diff --git a/packages/x-data-grid-premium/src/hooks/features/cellSelection/useGridCellSelection.ts b/packages/x-data-grid-premium/src/hooks/features/cellSelection/useGridCellSelection.ts
index 755b116f5df74..634fbdad61b93 100644
--- a/packages/x-data-grid-premium/src/hooks/features/cellSelection/useGridCellSelection.ts
+++ b/packages/x-data-grid-premium/src/hooks/features/cellSelection/useGridCellSelection.ts
@@ -293,7 +293,8 @@ export const useGridCellSelection = (
       }
 
       const { x: mouseX, y: mouseY } = mousePosition.current;
-      const { height, width } = dimensions.viewportInnerSize;
+      const { width, height: viewportOuterHeight } = dimensions.viewportOuterSize;
+      const height = viewportOuterHeight - totalHeaderHeight;
 
       let deltaX = 0;
       let deltaY = 0;
@@ -330,7 +331,7 @@ export const useGridCellSelection = (
     }
 
     autoScroll();
-  }, [apiRef, dimensions]);
+  }, [apiRef, dimensions, totalHeaderHeight]);
 
   const handleCellMouseOver = React.useCallback<GridEventListener<'cellMouseOver'>>(
     (params, event) => {
@@ -354,7 +355,8 @@ export const useGridCellSelection = (
       }
 
       const { x, y } = virtualScrollerRect;
-      const { height, width } = dimensions.viewportInnerSize;
+      const { width, height: viewportOuterHeight } = dimensions.viewportOuterSize;
+      const height = viewportOuterHeight - totalHeaderHeight;
       const mouseX = event.clientX - x;
       const mouseY = event.clientY - y - totalHeaderHeight;
       mousePosition.current = { x: mouseX, y: mouseY };
diff --git a/packages/x-data-grid/src/components/containers/GridRootStyles.ts b/packages/x-data-grid/src/components/containers/GridRootStyles.ts
index c0549e40a8c0a..f66edba975eac 100644
--- a/packages/x-data-grid/src/components/containers/GridRootStyles.ts
+++ b/packages/x-data-grid/src/components/containers/GridRootStyles.ts
@@ -157,25 +157,47 @@ export const GridRootStyles = styled('div', {
   const hoverColor = (t.vars || t).palette.action.hover;
 
   const selectedOpacity = (t.vars || t).palette.action.selectedOpacity;
+  const selectedHoverOpacity = t.vars
+    ? (`calc(${hoverOpacity} + ${selectedOpacity})` as unknown as number) // TODO: Improve type
+    : hoverOpacity + selectedOpacity;
   const selectedBackground = t.vars
     ? `rgba(${t.vars.palette.primary.mainChannel} / ${selectedOpacity})`
     : alpha(t.palette.primary.main, selectedOpacity);
 
   const selectedHoverBackground = t.vars
-    ? `rgba(${t.vars.palette.primary.mainChannel} / calc(
-                ${t.vars.palette.action.selectedOpacity} +
-                ${t.vars.palette.action.hoverOpacity}
-              ))`
-    : alpha(
-        t.palette.primary.main,
-        t.palette.action.selectedOpacity + t.palette.action.hoverOpacity,
-      );
+    ? `rgba(${t.vars.palette.primary.mainChannel} / ${selectedHoverOpacity})`
+    : alpha(t.palette.primary.main, selectedHoverOpacity);
 
   const blendFn = t.vars ? blendCssVars : blend;
 
-  const pinnedHoverBackground = blendFn(pinnedBackground, hoverColor, hoverOpacity);
-  const pinnedSelectedBackground = blendFn(pinnedBackground, selectedBackground, selectedOpacity);
-  const pinnedSelectedHoverBackground = blendFn(pinnedSelectedBackground, hoverColor, hoverOpacity);
+  const getPinnedBackgroundStyles = (backgroundColor: string) => ({
+    [`& .${c['cell--pinnedLeft']}, & .${c['cell--pinnedRight']}`]: {
+      backgroundColor,
+      '&.Mui-selected': {
+        backgroundColor: blendFn(backgroundColor, selectedBackground, selectedOpacity),
+        '&:hover': {
+          backgroundColor: blendFn(backgroundColor, selectedBackground, selectedHoverOpacity),
+        },
+      },
+    },
+  });
+
+  const pinnedBackgroundColor = blendFn(pinnedBackground, hoverColor, hoverOpacity);
+  const pinnedHoverStyles = getPinnedBackgroundStyles(pinnedBackgroundColor);
+
+  const pinnedSelectedBackgroundColor = blendFn(
+    pinnedBackground,
+    selectedBackground,
+    selectedOpacity,
+  );
+  const pinnedSelectedStyles = getPinnedBackgroundStyles(pinnedSelectedBackgroundColor);
+
+  const pinnedSelectedHoverBackgroundColor = blendFn(
+    pinnedBackground,
+    selectedHoverBackground,
+    selectedHoverOpacity,
+  );
+  const pinnedSelectedHoverStyles = getPinnedBackgroundStyles(pinnedSelectedHoverBackgroundColor);
 
