Move popover padding into the component

This makes sure all popovers are styled the same way.

src/components/HoverPopover.svelte

@@ -28,6 +28,7 @@
     position: relative;
     right: 1rem;
     z-index: 10;
+    padding: 1rem;
   }
 </style>
 

src/views/projects/Source/BranchSelector.svelte

@@ -50,10 +50,7 @@
           <IconSmall name="branch" />
           <div class="identifier">{project.defaultBranch}</div>
         </Button>
-        <div
-          class="txt-small"
-          style:padding="0.5rem 0.5rem 0.5rem 0.75rem"
-          slot="popover">
+        <div class="txt-small" slot="popover">
           <div style:margin-bottom="1rem">
             You are currently browsing the canonical branch.
           </div>

src/views/projects/Source/Header.svelte

@@ -109,10 +109,7 @@
         {pluralize("contributor", tree.stats.contributors)}
       </div>
     </Button>
-    <div
-      class="txt-small"
-      style:padding="0.5rem 0.5rem 0.5rem 0.75rem"
-      slot="popover">
+    <div class="txt-small" slot="popover">
       <div style:margin-bottom="1rem">Coming soon.</div>
       <div>Listing all contributors is not yet implemented.</div>
     </div>