body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol";
    margin: 0;
    background-color: #f0f2f5;
    color: #333;
}

/* Help tooltip */
.help-icon {
    display:inline-block;
    width:16px;
    height:16px;
    line-height:16px;
    text-align:center;
    font-size:11px;
    font-weight:bold;
    border-radius:50%;
    background:#007bff;
    color:#fff;
    cursor:default;
    margin-left:6px;
    position:relative;
}
.help-icon .tooltip-text {
    visibility:hidden;
    opacity:0;
    position:absolute;
    top:22px;
    left:50%;
    transform:translateX(-50%);
    background:#222;
    color:#fff;
    padding:8px 10px;
    border-radius:4px;
    font-size:11px;
    width:240px;
    z-index:1000;
    transition:opacity .15s ease;
    pointer-events:none;
    box-shadow:0 4px 10px rgba(0,0,0,.25);
}
.help-icon:hover .tooltip-text { visibility:visible; opacity:1; }

/* Code modal */
#code-modal-overlay {
    position:fixed;
    top:0;left:0;right:0;bottom:0;
    background:rgba(0,0,0,0.55);
    display:none;
    align-items:flex-start;
    justify-content:center;
    padding:40px 30px;
    z-index:2000;
}
#code-modal {
    background:#fff;
    width: min(1200px, 100%);
    max-height: calc(100vh - 80px);
    display:flex;
    flex-direction:column;
    border-radius:8px;
    box-shadow:0 10px 30px rgba(0,0,0,.25);
    overflow:hidden;
}
#code-modal header {
    display:flex;
    align-items:center;
    justify-content:space-between;
    padding:12px 18px;
    background:#0d6efd;
    color:#fff;
}
#code-modal header h3 { margin:0; font-size:1rem; }
#code-modal .close-btn {
    background:rgba(255,255,255,0.15);
    border:none;
    color:#fff;
    padding:4px 10px;
    font-size:0.8rem;
    border-radius:4px;
    cursor:pointer;
}
#code-modal .close-btn:hover { background:rgba(255,255,255,0.3); }
#code-modal .tab-bar { display:flex; gap:4px; padding:8px 12px; background:#f5f6f7; border-bottom:1px solid #e3e5e8; }
#code-modal .tab-bar button { background:#e9ecef; border:1px solid #d0d4d8; padding:6px 12px; border-radius:4px; cursor:pointer; font-size:0.8rem; }
#code-modal .tab-bar button.active { background:#0d6efd; color:#fff; border-color:#0d6efd; }
#code-modal .code-pane { flex:1; overflow:auto; padding:16px; background:#1e1e1e; }
#code-modal pre { margin:0; font-size:13px; line-height:1.4; color:#dcdcdc; }
#code-modal .actions { display:flex; gap:8px; padding:8px 12px; justify-content:flex-end; background:#f5f6f7; border-top:1px solid #e3e5e8; }
#code-modal .actions button { background:#0d6efd; color:#fff; border:none; padding:6px 12px; font-size:0.75rem; border-radius:4px; cursor:pointer; }
#code-modal .actions button.secondary { background:#6c757d; }
#code-modal .actions button:hover { filter:brightness(1.05); }

#open-code-modal-btn {
    display:block;
    width:100%;
    padding:10px;
    margin-bottom:10px;
    background-color:#6f42c1; /* distinct purple accent */
    color:#fff;
    border:none;
    border-radius:4px;
    cursor:pointer;
    font-size:0.9rem;
    text-align:center;
    transition:background-color .2s;
}
#open-code-modal-btn:hover { background-color:#59359d; }

#app {
    display: grid;
    grid-template-columns: 240px 1fr 340px;
    grid-template-rows: 100vh;
    height: 100vh;
}

.panel {
    background-color: #fff;
    padding: 16px;
    box-shadow: 0 0 10px rgba(0,0,0,0.05);
    z-index: 1;
}

