webconfig: Remove weird position: absolute

This made the current prompt appear directly under the tab,
disregarding the padding.

That means it looked inconsistent with the colors. (note there's still
less padding on the side, but at least that allows more actual content
- prompts are often fairly wide)

share/tools/web_config/fishconfig.css

@@ -77,11 +77,6 @@ code {
 /* This may be placed directly inside a tab, to prevent its contents from growing vertically. */
 .height_limiter {
     display: flex;
-    position: absolute;
-    top: 0;
-    bottom: 0;
-    left: 0;
-    right: 0;
     flex-direction: column;
 }