fix: pure Canvas 2D renderer at exact device pixel dimensions

Canvas renders as single bitmap at devicePixelRatio-matched dimensions.
No SVG, no CSS transforms, no GPU scaling = no compositor tile seams.
Full redraw on zoom/pan with canvas isPointInPath hit testing.

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

layouts/shortcodes/world-map.html

@@ -6,10 +6,8 @@
 .ifk-map-wrap h3 { text-align: center; margin-bottom: 0.5rem; font-size: 1.25rem; }
 .ifk-map-subtitle { text-align: center; color: #666; font-size: 0.85rem; margin-bottom: 1rem; }
 .ifk-map-container { position: relative; width: 100%; height: 420px; border-radius: 8px; overflow: hidden; }
-.ifk-map-svg { width: 100%; height: 100%; display: block; cursor: grab; background: #c8d3df; }
-.ifk-map-svg:active { cursor: grabbing; }
-.ifk-map-svg .country { stroke: #94a3b8; stroke-width: 0.3; transition: stroke-width 0.15s; }
-.ifk-map-svg .country.has-data:hover { stroke: #667eea; stroke-width: 1.2; cursor: pointer; }
+.ifk-map-canvas { width: 100%; height: 100%; display: block; cursor: grab; image-rendering: auto; }
+.ifk-map-canvas:active { cursor: grabbing; }
 .ifk-map-controls { position: absolute; top: 10px; right: 10px; display: flex; flex-direction: column; gap: 4px; z-index: 10; }
 .ifk-map-controls button { width: 30px; height: 30px; background: #fff; border: 1px solid #ccc; border-radius: 4px; font-size: 16px; cursor: pointer; display: flex; align-items: center; justify-content: center; color: #333; }
 .ifk-map-controls button:hover { background: #f0f0f0; }
@@ -33,7 +31,7 @@
   <h3>{{ if eq $lang "de" }}Interaktive Weltkarte: Kinderschutzgesetze{{ else if eq $lang "fr" }}Carte interactive : lois de protection de l'enfance{{ else }}Interactive Map: Child Protection Laws{{ end }}</h3>
   <p class="ifk-map-subtitle">{{ if eq $lang "de" }}Klicken Sie auf ein Land für Details{{ else if eq $lang "fr" }}Cliquez sur un pays pour plus de détails{{ else }}Click a country for details{{ end }}</p>
   <div class="ifk-map-container" id="ifk-map-container">
-    <svg class="ifk-map-svg" id="ifk-map-svg" xmlns="http://www.w3.org/2000/svg"></svg>
+    <canvas class="ifk-map-canvas" id="ifk-map-canvas"></canvas>
     <div class="ifk-map-controls">
       <button id="ifk-zoom-in" title="Zoom in">+</button>
       <button id="ifk-zoom-out" title="Zoom out">&minus;</button>
@@ -68,101 +66,186 @@
   var byIsoNum = {};
   countries.forEach(function(c) { byIsoNum[c.isoNum] = c; });
 
-  // Map dimensions (Equirectangular projection)
   var W = 960, H = 480;
-  var svg = document.getElementById('ifk-map-svg');
+  var canvas = document.getElementById('ifk-map-canvas');
   var container = document.getElementById('ifk-map-container');
   var popup = document.getElementById('ifk-map-popup');
   var popupContent = document.getElementById('ifk-popup-content');
+  var dpr = window.devicePixelRatio || 1;
 
   // ViewBox state
   var vb = { x: 0, y: 0, w: W, h: H };
   var VB_INIT = { x: 0, y: 0, w: W, h: H };
-  var MIN_W = W / 16; // max zoom in
+  var MIN_W = W / 16;
 
-  function setViewBox() {
-    svg.setAttribute('viewBox', vb.x + ' ' + vb.y + ' ' + vb.w + ' ' + vb.h);
+  // Sizing: match exact device pixels to prevent GPU scaling
+  function sizeCanvas() {
+    var rect = container.getBoundingClientRect();
+    canvas.width = Math.round(rect.width * dpr);
+    canvas.height = Math.round(rect.height * dpr);
+    canvas.style.width = rect.width + 'px';
+    canvas.style.height = rect.height + 'px';
   }
 
-  // Equirectangular projection
   function projectCoord(lon, lat) {
     return [(lon + 180) * (W / 360), (90 - lat) * (H / 180)];
   }
 
