:root {
    --bg-main: #0B0E14;
    --bg-panel: #151A23;
    --bg-hover: #1f2532;
    --border-color: #2a3140;

    --text-main: #E2E8F0;
    --text-muted: #94A3B8;

    --color-primary: #3B82F6;
    --color-success: #10B981;
    --color-warning: #F59E0B;
    --color-danger: #EF4444;
    --color-info: #8B5CF6;

    --layer-2: #2563EB;
    /* Blue for L2 */
    --layer-3: #10B981;
    /* Green for L3 */
    --layer-4: #F59E0B;
    /* Orange for L4 */
    --layer-7: #8B5CF6;
    /* Purple for L7 */

    --font-ui: 'Inter', system-ui, sans-serif;
    --font-mono: 'Fira Code', monospace;
}

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

body {
    font-family: var(--font-ui);
    background-color: var(--bg-main);
    color: var(--text-main);
    height: 100vh;
    overflow: hidden;
}

.app-layout {
    display: flex;
    height: 100%;
}

.hidden {
    display: none !important;
}

/* Sidebar */
.sidebar {
    width: 320px;
    background-color: var(--bg-panel);
    border-right: 1px solid var(--border-color);
    display: flex;
    flex-direction: column;
    overflow-y: auto;
}

.brand {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    color: var(--color-primary);
    padding: 1.5rem 1.5rem 1rem;
}

.brand h1 {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--text-main);
}

.settings-panel {
    padding: 1rem 1.5rem;
    border-bottom: 1px solid var(--border-color);
}

.settings-panel h3 {
    font-size: 0.85rem;
    text-transform: uppercase;
    color: var(--text-muted);
    font-weight: 600;
    margin-bottom: 1rem;
}

.control-group {
    margin-bottom: 1rem;
}

.control-group label {
    display: block;
    font-size: 0.8rem;
    margin-bottom: 0.25rem;
    color: var(--text-main);
}

.control-group select {
    width: 100%;
    background: var(--bg-main);
    border: 1px solid var(--border-color);
    color: var(--text-main);
    font-family: var(--font-ui);
    font-size: 0.85rem;
    padding: 0.5rem;
    border-radius: 4px;
    outline: none;
}

.control-group select:focus {
    border-color: var(--color-primary);
}

.layer-group[data-layer="l2"] label {
    color: var(--layer-2);
}

.layer-group[data-layer="l3"] label {
    color: var(--layer-3);
}

.layer-group[data-layer="l4"] label {
    color: var(--layer-4);
}

.layer-group[data-layer="l7"] label {
    color: var(--layer-7);
}

.action-buttons {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
    margin-top: 1.5rem;
}

.btn {
    padding: 0.5rem 1rem;
    border-radius: 6px;
    font-family: var(--font-ui);
    font-size: 0.85rem;
    font-weight: 500;
    cursor: pointer;
    border: 1px solid transparent;
    text-align: center;
    transition: all 0.2s;
}

.btn-primary {
    background: var(--color-primary);
    color: #fff;
}

.btn-primary:hover {
    background: #2563EB;
}

.btn-outline {
    background: transparent;
    border-color: var(--border-color);
    color: var(--text-main);
}

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

.info-panel {
    padding: 1.5rem;
    flex: 1;
    display: flex;
    flex-direction: column;
    background: var(--bg-main);
}

.empty-info {
    color: var(--text-muted);
    font-size: 0.85rem;
    font-style: italic;
    text-align: center;
    margin-top: 2rem;
}

.info-card {
    font-size: 0.85rem;
    line-height: 1.5;
}

.info-card h4 {
    font-family: var(--font-mono);
    color: var(--color-primary);
    margin-bottom: 0.5rem;
    font-size: 1rem;
}

.info-card .size {
    font-size: 0.75rem;
    color: var(--text-muted);
    margin-bottom: 1rem;
    text-transform: uppercase;
}

.info-card .desc {
    margin-bottom: 1rem;
    color: var(--text-main);
}

.info-card input,
.info-card textarea {
    width: 100%;
    padding: 0.5rem;
    font-family: var(--font-mono);
    font-size: 0.8rem;
    background: var(--bg-panel);
    border: 1px solid var(--border-color);
    color: var(--text-main);
    border-radius: 4px;
    margin-bottom: 0.5rem;
}

/* Main Area */
.main-content {
    flex: 1;
    display: flex;
    flex-direction: column;
    position: relative;
}

.toolbar {
    display: flex;
    background: var(--bg-panel);
    border-bottom: 1px solid var(--border-color);
    padding: 0 1.5rem;
}

.tabs {
    display: flex;
}

.tab {
    background: none;
    border: none;
    padding: 1rem;
    color: var(--text-muted);
    font-family: inherit;
    font-size: 0.9rem;
    font-weight: 500;
    cursor: pointer;
    border-bottom: 2px solid transparent;
}

