:root {
    /* Background colors */
    --bg-primary: #0b1f33;           /* Main background color */
    --bg-secondary: #0f2743;         /* Secondary background (panels) */
    --bg-tertiary: #0d2239;          /* Tertiary background (nested elements) */

    /* Grid colors */
    --bg-grid-subtle: rgba(143, 189, 224, 0.055);  /* Fine grid lines */
    --bg-grid-strong: rgba(143, 189, 224, 0.11);   /* Bold grid lines */

    /* Border colors */
    --border-primary: #1e4166;       /* Primary border color */
    --border-secondary: #17324f;     /* Secondary/softer border */

    /* Text colors */
    --text-primary: #e8f1f8;         /* Primary text (light) */
    --text-secondary: #86a9c7;       /* Secondary text (muted) */
    --text-tertiary: #4d6d8c;        /* Tertiary text (very muted) */

    /* Accent colors */
    --accent-primary: #ffb454;       /* Primary accent (orange) */
    --accent-secondary: #a97c3d;     /* Secondary accent (darker orange) */

    /* Edge color */
    --edge-color: #4f7ea8;           /* Color for reference edges */

    /* Status colors */
    --color-danger: #ff6f6f;         /* Error/warning color */

    /* Typography */
    --font-mono: ui-monospace, "SFMono-Regular", "JetBrains Mono", "Fira Code", Menlo, Consolas, monospace;
    --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Inter, Helvetica, Arial, sans-serif;

    /* Spacing scale (base unit: 4px) */
    --space-xxs: 4px;
    --space-xs: 8px;
    --space-sm: 12px;
    --space-md: 16px;
    --space-lg: 24px;
    --space-xl: 32px;

    /* Border radius */
    --radius-sm: 3px;
    --radius-md: 4px;

    /* Transitions */
    --transition-fast: 0.12s ease;
    --transition-normal: 0.2s ease;

    /* Shadows */
    --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.25);
    --shadow-md: 0 4px 14px rgba(0, 0, 0, 0.35);
    --shadow-lg: 0 4px 18px rgba(0, 0, 0, 0.35);
}


/* Reset and Base Styles */

*,
*::before,
*::after {
    box-sizing: border-box;
}

html,
body {
    margin: 0;
    padding: 0;
    width: 100%;
    height: 100%;
    background: var(--bg-primary);
    color: var(--text-primary);
    font-family: var(--font-sans), serif;
    overflow: hidden;
}


/* Application Layout */

#app {
    display: grid;
    grid-template-columns: 300px 1fr;
    grid-template-rows: 52px 1fr;
    grid-template-areas: "topbar topbar" "sidebar stage";
    width: 100vw;
    height: 100vh;
}


/* Topbar Styles */

#topbar {
    grid-area: topbar;
    display: flex;
    align-items: center;
    gap: var(--space-sm);
    padding: 0 var(--space-md);
    background: var(--bg-secondary);
    border-bottom: 1px solid var(--border-primary);
    z-index: 5;
}

#topbar .brand {
    font-family: var(--font-mono), serif;
    font-weight: 700;
    letter-spacing: 0.14em;
    font-size: 13px;
    color: var(--text-primary);
    white-space: nowrap;
}

#topbar .brand span {
    color: var(--accent-primary);
}

#topbar .spacer {
    flex: 1;
}


/* Button Styles */

.button {
    font-family: var(--font-sans), serif;
    font-size: 12px;
    font-weight: 600;
    color: var(--text-primary);
    background: var(--bg-tertiary);
    border: 1px solid var(--border-primary);
    border-radius: var(--radius-sm);
    padding: 7px 12px;
    cursor: pointer;
    transition: border-color var(--transition-fast),
    color var(--transition-fast),
    background var(--transition-fast);
}

.button:hover {
    border-color: var(--accent-primary);
    color: var(--accent-primary);
}

.button:active {
    transform: translateY(1px);
}

.button.primary {
    border-color: var(--accent-secondary);
    color: var(--accent-primary);
}

.button.small {
    padding: 4px 8px;
    font-size: 11px;
}


/* Sidebar Styles */

#sidebar {
    grid-area: sidebar;
    background: var(--bg-secondary);
    border-right: 1px solid var(--border-primary);
    overflow-y: auto;
    padding: var(--space-md);
    display: flex;
    flex-direction: column;
    gap: var(--space-lg);
}

