:root {
    --primary-color: #ea8400;
    --primary-hover: #d67300;
    --primary-light: rgba(234, 132, 0, 0.1);
    --success-color: #10b981;
    --success-hover: #059669;
    --warning-color: #f59e0b;
    --danger-color: #ef4444;
    --surface-color: #ffffff;
    --surface-elevated: #f8fafc;
    --border-color: #e2e8f0;
    --text-primary: #1e293b;
    --text-secondary: #64748b;
    --text-muted: #94a3b8;
    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
    --radius-sm: 6px;
    --radius-md: 10px;
    --radius-lg: 16px;
    --radius-xl: 24px;
    --transition-fast: 150ms ease;
    --transition-normal: 250ms ease;
    --transition-slow: 350ms ease;
    --s-pol-color: #3b82f6;
    --p-pol-color: #ef4444;
    --brewster-color: #f59e0b;
    --refracted-color: #10b981;
}

.dark-mode {
    --primary-color: #ff9d1a;
    --primary-hover: #ea8400;
    --primary-light: rgba(255, 157, 26, 0.15);
    --surface-color: #1e293b;
    --surface-elevated: #334155;
    --border-color: #475569;
    --text-primary: #f1f5f9;
    --text-secondary: #cbd5e1;
    --text-muted: #94a3b8;
}

/* ---------- aperture propagation (N5) ---------- */
.options-sidebar {
    position: static;
}

.tool-content {
    grid-template-columns: 300px minmax(0, 1fr);
}

.canvas-area {
    min-width: 0;
}

.ap-select {
    width: 100%;
    padding: 7px 10px;
    border-radius: var(--radius-sm);
    border: 1px solid var(--border-color);
    background: var(--surface-color);
    color: var(--text-primary);
    font-size: 0.88rem;
}

.ap-check {
    display: flex;
    align-items: flex-start;
    gap: 8px;
    font-size: 0.86rem;
    color: var(--text-secondary);
    cursor: pointer;
    margin-bottom: 10px;
}

.ap-check input {
    margin-top: 3px;
}

.ap-seg {
    display: flex;
    gap: 6px;
    margin-bottom: 14px;
    flex-wrap: wrap;
}

.ap-seg label {
    flex: 1 1 0;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 5px;
    padding: 7px 6px;
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    font-size: 0.85rem;
    color: var(--text-secondary);
    cursor: pointer;
    background: var(--surface-color);
}

.ap-seg label:has(input:checked) {
    border-color: var(--primary-color);
    color: var(--text-primary);
    background: var(--primary-light);
    font-weight: 600;
}

.ap-row-buttons {
    display: flex;
    gap: 8px;
    flex-wrap: wrap;
    margin-top: 10px;
}

.ap-row-buttons .action-btn {
    flex: 1 1 auto;
    padding: 8px 12px;
    font-size: 0.85rem;
}

.ap-hint,
.preset-note {
    margin: 8px 0 0;
    font-size: 0.82rem;
    line-height: 1.45;
    color: var(--text-secondary);
}

.preset-buttons .preset-option {
    padding: 8px 8px;
    font-size: 0.8rem;
}

.ap-status {
    margin: 0;
    font-size: 0.86rem;
    color: var(--text-secondary);
    min-height: 1.3em;
}

.ap-status.busy::before {
    content: "";
    display: inline-block;
    width: 0.8em;
    height: 0.8em;
    margin-right: 6px;
    border-radius: 50%;
    border: 2px solid var(--primary-color);
    border-right-color: transparent;
    vertical-align: -1px;
    animation: ap-spin 0.8s linear infinite;
}

@keyframes ap-spin {
    to {
        transform: rotate(360deg);
    }
}

@media (prefers-reduced-motion: reduce) {
    .ap-status.busy::before {
        animation: none;
    }

    .icon-wave {
        animation: none !important;
    }
}

#apCanvas.painting {
    cursor: crosshair;
    touch-action: none;
}

#intCanvas {
    cursor: crosshair;
}

#readouts {
    grid-template-columns: repeat(auto-fill, minmax(min(250px, 100%), 1fr));
    margin-top: 6px;
}

#readouts>div {
    align-items: baseline;
}

#readouts dd {
    margin: 0;
    white-space: normal;
    text-align: right;
    overflow-wrap: anywhere;
}

#warnHost .optics-warning {
    margin: 4px 0;
}

.ap-related ul {
    display: flex;
    flex-wrap: wrap;
    gap: 6px 18px;
    padding-left: 18px;
}

@media (max-width: 1024px) {
    .tool-content {
        grid-template-columns: minmax(0, 1fr);
    }
}

@media (max-width: 480px) {
    .tool-main {
        padding: 0 12px 32px;
    }

    .tool-header h1 {
        font-size: 1.6rem;
    }

    .stats-bar {
        gap: 10px 16px;
        padding: 12px;
    }
}