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

:root {
    --bg-primary: #0a0a0f;
    --bg-secondary: #12121a;
    --bg-tertiary: #1a1a25;
    --text-primary: #e0e0e0;
    --text-secondary: #888;
    --accent-green: #00ff88;
    --accent-cyan: #00d4ff;
    --accent-purple: #a855f7;
    --error: #ff4444;
    --success: #00ff88;
}

body {
    font-family: 'SF Mono', 'Fira Code', 'Consolas', monospace;
    background: var(--bg-primary);
    color: var(--text-primary);
    min-height: 100vh;
    line-height: 1.6;
}

.container {
    max-width: 900px;
    margin: 0 auto;
    padding: 2rem;
}

header {
    text-align: center;
    margin-bottom: 2rem;
    padding-bottom: 1rem;
    border-bottom: 1px solid var(--bg-tertiary);
}

header h1 {
    font-size: 2.5rem;
    background: linear-gradient(135deg, var(--accent-green), var(--accent-cyan));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    margin-bottom: 0.5rem;
}

.tagline {
    color: var(--text-secondary);
    font-size: 0.9rem;
}

.mode-selector {
    display: flex;
    justify-content: center;
    gap: 2rem;
    margin-bottom: 1.5rem;
}

.mode-selector label {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    cursor: pointer;
    padding: 0.75rem 1.5rem;
    border: 1px solid var(--bg-tertiary);
    border-radius: 8px;
    transition: all 0.3s;
}

.mode-selector label:has(input:checked) {
    border-color: var(--accent-green);
    background: rgba(0, 255, 136, 0.1);
}

.mode-selector input[type="radio"] {
    accent-color: var(--accent-green);
}

.tabs {
    display: flex;
    gap: 0;
    margin-bottom: 1.5rem;
}

.tab {
    flex: 1;
    padding: 1rem;
    background: var(--bg-secondary);
    border: none;
    color: var(--text-secondary);
    font-family: inherit;
    font-size: 1rem;
    cursor: pointer;
    transition: all 0.3s;
}

.tab:first-child {
    border-radius: 8px 0 0 8px;
}

.tab:last-child {
    border-radius: 0 8px 8px 0;
}

.tab.active {
    background: var(--accent-green);
    color: var(--bg-primary);
    font-weight: bold;
}

.tab-content {
    background: var(--bg-secondary);
    padding: 1.5rem;
    border-radius: 8px;
    margin-bottom: 1.5rem;
}

.tab-content.hidden {
    display: none;
}

.input-group, .output-group {
    margin-bottom: 1rem;
}

.input-group label, .output-group label {
    display: block;
    margin-bottom: 0.5rem;
    color: var(--text-secondary);
    font-size: 0.85rem;
    text-transform: uppercase;
    letter-spacing: 1px;
}

textarea {
    width: 100%;
    min-height: 120px;
    padding: 1rem;
    background: var(--bg-tertiary);
    border: 1px solid transparent;
    border-radius: 6px;
    color: var(--text-primary);
    font-family: inherit;
    font-size: 0.95rem;
    resize: vertical;
    transition: border-color 0.3s;
}

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

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

.controls {
    display: flex;
    gap: 1rem;
    margin-bottom: 1rem;
}

.primary-btn, .secondary-btn {
    padding: 0.75rem 1.5rem;
    border: none;
    border-radius: 6px;
    font-family: inherit;
    font-size: 1rem;
    cursor: pointer;
    display: flex;
    align-items: center;
    gap: 0.5rem;
    transition: all 0.3s;
}

.primary-btn {
    background: linear-gradient(135deg, var(--accent-green), var(--accent-cyan));
    color: var(--bg-primary);
    font-weight: bold;
}

.primary-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 20px rgba(0, 255, 136, 0.3);
}

.primary-btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
    transform: none;
}

.secondary-btn {
    background: var(--bg-tertiary);
    color: var(--text-primary);
    border: 1px solid var(--text-secondary);
}

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

.secondary-btn.hidden {
    display: none;
}

.status {
    padding: 0.75rem;
    border-radius: 6px;
    font-size: 0.9rem;
    min-height: 2.5rem;
}

.status.success {
    background: rgba(0, 255, 136, 0.1);
    color: var(--success);
}

.status.error {
    background: rgba(255, 68, 68, 0.1);
    color: var(--error);
}

.status.info {
    background: rgba(0, 212, 255, 0.1);
    color: var(--accent-cyan);
}

.visualizer-container {
    margin-bottom: 1rem;
    position: relative;
}

#spectrogram {
    width: 100%;
    height: 200px;
    background: #000;
    border-radius: 6px;
    border: 1px solid var(--bg-tertiary);
}

.frequency-labels {
    display: flex;
    justify-content: space-between;
    padding: 0.25rem 0.5rem;
    font-size: 0.75rem;
    color: var(--text-secondary);
}

.output-box {
    min-height: 80px;
    padding: 1rem;
    background: var(--bg-tertiary);
    border-radius: 6px;
    font-family: inherit;
    word-break: break-all;
    white-space: pre-wrap;
}

.output-box:empty::before {
    content: 'Waiting for transmission...';
    color: var(--text-secondary);
    font-style: italic;
}

.settings-panel {
    background: var(--bg-secondary);
    padding: 1.5rem;
    border-radius: 8px;
    margin-bottom: 1.5rem;
}

.settings-panel h3 {
    margin-bottom: 1rem;
    font-size: 0.9rem;
    color: var(--text-secondary);
    text-transform: uppercase;
    letter-spacing: 1px;
}

.setting {
    display: flex;
    align-items: center;
    gap: 1rem;
    margin-bottom: 0.75rem;
}

.setting label {
    flex: 0 0 180px;
    font-size: 0.85rem;
}

.setting input[type="range"] {
    flex: 1;
    accent-color: var(--accent-green);
}

.setting span {
    flex: 0 0 60px;
    text-align: right;
    font-size: 0.85rem;
    color: var(--accent-cyan);
}

footer {
    text-align: center;
    padding-top: 1rem;
    border-top: 1px solid var(--bg-tertiary);
    color: var(--text-secondary);
    font-size: 0.8rem;
}

@keyframes pulse {
    0%, 100% { opacity: 1; }
    50% { opacity: 0.5; }
}

.transmitting {
    animation: pulse 1s infinite;
}

@media (max-width: 600px) {
    .container {
        padding: 1rem;
    }

    header h1 {
        font-size: 1.8rem;
    }

    .mode-selector {
        flex-direction: column;
        gap: 0.5rem;
    }

    .setting {
        flex-wrap: wrap;
    }

    .setting label {
        flex: 1 1 100%;
    }
}