Make figcaption visible

Makes the figcaption Element for the post.html Template visible.

The figcaption content is now overlayed translucently on top of the image having the maximum width of one row. On hover it will expand to the full necessary height to display the whole content.

sass/_utils.scss

@@ -2,3 +2,13 @@
   width: 70%;
   height: 70%;
 }
+
+.caption {
+  display: flex;
+  justify-content: center;
+  padding: 4px 10px 4px 10px;
+}
+
+.tag.caption {
+  width: 100%;
+}