Improve profile page elements, reduce jank

Fixes #167

src/sass/profile/_base.scss

@@ -15,23 +15,22 @@
 }
 
 .profile-banner {
-    padding-bottom: 4px;
+    margin-bottom: 4px;
+    background-color: var(--bg_panel);
 
     a {
-        display: inherit;
-        line-height: 0;
+        display: block;
+        position: relative;
+        padding: 33.34% 0 0 0;
     }
 
     img {
-        width: 100%;
+        max-width: 100%;
+        position: absolute;
+        top: 0;
     }
 }
 
-.profile-banner-color {
-    width: 100%;
-    padding-bottom: 25%;
-}
-
 .profile-tab {
     padding: 0 4px 0 0;
     box-sizing: border-box;

src/sass/profile/card.scss

@@ -35,19 +35,25 @@
 }
 
 .profile-card-avatar {
-    display: block;
+    display: inline-block;
+    position: relative;
     width: 100%;
-    padding-bottom: 6px;
     margin-right: 4px;
+    margin-bottom: 6px;
+
+    &:after {
+        content: '';
+        display: block;
+        margin-top: 100%;
+    }
 
     img {
-        display: block;
         box-sizing: border-box;
+        position: absolute;
         width: 100%;
         height: 100%;
-        margin: 0;
         border: 4px solid var(--darker_grey);
-        background: var(--bg_color);
+        background: var(--bg_panel);
     }
 }
 
@@ -113,8 +119,8 @@
     }
 
     .profile-card-avatar {
-        height: 60px;
-        width: unset;
+        width: 80px;
+        height: 80px;
 
         img {
             border-width: 2px;

src/sass/profile/photo-rail.scss

@@ -32,6 +32,7 @@
         a {
             position: relative;
             border-radius: 5px;
+            background-color: var(--darker_grey);
 
             &:before {
                 content: "";