   const selectedStyles = {
     backgroundColor: selectedBackground,
@@ -632,23 +654,14 @@ export const GridRootStyles = styled('div', {
       position: 'sticky',
       zIndex: 3,
       background: 'var(--DataGrid-pinnedBackground)',
+      '&.Mui-selected': {
+        backgroundColor: pinnedSelectedBackgroundColor,
+      },
     },
     [`& .${c.virtualScrollerContent} .${c.row}`]: {
-      '&:hover': {
-        [`& .${c['cell--pinnedLeft']}, & .${c['cell--pinnedRight']}`]: {
-          backgroundColor: pinnedHoverBackground,
-        },
-      },
-      [`&.Mui-selected`]: {
-        [`& .${c['cell--pinnedLeft']}, & .${c['cell--pinnedRight']}`]: {
-          backgroundColor: pinnedSelectedBackground,
-        },
-        '&:hover': {
-          [`& .${c['cell--pinnedLeft']}, & .${c['cell--pinnedRight']}`]: {
-            backgroundColor: pinnedSelectedHoverBackground,
-          },
-        },
-      },
+      '&:hover': pinnedHoverStyles,
+      '&.Mui-selected': pinnedSelectedStyles,
+      '&.Mui-selected:hover': pinnedSelectedHoverStyles,
     },
     [`& .${c.cellOffsetLeft}`]: {
       flex: '0 0 auto',
@@ -778,6 +791,6 @@ function blend(background: string, overlay: string, opacity: number, gamma: numb
 }
 
 const removeOpacity = (color: string) => `rgb(from ${color} r g b / 1)`;
-function blendCssVars(background: string, overlay: string, opacity: number) {
+function blendCssVars(background: string, overlay: string, opacity: string | number) {
   return `color-mix(in srgb,${background}, ${removeOpacity(overlay)} calc(${opacity} * 100%))`;
 }
diff --git a/packages/x-data-grid/src/hooks/features/scroll/useGridScroll.ts b/packages/x-data-grid/src/hooks/features/scroll/useGridScroll.ts
index 798ffd854c01b..f8628fa5451c4 100644
--- a/packages/x-data-grid/src/hooks/features/scroll/useGridScroll.ts
+++ b/packages/x-data-grid/src/hooks/features/scroll/useGridScroll.ts
@@ -21,24 +21,24 @@ import { gridDimensionsSelector } from '../dimensions';
 // Logic copied from https://www.w3.org/TR/wai-aria-practices/examples/listbox/js/listbox.js
 // Similar to https://developer.mozilla.org/en-US/docs/Web/API/Element/scrollIntoView
 function scrollIntoView(dimensions: {
-  clientHeight: number;
-  scrollTop: number;
-  offsetHeight: number;
-  offsetTop: number;
+  containerSize: number;
+  scrollPosition: number;
+  elementSize: number;
+  elementOffset: number;
 }) {
-  const { clientHeight, scrollTop, offsetHeight, offsetTop } = dimensions;
+  const { containerSize, scrollPosition, elementSize, elementOffset } = dimensions;
 
-  const elementBottom = offsetTop + offsetHeight;
+  const elementEnd = elementOffset + elementSize;
   // Always scroll to top when cell is higher than viewport to avoid scroll jump
   // See https://github.com/mui/mui-x/issues/4513 and https://github.com/mui/mui-x/issues/4514
-  if (offsetHeight > clientHeight) {
-    return offsetTop;
+  if (elementSize > containerSize) {
+    return elementOffset;
   }
-  if (elementBottom - clientHeight > scrollTop) {
-    return elementBottom - clientHeight;
+  if (elementEnd - containerSize > scrollPosition) {
+    return elementEnd - containerSize;
   }
-  if (offsetTop < scrollTop) {
-    return offsetTop;
+  if (elementOffset < scrollPosition) {
+    return elementOffset;
   }
   return undefined;
 }
@@ -96,10 +96,10 @@ export const useGridScroll = (
         }
         // When using RTL, `scrollLeft` becomes negative, so we must ensure that we only compare values.
         scrollCoordinates.left = scrollIntoView({
-          clientHeight: dimensions.viewportInnerSize.width,
-          scrollTop: Math.abs(virtualScrollerRef.current!.scrollLeft),
-          offsetHeight: cellWidth,
-          offsetTop: columnPositions[params.colIndex],
+          containerSize: dimensions.viewportOuterSize.width,
+          scrollPosition: Math.abs(virtualScrollerRef.current!.scrollLeft),
+          elementSize: cellWidth,
+          elementOffset: columnPositions[params.colIndex],
         });
       }
       if (params.rowIndex !== undefined) {
@@ -116,10 +116,10 @@ export const useGridScroll = (
           : rowsMeta.currentPageTotalHeight - rowsMeta.positions[elementIndex];
 
         scrollCoordinates.top = scrollIntoView({
-          clientHeight: dimensions.viewportInnerSize.height,
-          scrollTop: virtualScrollerRef.current!.scrollTop,
-          offsetHeight: targetOffsetHeight,
-          offsetTop: rowsMeta.positions[elementIndex],
+          containerSize: dimensions.viewportInnerSize.height,
+          scrollPosition: virtualScrollerRef.current!.scrollTop,
+          elementSize: targetOffsetHeight,
+          elementOffset: rowsMeta.positions[elementIndex],
         });
       }