Frontend improvements: CSS foundations, accessibility, UX enhancements

CSS: Add design token variables (spacing, timing, weights, z-index layers),
migrate all hardcoded z-index to named vars, fix light theme contrast for
WCAG AA, add skeleton loading cards, mask-composite fallback, card padding.

Accessibility: aria-live on toast, aria-label on health dots, sr-only class,
graph container keyboard focusable, MQTT password wrapped in form element.

UX: Modal auto-focus on open, inline field validation with blur, undo toast
with countdown, bulk action progress indicator, API error toast on failure.

i18n: Add common.undo, validation.required, bulk.processing, api.error.*
keys in EN/RU/ZH.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

server/src/wled_controller/static/css/base.css

@@ -12,11 +12,47 @@
     --warning-color: #ff9800;
     --info-color: #2196F3;
     --font-mono: 'Cascadia Code', 'Fira Code', 'JetBrains Mono', 'SF Mono', 'Consolas', 'Liberation Mono', monospace;
+
+    /* Spacing scale */
+    --space-xs: 4px;
+    --space-sm: 8px;
+    --space-md: 12px;
+    --space-lg: 20px;
+    --space-xl: 40px;
+
+    /* Border radius */
     --radius: 8px;
     --radius-sm: 4px;
     --radius-md: 8px;
     --radius-lg: 12px;
     --radius-pill: 100px;
+
+    /* Animation timing */
+    --duration-fast: 0.15s;
+    --duration-normal: 0.25s;
+    --duration-slow: 0.4s;
+    --ease-out: cubic-bezier(0.16, 1, 0.3, 1);
+    --ease-spring: cubic-bezier(0.34, 1.56, 0.64, 1);
+
+    /* Font weights */
+    --weight-normal: 400;
+    --weight-medium: 500;
+    --weight-semibold: 600;
+    --weight-bold: 700;
+
+    /* Z-index layers */
+    --z-card-elevated: 10;
+    --z-sticky: 100;
+    --z-dropdown: 200;
+    --z-bulk-toolbar: 1000;
+    --z-modal: 2000;
+    --z-log-overlay: 2100;
+    --z-confirm: 2500;
+    --z-command-palette: 3000;
+    --z-toast: 3000;
+    --z-overlay-spinner: 9999;
+    --z-lightbox: 10000;
+    --z-connection: 10000;
 }
 
 /* ── SVG icon base ── */
@@ -59,8 +95,8 @@
     --card-bg: #ffffff;
     --text-color: #333333;
     --text-primary: #333333;
-    --text-secondary: #666;
+    --text-secondary: #595959;
-    --text-muted: #999;
+    --text-muted: #767676;
     --border-color: #e0e0e0;
     --display-badge-bg: rgba(255, 255, 255, 0.85);
     --primary-text-color: #3d8b40;
@@ -186,7 +222,7 @@ body,
 .dashboard-target,
 .perf-chart-card,
 header {
-    transition: background-color 0.3s ease, color 0.3s ease, border-color 0.3s ease;
+    transition: background-color var(--duration-normal) ease, color var(--duration-normal) ease, border-color var(--duration-normal) ease;
 }
 
 /* ── Respect reduced motion preference ── */

server/src/wled_controller/static/css/cards.css

@@ -2,6 +2,59 @@ section {
     margin-bottom: 40px;
 }
 
+/* ── Skeleton loading placeholders ── */
+@keyframes skeletonPulse {
+    0%, 100% { opacity: 0.06; }
+    50%      { opacity: 0.12; }
+}
+
+.skeleton-card {
+    background: var(--card-bg);
+    border: 1px solid var(--border-color);
+    border-radius: var(--radius-md);
+    padding: 16px 20px 20px;
+    display: flex;
+    flex-direction: column;
+    gap: 12px;
+    min-height: 140px;
+}
+
+.skeleton-line {
+    height: 14px;
+    border-radius: 4px;
+    background: var(--text-color);
+    animation: skeletonPulse 1.5s ease-in-out infinite;
+}
+
+.skeleton-line-title {
+    width: 60%;
+    height: 18px;
+}
+
+.skeleton-line-short {
+    width: 40%;
+}
+
+.skeleton-line-medium {
+    width: 75%;
+}
+
+.skeleton-actions {
+    display: flex;
+    gap: 8px;
+    margin-top: auto;
+    padding-top: 12px;
+    border-top: 1px solid var(--border-color);
+}
+
+.skeleton-btn {
+    height: 32px;
+    flex: 1;
+    border-radius: var(--radius-sm);
+    background: var(--text-color);
+    animation: skeletonPulse 1.5s ease-in-out infinite;
+}
+
 .displays-grid,
 .devices-grid {
     display: grid;
@@ -54,7 +107,7 @@ section {
     background: var(--card-bg);
     border: 1px solid var(--border-color);
     border-radius: var(--radius-md);
-    padding: 12px 20px 20px;
+    padding: 16px 20px 20px;
     position: relative;
     transition: transform 0.2s ease, box-shadow 0.2s ease, border-color 0.2s ease;
     display: flex;
@@ -152,6 +205,17 @@ section {
     animation: rotateBorder 4s linear infinite;
 }
 