#left-panel {
    border-right: 1px solid #d9d9d9;
}

#right-panel {
    border-left: 1px solid #d9d9d9;
    display:flex;
    flex-direction:column;
    padding:0;
}

#properties-section, #code-section {
    padding:16px;
}

#properties-section { flex:1; display:flex; flex-direction:column; min-height:0; }
#properties-panel-content { overflow:auto; flex:1; padding-right:4px; }

#code-section { border-top:1px solid #e3e3e3; max-height:46%; display:flex; flex-direction:column; }
#code-panel-content { overflow:auto; flex:1; }

#prop-device-tabs { display:flex; gap:4px; }
#prop-device-tabs button { background:#e9ecef; border:1px solid #cfd2d6; border-radius:4px; padding:4px 6px; cursor:pointer; font-size:0.65rem; line-height:1; }
#prop-device-tabs button.active { background:#0d6efd; color:#fff; border-color:#0d6efd; }
#prop-device-tabs button.has-override { position:relative; }
#prop-device-tabs button.has-override::after { content:''; position:absolute; top:2px; right:2px; width:6px; height:6px; background:#dc3545; border-radius:50%; box-shadow:0 0 0 1px #fff; }
.section-header { display:flex; align-items:center; justify-content:space-between; margin-bottom:8px; }

h2 {
    font-size: 1.1rem;
    margin-top: 0;
    padding-bottom: 10px;
    border-bottom: 1px solid #eee;
}

#canvas {
    display: flex;
    flex-direction: column;
    padding: 20px;
    overflow: auto;
    background-color: #f0f2f5;
}

#device-controls {
    display: flex;
    justify-content: center;
    margin-bottom: 20px;
}

#device-controls button {
    background-color: #fff;
    border: 1px solid #ccc;
    padding: 8px 16px;
    cursor: pointer;
    border-radius: 4px;
    margin: 0 5px;
    font-size: 0.9rem;
    transition: background-color 0.2s, color 0.2s;
}

#device-controls button.active {
    background-color: #007bff;
    color: white;
    border-color: #007bff;
}

#preview-container {
    flex-grow: 1;
    display: flex;
    align-items: center;
    justify-content: center;
}

#preview {
    background-color: white;
    width: 100%;
    height: 100%;
    box-shadow: 0 0 20px rgba(0,0,0,0.1);
    border-radius: 4px;
    border: 1px solid #ccc;
    transition: width 0.3s ease-in-out;
}

#element-controls button {
    display: block;
    width: 100%;
    padding: 10px;
    margin-bottom: 10px;
    background-color: #007bff;
    color: white;
    border: none;
    border-radius: 4px;
    cursor: pointer;
    font-size: 0.9rem;
    text-align: left;
    transition: background-color 0.2s;
}
/* History buttons inline row */
.history-row { display:flex; gap:6px; margin-bottom:10px; }
.history-row .history-btn { flex:1 1 auto; text-align:center; font-size:0.75rem; padding:6px 8px; background:#495057; }
.history-row .history-btn:disabled { opacity:.45; cursor:not-allowed; }
.history-row .history-btn:not(:disabled):hover { filter:brightness(1.1); }

#element-controls button:hover {
    background-color: #0056b3;
}

#clear-btn {
    background-color: #dc3545;
    margin-top: 20px;
    text-align: center;
    display: block;
    width: 100%;
    padding: 10px;
    color: white;
    border: none;
    border-radius: 4px;
    cursor: pointer;
    font-size: 0.9rem;
    transition: background-color 0.2s;
}

#clear-btn:hover {
    background-color: #c82333;
}

.preset-container {
    margin-top: 20px;
}

.preset-container label {
    display: block;
    margin-bottom: 5px;
    font-size: 0.9rem;
    color: #555;
}

.preset-container select {
    width: 100%;
    padding: 8px;
    border: 1px solid #ccc;
    border-radius: 4px;
    font-size: 0.9rem;
}

.row {
    display: flex;
    border: 1px dashed #ccc;
    margin: 5px;
    padding: 10px;
    min-height: 50px;
}

