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

:root {
    --primary-color: #3b82f6;
    --primary-hover: #2563eb;
    --secondary-color: #64748b;
    --success-color: #22c55e;
    --danger-color: #ef4444;
    --background: #0f172a;
    --surface: #1e293b;
    --surface-hover: #334155;
    --text-primary: #f1f5f9;
    --text-secondary: #94a3b8;
    --border-color: #334155;
    --shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.3);
    --radius: 12px;
    --transition: all 0.2s ease;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, sans-serif;
    background: var(--background);
    color: var(--text-primary);
    min-height: 100vh;
    line-height: 1.6;
}

.container {
    max-width: 800px;
    margin: 0 auto;
    padding: 2rem 1rem;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

/* Header Styles */
header {
    text-align: center;
    margin-bottom: 2rem;
}

.logo-container {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 1rem;
    margin-bottom: 0.5rem;
}

.logo {
    width: 48px;
    height: 48px;
    object-fit: contain;
}

h1 {
    font-size: 2rem;
    font-weight: 700;
    background: linear-gradient(135deg, var(--primary-color), #a855f7);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.subtitle {
    color: var(--text-secondary);
    font-size: 1rem;
}

/* Main Content */
main {
    flex: 1;
    display: flex;
    flex-direction: column;
    gap: 2rem;
}

/* Converter Section */
.converter-section {
    background: var(--surface);
    border-radius: var(--radius);
    padding: 1.5rem;
    box-shadow: var(--shadow);
}

.mode-toggle {
    display: flex;
    gap: 0.5rem;
    margin-bottom: 1.5rem;
    background: var(--background);
    padding: 0.25rem;
    border-radius: var(--radius);
}

.mode-btn {
    flex: 1;
    padding: 0.75rem 1rem;
    border: none;
    background: transparent;
    color: var(--text-secondary);
    font-size: 0.9rem;
    font-weight: 500;
    cursor: pointer;
    border-radius: calc(var(--radius) - 4px);
    transition: var(--transition);
}

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

.mode-btn.active {
    background: var(--primary-color);
    color: white;
}

/* Input/Output Sections */
.input-section,
.output-section {
    margin-bottom: 1rem;
}

label {
    display: block;
    font-size: 0.875rem;
    font-weight: 500;
    color: var(--text-secondary);
    margin-bottom: 0.5rem;
}

textarea {
    width: 100%;
    padding: 1rem;
    border: 2px solid var(--border-color);
    border-radius: var(--radius);
    background: var(--background);
    color: var(--text-primary);
    font-size: 1rem;
    font-family: 'Courier New', monospace;
    resize: vertical;
    transition: var(--transition);
}

textarea:focus {
    outline: none;
    border-color: var(--primary-color);
}

textarea::placeholder {
    color: var(--text-secondary);
    opacity: 0.7;
}

textarea[readonly] {
    background: rgba(15, 23, 42, 0.5);
    cursor: default;
}

.char-count {
    text-align: right;
    font-size: 0.75rem;
    color: var(--text-secondary);
    margin-top: 0.25rem;
}

/* Controls */
.controls {
    display: flex;
    gap: 0.75rem;
    margin-bottom: 1.5rem;
}

.primary-btn,
.secondary-btn {
    flex: 1;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    padding: 0.875rem 1.5rem;
    border: none;
    border-radius: var(--radius);
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
}

.primary-btn {
    background: var(--primary-color);
    color: white;
}

.primary-btn:hover {
    background: var(--primary-hover);
    transform: translateY(-1px);
}

.secondary-btn {
    background: var(--surface-hover);
    color: var(--text-primary);
}

.secondary-btn:hover {
    background: #475569;
}

.btn-icon {
    font-size: 1rem;
}

/* Output Actions */
.output-actions {
    display: flex;
    gap: 0.5rem;
    margin-top: 0.75rem;
}

