:root {
    --text-primary: #0f172a;
    --text-secondary: #64748b;
    --accent-color: #0f4c81;
    --accent-hover: #1b5e98;
    --danger-color: #b91c1c;
    
    /* CAD Theme Overrides */
    --panel-bg: #ffffff;
    --panel-border: #cbd5e1;
    --panel-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    --app-bg: #f8fafc;
    --header-bg: #f1f5f9;
    
    --radius-md: 6px;
    --radius-lg: 8px;
}

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

html, body {
    height: 100%;
    margin: 0;
    padding: 0;
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
    color: var(--text-primary);
    display: flex;
    flex-direction: column;
    overflow: hidden;
    /* CAD Theme Solid Background */
    background: var(--app-bg);
}

.app-container {
    display: flex;
    flex-direction: column;
    flex: 1;
    min-height: 0;
    width: 100%;
    padding: 16px;
    gap: 16px;
}

/* CAD Panels (Overrides glass-panel) */
.glass-panel {
    background: var(--panel-bg);
    border: 1px solid var(--panel-border);
    border-radius: var(--radius-lg);
    box-shadow: var(--panel-shadow);
}

/* Header */
.app-header {
    height: 50px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0 8px;
    gap: 6px;
    flex-shrink: 0;
    background: var(--header-bg);
    border-bottom: 1px solid var(--panel-border);
    box-shadow: var(--panel-shadow);
    z-index: 10;
}

.header-left .logo {
    display: flex;
    align-items: center;
    gap: 6px;
    flex-shrink: 0;
}

.header-left .logo img {
    height: 28px;
}

.header-left .logo h1 {
    font-family: 'Outfit', sans-serif;
    font-size: 0.95rem;
    font-weight: 700;
    margin: 0;
    color: var(--text-primary);
    display: flex;
    flex-direction: row;
    align-items: center;
    gap: 4px;
    white-space: nowrap;
}

.header-left .logo span {
    font-size: 0.65rem;
    color: var(--text-secondary);
    background: rgba(15, 23, 42, 0.05);
    padding: 1px 4px;
    border-radius: 4px;
    border: 1px solid rgba(15, 23, 42, 0.1);
    font-weight: 600;
    margin-top: 0;
}

/* Toolbar */
.header-center {
    display: flex;
    justify-content: center;
    align-items: center;
    flex-shrink: 1;
}

.toolbar {
    display: flex;
    align-items: center;
    gap: 3px;
    background: rgba(255, 255, 255, 0.8);
    padding: 3px 5px;
    border-radius: 8px;
    border: 1px solid #cbd5e1;
    overflow: visible;
}

.tool-btn {
    background: #ffffff;
    border: 1px solid #e2e8f0;
    color: #475569;
    height: 28px;
    padding: 0 8px;
    border-radius: 5px;
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 4px;
    cursor: pointer;
    transition: all 0.15s ease;
    font-size: 0.76rem;
    font-weight: 600;
    box-shadow: 0 1px 2px rgba(0,0,0,0.03);
    flex-shrink: 0;
}

.tool-btn svg {
    width: 13px;
    height: 13px;
    color: #64748b;
}

.tool-btn span {
    white-space: nowrap;
}

.tool-btn:hover {
    background: #f8fafc;
    border-color: #cbd5e1;
    color: var(--accent-color);
    box-shadow: 0 2px 4px rgba(0,0,0,0.05);
}

.tool-btn:hover svg {
    color: var(--accent-color);
}

.tool-btn.active {
    background: #eff6ff;
    border-color: #bfdbfe;
    color: #1d4ed8;
    box-shadow: none;
}

.tool-btn.active svg {
    color: #1d4ed8;
}

.tool-btn.danger:hover {
    color: #ef4444;
    background: #fef2f2;
    border-color: #fecaca;
}
.tool-btn.danger:hover svg {
    color: #ef4444;
}



.toolbar .divider {
    width: 1px;
    height: 18px;
    background-color: var(--panel-border);
    margin: 0 4px;
}

/* Action Buttons */
.header-right {
    display: flex;
    align-items: center;
    gap: 8px;
    flex-shrink: 0;
}

