
    border: 1px solid var(--border);
}

.toggle-checkbox {
    -webkit-appearance: none;
    appearance: none;
    width: 40px;
    height: 20px;
    background: var(--bg-input);
    border: 1px solid var(--border);
    border-radius: 10px;
    position: relative;
    cursor: pointer;
    transition: background var(--transition);
}

.toggle-checkbox:checked {
    background: var(--accent);
}

.toggle-checkbox::before {
    content: '';
    position: absolute;
    width: 14px;
    height: 14px;
    background: #fff;
    border-radius: 50%;
    top: 2px;
    left: 2px;
    transition: transform var(--transition);
}

.toggle-checkbox:checked::before {
    transform: translateX(20px);
}

/* ---------- Reference Chart ---------- */
.reference {
    margin: var(--space-xl) 0;
}

.reference__toggle {
    cursor: pointer;
    padding: var(--space-md) var(--space-lg);
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius-lg);
    list-style: none;
    transition: background var(--transition);
}

.reference__toggle:hover {
    background: var(--bg-card-hover);
}

.reference__toggle::-webkit-details-marker {
    display: none;
}

.reference__title {
    font-size: 1.1rem;
    font-weight: 600;
    color: var(--text-primary);
    margin: 0;
}

details[open] > .reference__toggle {
    border-radius: var(--radius-lg) var(--radius-lg) 0 0;
    border-bottom: none;
}

details[open] > .reference__content,
.reference details[open] > .reference__content {
    border: 1px solid var(--border);
    border-top: none;
    border-radius: 0 0 var(--radius-lg) var(--radius-lg);
}

.reference__content {
    background: var(--bg-secondary);
    border-radius: var(--radius-lg);
    border: 1px solid var(--border);
    overflow: hidden;
}

.reference__chart {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(140px, 1fr));
    gap: 4px;
    padding: var(--space-md);
}

.ref-item {
    display: flex;
    align-items: center;
    gap: var(--space-sm);
    padding: 8px 12px;
    background: var(--bg-card);
    border-radius: var(--radius-sm);
    cursor: pointer;
    transition: all var(--transition);
}

.ref-item:hover {
    background: var(--bg-card-hover);
    transform: scale(1.02);
}

.ref-item__char {
    font-weight: 700;
    font-size: 1rem;
    color: var(--text-primary);
    min-width: 18px;
    text-align: center;
}

.ref-item__morse {
    font-family: var(--font-mono);
    font-size: 0.85rem;
    color: var(--accent);
    letter-spacing: 2px;
}

/* ---------- Footer ---------- */
.footer {
    text-align: center;
    padding: var(--space-xl) 0 var(--space-md);
    color: var(--text-muted);
    font-size: 0.8rem;
}

.footer a {
    color: var(--accent);
    text-decoration: none;
    transition: color var(--transition);
}

.footer a:hover {
    color: var(--accent-2);
}

/* ---------- Toast Notifications ---------- */
.toast {
    position: fixed;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%) scale(0.9);
    background: rgba(30, 41, 59, 0.95);
    border: 1px solid var(--accent);
    border-radius: var(--radius-lg);
    padding: 20px 40px;
    color: var(--text-primary);
    font-size: 1.1rem;
    font-weight: 500;
    box-shadow: var(--shadow-lg), 0 0 40px rgba(0, 0, 0, 0.6);
    z-index: 2000;
    opacity: 0;
    transition: all 0.4s cubic-bezier(0.18, 0.89, 0.32, 1.28);
    pointer-events: none;
    text-align: center;
    backdrop-filter: blur(12px);
    max-width: 85%;
    line-height: 1.4;
}

.toast--visible {
    transform: translate(-50%, -50%) scale(1);
    opacity: 1;
}

/* ---------- Responsive ---------- */
@media (max-width: 768px) {
    html, body {
        overflow-x: hidden;
        width: 100%;
    }

    .app {
        padding: var(--space-sm);
        max-width: 100vw;
    }

    .header {
        flex-direction: column;
        align-items: flex-start;
        gap: var(--space-sm);
    }

    .header__controls {
        width: 100%;
    }

    .speed-control, .freq-control {
        flex: 1;
        min-width: 0;
    }

    .speed-control__slider, .freq-control__slider {
        flex: 1;
        min-width: 50px;
    }

    /* Scrollable tabs for mobile */
    .tabs {
        overflow-x: auto;
        overflow-y: hidden;
        -webkit-overflow-scrolling: touch;
        scrollbar-width: none;
        border-radius: var(--radius-md);
        flex-wrap: nowrap;
    }

