Landscape kiosk overhaul: 3-column layout, resilient updates, visual polish

- Add 3-column balanced site distribution using greedy weight algorithm
- Build new DOM off-screen in DocumentFragment, swap atomically (no flash)
- Skip empty API responses and preserve display on transient errors
- Remove news ticker from UI and grid layout
- Add blue-to-red gradient on site header bars
- Bump font sizes: destinations 1.4em, countdowns 1.5em, line numbers 1.6em
- Add breathing pulse animation on daylight bar sun/moon icons
- Fix daylight bar indicator snapping to position on first render
- Make config button visible in landscape with semi-transparent background
- Add weather forecast strip as grid row 4 with compact styling

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

public/js/components/DeparturesManager.js

@@ -507,33 +507,81 @@ class DeparturesManager {
     displayMultipleSites(sites) {
         const config = this.getConfig();
         const enabledSites = config.sites.filter(site => site.enabled);
-        
-        this.container.innerHTML = '';
-        
+
+        // Build new content off-DOM first, then swap in one operation
+        const fragment = document.createDocumentFragment();
+
+        // Build site containers
+        const siteElements = [];
         sites.forEach(site => {
             const siteConfig = enabledSites.find(s => s.id === site.siteId);
             if (!siteConfig) return;
-            
+
+            // Skip sites that returned empty departures (API hiccup)
+            // but keep sites with explicit errors so user sees feedback
+            if (site.data && site.data.departures && site.data.departures.length === 0 && !site.error) {
+                return;
+            }
+
             const siteContainer = document.createElement('div');
             siteContainer.className = 'site-container';
-            
+
             const siteHeader = document.createElement('div');
             siteHeader.className = 'site-header';
-            siteHeader.innerHTML = `<span class="site-name">${site.siteName || siteConfig.name}</span>`;
+            const siteName = document.createElement('span');
+            siteName.className = 'site-name';
+            siteName.textContent = site.siteName || siteConfig.name;
+            siteHeader.appendChild(siteName);
             siteContainer.appendChild(siteHeader);
-            
-            if (site.data && site.data.departures) {
+
+            let cardCount = 0;
+            if (site.data && site.data.departures && site.data.departures.length > 0) {
                 const lineGroups = this.groupDeparturesByLineNumber(site.data.departures);
                 this.displayGroupedDeparturesByLine(lineGroups, siteContainer);
+                cardCount = Object.keys(lineGroups).length;
             } else if (site.error) {
                 const errorElement = document.createElement('div');
                 errorElement.className = 'error';
                 errorElement.textContent = `Error loading departures for ${site.siteName}: ${site.error}`;
                 siteContainer.appendChild(errorElement);
+                cardCount = 1;
             }
-            
-            this.container.appendChild(siteContainer);
+
+            siteElements.push({ element: siteContainer, weight: cardCount + 1 });
         });
+
+        // If no sites have data at all, keep existing display (don't flash empty)
+        if (siteElements.length === 0) return;
+
+        // In landscape mode, distribute sites into balanced columns
+        if (document.body.classList.contains('landscape') && siteElements.length > 1) {
+            const numCols = Math.min(3, siteElements.length);
+            const columns = [];
+            const weights = [];
+            for (let i = 0; i < numCols; i++) {
+                const col = document.createElement('div');
+                col.className = 'departure-column';
+                columns.push(col);
+                weights.push(0);
+            }
+
+            // Greedy: assign each site to the lightest column
+            siteElements.forEach(({ element, weight }) => {
+                const minIdx = weights.indexOf(Math.min(...weights));
+                columns[minIdx].appendChild(element);
+                weights[minIdx] += weight;
+            });
+
+            columns.forEach(col => fragment.appendChild(col));
+        } else {
+            siteElements.forEach(({ element }) => {
+                fragment.appendChild(element);
+            });
+        }
+
+        // Swap old content for new in one operation (no flash)
+        this.container.textContent = '';
+        this.container.appendChild(fragment);
     }
 
     /**
@@ -576,14 +624,15 @@ class DeparturesManager {
             } else {
                 console.error('Error fetching departures:', error);
             }
-            
-            this.container.innerHTML = `
-                <div class="error">
-                    <p>Failed to load departures. Please try again later.</p>
-                    <p>Error: ${error.message}</p>
-                    <p>Make sure the Node.js server is running: <code>node server.js</code></p>
-                </div>
-            `;
+
+            // On transient errors, keep existing data on screen.
+            // Only show error if we have no data at all yet.
+            if (!this.container.children.length) {
+                const errorDiv = document.createElement('div');
+                errorDiv.className = 'error';
+                errorDiv.textContent = `Failed to load departures: ${error.message}`;
+                this.container.appendChild(errorDiv);
+            }
         }
     }