/* ============================================================================
   CSS RESET & BASE
   ============================================================================ */

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

html, body {
    height: 100%;
    overflow: hidden;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    font-size: var(--font-base);
    color: var(--color-text-primary);
    background: var(--color-bg-primary);
}

/* ============================================================================
   SCALABLE UI VARIABLES
   ============================================================================ */

:root {
    --scale-factor: 1.2;
    --header-scale: 1.2;

    --header-height: calc(50px * var(--header-scale));
    --sidebar-left-width: calc(250px * var(--scale-factor));
    --sidebar-right-width: calc(310px * var(--scale-factor));
    --button-icon-size: calc(36px * var(--scale-factor));
    --button-small-size: calc(24px * var(--scale-factor));
    --color-picker-size: calc(32px * var(--scale-factor));
    --texture-preview-size: calc(64px * var(--scale-factor));

    --font-heading: calc(16px * var(--scale-factor));
    --font-large: calc(14px * var(--scale-factor));
    --font-base: calc(13px * var(--scale-factor));
    --font-button: calc(12px * var(--scale-factor));
    --font-section-header: calc(11px * var(--scale-factor));
    --font-small: calc(10px * var(--scale-factor));
    --font-tiny: calc(9px * var(--scale-factor));

    --spacing-xs: calc(2px * var(--scale-factor));
    --spacing-sm: calc(4px * var(--scale-factor));
    --spacing-md: calc(8px * var(--scale-factor));
    --spacing-lg: calc(12px * var(--scale-factor));
    --spacing-xl: calc(14px * var(--scale-factor));

    --radius-sm: calc(3px * var(--scale-factor));
    --radius-md: calc(4px * var(--scale-factor));
    --radius-lg: calc(50% * var(--scale-factor));

    --color-bg-primary: #1a1a1e;
    --color-bg-secondary: #252529;
    --color-bg-tertiary: #2d2d32;
    --color-bg-input: #1e1e22;
    --color-border: #3a3a40;
    --color-text-primary: #e0e0e0;
    --color-text-secondary: #b0b0b0;
    --color-text-muted: #888;
    --color-text-hint: #666;
    --color-accent: #4a9eff;
    --color-accent-hover: #6ab0ff;
    --color-accent-active: #4aa0ff;
    --color-danger: #ff4444;
    --color-danger-hover: #ff6666;
    --color-success: #4caf50;
    --color-warning: #ff9800;
}

/* ============================================================================
   LAYOUT
   ============================================================================ */

#app {
    display: flex;
    flex-direction: column;
    height: 100vh;
    width: 100vw;
}

#header {
    height: var(--header-height);
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0 calc(16px * var(--header-scale));
    background: var(--color-bg-secondary);
    border-bottom: 1px solid var(--color-border);
    flex-shrink: 0;
}

#main {
    flex: 1;
    display: flex;
    flex-direction: row;
    overflow: hidden;
}

#sidebar-left {
    width: var(--sidebar-left-width);
    overflow-y: auto;
    background: var(--color-bg-primary);
    border-right: 1px solid var(--color-border);
    flex-shrink: 0;
    display: flex;
    flex-direction: column;
}

#sidebar-copyright {
    margin-top: auto;
    padding: calc(8px * var(--scale-factor)) calc(12px * var(--scale-factor));
    font-size: calc(11px * var(--scale-factor));
    color: var(--color-text-muted);
    text-align: center;
    border-top: 1px solid var(--color-border);
}

#sidebar-copyright a {
    color: var(--color-text-secondary);
    text-decoration: none;
}

#sidebar-copyright a:hover {
    text-decoration: underline;
}

#sidebar-copyright .repo-link {
    display: inline-flex;
    align-items: center;
    gap: 4px;
    margin-top: calc(4px * var(--scale-factor));
}

#sidebar-copyright .repo-link img {
    opacity: 0.85;
    transition: opacity 0.2s, filter 0.2s;
}