-  function projectRing(ring) {
-    var d = '';
-    for (var i = 0; i < ring.length; i++) {
-      var p = projectCoord(ring[i][0], ring[i][1]);
-      d += (i === 0 ? 'M' : 'L') + p[0].toFixed(1) + ',' + p[1].toFixed(1);
+  // Pre-computed paths for hit testing
+  var countryPaths = [];
+  var geoData = null;
+
+  function drawMap() {
+    var ctx = canvas.getContext('2d');
+    var cw = canvas.width, ch = canvas.height;
+    // Transform from viewBox to canvas
+    var sx = cw / vb.w, sy = ch / vb.h;
+
+    ctx.clearRect(0, 0, cw, ch);
+
+    // Ocean background
+    ctx.fillStyle = '#c8d3df';
+    ctx.fillRect(0, 0, cw, ch);
+
+    if (!geoData) return;
+
+    // Draw land base fill
+    ctx.fillStyle = '#ffffff';
+    drawGeometry(ctx, geoData.land, sx, sy, true);
+
+    // Draw country fills
+    geoData.features.forEach(function(f) {
+      var id = String(f.id).padStart(3, '0');
+      var c = byIsoNum[id];
+      if (c) {
+        ctx.globalAlpha = 0.65;
+        ctx.fillStyle = STATUS_COLORS[c.status];
+      } else {
+        ctx.globalAlpha = 1;
+        ctx.fillStyle = '#ffffff';
       }
-    return d + 'Z';
+      drawGeometry(ctx, f.geometry, sx, sy, true);
+    });
+
+    ctx.globalAlpha = 1;
+
+    // Draw borders
+    ctx.strokeStyle = '#94a3b8';
+    ctx.lineWidth = 0.5 * sx / (cw / vb.w);
+    drawGeometry(ctx, geoData.borders, sx, sy, false);
   }
 
-  function projectGeometry(geom) {
-    var d = '';
+  function drawGeometry(ctx, geom, sx, sy, fill) {
+    ctx.beginPath();
+    var coords;
     if (geom.type === 'Polygon') {
-      geom.coordinates.forEach(function(ring) { d += projectRing(ring); });
+      geom.coordinates.forEach(function(ring) { traceRing(ctx, ring, sx, sy); });
     } else if (geom.type === 'MultiPolygon') {
       geom.coordinates.forEach(function(poly) {
-        poly.forEach(function(ring) { d += projectRing(ring); });
+        poly.forEach(function(ring) { traceRing(ctx, ring, sx, sy); });
       });
+    } else if (geom.type === 'MultiLineString') {
+      geom.coordinates.forEach(function(line) { traceLine(ctx, line, sx, sy); });
+    } else if (geom.type === 'LineString') {
+      traceLine(ctx, geom.coordinates, sx, sy);
     }
-    return d;
+    if (fill) ctx.fill('evenodd');
+    else ctx.stroke();
   }
 
-  // Build SVG
+  function traceRing(ctx, ring, sx, sy) {
+    for (var i = 0; i < ring.length; i++) {
+      var p = projectCoord(ring[i][0], ring[i][1]);
+      var x = (p[0] - vb.x) * sx;
+      var y = (p[1] - vb.y) * sy;
+      if (i === 0) ctx.moveTo(x, y);
+      else ctx.lineTo(x, y);
+    }
+    ctx.closePath();
+  }
+
+  function traceLine(ctx, line, sx, sy) {
+    for (var i = 0; i < line.length; i++) {
+      var p = projectCoord(line[i][0], line[i][1]);
+      var x = (p[0] - vb.x) * sx;
+      var y = (p[1] - vb.y) * sy;
+      if (i === 0) ctx.moveTo(x, y);
+      else ctx.lineTo(x, y);
+    }
+  }
+
+  // Load data
   fetch('{{ "data/countries-50m.json" | relURL }}')
     .then(function(r) { return r.json(); })
     .then(function(topo) {
       var geo = topojson.feature(topo, topo.objects.countries);
       var borders = topojson.mesh(topo, topo.objects.countries, function(a, b) { return a !== b; });
-
-      // Land base fill (covers gaps at poles between country polygons)
       var land = topojson.feature(topo, topo.objects.land);
-      var landPath = document.createElementNS('http://www.w3.org/2000/svg', 'path');
-      landPath.setAttribute('d', projectGeometry(land.features ? land.features[0].geometry : land.geometry));
-      landPath.setAttribute('fill', '#ffffff');
-      landPath.setAttribute('stroke', 'none');
-      landPath.setAttribute('pointer-events', 'none');
-      svg.appendChild(landPath);
+      var landGeom = land.features ? land.features[0].geometry : land.geometry;
 
