Fix smooth scrolling of table

package.json

@@ -39,18 +39,18 @@
     "@rollup/plugin-terser": "0.4.4",
     "@rollup/plugin-typescript": "12.1.1",
     "@testing-library/react": "16.0.1",
-    "@types/node": "22.8.1",
+    "@types/node": "22.8.2",
     "@types/react": "18.3.12",
     "@types/react-dom": "18.3.1",
-    "@vitest/coverage-v8": "2.1.3",
+    "@vitest/coverage-v8": "2.1.4",
     "eslint": "9.13.0",
     "eslint-plugin-react": "7.37.2",
     "http-server": "14.1.1",
     "jsdom": "25.0.1",
     "tslib": "2.8.0",
     "typescript": "5.6.3",
-    "typescript-eslint": "8.11.0",
-    "vitest": "2.1.3"
+    "typescript-eslint": "8.12.1",
+    "vitest": "2.1.4"
   },
   "peerDependencies": {
     "react": "^18.2.0",

src/HighTable.tsx

@@ -119,7 +119,6 @@ export default function HighTable({
       const scrollTop = scrollRef.current?.scrollTop || 0 // scroll position
 
       // determine rows to fetch based on current scroll position
-      // TODO: compute the floor delta so offsetTop adjustment is smooth
       const startView = Math.floor(data.numRows * scrollTop / scrollHeight)
       const endView = Math.ceil(data.numRows * (scrollTop + clientHeight) / scrollHeight)
       const start = Math.max(0, startView - overscan)
@@ -129,8 +128,7 @@ export default function HighTable({
       if (isNaN(end)) throw new Error('invalid end row ' + end)
       if (end - start > 1000) throw new Error('too many rows to fetch ' + (end - start))
 
-      const preOffset = Math.min(overscan + padding, startView) * rowHeight
-      const offsetTop = Math.max(0, scrollTop - preOffset)
+      const offsetTop = Math.max(0, start - padding) * rowHeight
 
       // Fetch a chunk of rows from the data frame
       try {