#sidebar-copyright .repo-link:hover img {
    opacity: 1;
    filter: drop-shadow(0 0 6px rgba(255, 255, 255, 0.8));
}

#sidebar-right {
    width: var(--sidebar-right-width);
    overflow-y: auto;
    background: var(--color-bg-primary);
    border-left: 1px solid var(--color-border);
    flex-shrink: 0;
}

#canvas-container {
    flex: 1;
    position: relative;
    background: var(--color-bg-primary);
    overflow: hidden;
}

#solar2d-iframe {
    width: 100%;
    height: 100%;
    display: block;
    border: none;
}

#iframe-loading-overlay {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    background: var(--color-bg-primary);
    z-index: 10;
    color: var(--color-text-muted);
    font-size: var(--font-large);
    gap: 16px;
}

.loading-spinner {
    width: var(--color-picker-size);
    height: var(--color-picker-size);
    border: 3px solid var(--color-border);
    border-top-color: var(--color-accent);
    border-radius: 50%;
    animation: spin 0.8s linear infinite;
}

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

#canvas-overlay {
    position: absolute;
    bottom: 8px;
    left: 8px;
    background: rgba(0, 0, 0, 0.5);
    padding: 4px 10px;
    border-radius: 4px;
    pointer-events: none;
    font-size: var(--font-section-header);
    color: var(--color-text-muted);
}

/* ============================================================================
   HEADER
   ============================================================================ */

.header-left, .header-center, .header-right {
    display: flex;
    align-items: center;
    gap: calc(8px * var(--header-scale));
}

.header-left h1 {
    font-size: calc(16px * var(--header-scale));
    font-weight: 600;
    color: var(--color-text-primary);
}

.beta-tag {
    font-size: calc(10px * var(--header-scale));
    font-weight: 700;
    color: var(--color-warning);
    background: rgba(255, 152, 0, 0.15);
    padding: 1px 6px;
    border-radius: 3px;
    margin-left: 6px;
    vertical-align: middle;
    cursor: default;
    letter-spacing: 0.5px;
}

.header-separator {
    width: 1px;
    height: 24px;
    background: var(--color-border);
    margin: 0 calc(4px * var(--header-scale));
}

.icon-btn {
    width: calc(36px * var(--header-scale));
    height: calc(36px * var(--header-scale));
    border: none;
    background: transparent;
    color: var(--color-text-primary);
    font-size: calc(20px * var(--header-scale));
    cursor: pointer;
    border-radius: 4px;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: background 0.15s;
}

.icon-btn:hover:not(:disabled) {
    background: var(--color-border);
}

.icon-btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

.zoom-display {
    font-size: calc(12px * var(--header-scale));
    color: var(--color-text-muted);
    min-width: 3em;
    text-align: center;
}

.help-link {
    color: var(--color-accent);
    text-decoration: none;
    font-size: calc(13px * var(--header-scale));
}

.help-link:hover {
    color: var(--color-accent-hover);
    text-decoration: underline;
}

.ui-scale-control {
    display: flex;
    align-items: center;
    gap: 6px;
    padding: 0 8px;
    user-select: none;
}

.ui-scale-control label {
    font-size: calc(11px * var(--header-scale));
    color: var(--color-text-secondary);
    white-space: nowrap;
}

.ui-scale-control input[type="range"] {
    width: 80px;
    height: 4px;
    -webkit-appearance: none;
    appearance: none;
    background: var(--color-border);
    border-radius: 2px;
    outline: none;
}

.ui-scale-control input[type="range"]::-webkit-slider-thumb {
    -webkit-appearance: none;
    width: 12px;
    height: 12px;
    background: var(--color-accent);
    border-radius: 50%;
    cursor: pointer;
}

.ui-scale-control input[type="range"]::-moz-range-thumb {
    width: 12px;
    height: 12px;
    background: var(--color-accent);
    border: none;
    border-radius: 50%;
    cursor: pointer;
}

