:root {
    --bg-primary: #0d1117;
    --bg-secondary: #161b22;
    --bg-card: #21262d;
    --border-color: #30363d;
    --text-primary: #f0f6fc;
    --text-secondary: #8b949e;
    --accent-color: #238636;
    --accent-hover: #2ea043;
    --danger-color: #da3633;
    --danger-hover: #f85149;
    --warning-color: #d29922;
    --info-color: #58a6ff;
    --font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    --radius-sm: 6px;
    --radius-md: 10px;
    --radius-lg: 16px;
    --shadow: 0 4px 12px rgba(0, 0, 0, 0.4);
}

[data-theme="light"] {
    --bg-primary: #f6f8fa;
    --bg-secondary: #ffffff;
    --bg-card: #f0f3f6;
    --border-color: #d0d7de;
    --text-primary: #1f2328;
    --text-secondary: #656d76;
    --accent-color: #1f883d;
    --accent-hover: #1a7f37;
    --danger-color: #cf222e;
    --danger-hover: #a40e26;
    --warning-color: #9a6700;
    --info-color: #0969da;
    --shadow: 0 4px 12px rgba(0, 0, 0, 0.08);
}

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

body {
    background-color: var(--bg-primary);
    color: var(--text-primary);
    font-family: var(--font-family);
    line-height: 1.5;
    padding: 1.5rem 1rem;
    min-height: 100vh;
}

.container {
    max-width: 1050px;
    margin: 0 auto;
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

/* Header */
header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding-bottom: 1rem;
    border-bottom: 1px solid var(--border-color);
    flex-wrap: wrap;
    gap: 1rem;
}

.header-brand h1 {
    font-size: 1.6rem;
    font-weight: 700;
    color: var(--text-primary);
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.header-brand h1 .badge {
    font-size: 0.75rem;
    background: var(--info-color);
    color: #fff;
    padding: 0.2rem 0.5rem;
    border-radius: var(--radius-sm);
    font-weight: 600;
}

.header-brand p {
    font-size: 0.9rem;
    color: var(--text-secondary);
    margin-top: 0.2rem;
}

.header-controls {
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

select, button, input {
    font-family: inherit;
    font-size: 0.9rem;
}

select {
    background-color: var(--bg-card);
    color: var(--text-primary);
    border: 1px solid var(--border-color);
    padding: 0.4rem 0.8rem;
    border-radius: var(--radius-sm);
    cursor: pointer;
    outline: none;
}

/* Cards & Grid Layout */
.grid-2 {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1.5rem;
}

@media (max-width: 800px) {
    .grid-2 {
        grid-template-columns: 1fr;
    }
}

.card {
    background-color: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    padding: 1.25rem;
    box-shadow: var(--shadow);
}

.card-title {
    font-size: 1.1rem;
    font-weight: 600;
    margin-bottom: 1rem;
    display: flex;
    align-items: center;
    justify-content: space-between;
    color: var(--text-primary);
}

/* Primary Action Bar */
.action-panel {
    background: linear-gradient(135deg, var(--bg-secondary) 0%, var(--bg-card) 100%);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    padding: 1.5rem;
    display: flex;
    flex-direction: column;
    gap: 1.25rem;
}

.clock-display-row {
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 1rem;
}

.digital-clock {
    font-family: "SF Mono", "Fira Code", Monaco, Consolas, monospace;
    font-size: 2rem;
    font-weight: 700;
    color: var(--info-color);
    letter-spacing: 1px;
}

.digital-clock-sub {
    font-size: 0.85rem;
    color: var(--text-secondary);
}

.main-buttons {
    display: flex;
    gap: 1rem;
    flex-wrap: wrap;
}

.btn {
    padding: 0.75rem 1.5rem;
    font-weight: 600;
    border-radius: var(--radius-md);
    border: none;
    cursor: pointer;
    transition: all 0.2s ease;
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
}

.btn-primary {
    background-color: var(--accent-color);
    color: #ffffff;
    font-size: 1.1rem;
}

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

.btn-danger {
    background-color: var(--danger-color);
    color: #ffffff;
    font-size: 1.1rem;
}

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

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

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

.btn-sm {
    padding: 0.35rem 0.75rem;
    font-size: 0.8rem;
}

/* NTP Status pill */
.ntp-pill {
    display: inline-flex;
    align-items: center;
    gap: 0.4rem;
    font-size: 0.85rem;
    padding: 0.25rem 0.6rem;
    border-radius: 20px;
    background: var(--bg-card);
    border: 1px solid var(--border-color);
}

