Improve school modal charts for mobile visualization

- Make charts taller on mobile with better aspect ratios (0.9 for <480px, 1.1 for <768px)
- Shorten chart title and dataset labels on mobile
- Add responsive font sizes for legend, title, and axis ticks
- Add mobile-specific styling for chart container, stats grid, and modal
- Add extra-small screen breakpoint (480px) for very narrow devices

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

frontend/app.js

@@ -160,7 +160,14 @@ const schoolMaps = new Map();
 
 // Helper to get chart aspect ratio based on screen size
 function getChartAspectRatio() {
-  return window.innerWidth <= 768 ? 1.2 : 2;
+  if (window.innerWidth <= 480) return 0.9; // Very small screens - taller chart
+  if (window.innerWidth <= 768) return 1.1; // Mobile - taller chart
+  return 2;
+}
+
+// Helper to check if we're on mobile
+function isMobile() {
+  return window.innerWidth <= 768;
 }
 
 // =============================================================================
@@ -1442,25 +1449,26 @@ async function openSchoolModal(urn) {
   const years = validData.map((d) => d.year);
   const ctx = elements.schoolDetailChart.getContext("2d");
 
+  const mobile = isMobile();
   schoolDetailChart = new Chart(ctx, {
     type: "bar",
     data: {
       labels: years,
       datasets: [
         {
-          label: "Reading %",
+          label: mobile ? "Reading" : "Reading %",
           data: validData.map((d) => d.reading_expected_pct),
           backgroundColor: "#2d7d7d",
           borderRadius: 4,
         },
         {
-          label: "Writing %",
+          label: mobile ? "Writing" : "Writing %",
           data: validData.map((d) => d.writing_expected_pct),
           backgroundColor: "#c9a227",
           borderRadius: 4,
         },
         {
-          label: "Maths %",
+          label: mobile ? "Maths" : "Maths %",
           data: validData.map((d) => d.maths_expected_pct),
           backgroundColor: "#e07256",
           borderRadius: 4,
@@ -1475,14 +1483,36 @@ async function openSchoolModal(urn) {
         legend: {
           position: "bottom",
           labels: {
-            font: { family: "'DM Sans', sans-serif" },
+            font: {
+              family: "'DM Sans', sans-serif",
+              size: mobile ? 11 : 12,
+            },
             usePointStyle: true,
+            pointStyle: "circle",
+            padding: mobile ? 12 : 16,
+            boxWidth: mobile ? 8 : 12,
           },
         },
         title: {
           display: true,
-          text: "KS2 Attainment Over Time (% meeting expected standard)",
-          font: { family: "'Playfair Display', serif", size: 16, weight: 600 },
+          text: mobile
+            ? "KS2 Attainment (% expected)"
+            : "KS2 Attainment Over Time (% meeting expected standard)",
+          font: {
+            family: "'Playfair Display', serif",
+            size: mobile ? 14 : 16,
+            weight: 600,
+          },
+          padding: {
+            bottom: mobile ? 12 : 16,
+          },
+        },
+        tooltip: {
+          callbacks: {
+            label: function(context) {
+              return `${context.dataset.label}: ${context.parsed.y}%`;
+            }
+          }
         },
       },
       scales: {
@@ -1490,9 +1520,18 @@ async function openSchoolModal(urn) {
           beginAtZero: true,
           max: 100,
           grid: { color: "#e5dfd5" },
+          ticks: {
+            font: { size: mobile ? 10 : 12 },
+            callback: function(value) {
+              return value + "%";
+            },
+          },
         },
         x: {
           grid: { display: false },
+          ticks: {
+            font: { size: mobile ? 10 : 12 },
+          },
         },
       },
     },