.ui-scale-control input[type="range"]::-moz-range-track {
    background: transparent;
    border: none;
}

#ui-scale-value {
    font-size: calc(11px * var(--header-scale));
    color: var(--color-text-secondary);
    min-width: 35px;
    text-align: right;
}

/* ============================================================================
   SIDEBAR COMMON
   ============================================================================ */

.sidebar-section {
    padding: var(--spacing-lg) var(--spacing-xl);
    border-bottom: 1px solid var(--color-border);
}

.sidebar-section h3 {
    font-size: var(--font-section-header);
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    color: var(--color-text-secondary);
    margin-bottom: var(--spacing-md);
}

.section-header-row {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.small-btn {
    width: var(--button-small-size);
    height: var(--button-small-size);
    border: 1px solid var(--color-border);
    background: var(--color-bg-tertiary);
    color: var(--color-text-primary);
    font-size: var(--font-heading);
    cursor: pointer;
    border-radius: 4px;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: background 0.15s;
}

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

.full-btn {
    width: 100%;
    padding: 6px 12px;
    border: 1px solid var(--color-border);
    background: var(--color-bg-tertiary);
    color: var(--color-text-primary);
    font-size: var(--font-button);
    cursor: pointer;
    border-radius: 4px;
    margin-top: 6px;
    transition: background 0.15s;
}

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

/* ============================================================================
   EMITTER LIST
   ============================================================================ */

.item-list {
    list-style: none;
}

.item-list li {
    display: flex;
    align-items: center;
    padding: 6px 8px;
    border-radius: 4px;
    cursor: pointer;
    margin-bottom: var(--spacing-xs);
    border-left: 3px solid transparent;
    transition: background 0.15s;
}

.item-list li:hover {
    background: var(--color-bg-tertiary);
}

.item-list li.selected {
    border-left-color: var(--color-accent);
    background: var(--color-bg-secondary);
}

.item-list li.dragging {
    opacity: 0.5;
    background: var(--color-border);
}

.item-list li.drag-over-top {
    border-top: 2px solid var(--color-accent);
    margin-top: -2px;
}

.item-list li.drag-over-bottom {
    border-bottom: 2px solid var(--color-accent);
    margin-bottom: -2px;
}

.item-list.drag-over-end {
    border-bottom: 2px solid var(--color-accent);
}

.emitter-name {
    flex: 1;
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
    font-size: var(--font-base);
}

.btn-duplicate, .btn-delete {
    width: 22px;
    height: 22px;
    border: none;
    background: transparent;
    color: var(--color-text-muted);
    font-size: var(--font-large);
    cursor: pointer;
    border-radius: 3px;
    display: flex;
    align-items: center;
    justify-content: center;
    opacity: 0;
    transition: opacity 0.15s, background 0.15s;
}

.item-list li:hover .btn-duplicate,
.item-list li:hover .btn-delete {
    opacity: 1;
}

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

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

/* ============================================================================
   OBJECT TYPE BADGES & ADD BUTTONS
   ============================================================================ */

.object-type-badge {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 18px;
    height: 18px;
    border-radius: 3px;
    font-size: var(--font-tiny);
    font-weight: 700;
    margin-right: 6px;
    flex-shrink: 0;
}

.object-type-badge.badge-emitter {
    background: #3a5a20;
    color: #8aff4a;
}

.object-type-badge.badge-image {
    background: #20405a;
    color: var(--color-accent-active);
}

.add-object-buttons {
    display: flex;
    gap: var(--spacing-sm);
    margin-top: var(--spacing-md);
}

.add-obj-btn {
    flex: 1;
    padding: 5px 8px;
    border: 1px solid var(--color-border);
    background: var(--color-bg-tertiary);
    color: var(--color-text-primary);
    font-size: var(--font-button);
    cursor: pointer;
    border-radius: 4px;
    text-align: center;
    transition: background 0.15s;
}

