Update file explorer.css

Closes #3452566

css/explorer.css

@@ -25,11 +25,13 @@
 
 .sdc-styleguide-page__viewer-wrapper {
   height: 100%;
+  position: relative; /* Ensure the viewer wrapper handles positioning */
+  overflow: hidden; /* Prevent overflow issues */
 }
 
 .sdc-styleguide-viewer {
   border: 2px dashed #161f50;
-  height: max(250px, 95%);
+  height: calc(100% - 2rem); /* Adjusting the height to accommodate border and padding */
   margin: 0 auto;
   max-width: 100%;
   overflow: auto;
@@ -38,8 +40,12 @@
 
 .sdc-styleguide-viewer__iframe {
   display: block;
-  height: 100%;
+  position: absolute; /* Ensure the iframe is positioned absolutely within its container */
+  top: 0;
+  left: 0;
   width: 100%;
+  height: 100%;
+  border: 0;
 }
 
 .sdc-styleguide-explorer__group {