Revert tabsets changes

Keep previous border radius and ensure
highlighted one is on top.

Author: josevalim

assets/css/tabset.css

@@ -11,7 +11,6 @@
 
 .tabset-tab {
   padding: .6rem var(--tabsetPadding);
-  min-height: 46px; /* matches admonition title, which has icon that adds height */
   font-family: var(--sansFontFamily);
   background-color: var(--tabBackground);
   color: var(--tab);
@@ -20,8 +19,8 @@
   border-top-width: 4px;
   border-top-color: var(--tabBorderTop);
   border-radius: 0;
-  border-top-left-radius: var(--borderRadius);
-  border-top-right-radius: var(--borderRadius);
+  border-top-left-radius: 4px;
+  border-top-right-radius: 4px;
   box-shadow: 0 -3px 4px var(--tabShadow) inset;
   cursor: pointer;
 }
@@ -30,6 +29,7 @@
   border-bottom-color: var(--tabBackground);
   border-top-color: var(--mainLight);
   box-shadow: none;
+  z-index: 1;
 }
 
 /* Keyboard navigation focus state (increased contrast) */