.col {
    border: 1px dashed #999;
    margin: 5px;
    padding: 10px;
    flex-grow: 1;
    min-height: 50px;
}

/* Grid visuals */
.grid-container {
    border:1px dashed #b5b5b5;
    margin:5px;
    padding:10px;
    background:#fff;
}
.grid-item {
    border:1px dashed #c7c7c7;
    background:linear-gradient(135deg,#fafafa,#f0f0f0);
    min-height:60px;
    display:flex;
    align-items:center;
    justify-content:center;
    font-size:0.7rem;
    position:relative;
}
.grid-item.selected { border:2px solid #007bff !important; }
.drag-over { outline:2px dashed #0d6efd; }
.dnd-insert-marker { pointer-events:none; border-top:2px solid #0d6efd; margin:2px 0; }

/* Property panel tweaks */
#properties-panel-content .input-group button.quick-btn[data-gridcols] { flex:0 0 auto; }
#properties-panel-content small.helper-note { display:block; font-size:0.65rem; color:#666; margin-top:4px; line-height:1.3; }

.selected {
    border: 2px solid #007bff !important;
    background-color: #e6f7ff;
}
.selected.multi-peer { box-shadow:0 0 0 2px rgba(13,110,253,0.35) inset; }

#properties-panel-content select, 
#properties-panel-content input {
    width: 100%;
    padding: 8px;
    border: 1px solid #ccc;
    border-radius: 4px;
    font-size: 0.9rem;
}

.input-group {
    display: flex;
    gap: 4px;
}

.input-group.wrap { flex-wrap:wrap; }
.input-group.wrap input { flex:1 1 140px; }
.input-group.wrap select { flex:0 0 80px; }

.input-group input {
    flex: 1;
}

.input-group select {
    width: 80px;
    flex-shrink: 0;
}

.quick-values {
    display: flex;
    gap: 4px;
    margin-top: 4px;
}

.quick-btn {
    background: #f8f9fa;
    border: 1px solid #dee2e6;
    padding: 4px 8px;
    border-radius: 3px;
    font-size: 0.8rem;
    cursor: pointer;
    transition: background-color 0.2s;
}

.quick-btn:hover {
    background: #e9ecef;
}

.quick-btn.active {
    background:#0d6efd;
    color:#fff;
    border-color:#0d6efd;
}

.spacing-grid, .alignment-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 8px;
}

.spacing-grid label, .alignment-grid label {
    font-size: 0.8rem;
    color: #666;
    margin-bottom: 2px;
}

/* Advanced spacing panel */
.adv-spacing-head { margin-top:8px; }
.adv-spacing-head .adv-toggle { background:#6c757d; color:#fff; border:none; padding:4px 8px; border-radius:4px; font-size:0.6rem; cursor:pointer; }
.adv-spacing-head .adv-toggle.open { background:#495057; }
#adv-spacing-panel .adv-group { background:#f8f9fa; border:1px solid #e2e6ea; padding:6px 8px; border-radius:4px; }
#adv-spacing-panel .adv-label { display:block; font-size:0.65rem; font-weight:600; margin-bottom:4px; text-transform:uppercase; letter-spacing:0.5px; color:#555; }
#adv-spacing-panel .adv-grid { display:grid; grid-template-columns:repeat(4,1fr); gap:4px; }
#adv-spacing-panel input { padding:4px 6px; font-size:0.65rem; }

#properties-panel-content .property { margin-bottom:18px; }
#properties-panel-content .property:last-child { margin-bottom:8px; }

/* Property override highlighting */
#properties-panel-content input.prop-override,
#properties-panel-content select.prop-override {
    outline:2px solid #dc3545;
    background:#fff5f5;
}
.override-helper { margin:0 0 10px; }
.override-helper .override-box { background:#fff3cd; border:1px solid #f3d39b; padding:4px 6px; border-radius:4px; display:flex; justify-content:space-between; align-items:center; }
.override-helper button.clear-redundant-btn { background:#dc3545; color:#fff; border:none; padding:2px 8px; font-size:0.6rem; border-radius:3px; cursor:pointer; }
.override-helper button.clear-redundant-btn:hover { filter:brightness(1.1); }