.add-obj-btn:hover {
    background: var(--color-accent);
    border-color: var(--color-accent);
}

/* Image source picker popup */
.image-source-picker {
    position: absolute;
    background: var(--color-bg-tertiary);
    border: 1px solid var(--color-accent);
    border-radius: 4px;
    z-index: 100;
    min-width: 200px;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.5);
    overflow: hidden;
}

.image-source-picker .picker-item {
    padding: 6px 12px;
    cursor: pointer;
    font-size: var(--font-button);
    color: var(--color-text-primary);
    transition: background 0.1s;
    border-bottom: 1px solid var(--color-border);
}

.image-source-picker .picker-item:last-child {
    border-bottom: none;
}

.image-source-picker .picker-item:hover {
    background: var(--color-accent);
    color: var(--color-bg-primary);
}

.image-source-picker .picker-header {
    padding: var(--spacing-sm) var(--spacing-lg);
    font-size: var(--font-tiny);
    color: var(--color-text-hint);
    text-transform: uppercase;
    letter-spacing: 0.5px;
    background: var(--color-bg-secondary);
}

.image-source-picker .picker-item-with-remove {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
}

.image-source-picker .picker-item-remove {
    cursor: pointer;
    color: var(--color-text-hint);
    font-size: 16px;
    line-height: 1;
    padding: 0 2px;
}

.image-source-picker .picker-item-remove:hover {
    color: #ff6666;
}

/* ============================================================================
   SCENE BUTTONS
   ============================================================================ */

.scene-buttons {
    display: flex;
    gap: calc(4px * var(--scale-factor));
    margin-top: calc(6px * var(--scale-factor));
}

.scene-btn {
    flex: 1;
    padding: calc(4px * var(--scale-factor)) calc(6px * var(--scale-factor));
    background: var(--color-bg-tertiary);
    color: var(--color-text-primary);
    border: 1px solid #444;
    border-radius: calc(3px * var(--scale-factor));
    cursor: pointer;
    font-size: var(--font-small);
}

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

.scene-btn:disabled {
    opacity: 0.5;
    cursor: default;
}

.scene-btn-danger:hover:not(:disabled) {
    background: #5a2020;
    border-color: #883333;
}

/* ============================================================================
   TEMPLATE SELECT
   ============================================================================ */

#scene-select,
#template-select {
    width: 100%;
    padding: 5px 8px;
    background: var(--color-bg-tertiary);
    color: var(--color-text-primary);
    border: 1px solid var(--color-border);
    border-radius: 4px;
    font-size: var(--font-button);
    margin-bottom: var(--spacing-sm);
}

/* ============================================================================
   BACKGROUND & GRID CONTROLS (Left Sidebar)
   ============================================================================ */

.bg-color-row {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
}

.sidebar-description {
    font-size: var(--font-small);
    color: var(--color-text-muted);
    line-height: 1.4;
    margin: 0 0 var(--spacing-md) 0;
}

.bg-color-row .sidebar-label {
    font-size: var(--font-section-header);
    color: var(--color-text-secondary);
    width: 80px;
    flex-shrink: 0;
}

.bg-color-row input[type="color"] {
    width: var(--color-picker-size);
    height: var(--color-picker-size);
    flex-shrink: 0;
}

.grid-size-row {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
}

.grid-size-row input[type="range"] {
    flex: 1;
    height: 4px;
    -webkit-appearance: none;
    appearance: none;
    background: var(--color-border);
    border-radius: 2px;
    outline: none;
}

.grid-size-row input[type="range"]::-webkit-slider-thumb {
    -webkit-appearance: none;
    width: 14px;
    height: 14px;
    background: var(--color-accent);
    border-radius: 50%;
    cursor: pointer;
}

.grid-size-row input[type="range"]::-moz-range-thumb {
    width: 14px;
    height: 14px;
    background: var(--color-accent);
    border: none;
    border-radius: 50%;
    cursor: pointer;
}

