:root {
    --bg-dark: #0a0a0a;
    --card-bg: #141414;
    --neon-green: #0f0;
    --neon-yellow: #ff0;
    --neon-red: #f00;
    --text-color: #eee;
}

body {
    background-color: var(--bg-dark);
    color: var(--text-color);
    font-family: 'Noto Sans KR', sans-serif;
    margin: 0;
}

.app-container {
    max-width: 700px;
    margin: 0 auto;
    padding: 20px;
    min-height: 100vh;
}

header {
    text-align: center;
    margin-bottom: 30px;
}

header h1 {
    font-family: 'Share Tech Mono', monospace;
    font-size: 1.8rem;
    color: var(--neon-green);
    text-shadow: 0 0 10px rgba(0, 255, 0, 0.3);
}

.back-link {
    color: #888;
    text-decoration: none;
    float: left;
}

/* Monitor Card */
.monitor-card {
    background: var(--card-bg);
    border: 1px solid #333;
    border-radius: 12px;
    padding: 20px;
    text-align: center;
    margin-bottom: 20px;
    position: relative;
    box-shadow: 0 0 20px rgba(0, 0, 0, 0.5);
}

.status-indicator {
    position: absolute;
    top: 20px;
    right: 20px;
    font-size: 0.8rem;
    font-weight: bold;
    color: #555;
}

.status-indicator.on {
    color: var(--neon-red);
    animation: blink 1s infinite;
}

@keyframes blink {
    50% {
        opacity: 0.5;
    }
}

.db-display {
    font-family: 'Share Tech Mono', monospace;
    font-size: 5rem;
    font-weight: bold;
    color: var(--neon-green);
    margin: 20px 0 10px;
    line-height: 1;
}

.unit {
    font-size: 1.5rem;
    color: #666;
}

.db-label {
    font-size: 1rem;
    color: #888;
    margin-bottom: 20px;
    height: 1.5em;
    /* fixed height */
}

canvas {
    width: 100%;
    height: 150px;
    background: #000;
    border: 1px solid #333;
    border-radius: 4px;
    margin-bottom: 20px;
}

/* Buttons */
.btn-primary {
    background: #222;
    border: 1px solid var(--neon-green);
    color: var(--neon-green);
    padding: 12px 30px;
    border-radius: 5px;
    font-family: 'Share Tech Mono', monospace;
    font-size: 1.1rem;
    cursor: pointer;
    transition: all 0.2s;
}

.btn-primary:hover {
    background: var(--neon-green);
    color: #000;
    box-shadow: 0 0 15px var(--neon-green);
}

.btn-primary.active {
    border-color: var(--neon-red);
    color: var(--neon-red);
}

.btn-primary.active:hover {
    background: var(--neon-red);
    color: #fff;
    box-shadow: 0 0 15px var(--neon-red);
}

/* Masking Card */
.masking-card {
    background: var(--card-bg);
    border: 1px solid #333;
    border-radius: 12px;
    padding: 20px;
}

.masking-card h2 {
    font-size: 1.1rem;
    margin-top: 0;
    margin-bottom: 20px;
    border-bottom: 1px solid #333;
    padding-bottom: 10px;
}

.masking-controls {
    display: flex;
    gap: 10px;
    margin-bottom: 20px;
    flex-wrap: wrap;
}

.mask-btn {
    flex: 1;
    background: #222;
    border: 1px solid #444;
    color: #ccc;
    padding: 10px;
    border-radius: 5px;
    cursor: pointer;
    transition: all 0.2s;
}

.mask-btn:hover {
    border-color: #888;
}

.mask-btn.active {
    background: #eee;
    color: #000;
    border-color: #fff;
    font-weight: bold;
}

.volume-control {
    display: flex;
    align-items: center;
    gap: 15px;
}

.volume-control label {
    font-size: 0.9rem;
    color: #888;
}

.volume-control input {
    flex: 1;
    cursor: pointer;
}