.action-btn {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 6px;
    height: 32px;
    padding: 0 12px;
    border: none;
    border-radius: var(--radius-md);
    font-family: inherit;
    font-size: 0.82rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s ease;
    box-shadow: 0 1px 2px rgba(0,0,0,0.05);
    text-decoration: none;
    box-sizing: border-box;
    white-space: nowrap;
}

.action-btn svg, .action-btn i {
    width: 15px;
    height: 15px;
}

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

.action-btn.primary:hover {
    background: var(--accent-hover);
}

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

.action-btn.secondary:hover {
    background: #e2e8f0;
}

.action-btn.danger {
    background: white;
    color: var(--danger-color);
    border: 1px solid #fca5a5;
}

.action-btn.danger:hover {
    background: #fee2e2;
}

.action-btn:disabled {
    background: #f1f5f9;
    color: #94a3b8;
    border-color: #e2e8f0;
    cursor: not-allowed;
    opacity: 0.7;
}

.action-btn:disabled:hover {
    background: #f1f5f9;
}

/* Workspace Layout */
.main-workspace {
    display: flex;
    flex: 1;
    overflow: hidden;
    gap: 16px;
}

/* Sidebars */
.sidebar-panel {
    width: 300px;
    display: flex;
    flex-direction: column;
    overflow-y: auto;
    flex-shrink: 0;
}

/* Sub-panels inside sidebars */
.panel-section {
    padding: 20px;
    border-bottom: 1px solid var(--panel-border);
    background: transparent;
}

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

.panel-section h2 {
    font-size: 0.9rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    margin-bottom: 16px;
    color: var(--text-primary);
}

.panel-section.flex-grow {
    flex: 1;
    overflow: hidden;
    border-bottom: none;
}

/* Form Controls */
.form-group {
    margin-bottom: 16px;
}

.form-group label {
    display: block;
    font-size: 0.8rem;
    color: var(--text-secondary);
    margin-bottom: 6px;
    font-weight: 500;
}

.form-control {
    width: 100%;
    padding: 8px 12px;
    border: 1px solid var(--panel-border);
    border-radius: var(--radius-md);
    font-family: inherit;
    font-size: 0.9rem;
    background: #f8fafc;
    color: var(--text-primary);
    transition: all 0.2s;
}

.form-control:focus {
    outline: none;
    border-color: var(--accent-color);
    background: white;
    box-shadow: 0 0 0 2px rgba(15, 76, 129, 0.1);
}

/* Custom Input Row for Coordinates */
.coord-input-row {
    display: flex;
    gap: 8px;
    align-items: flex-end;
}
.coord-input-row > div {
    flex: 1;
    min-width: 0;
}
.coord-input-row button {
    flex-shrink: 0;
    width: 40px;
    height: 40px;
    padding: 0;
    display: flex;
    justify-content: center;
    align-items: center;
}

/* Tabs & Tables */
.tabs {
    display: flex;
    background: #f1f5f9;
    border-radius: var(--radius-md);
    padding: 4px;
    margin-bottom: 16px;
}

.properties-content {
    background: #f8fafc;
    border-radius: var(--radius-md);
    padding: 15px;
    font-size: 0.9rem;
    border: 1px solid var(--panel-border);
}

.tab-btn {
    flex: 1;
    padding: 8px 0;
    background: transparent;
    border: none;
    border-radius: 6px;
    color: var(--text-secondary);
    font-weight: 600;
    font-size: 0.8125rem;
    cursor: pointer;
    transition: all 0.2s;
}

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

.tab-btn.active {
    background: white;
    color: var(--accent-color);
    box-shadow: 0 2px 4px rgba(0,0,0,0.05);
}

.tab-content {
    display: none;
    flex: 1;
    overflow: hidden;
    flex-direction: column;
}

.tab-content.active {
    display: flex;
}

.table-scroll {
    flex: 1;
    overflow-y: auto;
    border-radius: var(--radius-md);
    background: #f8fafc;
    border: 1px solid var(--panel-border);
}

.data-table {
    width: 100%;
    border-collapse: collapse;
    font-size: 0.8125rem;
}