+/* Fallback for browsers without mask-composite support (older Firefox) */
+@supports not (mask-composite: exclude) {
+    .card-running::before {
+        -webkit-mask: none;
+        mask: none;
+        background: none;
+        border: 2px solid var(--primary-color);
+        opacity: 0.7;
+    }
+}
+
 @keyframes rotateBorder {
     to { --border-angle: 360deg; }
 }
@@ -1192,7 +1256,7 @@ ul.section-tip li {
     display: flex;
     align-items: center;
     gap: 12px;
-    z-index: 1000;
+    z-index: var(--z-bulk-toolbar);
     box-shadow: 0 -4px 24px rgba(0, 0, 0, 0.3);
     transition: transform 0.25s ease;
     white-space: nowrap;

server/src/wled_controller/static/css/components.css

@@ -193,6 +193,21 @@ select:focus {
     box-shadow: 0 0 0 3px rgba(76, 175, 80, 0.15);
 }
 
+/* Inline validation states */
+input.field-invalid,
+select.field-invalid {
+    border-color: var(--danger-color);
+    box-shadow: 0 0 0 2px color-mix(in srgb, var(--danger-color) 15%, transparent);
+}
+
+.field-error-msg {
+    display: block;
+    color: var(--danger-color);
+    font-size: 0.78rem;
+    margin-top: 4px;
+    line-height: 1.3;
+}
+
 /* Remove browser autofill styling */
 input:-webkit-autofill,
 input:-webkit-autofill:hover,
@@ -260,7 +275,7 @@ input:-webkit-autofill:focus {
     flex-direction: column;
     align-items: center;
     justify-content: center;
-    z-index: 9999;
+    z-index: var(--z-overlay-spinner);
     backdrop-filter: blur(4px);
 }
 
@@ -353,7 +368,7 @@ input:-webkit-autofill:focus {
     font-size: 15px;
     opacity: 0;
     transition: opacity 0.4s cubic-bezier(0.16, 1, 0.3, 1), transform 0.4s cubic-bezier(0.16, 1, 0.3, 1);
-    z-index: 3000;
+    z-index: var(--z-toast);
     box-shadow: 0 4px 20px var(--shadow-color);
     min-width: 300px;
     text-align: center;
@@ -384,6 +399,52 @@ input:-webkit-autofill:focus {
     background: var(--info-color);
 }
 
+/* Toast with undo action */
+.toast-with-action {
+    display: flex;
+    align-items: center;
+    gap: 12px;
+}
+
+.toast-message {
+    flex: 1;
+}
+
+.toast-undo-btn {
+    background: rgba(255, 255, 255, 0.25);
+    border: 1px solid rgba(255, 255, 255, 0.4);
+    color: white;
+    padding: 4px 12px;
+    border-radius: var(--radius-sm);
+    font-weight: var(--weight-semibold, 600);
+    font-size: 0.85rem;
+    cursor: pointer;
+    transition: background var(--duration-fast, 0.15s);
+    white-space: nowrap;
+    flex-shrink: 0;
+}
+
+.toast-undo-btn:hover {
+    background: rgba(255, 255, 255, 0.4);
+}
+
+.toast-timer {
+    width: 100%;
+    height: 3px;
+    position: absolute;
+    bottom: 0;
+    left: 0;
+    border-radius: 0 0 var(--radius-md) var(--radius-md);
+    background: rgba(255, 255, 255, 0.3);
+    transform-origin: left;
+    animation: toastTimer var(--toast-duration, 5s) linear forwards;
+}
+
+@keyframes toastTimer {
+    from { transform: scaleX(1); }
+    to   { transform: scaleX(0); }
+}
+
 /* ── Card Tags ──────────────────────────────────────────── */
 