.grid-size-row input[type="number"] {
    width: 50px;
    padding: 3px 4px;
    background: var(--color-bg-tertiary);
    color: var(--color-text-primary);
    border: 1px solid var(--color-border);
    border-radius: 3px;
    font-size: var(--font-section-header);
    text-align: right;
    flex-shrink: 0;
    -moz-appearance: textfield;
}
.grid-size-row input[type="number"]::-webkit-inner-spin-button,
.grid-size-row input[type="number"]::-webkit-outer-spin-button {
    -webkit-appearance: none;
    margin: 0;
}

.grid-size-row input[type="number"]:focus {
    border-color: var(--color-accent);
    outline: none;
}

/* ============================================================================
   EXPORT BUTTONS
   ============================================================================ */

.export-message {
    font-size: var(--font-small);
    color: var(--color-text-muted);
    margin: 0 0 var(--spacing-sm) 0;
}

.export-buttons {
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-sm);
    margin-bottom: var(--spacing-md);
}

.export-btn {
    flex: 1;
    min-width: 50px;
    padding: 5px 8px;
    border: 1px solid var(--color-border);
    background: var(--color-bg-tertiary);
    color: var(--color-text-primary);
    font-size: var(--font-section-header);
    cursor: pointer;
    border-radius: 4px;
    text-align: center;
    transition: background 0.15s, border-color 0.15s;
}

.export-btn:hover:not(:disabled) {
    background: var(--color-border);
    border-color: var(--color-accent);
}

.export-btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

/* ============================================================================
   PARAMETER SECTIONS (Right Sidebar)
   ============================================================================ */

.param-section {
    border-bottom: 1px solid var(--color-border);
}

.section-header {
    display: flex;
    align-items: center;
    padding: var(--spacing-md) var(--spacing-xl);
    cursor: pointer;
    transition: background 0.15s;
}

.section-header:hover {
    background: var(--color-bg-secondary);
}

.section-header h3 {
    margin: 0;
    font-size: var(--font-base);
    font-weight: 600;
    text-transform: none;
    color: var(--color-text-primary);
}

.toggle-icon {
    margin-right: var(--spacing-md);
    font-family: monospace;
    font-size: var(--font-small);
    color: var(--color-text-muted);
    width: 10px;
}

.section-content {
    padding: var(--spacing-sm) var(--spacing-xl) var(--spacing-lg);
}

#params-container.disabled {
    opacity: 0.5;
    pointer-events: none;
}

/* ============================================================================
   PARAMETER ROWS
   ============================================================================ */

.param-row {
    display: flex;
    align-items: center;
    margin-bottom: 6px;
    gap: var(--spacing-md);
}

.param-row label {
    width: 90px;
    flex-shrink: 0;
    font-size: var(--font-section-header);
    color: var(--color-text-secondary);
}

.param-row label .hint {
    font-size: var(--font-small);
    color: #555;
}

.param-row input[type="range"] {
    flex: 1;
    min-width: 60px;
    height: 4px;
    -webkit-appearance: none;
    appearance: none;
    background: var(--color-border);
    border-radius: 2px;
    outline: none;
}

.param-row input[type="range"]::-webkit-slider-thumb {
    -webkit-appearance: none;
    width: 14px;
    height: 14px;
    background: var(--color-accent);
    border-radius: 50%;
    cursor: pointer;
}

.param-row input[type="range"]::-moz-range-thumb {
    width: 14px;
    height: 14px;
    background: var(--color-accent);
    border: none;
    border-radius: 50%;
    cursor: pointer;
}

.param-row input[type="number"] {
    width: 60px;
    flex-shrink: 0;
    padding: 3px 4px;
    background: var(--color-bg-tertiary);
    color: var(--color-text-primary);
    border: 1px solid var(--color-border);
    border-radius: 3px;
    font-size: var(--font-section-header);
    text-align: right;
}