    .tabs::-webkit-scrollbar {
        display: none;
    }

    .tab {
        padding: var(--space-sm) var(--space-sm);
        font-size: 0.75rem;
        gap: 2px;
        flex-direction: column;
        flex: 0 0 auto;
        min-width: 64px;
        white-space: nowrap;
    }

    .tab span {
        font-size: 0.65rem;
    }

    .tab__icon {
        width: 18px;
        height: 18px;
    }

    /* Panel controls stack on mobile */
    .panel__controls {
        grid-template-columns: 1fr;
    }

    .panel__header {
        text-align: center;
    }

    .panel__desc {
        font-size: 0.85rem;
    }

    .challenge-card {
        padding: var(--space-md);
    }

    .challenge-card__morse {
        font-size: 1.2rem;
        letter-spacing: 3px;
        word-break: break-all;
    }

    .morse-output, .text-output {
        font-size: 0.95rem;
        letter-spacing: 2px;
        word-break: break-all;
        max-width: 100%;
    }

    .input--lg {
        font-size: 1rem;
        letter-spacing: 2px;
    }

    textarea, input[type="text"] {
        max-width: 100%;
    }

    .trainer__score {
        grid-template-columns: repeat(2, 1fr);
    }

    .score-card__value {
        font-size: 1.2rem;
    }

    .reference__chart {
        grid-template-columns: repeat(auto-fill, minmax(90px, 1fr));
    }

    .trainer__difficulty {
        flex-direction: column;
        align-items: stretch;
    }

    .audio-decoder__controls {
        flex-direction: column;
    }

    .audio-control {
        min-width: 0;
    }

    .waveform-canvas {
        height: 90px;
    }

    .contest__type {
        flex-direction: column;
        align-items: flex-start;
    }

    .contest__fields {
        grid-template-columns: 1fr;
    }

    .encoder__actions, .decoder__actions {
        flex-wrap: wrap;
    }

    .btn-group {
        width: 100%;
        flex-wrap: wrap;
    }

    .btn {
        min-height: 44px; /* Touch-friendly */
    }
}

@media (max-width: 400px) {
    html {
        font-size: 14px;
    }

    .header__title {
        font-size: 1.3rem;
    }

    .encoder__actions, .decoder__actions, .trainer__answer-actions {
        flex-direction: column;
    }

    .btn {
        justify-content: center;
        width: 100%;
    }

    .btn-group {
        width: 100%;
    }

    .btn-group .btn {
        flex: 1;
        justify-content: center;
    }

    .trainer__score {
        grid-template-columns: repeat(2, 1fr);
    }

    .audio-decoder__actions {
        flex-direction: column;
    }

    .audio-decoder__copy-actions {
        flex-direction: column;
    }

    .contest__actions {
        flex-direction: column;
    }

    .contest__fields {
        grid-template-columns: 1fr;
    }

    .tab {
        min-width: 56px;
        padding: 6px 4px;
    }

    .tab span {
        font-size: 0.6rem;
    }
}

/* ---------- Visual Morse (Signal Lamp) ---------- */
.lamp-container {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: var(--space-xl);
    background: var(--bg-secondary);
    border-radius: var(--radius-lg);
    border: 1px solid var(--border);
    margin-bottom: var(--space-lg);
    position: relative;
    min-height: 200px;
}

.signal-lamp {
    width: 80px;
    height: 80px;
    background: #333;
    border-radius: 50%;
    border: 4px solid #444;
    box-shadow: inset 0 0 10px rgba(0,0,0,0.5), 0 0 5px rgba(0,0,0,0.2);
    transition: background 0.05s ease, box-shadow 0.05s ease;
    position: relative;
}

.signal-lamp--on {
    background: #fff;
    box-shadow: 0 0 40px #fff, 0 0 80px rgba(255,255,255,0.4);
}

.lamp-replay {
    position: absolute;
    bottom: var(--space-md);
    right: var(--space-md);
}

.visual-encoder, .visual-decoder {
    display: flex;
    flex-direction: column;
    gap: var(--space-lg);
}

.feedback-msg {
    min-height: 1.5rem;
    font-weight: 500;
    text-align: center;
    margin-top: var(--space-sm);
}

.feedback-msg--success { color: #10b981; }
.feedback-msg--error { color: #ef4444; }

@media (max-width: 768px) {
    .signal-lamp {
        width: 60px;
        height: 60px;
    }
    
    .lamp-container {
        min-height: 150px;
    }
}