.status-dot {
    width: 8px;
    height: 8px;
    border-radius: 50%;
    background-color: var(--text-secondary);
}

.status-dot.synced { background-color: var(--accent-color); box-shadow: 0 0 6px var(--accent-color); }
.status-dot.syncing { background-color: var(--warning-color); animation: pulse 1s infinite; }
.status-dot.error { background-color: var(--danger-color); }

@keyframes pulse {
    0%, 100% { opacity: 1; }
    50% { opacity: 0.3; }
}

/* Form Controls & Toggles */
.form-group {
    display: flex;
    flex-direction: column;
    gap: 0.4rem;
    margin-bottom: 0.8rem;
}

.form-group label {
    font-size: 0.85rem;
    color: var(--text-secondary);
    font-weight: 500;
}

.toggle-label {
    display: flex;
    align-items: center;
    gap: 0.6rem;
    cursor: pointer;
    user-select: none;
    font-size: 0.9rem;
}

.toggle-label input[type="checkbox"] {
    width: 18px;
    height: 18px;
    accent-color: var(--accent-color);
    cursor: pointer;
}

.setting-desc {
    font-size: 0.78rem;
    color: var(--text-secondary);
    margin-left: 1.8rem;
    margin-top: -0.2rem;
    margin-bottom: 0.6rem;
}

.slider-container {
    display: flex;
    align-items: center;
    gap: 1rem;
}

.slider-container input[type="range"] {
    flex: 1;
    accent-color: var(--accent-color);
    cursor: pointer;
}

/* Visualizer & Oscilloscope */
.canvas-wrapper {
    background-color: #05070a;
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    overflow: hidden;
    margin-bottom: 0.75rem;
}

canvas {
    display: block;
    width: 100%;
}

.frame-inspector {
    display: grid;
    grid-template-columns: repeat(30, 1fr);
    gap: 3px;
    margin-top: 0.75rem;
}

@media (max-width: 600px) {
    .frame-inspector {
        grid-template-columns: repeat(15, 1fr);
    }
}

.cell {
    height: 28px;
    border-radius: 3px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 0.65rem;
    font-family: monospace;
    font-weight: bold;
    color: #ffffff;
    background-color: #21262d;
    transition: transform 0.1s ease;
}

.cell.marker { background-color: #da3633; }
.cell.bit1 { background-color: #d29922; }
.cell.bit0 { background-color: #238636; }
.cell.missing { background-color: #484f58; }

.cell.current {
    box-shadow: 0 0 10px #58a6ff;
    border: 2px solid #ffffff;
    transform: scale(1.15);
    z-index: 2;
}

.symbol-legend {
    display: flex;
    gap: 1rem;
    font-size: 0.8rem;
    margin-top: 0.5rem;
    flex-wrap: wrap;
}

.legend-item {
    display: flex;
    align-items: center;
    gap: 0.4rem;
}

.legend-color {
    width: 12px;
    height: 12px;
    border-radius: 2px;
}

.legend-color.marker { background-color: #da3633; }
.legend-color.bit1 { background-color: #d29922; }
.legend-color.bit0 { background-color: #238636; }

/* Status Bar Info */
.info-strip {
    display: flex;
    justify-content: space-between;
    font-size: 0.85rem;
    background-color: var(--bg-card);
    padding: 0.6rem 1rem;
    border-radius: var(--radius-sm);
    border: 1px solid var(--border-color);
}

/* Safety Callout */
.alert-box {
    border-radius: var(--radius-md);
    padding: 1rem 1.25rem;
    border-left: 4px solid var(--danger-color);
    background-color: rgba(218, 54, 51, 0.1);
    font-size: 0.88rem;
}

.alert-box h4 {
    color: var(--danger-color);
    margin-bottom: 0.3rem;
    display: flex;
    align-items: center;
    gap: 0.4rem;
}

/* Accordion / Info Details */
details {
    background-color: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    padding: 0.75rem 1rem;
}

details summary {
    cursor: pointer;
    font-weight: 600;
    outline: none;
    color: var(--text-primary);
}

details p, details ol {
    margin-top: 0.75rem;
    font-size: 0.9rem;
    color: var(--text-secondary);
    padding-left: 1.2rem;
}

details li {
    margin-bottom: 0.4rem;
}

/* Footer */
footer {
    text-align: center;
    font-size: 0.8rem;
    color: var(--text-secondary);
    padding: 1.5rem 0 0.5rem;
    border-top: 1px solid var(--border-color);
}

footer a {
    color: var(--info-color);
    text-decoration: none;
}

footer a:hover {
    text-decoration: underline;
}