completed extend-controls docs

doc/themes/next/source/css/_custom/custom.styl

@@ -1,21 +1,37 @@
 // Custom styles.
 
-.table-container table{
+.post-body figure {
+  border-radius: 4px;
+}
+
+.post-body img {
+  border-radius: 10px;
+}
+
+.site-author-image {
+  border-radius: 50%;
+}
+
+.table-container {
+  border-radius: 4px;
+}
+
+.table-container table {
   background-color: #eee;
   border-collapse:separate;
   border-spacing: 0 4px;
   padding: 0 6px 2px 6px;
 }
 
-.table-container th, td{
+.table-container th, td {
   border: 0;
 }
 
-.table-container tr td:first-child{
+.table-container tr td:first-child {
   border-radius: 4px 0 0 4px;
 }
 
-.table-container tr td:last-child{
+.table-container tr td:last-child {
   border-radius: 0 4px 4px 0;
 }