.param-row input[type="number"]:focus {
    border-color: var(--color-accent);
    outline: none;
}

.param-row input[type="number"]::-webkit-inner-spin-button,
.param-row input[type="number"]::-webkit-outer-spin-button {
    -webkit-appearance: none;
    margin: 0;
}
.param-row input[type="number"] {
    -moz-appearance: textfield;
}

.param-row select {
    flex: 1;
    padding: 4px 6px;
    background: var(--color-bg-tertiary);
    color: var(--color-text-primary);
    border: 1px solid var(--color-border);
    border-radius: 3px;
    font-size: var(--font-section-header);
}

.param-row select:focus {
    border-color: var(--color-accent);
    outline: none;
}

/* ============================================================================
   COLOR CONTROLS
   ============================================================================ */

.color-row {
    display: flex;
    align-items: center;
    margin-bottom: var(--spacing-md);
    gap: var(--spacing-md);
}

input[type="color"] {
    -webkit-appearance: none;
    width: var(--color-picker-size);
    height: var(--color-picker-size);
    border: 1px solid var(--color-border);
    border-radius: 4px;
    cursor: pointer;
    padding: 0;
    background: transparent;
}

input[type="color"]::-webkit-color-swatch-wrapper {
    padding: var(--spacing-xs);
}

input[type="color"]::-webkit-color-swatch {
    border: none;
    border-radius: 2px;
}

.variance-group {
    margin-top: var(--spacing-md);
    border-top: 1px solid var(--color-bg-tertiary);
    padding-top: 6px;
}

.variance-group > label {
    display: block;
    font-size: var(--font-small);
    color: var(--color-text-hint);
    margin-bottom: var(--spacing-sm);
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.variance-inputs {
    display: flex;
    gap: var(--spacing-sm);
}

.variance-inputs .variance-field {
    flex: 1;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--spacing-xs);
}

.variance-inputs .variance-field label {
    font-size: var(--font-tiny);
    color: #555;
    width: auto;
}

.variance-inputs .variance-field input {
    width: 100%;
    padding: 2px 3px;
    background: var(--color-bg-tertiary);
    color: var(--color-text-primary);
    border: 1px solid var(--color-border);
    border-radius: 3px;
    font-size: var(--font-small);
    text-align: center;
}

.variance-inputs .variance-field input[type="number"]::-webkit-inner-spin-button,
.variance-inputs .variance-field input[type="number"]::-webkit-outer-spin-button {
    -webkit-appearance: none;
    margin: 0;
}
.variance-inputs .variance-field input[type="number"] {
    -moz-appearance: textfield;
}

/* ============================================================================
   TEXTURE SECTION
   ============================================================================ */

/* Checkerboard background to indicate transparency in particle textures */
.texture-preview {
    width: var(--texture-preview-size);
    height: var(--texture-preview-size);
    border: 1px solid var(--color-border);
    border-radius: 4px;
    margin-bottom: var(--spacing-md);
    background-image:
        linear-gradient(45deg, var(--color-bg-tertiary) 25%, transparent 25%),
        linear-gradient(-45deg, var(--color-bg-tertiary) 25%, transparent 25%),
        linear-gradient(45deg, transparent 75%, var(--color-bg-tertiary) 75%),
        linear-gradient(-45deg, transparent 75%, var(--color-bg-tertiary) 75%);
    background-size: 8px 8px;
    background-position: 0 0, 0 4px, 4px -4px, -4px 0px;
    overflow: hidden;
    display: flex;
    align-items: center;
    justify-content: center;
}

.texture-preview img {
    max-width: 100%;
    max-height: 100%;
    object-fit: contain;
}

.file-btn {
    display: inline-block;
    padding: 5px 10px;
    background: var(--color-bg-tertiary);
    border: 1px solid var(--color-border);
    border-radius: 4px;
    color: var(--color-text-primary);
    font-size: var(--font-section-header);
    cursor: pointer;
    transition: background 0.15s;
}

