Fix some CSS issues

- Remove italics from quotes. It looks dumb.
- Make "vertical" fill all available horizontal space.

assets/css/main.css

@@ -51,6 +51,7 @@ ul {
 .horizontal-center {
     display: flex;
     justify-content: center;
+    width: 100%;
 }
 
 .vertical {
@@ -85,5 +86,4 @@ ul {
     border-left-style: solid;
     border-color: gray;
     padding-left: 4px;
-    font-style: italic;
 }