:root {
    --bg-color: #f3f4f6;
    --sidebar-bg: #ffffff;
    --text-primary: #111827;
    --text-secondary: #6b7280;
    --border-color: #e5e7eb;
    
    --primary-color: #2563eb;
    --primary-hover: #1d4ed8;
    --danger-color: #ef4444;

    /* Element Colors */
    --color-path: #3b82f6;
    --color-edge: #111827;
    --color-node: #ef4444;
    --color-district: rgba(16, 185, 129, 0.4);
    --color-district-border: #10b981;
    --color-landmark: #f59e0b;

    --font-family: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
}

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

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

.app-container {
    display: flex;
    height: 100vh;
}

/* Sidebar */
.sidebar {
    width: 300px;
    background-color: var(--sidebar-bg);
    border-right: 1px solid var(--border-color);
    display: flex;
    flex-direction: column;
    padding: 1.5rem;
    overflow-y: auto; /* Scrollable if height is small */
    flex-shrink: 0;
    box-shadow: 2px 0 10px rgba(0,0,0,0.02);
    z-index: 10;
}

.sidebar-header {
    margin-bottom: 2rem;
}

.sidebar-header h1 {
    font-size: 1.5rem;
    font-weight: 700;
    line-height: 1.2;
    color: var(--text-primary);
}

.subtitle {
    font-size: 0.875rem;
    color: var(--text-secondary);
    margin-top: 0.25rem;
}

/* Panels */
.panel {
    margin-bottom: 2rem;
    border-bottom: 1px solid var(--border-color);
    padding-bottom: 1.5rem;
}

.panel:last-child {
    border-bottom: none;
}

.panel h2 {
    font-size: 0.75rem;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    color: var(--text-secondary);
    margin-bottom: 1rem;
    font-weight: 600;
}

/* Tools Grid */
.tools-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 0.75rem;
}

.tool-btn {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: 0.75rem;
    background: #f9fafb;
    border: 1px solid var(--border-color);
    border-radius: 0.5rem;
    cursor: pointer;
    transition: all 0.2s ease;
    color: var(--text-secondary);
}

.tool-btn:hover {
    background: #f3f4f6;
    border-color: #d1d5db;
    color: var(--text-primary);
}

.tool-btn.active {
    background: #eff6ff;
    border-color: var(--primary-color);
    color: var(--primary-color);
    box-shadow: 0 0 0 1px var(--primary-color);
}

.tool-btn svg {
    margin-bottom: 0.25rem;
}

.icon {
    display: block;
    width: 24px;
    height: 4px; /* Default for line-like icons */
    margin-bottom: 8px;
    border-radius: 2px;
}

/* Custom Tool Icons via CSS shapes for simplicity */
.tool-btn .path-icon { background: var(--color-path); height: 3px; width: 20px; transform: rotate(-45deg); margin-top: 5px; }
.tool-btn .edge-icon { background: var(--color-edge); height: 6px; width: 24px; border-radius: 0; }
.tool-btn .node-icon { background: var(--color-node); width: 14px; height: 14px; border-radius: 50%; }
.tool-btn .district-icon { background: var(--color-district); width: 20px; height: 20px; border: 2px solid var(--color-district-border);  }
.tool-btn .landmark-icon { 
    width: 0; height: 0; 
    border-left: 8px solid transparent; 
    border-right: 8px solid transparent; 
    border-bottom: 16px solid var(--color-landmark);
    background: transparent;
}

.tool-btn span {
    font-size: 0.75rem;
    font-weight: 500;
}

/* Forms */
.form-group {
    margin-bottom: 1rem;
}

.form-group label {
    display: block;
    font-size: 0.75rem;
    font-weight: 500;
    margin-bottom: 0.5rem;
    color: var(--text-secondary);
}

.form-group input,
.form-group select {
    width: 100%;
    padding: 0.5rem;
    border: 1px solid var(--border-color);
    border-radius: 0.375rem;
    font-size: 0.875rem;
    background: #fff;
    color: var(--text-primary);
}

.form-group input:focus,
.form-group select:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 2px rgba(37, 99, 235, 0.1);
}

.btn {
    width: 100%;
    padding: 0.625rem;
    border-radius: 0.375rem;
    font-size: 0.875rem;
    font-weight: 500;
    cursor: pointer;
    border: 1px solid transparent;
    transition: background-color 0.2s;
    margin-bottom: 0.5rem;
}

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

.btn.secondary {
    background-color: white;
    border-color: var(--border-color);
    color: var(--text-primary);
}
.btn.secondary:hover { background-color: #f9fafb; border-color: #d1d5db; }

.btn.danger {
    background-color: #fee2e2;
    color: var(--danger-color);
}
.btn.danger:hover { background-color: #fecaca; }

/* Layers List */
.layers-list {
    list-style: none;
}

.layer-item {
    display: flex;
    align-items: center;
    padding: 0.5rem 0;
    font-size: 0.875rem;
    cursor: pointer;
    color: var(--text-primary);
}

.layer-item input {
    margin-right: 0.75rem;
}

.color-indicator {
    width: 12px;
    height: 12px;
    border-radius: 2px;
    margin-right: 0.5rem;
    display: inline-block;
}

.color-indicator.path { background: var(--color-path); }
.color-indicator.edge { background: var(--color-edge); }
.color-indicator.node { background: var(--color-node); border-radius: 50%; }
.color-indicator.district { background: var(--color-district-border); }
.color-indicator.landmark { background: var(--color-landmark); }

/* Workspace */
.workspace {
    flex: 1;
    background-color: #e5e5e5; /* Neutral contrast for canvas paper */
    display: flex;
    align-items: center;
    justify-content: center;
    position: relative;
    overflow: auto;
    background-image: radial-gradient(#d4d4d4 1px, transparent 1px);
    background-size: 20px 20px; /* Subtle Grid */
}

#canvas-wrapper {
    box-shadow: 0 4px 20px rgba(0,0,0,0.1);
    background: white;
    line-height: 0; /* Removing extra height */
}

canvas {
    display: block;
    cursor: crosshair;
}
canvas.tool-select { cursor: default; }
canvas.tool-move { cursor: grab; }
canvas.tool-move:active { cursor: grabbing; }

.help-panel {
    border: none;
    background: #f0f9ff;
    padding: 1rem;
    border-radius: 0.5rem;
    color: #0c4a6e;
    line-height: 1.4;
}