/* ============================================================================
   CSS Variables for Light/Dark Theme (#19)
   ========================================================================== */
:root {
    --bg-primary: #f9fafb;
    --bg-secondary: #ffffff;
    --bg-tertiary: #f3f4f6;
    --text-primary: #111827;
    --text-secondary: #6b7280;
    --border-color: #e5e7eb;
    --shadow: rgba(0, 0, 0, 0.1);
    --accent: #3b82f6;
}

.dark-theme {
    --bg-primary: #111827;
    --bg-secondary: #1f2937;
    --bg-tertiary: #374151;
    --text-primary: #f9fafb;
    --text-secondary: #d1d5db;
    --border-color: #4b5563;
    --shadow: rgba(0, 0, 0, 0.5);
    --accent: #60a5fa;
}

body {
    background: var(--bg-primary);
    color: var(--text-primary);
    font-family: 'Inter', sans-serif;
    margin: 0;
    padding: 0;
    text-align: center;
    transition: background 0.3s ease, color 0.3s ease;
}

.app {
    padding: 1rem 0.5rem;
}

h1 {
    margin-bottom: 10px;
}

.status-section {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
    gap: 10px;
    margin: 20px auto;
    max-width: 900px;
}

button {
    border: none;
    padding: 10px 20px;
    border-radius: 8px;
    cursor: pointer;
}

.btn-on {
    background: #2ecc71;
}

.btn-off {
    background: #e74c3c;
}