.data-table th {
    background-color: #f1f5f9;
    color: var(--text-secondary);
    font-weight: 600;
    text-align: left;
    padding: 10px 12px;
    position: sticky;
    top: 0;
    border-bottom: 1px solid var(--panel-border);
}

.data-table td {
    padding: 10px 12px;
    border-bottom: 1px solid var(--panel-border);
}

.data-table tr:hover td {
    background-color: #f8fafc;
}

/* Canvas Area */
.canvas-container {
    flex: 1;
    position: relative;
    background-color: #f8fafc;
}

/* Dot Grid Background */
.canvas-container::before {
    content: '';
    position: absolute;
    top: 0; left: 0; right: 0; bottom: 0;
    background-image: radial-gradient(rgba(0,0,0,0.1) 1px, transparent 1px);
    background-size: 24px 24px;
    background-position: -12px -12px;
    pointer-events: none;
}

#trussCanvas {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    cursor: crosshair;
}

.canvas-overlays {
    position: absolute;
    bottom: 20px;
    left: 20px;
    right: 20px;
    display: flex;
    justify-content: space-between;
    align-items: flex-end;
    pointer-events: none;
}

.zoom-controls {
    position: absolute;
    top: 20px;
    left: 20px;
    z-index: 10;
    pointer-events: auto;
    display: flex;
    flex-direction: column;
    gap: 0;
    background: white;
    padding: 5px;
    border-radius: var(--radius-md);
    box-shadow: var(--panel-shadow);
    border: 1px solid var(--panel-border);
}

.zoom-controls button {
    background: transparent;
    border: none;
    color: var(--text-secondary);
    width: 32px;
    height: 32px;
    border-radius: 6px;
    cursor: pointer;
    display: flex;
    justify-content: center;
    align-items: center;
    transition: all 0.2s;
}

.zoom-controls button:hover {
    background: #f1f5f9;
    color: var(--text-primary);
}

.status-bar {
    pointer-events: auto;
    background: white;
    padding: 8px 16px;
    border-radius: 20px;
    font-size: 0.8125rem;
    font-weight: 500;
    color: var(--text-secondary);
    box-shadow: var(--panel-shadow);
    border: 1px solid var(--panel-border);
}

/* Diagram Toggles */
.diagram-toggles {
    display: flex;
    gap: 4px;
}

.diagram-toggles.hidden {
    display: none !important;
}

.toggle-btn {
    background: transparent;
    border: none;
    padding: 6px 12px;
    font-size: 0.8rem;
    font-weight: 600;
    color: var(--text-secondary);
    border-radius: 4px;
    cursor: pointer;
    transition: all 0.2s;
}

.toggle-btn:hover {
    background: #f1f5f9;
    color: var(--text-primary);
}

.toggle-btn.active {
    background: var(--accent-color);
    color: white;
}

/* Results Content styling */
.results-content {
    flex: 1;
    overflow-y: auto;
    overflow-x: hidden;
}

.result-item {
    padding: 12px;
    border: 1px solid var(--panel-border);
    border-radius: var(--radius-md);
    margin-bottom: 10px;
    background: white;
}
.result-title {
    font-weight: 600;
    font-size: 0.85rem;
    margin-bottom: 6px;
    color: var(--text-primary);
}
.result-val {
    font-size: 0.8125rem;
    display: flex;
    justify-content: space-between;
}
.tension { color: #2563eb; font-weight: 700; }
.compression { color: #ef4444; font-weight: 700; }
.zero-force { color: var(--text-secondary); font-style: italic; }

.empty-state {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    text-align: center;
    padding: 40px 20px;
    color: var(--text-secondary);
    background: #f8fafc;
    border-radius: var(--radius-md);
    border: 1px dashed var(--panel-border);
}

.empty-state svg {
    margin-bottom: 12px;
    color: #94a3b8;
    opacity: 0.5;
}

/* Custom Scrollbar */
::-webkit-scrollbar {
    width: 6px;
    height: 6px;
}
::-webkit-scrollbar-track {
    background: transparent;
}
::-webkit-scrollbar-thumb {
    background: rgba(0,0,0,0.15);
    border-radius: 3px;
}
::-webkit-scrollbar-thumb:hover {
    background: rgba(0,0,0,0.25);
}