diff --git a/app/routes/home.tsx b/app/routes/home.tsx
index 5808bdb..2e4b69f 100644
--- a/app/routes/home.tsx
+++ b/app/routes/home.tsx
@@ -42,19 +42,33 @@ export default function Home() {
   const [plotType, setPlotType] = useState<PlotType>("scatter");
   const [colorscale, setColorscale] = useState<string>(COLORSCALES[0]);
 
+  // First row after header = axis sizes (X max, Y max, Z max); rest = plot data.
+  const plotData = rows.length > 1 ? rows.slice(1) : rows;
+  const axisSizes =
+    rows.length > 1 && x && y && z
+      ? (() => {
+        const sx = Number(rows[0][x]);
+        const sy = Number(rows[0][y]);
+        const sz = Number(rows[0][z]);
+        return [sx, sy, sz].every((n) => Number.isFinite(n))
+          ? { x: sx, y: sy, z: sz }
+          : null;
+      })()
+      : null;
+
   // Build surface grid from scattered (x,y,z) points. Returns null if data isn't a grid.
   function buildSurfaceGrid(): {
     xUnique: number[];
     yUnique: number[];
     zMatrix: number[][];
   } | null {
-    const xVals = rows.map((r) => Number(r[x]));
-    const yVals = rows.map((r) => Number(r[y]));
-    const zVals = rows.map((r) => Number(r[z]));
+    const xVals = plotData.map((r) => Number(r[x]));
+    const yVals = plotData.map((r) => Number(r[y]));
+    const zVals = plotData.map((r) => Number(r[z]));
     const xUnique = [...new Set(xVals)].sort((a, b) => a - b);
     const yUnique = [...new Set(yVals)].sort((a, b) => a - b);
     const keyToZ = new Map<string, number>();
-    for (let i = 0; i < rows.length; i++) {
+    for (let i = 0; i < plotData.length; i++) {
       const k = `${xVals[i]},${yVals[i]}`;
       if (!keyToZ.has(k)) keyToZ.set(k, zVals[i]);
     }
@@ -75,9 +89,9 @@ export default function Home() {
       const Plotly = await import("plotly.js-dist-min");
       if (cancelled) return;
 
-      const xVals = rows.map((r) => Number(r[x]));
-      const yVals = rows.map((r) => Number(r[y]));
-      const zVals = rows.map((r) => Number(r[z]));
+      const xVals = plotData.map((r) => Number(r[x]));
+      const yVals = plotData.map((r) => Number(r[y]));
+      const zVals = plotData.map((r) => Number(r[z]));
 
       const grid = buildSurfaceGrid();
       const useSurface = plotType === "surface" && grid !== null;
@@ -104,6 +118,21 @@ export default function Home() {
           },
         };
 
+      const sceneLayout: {
+        xaxis: { title: { text: string }; range?: [number, number] };
+        yaxis: { title: { text: string }; range?: [number, number] };
+        zaxis: { title: { text: string }; range?: [number, number] };
+      } = {
+        xaxis: { title: { text: x } },
+        yaxis: { title: { text: y } },
+        zaxis: { title: { text: z } },
+      };
+      if (axisSizes) {
+        sceneLayout.xaxis.range = [0, axisSizes.x];
+        sceneLayout.yaxis.range = [0, axisSizes.y];
+        sceneLayout.zaxis.range = [0, axisSizes.z];
+      }
+
       Plotly.newPlot(
         plotRef.current!,
         [trace],
@@ -111,11 +140,7 @@ export default function Home() {
           paper_bgcolor: "#0b0d12",
           plot_bgcolor: "#0b0d12",
           font: { color: "#cfd3ff" },
-          scene: {
-            xaxis: { title: { text: x } },
-            yaxis: { title: { text: y } },
-            zaxis: { title: { text: z } },
-          },
+          scene: sceneLayout,
           margin: { l: 0, r: 0, t: 0, b: 0 },
         },
         { responsive: true }
@@ -198,6 +223,12 @@ export default function Home() {
                        file:rounded file:px-2 file:py-1"
           />
         </Control>
+        <p className="text-xs text-muted">
+          First data row = axis sizes (X max, Y max, Z max). Plot uses rows after that.{" "}
+          <a href="/example-surface.csv" className="text-accent underline" download>
+            Example (surface)
+          </a>
+        </p>
 
         <Control label="X axis">
           <select
@@ -270,16 +301,16 @@ export default function Home() {
         </Control>
 
         {plotType === "surface" &&
-          rows.length > 0 &&
+          plotData.length > 0 &&
           buildSurfaceGrid() === null && (
             <p className="text-xs text-amber-500/90">
-              Surface needs a full X×Y grid of points. Showing dots instead.
+              Surface needs a full X and Y grid of points. Showing dots instead.
             </p>
           )}
 
         <button
           onClick={exportPNG}
-          className="w-full mt-2 bg-accent text-black text-sm rounded px-2 py-1 hover:opacity-90"
+          className="w-full mt-2 bg-accent text-sm rounded px-2 py-1 hover:opacity-90"
         >
           Export PNG
         </button>