AddRemove: make a button that adds constraints

app-proto/full-interface/main.css

@@ -4,9 +4,11 @@ body {
   background-color: #222;
 }
 
-/* outline */
+/* sidebar */
 
-#outline {
+#sidebar {
+  display: flex;
+  flex-direction: column;
   float: left;
   width: 450px;
   height: 100vh;
@@ -15,6 +17,28 @@ body {
   border-width: 0px 1px 0px 0px;
   border-style: solid;
   border-color: #555;
+}
+
+/* add-remove */
+
+#add-remove {
+  display: flex;
+  gap: 8px;
+  margin: 8px;
+}
+
+#add-remove > button {
+  width: 32px;
+  height: 32px;
+  font-size: large;
+}
+
+/* outline */
+
+#outline {
+  flex-grow: 1;
+  margin: 0px;
+  padding: 0px;
   overflow-y: scroll;
 }