 .card-tags {
@@ -604,7 +665,7 @@ textarea:focus-visible {
 
 .icon-select-popup {
     position: fixed;
-    z-index: 10000;
+    z-index: var(--z-lightbox);
     overflow: hidden;
     opacity: 0;
     transition: opacity 0.15s ease;
@@ -683,7 +744,7 @@ textarea:focus-visible {
 .type-picker-overlay {
     position: fixed;
     inset: 0;
-    z-index: 3000;
+    z-index: var(--z-command-palette);
     display: flex;
     justify-content: center;
     padding-top: 15vh;
@@ -758,7 +819,7 @@ textarea:focus-visible {
     display: none;
     position: fixed;
     inset: 0;
-    z-index: 10000;
+    z-index: var(--z-lightbox);
     background: rgba(0, 0, 0, 0.5);
     justify-content: center;
     align-items: flex-start;

server/src/wled_controller/static/css/layout.css

@@ -5,7 +5,7 @@ header {
     padding: 8px 20px;
     position: sticky;
     top: 0;
-    z-index: 100;
+    z-index: var(--z-sticky);
     background: var(--bg-color);
     border-bottom: 2px solid var(--border-color);
 }
@@ -133,7 +133,7 @@ h2 {
 .connection-overlay {
     position: fixed;
     inset: 0;
-    z-index: 10000;
+    z-index: var(--z-connection);
     display: flex;
     align-items: center;
     justify-content: center;
@@ -177,6 +177,19 @@ h2 {
     animation: conn-spin 0.8s linear infinite;
 }
 
+/* Visually hidden — screen readers only */
+.sr-only {
+    position: absolute;
+    width: 1px;
+    height: 1px;
+    padding: 0;
+    margin: -1px;
+    overflow: hidden;
+    clip: rect(0, 0, 0, 0);
+    white-space: nowrap;
+    border: 0;
+}
+
 /* WLED device health indicator */
 .health-dot {
     display: inline-block;
@@ -448,7 +461,7 @@ h2 {
 #command-palette {
     position: fixed;
     inset: 0;
-    z-index: 3000;
+    z-index: var(--z-command-palette);
     display: flex;
     justify-content: center;
     padding-top: 15vh;

server/src/wled_controller/static/css/mobile.css

@@ -154,7 +154,7 @@
         bottom: 0;
         left: 0;
         right: 0;
-        z-index: 100;
+        z-index: var(--z-sticky);
         background: var(--card-bg);
         border-bottom: none;
         border-top: 1px solid var(--border-color);

server/src/wled_controller/static/css/modal.css

@@ -7,7 +7,7 @@
     width: 100%;
     height: 100%;
     background: rgba(0, 0, 0, 0.8);
-    z-index: 2000;
+    z-index: var(--z-modal);
     align-items: center;
     justify-content: center;
     animation: fadeIn 0.2s ease-out;
@@ -16,7 +16,7 @@
 
 /* Confirm dialog must stack above all other modals */
 #confirm-modal {
-    z-index: 2500;
+    z-index: var(--z-confirm);
 }
 
 /* Audio test spectrum canvas */
@@ -393,7 +393,7 @@
 .log-overlay {
     position: fixed;
     inset: 0;
-    z-index: 2100;
+    z-index: var(--z-log-overlay);
     display: flex;
     flex-direction: column;
     background: var(--bg-color, #111);
@@ -1007,7 +1007,7 @@
     width: 100%;
     height: 100%;
     background: rgba(0, 0, 0, 0.92);
-    z-index: 10000;
+    z-index: var(--z-lightbox);
     justify-content: center;
     align-items: center;
     cursor: zoom-out;

server/src/wled_controller/static/js/app.ts

@@ -18,8 +18,9 @@ import { initTabIndicator, updateTabIndicator } from './core/tab-indicator.ts';
 // Layer 2: ui
 import {
     toggleHint, lockBody, unlockBody, closeLightbox,
-    showToast, showConfirm, closeConfirmModal,
+    showToast, showUndoToast, showConfirm, closeConfirmModal,
     openFullImageLightbox, showOverlaySpinner, hideOverlaySpinner,
+    setFieldError, clearFieldError, setupBlurValidation,
 } from './core/ui.ts';
 