.section-label {
    font-family: var(--font-mono), serif;
    font-size: 10px;
    letter-spacing: 0.16em;
    color: var(--text-secondary);
    margin-bottom: var(--space-xs);
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.section-label small {
    color: var(--text-tertiary);
    letter-spacing: normal;
    font-size: 10px;
}


/* Form Controls */

input[type="text"],
select {
    width: 100%;
    background: var(--bg-tertiary);
    border: 1px solid var(--border-primary);
    color: var(--text-primary);
    font-family: var(--font-mono), serif;
    font-size: 12px;
    padding: 7px 9px;
    border-radius: var(--radius-sm);
    outline: none;
}

input[type="text"]:focus,
select:focus {
    border-color: var(--accent-primary);
}

select {
    cursor: pointer;
}


/* File Tree Styles */

#fileTree {
    max-height: 240px;
    overflow-y: auto;
    border: 1px solid var(--border-secondary);
    border-radius: var(--radius-sm);
    background: var(--bg-tertiary);
    padding: var(--space-xxs) 0;
    font-family: var(--font-mono), serif;
    font-size: 11px;
}

.tree-folder > summary {
    display: flex;
    align-items: center;
    gap: 6px;
    padding: var(--space-xxs) var(--space-sm);
    cursor: pointer;
    color: var(--text-secondary);
    list-style: none;
}

.tree-folder > summary::-webkit-details-marker {
    display: none;
}

.tree-folder > summary::marker {
    content: "";
}

.tree-folder > summary::before {
    content: "▶";
    font-size: 9px;
    color: var(--text-tertiary);
    display: inline-block;
    transition: transform var(--transition-fast);
}

.tree-folder[open] > summary::before {
    transform: rotate(90deg);
}

.tree-folder > summary:hover {
    color: var(--accent-primary);
}

.tree-children {
    padding-left: 8px;
    margin-left: 8px;
    border-left: 1px solid var(--border-secondary);
}

.tree-file {
    display: flex;
    align-items: center;
    gap: 7px;
    min-width: fit-content;
    padding: var(--space-xxs) var(--space-sm);
    color: var(--text-primary);
}

.tree-file::before {
    content: "";
    width: 4px;
    height: 4px;
    border-radius: 50%;
    background: var(--text-tertiary);
    flex-shrink: 0;
}

.tree-file:hover {
    background: rgba(255, 180, 84, 0.06);
}

.tree-file .name {
    flex: 1;
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
    cursor: pointer;
}

.tree-file .count {
    color: var(--text-tertiary);
    font-size: 10px;
}

.tree-folder input,
.tree-file input {
    accent-color: var(--accent-primary);
    flex-shrink: 0;
}

.row-buttons {
    display: flex;
    gap: 6px;
    margin-top: var(--space-xxs);
}


/* Checkbox Line (for isolate search option) */

.checkbox-line {
    display: flex;
    align-items: center;
    gap: 7px;
    font-size: 12px;
    color: var(--text-secondary);
    margin-top: var(--space-xxs);
    cursor: pointer;
}

.checkbox-line input {
    accent-color: var(--accent-primary);
}


/* Legend Styles */

#legend {
    display: flex;
    flex-direction: column;
    gap: 5px;
}

.legend-row {
    display: flex;
    align-items: center;
    gap: 7px;
    font-size: 11px;
    color: var(--text-secondary);
    font-family: var(--font-mono), serif;
}

.swatch {
    width: 10px;
    height: 10px;
    border-radius: 2px;
    flex-shrink: 0;
}

.swatch.line {
    width: 16px;
    height: 2px;
    border-radius: 0;
}


/* Inspector Styles */

#inspector {
    font-family: var(--font-mono), serif;
    font-size: 12px;
    color: var(--text-secondary);
    line-height: 1.55;
    background: var(--bg-tertiary);
    border: 1px solid var(--border-secondary);
    border-radius: var(--radius-sm);
    padding: 10px;
    min-height: 60px;
}

#inspector .title {
    color: var(--accent-primary);
    font-weight: 700;
    margin-bottom: var(--space-xxs);
    word-break: break-all;
}