/* Resizable column handles */
.resize-handle {
    width:6px;
    background:rgba(0,0,0,0.1);
    cursor:col-resize;
    align-self:stretch;
    border-radius:3px;
    position:relative;
    transition:background .15s;
}
.resize-handle:hover, .resize-handle.dragging { background:rgba(0,0,0,0.25); }
.resize-handle:before { content:''; position:absolute; top:50%; left:50%; transform:translate(-50%,-50%); width:2px; height:60%; background:rgba(0,0,0,0.35); border-radius:1px; }

#properties-panel-content label {
    display: block;
    margin-bottom: 5px;
    font-size: 0.9rem;
    color: #555;
}

#code-panel-content pre {
    background-color: #f8f9fa;
    border: 1px solid #e9ecef;
    border-radius: 4px;
    padding: 10px;
    white-space: pre-wrap;
    word-break: break-all;
    font-family: "SFMono-Regular", Consolas, "Liberation Mono", Menlo, Courier, monospace;
    font-size: 0.85rem;
}

#generate-code-btn {
    display: block;
    width: 100%;
    padding: 10px;
    margin-bottom: 10px;
    background-color: #28a745;
    color: white;
    border: none;
    border-radius: 4px;
    cursor: pointer;
    font-size: 0.9rem;
    text-align: center;
    transition: background-color 0.2s;
}

#generate-code-btn:hover {
    background-color: #218838;
}

/* Secondary action button (e.g., Run Validation) */
.secondary-action {
    display:block;
    width:100%;
    padding:10px;
    margin-bottom:10px;
    background:#0d6efd;
    color:#fff;
    border:none;
    border-radius:4px;
    cursor:pointer;
    font-size:0.85rem;
    text-align:center;
    transition:background .2s;
}
.secondary-action:hover { background:#0b5ed7; }

/* Breadcrumb */
.breadcrumb { display:flex; flex-wrap:wrap; gap:4px; font-size:0.65rem; margin:0 0 8px; }
.breadcrumb .crumb { background:#e9ecef; border:1px solid #ced4da; padding:2px 6px; border-radius:3px; cursor:pointer; }
.breadcrumb .crumb:hover { background:#dee2e6; }
.breadcrumb .crumb-sep { color:#888; padding:0 2px; }

/* Validation results */
.validation-results { margin-top:8px; font-size:0.65rem; max-height:120px; overflow:auto; background:#f8f9fa; border:1px solid #e3e6e9; padding:6px 8px; border-radius:4px; }
.validation-results .issue { display:flex; justify-content:space-between; align-items:center; gap:6px; background:#fff; border:1px solid #e2e6ea; padding:4px 6px; border-radius:3px; margin-bottom:4px; }
.validation-results .issue button { background:#ffc107; border:none; padding:2px 6px; font-size:0.6rem; border-radius:3px; cursor:pointer; }
.validation-results .issue button:hover { filter:brightness(1.05); }
.validation-results .ok { background:#d1e7dd; color:#0f5132; padding:6px 8px; border-radius:4px; border:1px solid #badbcc; }
.validation-results .val-actions { text-align:right; margin-top:6px; }
.validation-results #fix-all-btn { background:#0d6efd; color:#fff; border:none; padding:4px 10px; font-size:0.6rem; border-radius:3px; cursor:pointer; }
.validation-results #fix-all-btn:hover { filter:brightness(1.05); }

/* Contrast badge */
.contrast-badge { font-size:0.6rem; padding:3px 6px; border-radius:3px; margin-bottom:6px; font-weight:600; display:inline-block; }
.contrast-badge.pass { background:#198754; color:#fff; }
.contrast-badge.fail { background:#dc3545; color:#fff; }