 // Layer 3: displays, tutorials
@@ -86,7 +87,7 @@ import {
     clonePatternTemplate,
 } from './features/pattern-templates.ts';
 import {
-    loadAutomations, openAutomationEditor, closeAutomationEditorModal,
+    loadAutomations, switchAutomationTab, openAutomationEditor, closeAutomationEditorModal,
     saveAutomationEditor, addAutomationCondition,
     toggleAutomationEnabled, cloneAutomation, deleteAutomation, copyWebhookUrl,
 } from './features/automations.ts';
@@ -208,11 +209,15 @@ Object.assign(window, {
     unlockBody,
     closeLightbox,
     showToast,
+    showUndoToast,
     showConfirm,
     closeConfirmModal,
     openFullImageLightbox,
     showOverlaySpinner,
     hideOverlaySpinner,
+    setFieldError,
+    clearFieldError,
+    setupBlurValidation,
 
     // core / api + i18n
     t,
@@ -365,6 +370,7 @@ Object.assign(window, {
 
     // automations
     loadAutomations,
+    switchAutomationTab,
     openAutomationEditor,
     closeAutomationEditorModal,
     saveAutomationEditor,

server/src/wled_controller/static/js/core/api.ts

@@ -4,6 +4,7 @@
 
 import { apiKey, setApiKey, refreshInterval, setRefreshInterval, displaysCache } from './state.ts';
 import { t } from './i18n.ts';
+import { showToast } from './ui.ts';
 
 export const API_BASE = '/api/v1';
 
@@ -68,6 +69,11 @@ export async function fetchWithAuth(url: string, options: FetchAuthOpts = {}): P
                 await new Promise(r => setTimeout(r, 500 * 2 ** attempt));
                 continue;
             }
+            // Final attempt failed — show user-facing error
+            const errMsg = (err as Error)?.name === 'AbortError'
+                ? t('api.error.timeout')
+                : t('api.error.network');
+            showToast(errMsg, 'error');
             throw err;
         }
     }

server/src/wled_controller/static/js/core/bulk-toolbar.ts

@@ -106,11 +106,23 @@ async function _executeAction(actionKey) {
         if (!ok) return;
     }
 
+    // Show progress state on toolbar
+    const el = _toolbarEl;
+    const actionBtns = el?.querySelectorAll('.bulk-action-btn') as NodeListOf<HTMLButtonElement>;
+    actionBtns?.forEach(btn => { btn.disabled = true; });
+    const countEl = el?.querySelector('.bulk-count');
+    const prevCount = countEl?.textContent || '';
+    if (countEl) countEl.textContent = t('bulk.processing') || 'Processing…';
+
     try {
         await action.handler(keys);
     } catch (e) {
         console.error(`Bulk action "${actionKey}" failed:`, e);
     }
 
+    // Restore toolbar state (in case exit doesn't happen)
+    actionBtns?.forEach(btn => { btn.disabled = false; });
+    if (countEl) countEl.textContent = prevCount;
+
     section.exitSelectionMode();
 }

server/src/wled_controller/static/js/core/card-sections.ts

@@ -62,6 +62,24 @@ function _getCollapsedMap(): Record<string, boolean> {
     catch { return {}; }
 }
 
+/** Generate skeleton placeholder cards for loading state. */
+export function renderSkeletonCards(count = 3, gridClass = 'devices-grid') {
+    let html = '';
+    for (let i = 0; i < count; i++) {
+        const delay = `animation-delay: ${i * 0.15}s`;
+        html += `<div class="skeleton-card">
+            <div class="skeleton-line skeleton-line-title" style="${delay}"></div>
+            <div class="skeleton-line skeleton-line-medium" style="${delay}"></div>
+            <div class="skeleton-line skeleton-line-short" style="${delay}"></div>
+            <div class="skeleton-actions">
+                <div class="skeleton-btn" style="${delay}"></div>
+                <div class="skeleton-btn" style="${delay}"></div>
+            </div>
+        </div>`;
+    }
+    return `<div class="${gridClass}">${html}</div>`;
+}
+
 export class CardSection {
 
     sectionKey: string;

server/src/wled_controller/static/js/core/modal.ts

@@ -6,7 +6,7 @@
  */
 
 import { t } from './i18n.ts';
-import { lockBody, unlockBody, setupBackdropClose, showConfirm, trapFocus, releaseFocus } from './ui.ts';
+import { lockBody, unlockBody, setupBackdropClose, showConfirm, trapFocus, releaseFocus, isTouchDevice } from './ui.ts';
 