#inspector .field b {
    color: var(--text-primary);
    font-weight: 600;
}

#inspector .link {
    color: var(--accent-primary);
    cursor: pointer;
    text-decoration: underline dotted;
}

#inspector .empty {
    color: var(--text-tertiary);
}


/* Stage Area */

#stage {
    grid-area: stage;
    position: relative;
    overflow: hidden;
    background: var(--bg-primary);
}

#graph {
    width: 100%;
    height: 100%;
    background-image:
        /* Fine grid */
        repeating-linear-gradient(
            0deg,
            var(--bg-grid-subtle) 0,
            var(--bg-grid-subtle) 1px,
            transparent 1px,
            transparent 24px
        ),
        repeating-linear-gradient(
            90deg,
            var(--bg-grid-subtle) 0,
            var(--bg-grid-subtle) 1px,
            transparent 1px,
            transparent 24px
        ),
        /* Bold grid */
        repeating-linear-gradient(
            0deg,
            var(--bg-grid-strong) 0,
            var(--bg-grid-strong) 1px,
            transparent 1px,
            transparent 120px
        ),
        repeating-linear-gradient(
            90deg,
            var(--bg-grid-strong) 0,
            var(--bg-grid-strong) 1px,
            transparent 1px,
            transparent 120px
        );
}


/* Corner Marks */

.corner-mark {
    position: absolute;
    width: 18px;
    height: 18px;
    opacity: 0.5;
    pointer-events: none;
}

.corner-mark::before,
.corner-mark::after {
    content: "";
    position: absolute;
    background: var(--text-secondary);
}

.corner-mark::before {
    width: 100%;
    height: 1px;
    top: 50%;
}

.corner-mark::after {
    height: 100%;
    width: 1px;
    left: 50%;
}

#mark-tl {
    top: 10px;
    left: 10px;
}

#mark-tr {
    top: 10px;
    right: 10px;
}

#mark-bl {
    bottom: 10px;
    left: 10px;
}


/* Title Block */

#statistics {
    position: absolute;
    right: 10px;
    bottom: 10px;
    background: var(--bg-secondary);
    border: 1px solid var(--border-primary);
    font-family: var(--font-mono), serif;
    font-size: 10px;
    color: var(--text-secondary);
    padding: 0;
    min-width: 230px;
    box-shadow: var(--shadow-lg);
}

#statistics .tb-head {
    background: var(--bg-tertiary);
    padding: 6px 10px;
    letter-spacing: 0.12em;
    color: var(--accent-primary);
    font-weight: 700;
    border-bottom: 1px solid var(--border-primary);
}

#statistics .tb-row {
    display: flex;
    justify-content: space-between;
    padding: 4px 10px;
    border-top: 1px solid var(--border-secondary);
}

#statistics .tb-row b {
    color: var(--text-primary);
    font-weight: 600;
}

#statistics .tb-row b.warn {
    color: var(--color-danger);
    cursor: help;
}

/* Tooltip */

#tooltip {
    position: absolute;
    pointer-events: none;
    background: var(--bg-secondary);
    border: 1px solid var(--border-primary);
    color: var(--text-primary);
    font-family: var(--font-mono), serif;
    font-size: 10.5px;
    padding: 6px 9px;
    border-radius: var(--radius-sm);
    max-width: 320px;
    line-height: 1.5;
    box-shadow: var(--shadow-md);
    display: none;
    z-index: 20;
}

/* Drop Overlay */

#dropOverlay {
    position: absolute;
    inset: 0;
    z-index: 30;
    background: rgba(11, 31, 51, 0.85);
    display: none;
    align-items: center;
    justify-content: center;
    font-family: var(--font-mono), serif;
    color: var(--accent-primary);
    font-size: 14px;
    border: 2px dashed var(--accent-secondary);
    letter-spacing: 0.1em;
}

#dropOverlay.show {
    display: flex;
}


/* Scrollbar Styles */

::-webkit-scrollbar {
    width: 8px;
    height: 8px;
}

::-webkit-scrollbar-track {
    background: var(--bg-tertiary);
}

::-webkit-scrollbar-thumb {
    background: var(--border-primary);
    border-radius: 4px;
}