.action-btn {
    display: flex;
    align-items: center;
    gap: 0.375rem;
    padding: 0.5rem 1rem;
    border: 1px solid var(--border-color);
    border-radius: calc(var(--radius) - 4px);
    background: transparent;
    color: var(--text-secondary);
    font-size: 0.875rem;
    cursor: pointer;
    transition: var(--transition);
}

.action-btn:hover {
    background: var(--surface-hover);
    color: var(--text-primary);
    border-color: var(--text-secondary);
}

/* Audio Section */
.audio-section {
    background: var(--surface);
    border-radius: var(--radius);
    padding: 1.5rem;
    box-shadow: var(--shadow);
}

.audio-section h2 {
    font-size: 1.125rem;
    margin-bottom: 1rem;
    color: var(--text-primary);
}

.audio-controls {
    display: flex;
    gap: 0.75rem;
    margin-bottom: 1.5rem;
}

.play-btn,
.stop-btn {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    padding: 0.75rem 1.5rem;
    border: none;
    border-radius: var(--radius);
    font-size: 0.9rem;
    font-weight: 500;
    cursor: pointer;
    transition: var(--transition);
}

.play-btn {
    background: var(--success-color);
    color: white;
    flex: 1;
}

.play-btn:hover:not(:disabled) {
    background: #16a34a;
}

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

.play-btn.playing {
    background: var(--danger-color);
}

.stop-btn {
    background: var(--surface-hover);
    color: var(--text-primary);
    padding: 0.75rem 1rem;
}

.stop-btn:hover:not(:disabled) {
    background: #475569;
}

/* Speed Control */
.speed-control {
    margin-bottom: 1rem;
}

.speed-control label {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    margin-bottom: 0.5rem;
}

#speedValue {
    color: var(--primary-color);
    font-weight: 600;
}

input[type="range"] {
    width: 100%;
    height: 6px;
    border-radius: 3px;
    background: var(--border-color);
    appearance: none;
    cursor: pointer;
}

input[type="range"]::-webkit-slider-thumb {
    appearance: none;
    width: 20px;
    height: 20px;
    border-radius: 50%;
    background: var(--primary-color);
    cursor: pointer;
    transition: var(--transition);
}

input[type="range"]::-webkit-slider-thumb:hover {
    transform: scale(1.1);
}

input[type="range"]::-moz-range-thumb {
    width: 20px;
    height: 20px;
    border-radius: 50%;
    background: var(--primary-color);
    border: none;
    cursor: pointer;
}

.speed-labels {
    display: flex;
    justify-content: space-between;
    font-size: 0.75rem;
    color: var(--text-secondary);
    margin-top: 0.25rem;
}

/* Audio Visualizer */
.audio-visualizer {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 4px;
    height: 40px;
    padding: 0.5rem;
    background: var(--background);
    border-radius: calc(var(--radius) - 4px);
}

.visualizer-bar {
    width: 8px;
    height: 8px;
    background: var(--primary-color);
    border-radius: 2px;
    transition: height 0.1s ease;
}

.audio-visualizer.active .visualizer-bar {
    animation: visualize 0.5s ease-in-out infinite alternate;
}

.audio-visualizer.active .visualizer-bar:nth-child(1) { animation-delay: 0s; }
.audio-visualizer.active .visualizer-bar:nth-child(2) { animation-delay: 0.1s; }
.audio-visualizer.active .visualizer-bar:nth-child(3) { animation-delay: 0.2s; }
.audio-visualizer.active .visualizer-bar:nth-child(4) { animation-delay: 0.1s; }
.audio-visualizer.active .visualizer-bar:nth-child(5) { animation-delay: 0s; }

@keyframes visualize {
    from {
        height: 8px;
        opacity: 0.5;
    }
    to {
        height: 32px;
        opacity: 1;
    }
}

/* Reference Section */
.reference-section {
    background: var(--surface);
    border-radius: var(--radius);
    padding: 1.5rem;
    box-shadow: var(--shadow);
}

