:root {
    --bg-primary: #0a0e27;
    --bg-secondary: #151932;
    --bg-tertiary: #1e2742;
    --bg-card: #1a1f3a;
    --bg-hover: #252b4a;
    --bg-border: #2a3458;
    --text-primary: #e2e8f0;
    --text-secondary: #94a3b8;
    --text-muted: #64748b;
    --accent-primary: #3b82f6;
    --accent-secondary: #8b5cf6;
    --success: #10b981;
    --danger: #ef4444;
    --warning: #f59e0b;
    --border-color: #2a3458;
    --heartbeat-color: #10b981;
    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.4);
    --shadow-lg: 0 10px 15px rgba(0, 0, 0, 0.5);
}

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

body {
    color: var(--text-primary);
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Malgun Gothic', 'Roboto', sans-serif;
    padding: 0px;
    min-height: 100vh;
    line-height: 1.6;
}

#heartbeat-container {
    padding: 16px;
    background: var(--bg-card);
    border-radius: 4px;
    border: 1px solid var(--border-color);
    box-shadow: var(--shadow-lg);
    transition: all 0.3s ease;
    cursor: pointer;
}

#heartbeat-container:hover {
    border-color: var(--accent-primary);
    box-shadow: 0 12px 24px rgba(59, 130, 246, 0.3);
}

#heartbeat-title {
    font-size: 14px;
    font-weight: 600;
    margin-bottom: 12px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 12px;
    color: var(--text-primary);
}

#heartbeat-title > span {
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 16px;
}

#heartbeat-info {
    font-size: 12px !important;
    color: var(--text-secondary);
    padding: 6px 12px;
    background: var(--bg-tertiary);
    border-radius: 4px;
    border: 1px solid var(--border-color);
    font-family: 'Courier New', monospace;
    font-weight: 500;
}

#heartbeat {
    display: block;
    width: 100%;
    height: 80px;
    background: linear-gradient(to bottom, #000000 0%, #0a0e27 100%);
    border: 1px solid var(--border-color);
    border-radius: 4px;
    margin-top: 12px;
    box-shadow: inset 0 2px 4px rgba(0, 0, 0, 0.5);
}

/* 스크롤바 스타일링 */
::-webkit-scrollbar {
    width: 8px;
    height: 8px;
}

::-webkit-scrollbar-track {
    background: var(--bg-secondary);
    border-radius: 4px;
}

::-webkit-scrollbar-thumb {
    background: var(--bg-tertiary);
    border-radius: 4px;
    border: 2px solid var(--bg-secondary);
}

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

/* 반응형 디자인 */
@media (max-width: 768px) {
    body {
        padding: 16px;
    }
    
    h2 {
        font-size: 20px;
    }
    
    #heartbeat-title {
        flex-direction: column;
        align-items: flex-start;
    }
}

/* 연결 상태 표시용 (추가 가능) */
.connection-status {
    display: inline-block;
    width: 8px;
    height: 8px;
    border-radius: 50%;
    background: var(--success);
    margin-right: 6px;
    box-shadow: 0 0 6px var(--success);
    animation: pulse 2s infinite;
}

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