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

.file-btn input[type="file"] {
    display: none;
}

.texture-actions {
    display: flex;
    gap: var(--spacing-sm);
    margin-top: 6px;
}

.texture-actions .file-btn {
    flex: 1;
    text-align: center;
}

.texture-remove-btn {
    background: #3a2020;
    border-color: #5a3030;
}

.texture-remove-btn:hover {
    background: #5a2020;
    border-color: var(--color-danger);
    color: var(--color-danger);
}

/* ============================================================================
   TOAST NOTIFICATIONS
   ============================================================================ */

#toast-container {
    position: fixed;
    bottom: 20px;
    left: 50%;
    transform: translateX(-50%);
    z-index: 9999;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--spacing-md);
    pointer-events: none;
}

.toast {
    background: #333;
    color: var(--color-text-primary);
    padding: 8px 20px;
    border-radius: 6px;
    font-size: var(--font-base);
    opacity: 0;
    transform: translateY(10px);
    transition: opacity 0.3s, transform 0.3s;
    pointer-events: auto;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.4);
}

.toast.show {
    opacity: 1;
    transform: translateY(0);
}

/* ============================================================================
   SCROLLBAR STYLING
   ============================================================================ */

::-webkit-scrollbar {
    width: 6px;
}

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

::-webkit-scrollbar-thumb {
    background: var(--color-border);
    border-radius: 3px;
}

::-webkit-scrollbar-thumb:hover {
    background: #4a4a50;
}

* {
    scrollbar-width: thin;
    scrollbar-color: var(--color-border) var(--color-bg-primary);
}

/* ============================================================================
   FOCUS INDICATORS
   ============================================================================ */

.icon-btn:focus-visible,
.small-btn:focus-visible,
.full-btn:focus-visible,
.export-btn:focus-visible,
.scene-btn:focus-visible,
select:focus-visible,
input[type="color"]:focus-visible {
    outline: 2px solid var(--color-accent);
    outline-offset: 2px;
}


/* ============================================================================
   CHECKBOX ROW
   ============================================================================ */

.checkbox-row {
    display: flex;
    align-items: center;
    gap: 6px;
    cursor: pointer;
    font-size: var(--font-section-header);
    color: var(--color-text-secondary);
    user-select: none;
}

.checkbox-row input[type="checkbox"] {
    accent-color: var(--color-accent);
    width: 14px;
    height: 14px;
    cursor: pointer;
}

/* ============================================================================
   CONTENT AREA CONTROLS
   ============================================================================ */

.section-hint {
    font-size: var(--font-small);
    color: var(--color-text-muted);
    margin: 0 0 var(--spacing-sm) 0;
    font-style: italic;
}

.canvas-size-row {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
}

.canvas-size-row label {
    font-size: var(--font-section-header);
    color: var(--color-text-hint);
    flex-shrink: 0;
}

.canvas-size-row input[type="number"] {
    width: 60px;
    padding: 3px 4px;
    background: var(--color-bg-tertiary);
    color: var(--color-text-primary);
    border: 1px solid var(--color-border);
    border-radius: 3px;
    font-size: var(--font-section-header);
    text-align: right;
    -moz-appearance: textfield;
}

.canvas-size-row input[type="number"]::-webkit-inner-spin-button,
.canvas-size-row input[type="number"]::-webkit-outer-spin-button {
    -webkit-appearance: none;
    margin: 0;
}

.canvas-size-x {
    font-size: var(--font-section-header);
    color: var(--color-text-hint);
}

#solar2d-iframe.fixed-size {
    width: auto;
    height: auto;
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
}

/* ============================================================================
   SHORTCUTS MODAL
   ============================================================================ */

.shortcuts-table {
    width: 100%;
    border-collapse: collapse;
    margin-bottom: 16px;
}

