Handle withheld tweets (#429)

* Handle withheld tweets

* Fix format of parser.nim

src/sass/timeline.scss

@@ -158,4 +158,8 @@
     padding: .75em;
     display: flex;
     position: relative;
+
+    &.unavailable {
+        flex-direction: column;
+    }
 }

src/sass/tweet/_base.scss

@@ -188,6 +188,7 @@
     height: 100%;
     padding: 12px;
     border: solid 1px var(--dark_grey);
+    box-sizing: border-box;
     border-radius: 10px;
     background-color: var(--bg_color);
 }