Fix weird dropdown cursor behavior

Author: elmisback

src/herbie/ExpressionTable.css

@@ -166,9 +166,6 @@
   margin-left: 17px;
   transition: all 1s ease-in;
 }
-.dropdown:hover {
-  cursor: pointer;
-}
 
 .expression-container:hover {
   outline: 2px solid var(--highlight);

src/herbie/HerbieUI.css

@@ -123,6 +123,7 @@ select {
 button {
   font-family: 'Ruda', sans-serif;
   font-size: 14px;
+  cursor: pointer;
 }
 
 button:disabled {

src/herbie/LocalError/newLocalError.tsx

@@ -97,7 +97,7 @@ function TreeRow({
   return (
     <>
       <tr className={ rowClassName }>
-        <td className="border px-4 py-2 program-col">
+        <td className="program-col">
           <span
             style={{ marginLeft: `${depth * 15}px`, cursor: "pointer" }}
             onClick={() => setIsExpanded(prev => !prev)}