.shortcuts-table tr {
    border-bottom: 1px solid var(--color-border);
}

.shortcuts-table td {
    padding: 8px 4px;
    font-size: var(--font-base);
    color: var(--color-text-primary);
}

.shortcut-key {
    white-space: nowrap;
    width: 50%;
}

kbd {
    display: inline-block;
    padding: 2px 6px;
    background: var(--color-bg-tertiary);
    border: 1px solid var(--color-border);
    border-radius: 3px;
    font-size: var(--font-small);
    font-family: monospace;
    color: var(--color-text-primary);
}

/* ============================================================================
   MODAL OVERLAY
   ============================================================================ */

.modal-overlay {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0, 0, 0, 0.7);
    z-index: 10000;
    display: flex;
    align-items: center;
    justify-content: center;
}

.modal-dialog {
    background: var(--color-bg-secondary);
    border: 1px solid var(--color-border);
    border-radius: 8px;
    padding: 24px 32px;
    max-width: 420px;
    width: 90%;
    box-shadow: 0 8px 32px rgba(0, 0, 0, 0.6);
}

.modal-dialog h2 {
    font-size: var(--font-heading);
    color: var(--color-text-primary);
    margin-bottom: 12px;
}

.modal-dialog p {
    font-size: var(--font-base);
    color: var(--color-text-secondary);
    line-height: 1.5;
    margin-bottom: 16px;
}

.confirm-buttons {
    display: flex;
    gap: 12px;
}

.confirm-btn {
    flex: 1;
    padding: 8px 16px;
    border: 1px solid var(--color-border);
    border-radius: 4px;
    font-size: var(--font-base);
    cursor: pointer;
    transition: background 0.15s;
}

.confirm-btn-danger {
    background: #c0392b;
    color: #fff;
    border-color: #c0392b;
}

.confirm-btn-danger:hover {
    background: #a93226;
}

.confirm-btn-cancel {
    background: var(--color-bg-tertiary);
    color: var(--color-text-primary);
}

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

.full-btn-danger {
    background: var(--color-bg-tertiary);
    color: #e74c3c;
    border-color: #e74c3c;
}

.full-btn-danger:hover {
    background: #c0392b;
    color: #fff;
}

/* ============================================================================
   RESPONSIVE
   ============================================================================ */

@media (max-width: 1100px) {
    :root {
        --sidebar-left-width: calc(200px * var(--scale-factor));
        --sidebar-right-width: calc(260px * var(--scale-factor));
    }
}

@media (max-width: 900px) {
    #main {
        flex-direction: column;
    }

    #sidebar-left {
        width: 100%;
        max-height: 180px;
        border-right: none;
        border-bottom: 1px solid var(--color-border);
        overflow-y: auto;
    }

    #sidebar-right {
        width: 100%;
        max-height: 250px;
        border-left: none;
        border-top: 1px solid var(--color-border);
        overflow-y: auto;
    }

    #canvas-container {
        min-height: 300px;
    }

    .sidebar-section {
        display: inline-block;
        vertical-align: top;
        width: auto;
        border-bottom: none;
        border-right: 1px solid var(--color-border);
    }
}

@media (max-width: 600px) {
    :root {
        --header-height: calc(40px * var(--header-scale));
    }

    .header-left h1 {
        font-size: calc(13px * var(--header-scale));
    }

    .ui-scale-control {
        display: none;
    }

    .help-link {
        display: none;
    }

    #sidebar-left {
        max-height: 150px;
    }

    #sidebar-right {
        max-height: 200px;
    }
}

/* ============================================================================
   REDUCED MOTION
   ============================================================================ */

@media (prefers-reduced-motion: reduce) {
    .loading-spinner {
        animation: none;
    }
    .toast {
        transition: none;
    }
    * {
        transition-duration: 0.01ms !important;
        animation-duration: 0.01ms !important;
    }
}