fix(dialog, panel): restore relative positioning in content area (#10749

)

**Related Issue:** #10095 

## Summary

Fixes layout issues in dialog and panel content area.

This reverts commit 239f4da.

packages/calcite-components/src/components/dialog/dialog.stories.ts

@@ -376,16 +376,8 @@ const themedStyle = html`--calcite-dialog-scrim-background-color: purple; --calc
 --calcite-dialog-content-space: 50px; --calcite-dialog-offset-x: 50px; --calcite-dialog-offset-y: -30px;`;
 
 export const withShellInside = (): string =>
-  html`<calcite-dialog
-    open
-    modal
-    heading="heading"
-    description="description"
-    scale="m"
-    width-scale="l"
-    style="--calcite-dialog-content-space: 0;"
-  >
-    <calcite-shell style="position:relative">
+  html`<calcite-dialog open modal heading="heading" description="description" scale="m" width-scale="l">
+    <calcite-shell>
       <calcite-shell-panel slot="panel-start">
         <calcite-action-bar slot="action-bar" expanded>
           <calcite-action-group>

packages/calcite-components/src/components/panel/panel.scss

@@ -164,7 +164,8 @@
   items-stretch
   overflow-auto
   h-full
-  focus-base;
+  focus-base
+  relative;
   padding: var(--calcite-panel-content-space, 0);
   background: var(--calcite-panel-background-color, var(--calcite-color-background));
 }