Give social items a static width

Otherwise it depends on the size of the sidebar, and it might get ugly
if ever the sidebar width is changed (say, for someone who tweaks the
theme and enlarge or shrink the sidebar).

static/css/hyde.css

@@ -108,15 +108,13 @@ html {
 }
 .sidebar-social-item {
   display: block;
-  padding: .25rem 0.5rem;
+  padding: .25rem 0.8rem;
   background: #fff2;
   margin: 0 .2rem;
   border-radius: .25rem;
   text-transform: uppercase;
   font-size: .8rem;
   font-weight: bold;
-  float: left;
-  width: 17%;
 }
 a.sidebar-social-item:hover,
 a.sidebar-social-item:focus {