.reference-section h2 {
    font-size: 1.125rem;
    margin-bottom: 1rem;
    color: var(--text-primary);
}

.reference-toggle {
    display: flex;
    gap: 0.5rem;
    margin-bottom: 1rem;
    flex-wrap: wrap;
}

.ref-btn {
    padding: 0.5rem 1rem;
    border: 1px solid var(--border-color);
    border-radius: calc(var(--radius) - 4px);
    background: transparent;
    color: var(--text-secondary);
    font-size: 0.875rem;
    cursor: pointer;
    transition: var(--transition);
}

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

.ref-btn.active {
    background: var(--primary-color);
    border-color: var(--primary-color);
    color: white;
}

.reference-chart {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(100px, 1fr));
    gap: 0.5rem;
}

.ref-item {
    display: flex;
    flex-direction: column;
    align-items: center;
    padding: 0.75rem;
    background: var(--background);
    border-radius: calc(var(--radius) - 4px);
    text-align: center;
}

.ref-char {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--primary-color);
    margin-bottom: 0.25rem;
}

.ref-morse {
    font-family: 'Courier New', monospace;
    font-size: 0.875rem;
    color: var(--text-secondary);
    letter-spacing: 2px;
}

/* Footer */
footer {
    text-align: center;
    padding: 2rem 0 1rem;
    margin-top: auto;
    color: var(--text-secondary);
    font-size: 0.875rem;
}

footer a {
    color: var(--primary-color);
    text-decoration: none;
    font-weight: 500;
    transition: var(--transition);
}

footer a:hover {
    color: var(--primary-hover);
    text-decoration: underline;
}

/* Toast Notification */
.toast {
    position: fixed;
    bottom: 2rem;
    left: 50%;
    transform: translateX(-50%) translateY(100px);
    background: var(--surface);
    color: var(--text-primary);
    padding: 1rem 1.5rem;
    border-radius: var(--radius);
    box-shadow: 0 10px 25px rgba(0, 0, 0, 0.3);
    font-size: 0.9rem;
    z-index: 1000;
    opacity: 0;
    transition: all 0.3s ease;
    border: 1px solid var(--border-color);
}

.toast.show {
    transform: translateX(-50%) translateY(0);
    opacity: 1;
}

.toast.success {
    border-color: var(--success-color);
}

.toast.error {
    border-color: var(--danger-color);
}

/* Mobile Responsiveness */
@media (max-width: 640px) {
    .container {
        padding: 1rem;
    }

    h1 {
        font-size: 1.5rem;
    }

    .logo {
        width: 36px;
        height: 36px;
    }

    .subtitle {
        font-size: 0.875rem;
    }

    .mode-toggle {
        flex-direction: column;
    }

    .mode-btn {
        padding: 0.625rem 1rem;
    }

    .converter-section,
    .audio-section,
    .reference-section {
        padding: 1rem;
    }

    .controls {
        flex-direction: column;
    }

    .primary-btn,
    .secondary-btn {
        width: 100%;
    }

    .output-actions {
        flex-wrap: wrap;
    }

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

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

    .play-btn,
    .stop-btn {
        width: 100%;
    }

    .reference-chart {
        grid-template-columns: repeat(3, 1fr);
    }

    .ref-item {
        padding: 0.5rem;
    }

    .ref-char {
        font-size: 1rem;
    }

    .ref-morse {
        font-size: 0.75rem;
    }
}

@media (max-width: 400px) {
    .reference-chart {
        grid-template-columns: repeat(2, 1fr);
    }
}

/* Accessibility */
@media (prefers-reduced-motion: reduce) {
    * {
        animation: none !important;
        transition: none !important;
    }
}

/* Focus states for accessibility */
button:focus-visible,
textarea:focus-visible,
input:focus-visible {
    outline: 2px solid var(--primary-color);
    outline-offset: 2px;
}