 export class Modal {
     static _stack: Modal[] = [];
@@ -40,6 +40,15 @@ export class Modal {
         trapFocus(this.el!);
         Modal._stack = Modal._stack.filter(m => m !== this);
         Modal._stack.push(this);
+        // Auto-focus first visible input (skip on touch to avoid virtual keyboard)
+        if (!isTouchDevice()) {
+            requestAnimationFrame(() => {
+                const input = this.el!.querySelector(
+                    '.modal-body input:not([type="hidden"]):not([disabled]):not([style*="display:none"]):not([style*="display: none"]), .modal-body select:not([disabled]), .modal-body textarea:not([disabled])'
+                ) as HTMLElement | null;
+                if (input && input.offsetParent !== null) input.focus();
+            });
+        }
     }
 
     forceClose() {

server/src/wled_controller/static/js/core/ui.ts

@@ -135,6 +135,43 @@ export function showToast(message: string, type = 'info') {
     }, 3000);
 }
 
+let _undoTimer: ReturnType<typeof setTimeout> | null = null;
+
+/**
+ * Show a toast with an Undo button. Executes `action` after `delay` ms
+ * unless the user clicks Undo (which calls `undoFn`).
+ */
+export function showUndoToast(message: string, action: () => void, undoFn: () => void, delay = 5000) {
+    if (_undoTimer) { clearTimeout(_undoTimer); _undoTimer = null; }
+
+    const toast = document.getElementById('toast')!;
+    toast.className = 'toast info show';
+    toast.style.setProperty('--toast-duration', `${delay}ms`);
+    toast.innerHTML = `<div class="toast-with-action">
+        <span class="toast-message">${message}</span>
+        <button class="toast-undo-btn">${t('common.undo')}</button>
+    </div>
+    <div class="toast-timer"></div>`;
+
+    let cancelled = false;
+
+    const undoBtn = toast.querySelector('.toast-undo-btn')!;
+    undoBtn.addEventListener('click', () => {
+        cancelled = true;
+        if (_undoTimer) { clearTimeout(_undoTimer); _undoTimer = null; }
+        undoFn();
+        toast.className = 'toast';
+        toast.innerHTML = '';
+    }, { once: true });
+
+    _undoTimer = setTimeout(() => {
+        _undoTimer = null;
+        if (!cancelled) action();
+        toast.className = 'toast';
+        toast.innerHTML = '';
+    }, delay);
+}
+
 export function showConfirm(message: string, title: string | null = null) {
     return new Promise((resolve) => {
         setConfirmResolve(resolve);
@@ -328,6 +365,49 @@ export function updateOverlayPreview(thumbnailSrc: string, stats: any) {
     }
 }
 
+// ── Inline field validation ──
+
+/** Mark a field as invalid with an error message. */
+export function setFieldError(input: HTMLInputElement | HTMLSelectElement, message: string) {
+    input.classList.add('field-invalid');
+    clearFieldError(input); // remove existing
+    if (message) {
+        const msg = document.createElement('span');
+        msg.className = 'field-error-msg';
+        msg.textContent = message;
+        input.parentElement?.appendChild(msg);
+    }
+}
+
+/** Clear field error state. */
+export function clearFieldError(input: HTMLInputElement | HTMLSelectElement) {
+    input.classList.remove('field-invalid');
+    const existing = input.parentElement?.querySelector('.field-error-msg');
+    if (existing) existing.remove();
+}
+
+/** Validate a required field on blur. Returns true if valid. */
+export function validateRequired(input: HTMLInputElement | HTMLSelectElement, errorMsg?: string): boolean {
+    const value = input.value.trim();
+    if (!value) {
+        setFieldError(input, errorMsg || t('validation.required'));
+        return false;
+    }
+    clearFieldError(input);
+    return true;
+}
+
+/** Set up blur validation on required fields within a container. */
+export function setupBlurValidation(container: HTMLElement) {
+    const fields = container.querySelectorAll('input[required], select[required]') as NodeListOf<HTMLInputElement | HTMLSelectElement>;
+    fields.forEach(field => {
+        field.addEventListener('blur', () => validateRequired(field));
+        field.addEventListener('input', () => {
+            if (field.classList.contains('field-invalid')) clearFieldError(field);
+        });
+    });
+}
+
 /** Toggle the thin loading bar on a tab panel during data refresh.
  *  Delays showing the bar by 400ms so quick loads never flash it. */
 const _refreshTimers: Record<string, ReturnType<typeof setTimeout>> = {};