-      // Country fills (ocean is CSS background on container)
+      geoData = { features: geo.features, borders: borders, land: landGeom };
+
+      // Pre-build hit-test data
       geo.features.forEach(function(f) {
         var id = String(f.id).padStart(3, '0');
         var c = byIsoNum[id];
-        var path = document.createElementNS('http://www.w3.org/2000/svg', 'path');
-        var d = projectGeometry(f.geometry);
-        if (!d) return;
-        path.setAttribute('d', d);
-        path.setAttribute('fill', c ? STATUS_COLORS[c.status] : '#ffffff');
-        path.setAttribute('fill-opacity', c ? '0.65' : '1');
-        path.setAttribute('class', 'country' + (c ? ' has-data' : ''));
-        path.setAttribute('data-iso', id);
-        svg.appendChild(path);
+        if (c) countryPaths.push({ id: id, geometry: f.geometry, data: c });
       });
 
-      // Borders (shared edges only)
-      var bordersD = projectGeometry(borders);
-      if (bordersD) {
-        var borderPath = document.createElementNS('http://www.w3.org/2000/svg', 'path');
-        borderPath.setAttribute('d', bordersD);
-        borderPath.setAttribute('fill', 'none');
-        borderPath.setAttribute('stroke', '#94a3b8');
-        borderPath.setAttribute('stroke-width', '0.3');
-        borderPath.setAttribute('pointer-events', 'none');
-        svg.appendChild(borderPath);
+      sizeCanvas();
+      drawMap();
+    });
+
+  // Resize handler
+  var resizeTimer;
+  window.addEventListener('resize', function() {
+    clearTimeout(resizeTimer);
+    resizeTimer = setTimeout(function() { sizeCanvas(); drawMap(); }, 100);
+  });
+
+  // Hit test: check if point is inside a country polygon
+  function hitTest(clientX, clientY) {
+    var rect = canvas.getBoundingClientRect();
+    var mx = clientX - rect.left;
+    var my = clientY - rect.top;
+    // Convert to map coords
+    var mapX = vb.x + (mx / rect.width) * vb.w;
+    var mapY = vb.y + (my / rect.height) * vb.h;
+    // Convert to lon/lat
+    var lon = (mapX / W) * 360 - 180;
+    var lat = 90 - (mapY / H) * 180;
+
+    // Use canvas isPointInPath for hit testing
+    var ctx = canvas.getContext('2d');
+    var sx = canvas.width / vb.w, sy = canvas.height / vb.h;
+    for (var i = 0; i < countryPaths.length; i++) {
+      ctx.beginPath();
+      var geom = countryPaths[i].geometry;
+      if (geom.type === 'Polygon') {
+        geom.coordinates.forEach(function(ring) { traceRing(ctx, ring, sx, sy); });
+      } else if (geom.type === 'MultiPolygon') {
+        geom.coordinates.forEach(function(poly) {
+          poly.forEach(function(ring) { traceRing(ctx, ring, sx, sy); });
+        });
+      }
+      if (ctx.isPointInPath(mx * dpr, my * dpr, 'evenodd')) {
+        return countryPaths[i];
+      }
+    }
+    return null;
   }
 
-      setViewBox();
+  // Hover cursor
+  canvas.addEventListener('mousemove', function(e) {
+    var hit = hitTest(e.clientX, e.clientY);
+    canvas.style.cursor = hit ? 'pointer' : 'grab';
+  });
 
   // Click handler
-      svg.addEventListener('click', function(e) {
-        var target = e.target;
-        if (!target.classList.contains('has-data')) { popup.style.display = 'none'; return; }
-        var id = target.getAttribute('data-iso');
-        var c = byIsoNum[id];
-        if (!c) return;
-
+  canvas.addEventListener('click', function(e) {
+    var hit = hitTest(e.clientX, e.clientY);
+    if (!hit) { popup.style.display = 'none'; return; }
+    var c = hit.data;
     var loc = c[LANG] || c.en;
     var labels = STATUS_LABELS[LANG] || STATUS_LABELS.en;
     var ageLabel = AGE_LABELS[LANG] || AGE_LABELS.en;
@@ -177,78 +260,68 @@
       html += '<a class="ifk-popup-link" href="#' + anchor + '">' + (readMore[LANG] || readMore.en) + '</a>';
     }
     popupContent.innerHTML = html;
-
-        // Position popup near click
     var rect = container.getBoundingClientRect();
     var px = e.clientX - rect.left;
     var py = e.clientY - rect.top;
-        // Keep popup within container
     popup.style.display = 'block';
-        var pw = popup.offsetWidth;
-        var ph = popup.offsetHeight;
-        var left = Math.min(px + 10, rect.width - pw - 10);
-        var top = Math.max(py - ph - 10, 10);
-        if (top < 10) top = py + 10;
-        popup.style.left = left + 'px';
-        popup.style.top = top + 'px';
+    var pw = popup.offsetWidth, ph = popup.offsetHeight;
+    popup.style.left = Math.min(px + 10, rect.width - pw - 10) + 'px';
+    popup.style.top = Math.max(py - ph - 10, 10) + 'px';
   });
 