.tab:hover {
    color: var(--text-main);
}

.tab.active {
    color: var(--color-primary);
    border-bottom-color: var(--color-primary);
}

.scroll-area {
    flex: 1;
    overflow-y: auto;
    padding: 2rem;
    background: var(--bg-main);
}

/* Packet Visualizer */
.packet-layer {
    margin-bottom: 2rem;
    border-radius: 8px;
    overflow: hidden;
    border: 1px solid var(--border-color);
    background: var(--bg-panel);
}

.layer-header {
    padding: 0.5rem 1rem;
    font-weight: 600;
    font-size: 0.9rem;
    font-family: var(--font-mono);
}

.layer-l2 .layer-header {
    background: rgba(37, 99, 235, 0.2);
    color: #60A5FA;
}

.layer-l3 .layer-header {
    background: rgba(16, 185, 129, 0.2);
    color: #34D399;
}

.layer-l4 .layer-header {
    background: rgba(245, 158, 11, 0.2);
    color: #FBBF24;
}

.layer-l7 .layer-header {
    background: rgba(139, 92, 246, 0.2);
    color: #A78BFA;
}

.layer-body {
    display: grid;
    grid-template-columns: repeat(32, 1fr);
    padding: 1rem;
    gap: 4px;
}

/* Grid blocks represent bits/bytes */
.field-block {
    background: rgba(255, 255, 255, 0.05);
    border: 1px solid rgba(255, 255, 255, 0.1);
    border-radius: 4px;
    padding: 0.5rem;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    text-align: center;
    cursor: pointer;
    position: relative;
    transition: all 0.2s;
    min-height: 60px;
}

.field-block:hover,
.field-block.active {
    background: rgba(255, 255, 255, 0.1);
    border-color: rgba(255, 255, 255, 0.3);
    transform: translateY(-2px);
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.2);
}

.layer-l2 .field-block.active {
    border-color: var(--layer-2);
    background: rgba(37, 99, 235, 0.15);
}

.layer-l3 .field-block.active {
    border-color: var(--layer-3);
    background: rgba(16, 185, 129, 0.15);
}

.layer-l4 .field-block.active {
    border-color: var(--layer-4);
    background: rgba(245, 158, 11, 0.15);
}

.layer-l7 .field-block.active {
    border-color: var(--layer-7);
    background: rgba(139, 92, 246, 0.15);
}

.fb-name {
    font-size: 0.75rem;
    font-weight: 600;
    color: var(--text-main);
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
    max-width: 100%;
}

.fb-val {
    font-family: var(--font-mono);
    font-size: 0.7rem;
    color: var(--text-muted);
    margin-top: 0.25rem;
    white-space: nowrap;
    max-width: 100%;
    overflow: hidden;
    text-overflow: ellipsis;
}

/* Layout grids for specific protocols */
/* Assuming a rows of 32 bits. 1 byte = 8 bits, so 4 bytes per row. 1 byte = span 8. */
.span-4 {
    grid-column: span 4;
}

/* 4 bits */
.span-8 {
    grid-column: span 8;
}

/* 8 bits = 1 byte */
.span-12 {
    grid-column: span 12;
}

.span-16 {
    grid-column: span 16;
}

/* 16 bits = 2 bytes */
.span-24 {
    grid-column: span 24;
}

.span-32 {
    grid-column: span 32;
}

/* 32 bits = 4 bytes full row */
.span-48 {
    grid-column: span 32;
}

/* Cap at 32 for UI flow */

/* Hex Dump */
.hex-toolbar {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1rem;
}

.hex-toolbar h3 {
    font-family: var(--font-mono);
    font-size: 1.1rem;
}

.hex-stats {
    font-family: var(--font-mono);
    font-size: 0.85rem;
    color: var(--text-muted);
}

.hex-container {
    background: var(--bg-panel);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 1rem;
    font-family: var(--font-mono);
    font-size: 0.85rem;
    line-height: 1.6;
    white-space: pre;
    overflow-x: auto;
}

.hex-byte {
    display: inline-block;
    width: 1.8rem;
    text-align: center;
    color: var(--text-main);
}

.hex-byte.l2 {
    color: #60A5FA;
}

.hex-byte.l3 {
    color: #34D399;
}

.hex-byte.l4 {
    color: #FBBF24;
}

.hex-byte.l7 {
    color: #A78BFA;
}

.hex-byte:hover {
    background: rgba(255, 255, 255, 0.1);
    cursor: help;
}

.hex-char {
    display: inline-block;
    width: 0.7rem;
    text-align: center;
    color: var(--text-muted);
}

.hex-offset {
    color: var(--text-muted);
    margin-right: 1rem;
    user-select: none;
}