server/src/wled_controller/static/js/features/dashboard.ts

@@ -587,7 +587,8 @@ function renderDashboardTarget(target: any, isRunning: boolean, devicesMap: Reco
         let healthDot = '';
         if (isLed && state.device_last_checked != null) {
             const cls = state.device_online ? 'health-online' : 'health-offline';
-            healthDot = `<span class="health-dot ${cls}"></span>`;
+            const statusLabel = state.device_online ? t('device.health.online') : t('device.health.offline');
+            healthDot = `<span class="health-dot ${cls}" role="status" aria-label="${statusLabel}"></span>`;
         }
 
         const cStyle = cardColorStyle(target.id);

server/src/wled_controller/static/js/features/devices.ts

@@ -156,7 +156,7 @@ export function createDeviceCard(device: Device & { state?: any }) {
         content: `
             <div class="card-header">
                 <div class="card-title" title="${escapeHtml(device.name || device.id)}">
-                    <span class="health-dot ${healthClass}" title="${healthTitle}"></span>
+                    <span class="health-dot ${healthClass}" title="${healthTitle}" role="status" aria-label="${healthTitle}"></span>
                     <span class="card-title-text">${device.name || device.id}</span>
                     ${device.url && device.url.startsWith('http') ? `<a class="device-url-badge" href="${device.url}" target="_blank" rel="noopener" title="${t('device.button.webui')}"><span class="device-url-text">${escapeHtml(device.url.replace(/^https?:\/\//, ''))}</span><span class="device-url-icon">${ICON_WEB}</span></a>` : (device.url && !device.url.startsWith('mock://') && !device.url.startsWith('ws://') && !device.url.startsWith('openrgb://') && !device.url.startsWith('http') ? `<span class="device-url-badge"><span class="device-url-text">${escapeHtml(device.url)}</span></span>` : '')}
                     ${healthLabel}

server/src/wled_controller/static/js/features/graph-editor.ts

@@ -914,7 +914,7 @@ function _graphHTML(): string {
     // Only set size from saved state; position is applied in _initMinimap via anchor logic
     const mmStyle = mmRect?.width ? `width:${mmRect.width}px;height:${mmRect.height}px;` : '';
     return `
-        <div class="graph-container">
+        <div class="graph-container" tabindex="0" role="application" aria-label="${t('graph.title')}">
             <div class="graph-toolbar">
                 <span class="graph-toolbar-drag" title="Drag to move">⠿</span>
                 <button class="btn-icon" onclick="graphFitAll()" title="${t('graph.fit_all')}">

server/src/wled_controller/static/js/features/targets.ts

@@ -715,12 +715,10 @@ export async function loadTargetsTab() {
             changedTargetIds = new Set([...ledResult.added, ...ledResult.replaced, ...ledResult.removed,
                                         ...kcResult.added, ...kcResult.replaced, ...kcResult.removed]);
 
