diff --git a/src/mach.js b/src/mach.js
index a7bf3a04..f8bc66e1 100644
--- a/src/mach.js
+++ b/src/mach.js
@@ -42,8 +42,10 @@ const mach = {
   machCanvasInit(width, height, id) {
     let canvas = document.createElement("canvas");
     canvas.id = "#mach-canvas-" + mach.canvases.length;
-    canvas.width = width;
-    canvas.height = height;
+    canvas.style.width = width + "px";
+    canvas.style.height = height + "px";
+    canvas.width = Math.floor(width * window.devicePixelRatio);
+    canvas.height = Math.floor(height * window.devicePixelRatio);
     canvas.tabIndex = 1;
 
     mach.setString(canvas.id, id);
@@ -71,17 +73,29 @@ const mach = {
   machCanvasSetSize(canvas, width, height) {
     const cv = mach.canvases[canvas];
     if (width > 0 && height > 0) {
-      cv.canvas.width = width;
-      cv.canvas.height = height;
+      cv.canvas.style.width = width + "px";
+      cv.canvas.style.height = height + "px";
+      cv.canvas.width = width * window.devicePixelRatio;
+      cv.canvas.height = height * window.devicePixelRatio;
     }
   },
 
-  machCanvasGetWidth(canvas) {
+  machCanvasGetWindowWidth(canvas) {
+    const cv = mach.canvases[canvas];
+    return cv.canvas.width / window.devicePixelRatio;
+  },
+
+  machCanvasGetWindowHeight(canvas) {
+    const cv = mach.canvases[canvas];
+    return cv.canvas.height / window.devicePixelRatio;
+  },
+
+  machCanvasGetFramebufferWidth(canvas) {
     const cv = mach.canvases[canvas];
     return cv.canvas.width;
   },
 
-  machCanvasGetHeight(canvas) {
+  machCanvasGetFramebufferHeight(canvas) {
     const cv = mach.canvases[canvas];
     return cv.canvas.height;
   },
diff --git a/src/wasm.zig b/src/wasm.zig
index 7fd3a43a..2b988100 100644
--- a/src/wasm.zig
+++ b/src/wasm.zig
@@ -9,8 +9,10 @@ const js = struct {
     extern fn machCanvasDeinit(canvas: CanvasId) void;
     extern fn machCanvasSetTitle(canvas: CanvasId, title: [*]const u8, len: u32) void;
     extern fn machCanvasSetSize(canvas: CanvasId, width: u32, height: u32) void;
-    extern fn machCanvasGetWidth(canvas: CanvasId) u32;
-    extern fn machCanvasGetHeight(canvas: CanvasId) u32;
+    extern fn machCanvasGetWindowWidth(canvas: CanvasId) u32;
+    extern fn machCanvasGetWindowHeight(canvas: CanvasId) u32;
+    extern fn machCanvasGetFramebufferWidth(canvas: CanvasId) u32;
+    extern fn machCanvasGetFramebufferHeight(canvas: CanvasId) u32;
 
     extern fn machPerfNow() f64;
     extern fn machLog(str: [*]const u8, len: u32) void;
@@ -41,14 +43,17 @@ pub const Core = struct {
 
     pub fn setShouldClose(_: *Core, _: bool) void {}
 
-    pub fn getFramebufferSize(_: *Core) !structs.Size {
-        return structs.Size{ .width = 0, .height = 0 };
+    pub fn getFramebufferSize(core: *Core) !structs.Size {
+        return structs.Size{
+            .width = js.machCanvasGetFramebufferWidth(core.id),
+            .height = js.machCanvasGetFramebufferHeight(core.id),
+        };
     }
 
     pub fn getWindowSize(core: *Core) !structs.Size {
         return structs.Size{
-            .width = js.machCanvasGetWidth(core.id),
-            .height = js.machCanvasGetHeight(core.id),
+            .width = js.machCanvasGetWindowWidth(core.id),
+            .height = js.machCanvasGetWindowHeight(core.id),
         };
     }