Fix up vote button CSS

public/content.css

@@ -343,15 +343,6 @@
     color: rgb(235, 235, 235);
 }
 
-.voteButton {
-	height: 24px;
-	width: 24px;
-	cursor: pointer;
-}
-.voteButton:hover {
-	filter: brightness(80%);
-}
-
 .segmentSummary {
 	outline: none !important;
 }
@@ -523,7 +514,7 @@ input::-webkit-inner-spin-button {
     position: absolute;
 }
 .helpButton:hover {
-	filter: brightness(80%);
+	opacity: 0.8;
 }
 
 .sbChatNotice iframe {

public/popup.css

@@ -190,6 +190,10 @@
   cursor: pointer;
 }
 
+.voteButton:hover {
+  opacity: 0.8;
+}
+
 /*
  * "Voted!" text that appears after voting on a segment
  */