-            // Re-render cached LED preview frames onto new canvas elements after reconciliation
+            // Restore LED preview state on replaced cards (panel hidden by default in HTML)
             for (const id of Array.from(ledResult.replaced) as any[]) {
-                const frame = _ledPreviewLastFrame[id];
+                if (ledPreviewWebSockets[id]) {
-                if (frame && ledPreviewWebSockets[id]) {
+                    _restoreLedPreviewState(id);
-                    const canvas = document.getElementById(`led-preview-canvas-${id}`);
-                    if (canvas) _renderLedStrip(canvas, frame);
                 }
             }
         } else {
@@ -1009,7 +1007,7 @@ export function createTargetCard(target: OutputTarget & { state?: any; metrics?:
         content: `
             <div class="card-header">
                 <div class="card-title" title="${escapeHtml(target.name)}">
-                    <span class="health-dot ${healthClass}" title="${healthTitle}"></span>
+                    <span class="health-dot ${healthClass}" title="${healthTitle}" role="status" aria-label="${healthTitle}"></span>
                     ${escapeHtml(target.name)}
                     <span class="target-error-indicator" title="${t('device.metrics.errors')}">${ICON_WARNING}</span>
                 </div>
@@ -1075,7 +1073,7 @@ export function createTargetCard(target: OutputTarget & { state?: any; metrics?:
                     </button>
                 `}
                 ${isProcessing ? `
-                    <button class="btn btn-icon ${ledPreviewWebSockets[target.id] ? 'btn-warning' : 'btn-secondary'}" onclick="toggleLedPreview('${target.id}')" title="LED Preview">
+                    <button class="btn btn-icon btn-secondary" data-led-preview-btn="${target.id}" onclick="toggleLedPreview('${target.id}')" title="LED Preview">
                         ${ICON_LED_PREVIEW}
                     </button>
                 ` : ''}
@@ -1234,7 +1232,9 @@ const _ledPreviewLastFrame = {};
  * one canvas per zone with labels. Otherwise, a single canvas.
  */
 function _buildLedPreviewHtml(targetId: any, device: any, bvsId: any, cssSource: any, colorStripSourceMap: any) {
-    const visible = ledPreviewWebSockets[targetId] ? '' : 'none';
+    // Always render hidden — JS toggles visibility. This keeps card HTML stable
+    // so reconciliation doesn't replace the card when preview is toggled.
+    const visible = 'none';
     const bvsAttr = bvsId ? ' data-has-bvs="1"' : '';
 
     // Check for per-zone preview
@@ -1356,7 +1356,13 @@ function _renderLedStrip(canvas: any, rgbBytes: any) {
 }
 
 function connectLedPreviewWS(targetId: any) {
-    disconnectLedPreviewWS(targetId);
+    // Close existing WS without touching DOM (caller manages panel/button state)
+    const oldWs = ledPreviewWebSockets[targetId];
+    if (oldWs) {
+        oldWs.onclose = null;
+        oldWs.close();
+        delete ledPreviewWebSockets[targetId];
+    }
 
     const key = localStorage.getItem('wled_api_key');
     if (!key) return;
@@ -1440,6 +1446,27 @@ function connectLedPreviewWS(targetId: any) {
     }
 }
 
+function _setPreviewButtonState(targetId: any, active: boolean) {
+    const btn = document.querySelector(`[data-led-preview-btn="${targetId}"]`);
+    if (btn) {
+        btn.classList.toggle('btn-warning', active);
+        btn.classList.toggle('btn-secondary', !active);
+    }
+}
+
+/** Restore preview panel visibility, button state, and last frame after card replacement. */
+function _restoreLedPreviewState(targetId: any) {
+    const panel = document.getElementById(`led-preview-panel-${targetId}`);
+    if (panel) panel.style.display = '';
+    _setPreviewButtonState(targetId, true);
+    // Re-render cached frame onto the new canvas
+    const frame = _ledPreviewLastFrame[targetId];
+    if (frame) {
+        const canvas = panel?.querySelector('.led-preview-canvas');
+        if (canvas) _renderLedStrip(canvas, frame);
+    }
+}
+
 function disconnectLedPreviewWS(targetId: any) {
     const ws = ledPreviewWebSockets[targetId];
     if (ws) {
@@ -1450,6 +1477,7 @@ function disconnectLedPreviewWS(targetId: any) {
     delete _ledPreviewLastFrame[targetId];
     const panel = document.getElementById(`led-preview-panel-${targetId}`);
     if (panel) panel.style.display = 'none';
+    _setPreviewButtonState(targetId, false);
 }
 
 export function disconnectAllLedPreviewWS() {
@@ -1464,6 +1492,7 @@ export function toggleLedPreview(targetId: any) {
         disconnectLedPreviewWS(targetId);
     } else {
         panel.style.display = '';
+        _setPreviewButtonState(targetId, true);
         connectLedPreviewWS(targetId);
     }
 }

server/src/wled_controller/static/locales/en.json

@@ -436,6 +436,11 @@
   "common.none_no_cspt": "None (no processing template)",
   "common.none_no_input": "None (no input source)",
   "common.none_own_speed": "None (use own speed)",
+  "common.undo": "Undo",
+  "validation.required": "This field is required",
+  "bulk.processing": "Processing…",
+  "api.error.timeout": "Request timed out — please try again",
+  "api.error.network": "Network error — check your connection",
   "palette.search": "Search…",
   "section.filter.placeholder": "Filter...",
   "section.filter.reset": "Clear filter",