-      // Close popup
   document.getElementById('ifk-popup-close').addEventListener('click', function(e) {
     e.stopPropagation();
     popup.style.display = 'none';
   });
 
-      // Zoom controls
+  // Zoom
   function zoomBy(factor) {
-        var cx = vb.x + vb.w / 2;
-        var cy = vb.y + vb.h / 2;
+    var cx = vb.x + vb.w / 2, cy = vb.y + vb.h / 2;
     var nw = Math.max(MIN_W, Math.min(VB_INIT.w, vb.w * factor));
     var nh = nw * (H / W);
     vb.w = nw; vb.h = nh;
     vb.x = Math.max(0, Math.min(W - vb.w, cx - vb.w / 2));
     vb.y = Math.max(0, Math.min(H - vb.h, cy - vb.h / 2));
-        setViewBox();
+    drawMap();
   }
-
   document.getElementById('ifk-zoom-in').addEventListener('click', function() { zoomBy(0.5); });
   document.getElementById('ifk-zoom-out').addEventListener('click', function() { zoomBy(2); });
   document.getElementById('ifk-zoom-reset').addEventListener('click', function() {
-        vb.x = VB_INIT.x; vb.y = VB_INIT.y; vb.w = VB_INIT.w; vb.h = VB_INIT.h;
-        setViewBox();
+    vb = { x: 0, y: 0, w: W, h: H };
+    drawMap();
   });
 
-      // Pan via drag
+  // Pan
   var dragging = false, dragStart = null;
-      svg.addEventListener('mousedown', function(e) {
-        if (e.target.closest('.ifk-map-controls') || e.target.closest('.ifk-map-popup')) return;
+  canvas.addEventListener('mousedown', function(e) {
     dragging = true;
     dragStart = { x: e.clientX, y: e.clientY, vbx: vb.x, vby: vb.y };
     e.preventDefault();
   });
   window.addEventListener('mousemove', function(e) {
     if (!dragging) return;
-        var scale = vb.w / svg.clientWidth;
+    var rect = canvas.getBoundingClientRect();
+    var scale = vb.w / rect.width;
     vb.x = Math.max(0, Math.min(W - vb.w, dragStart.vbx - (e.clientX - dragStart.x) * scale));
     vb.y = Math.max(0, Math.min(H - vb.h, dragStart.vby - (e.clientY - dragStart.y) * scale));
-        setViewBox();
+    drawMap();
   });
   window.addEventListener('mouseup', function() { dragging = false; });
 
-      // Touch support
-      svg.addEventListener('touchstart', function(e) {
+  // Touch
+  canvas.addEventListener('touchstart', function(e) {
     if (e.touches.length !== 1) return;
     dragging = true;
     dragStart = { x: e.touches[0].clientX, y: e.touches[0].clientY, vbx: vb.x, vby: vb.y };
   }, { passive: true });
-      svg.addEventListener('touchmove', function(e) {
+  canvas.addEventListener('touchmove', function(e) {
     if (!dragging || e.touches.length !== 1) return;
-        var scale = vb.w / svg.clientWidth;
+    var rect = canvas.getBoundingClientRect();
+    var scale = vb.w / rect.width;
     vb.x = Math.max(0, Math.min(W - vb.w, dragStart.vbx - (e.touches[0].clientX - dragStart.x) * scale));
     vb.y = Math.max(0, Math.min(H - vb.h, dragStart.vby - (e.touches[0].clientY - dragStart.y) * scale));
-        setViewBox();
+    drawMap();
   }, { passive: true });
-      svg.addEventListener('touchend', function() { dragging = false; }, { passive: true });
-    });
+  canvas.addEventListener('touchend', function() { dragging = false; }, { passive: true });
 })();
 </script>