remove event listeners on deactivation. fix css

apps/remix-ide/src/app/plugins/solidity-umlgen.tsx

@@ -62,7 +62,7 @@ export class SolidityUmlGen extends ViewPlugin implements ISolidityUmlGen {
   }
 
   onDeactivation(): void {
-    
+    this.off('solidity', 'compilationFinished')
   }
 
   generateCustomAction = async (action: customAction) => {

libs/remix-ui/solidity-uml-gen/src/lib/solidity-uml-gen.tsx

@@ -61,9 +61,9 @@ export function RemixUiSolidityUmlGen ({ plugin, updatedSvg, loading }: RemixUiS
 
   const DefaultInfo = () => (
     <div className="d-flex flex-column justify-content-center align-items-center mt-5">
-      <h2 className="h2"><p>To view your contract as a Uml Diragram</p></h2>
-      <h3 className="h3"><p>Right Click on your contract file (Usually ends with .sol)</p></h3>
-      <h3 className="h3 text-left"><p>Click on Generate UML</p></h3>
+      <h2 className="h2 align-self-start"><p>To view your contract as a Uml Diragram</p></h2>
+      <h3 className="h4 align-self-start"><p>Right Click on your contract file (Usually ends with .sol)</p></h3>
+      <h3 className="h4 align-self-start"><p>Click on Generate UML</p></h3>
     </div>
   )
   const Display = () => (