server/src/wled_controller/static/locales/ru.json

@@ -436,6 +436,11 @@
   "common.none_no_cspt": "Нет (без шаблона обработки)",
   "common.none_no_input": "Нет (без источника)",
   "common.none_own_speed": "Нет (своя скорость)",
+  "common.undo": "Отменить",
+  "validation.required": "Обязательное поле",
+  "bulk.processing": "Обработка…",
+  "api.error.timeout": "Превышено время ожидания — попробуйте снова",
+  "api.error.network": "Ошибка сети — проверьте подключение",
   "palette.search": "Поиск…",
   "section.filter.placeholder": "Фильтр...",
   "section.filter.reset": "Очистить фильтр",

server/src/wled_controller/static/locales/zh.json

@@ -436,6 +436,11 @@
   "common.none_no_cspt": "无（无处理模板）",
   "common.none_no_input": "无（无输入源）",
   "common.none_own_speed": "无（使用自身速度）",
+  "common.undo": "撤销",
+  "validation.required": "此字段为必填项",
+  "bulk.processing": "处理中…",
+  "api.error.timeout": "请求超时 — 请重试",
+  "api.error.network": "网络错误 — 请检查连接",
   "palette.search": "搜索…",
   "section.filter.placeholder": "筛选...",
   "section.filter.reset": "清除筛选",

server/src/wled_controller/templates/index.html

@@ -95,13 +95,20 @@
         <div class="tabs">
             <div class="tab-panel" id="tab-dashboard" role="tabpanel" aria-labelledby="tab-btn-dashboard">
                 <div id="dashboard-content">
-                    <div class="loading-spinner"></div>
+                    <div class="devices-grid">
+                        <div class="skeleton-card"><div class="skeleton-line skeleton-line-title"></div><div class="skeleton-line skeleton-line-medium"></div><div class="skeleton-line skeleton-line-short"></div><div class="skeleton-actions"><div class="skeleton-btn"></div><div class="skeleton-btn"></div></div></div>
+                        <div class="skeleton-card"><div class="skeleton-line skeleton-line-title"></div><div class="skeleton-line skeleton-line-medium"></div><div class="skeleton-line skeleton-line-short"></div><div class="skeleton-actions"><div class="skeleton-btn"></div><div class="skeleton-btn"></div></div></div>
+                        <div class="skeleton-card"><div class="skeleton-line skeleton-line-title"></div><div class="skeleton-line skeleton-line-medium"></div><div class="skeleton-line skeleton-line-short"></div><div class="skeleton-actions"><div class="skeleton-btn"></div><div class="skeleton-btn"></div></div></div>
+                    </div>
                 </div>
             </div>
 
             <div class="tab-panel" id="tab-automations" role="tabpanel" aria-labelledby="tab-btn-automations">
-                <div id="automations-content">
+                <div class="tree-layout">
-                    <div class="loading-spinner"></div>
+                    <nav class="tree-sidebar" id="automations-tree-nav"></nav>
+                    <div class="tree-content" id="automations-content">
+                        <div class="loading-spinner"></div>
+                    </div>
                 </div>
             </div>
 
@@ -159,7 +166,7 @@
         <svg class="icon" viewBox="0 0 24 24"><path d="m18 15-6-6-6 6"/></svg>
     </button>
 
-    <div id="toast" class="toast"></div>
+    <div id="toast" class="toast" role="status" aria-live="polite" aria-atomic="true"></div>
 
     {% include 'modals/calibration.html' %}
     {% include 'modals/advanced-calibration.html' %}

server/src/wled_controller/templates/modals/settings.html

@@ -181,6 +181,7 @@
 
             <!-- ═══ MQTT tab ═══ -->
             <div id="settings-panel-mqtt" class="settings-panel">
+                <form onsubmit="saveMqttSettings(); return false;" autocomplete="off">
                 <div class="form-group">
                     <div class="label-row">
                         <label data-i18n="settings.mqtt.label">MQTT</label>
@@ -227,8 +228,9 @@
                         </div>
                     </div>
 
-                    <button class="btn btn-primary" onclick="saveMqttSettings()" style="width:100%" data-i18n="settings.mqtt.save">Save MQTT Settings</button>
+                    <button type="submit" class="btn btn-primary" style="width:100%" data-i18n="settings.mqtt.save">Save MQTT Settings</button>
                 </div>
+                </form>
             </div>
 
             <div id="settings-error" class="error-message" style="display:none;"></div>