popup improvements

- set max size of close button in popups to prevent stretching
- image picker buttons are now distanced away from content
- if an image in image picker couldn't load, it now disappears instead of displaying ":("

src/front/cobalt.css

@@ -438,7 +438,7 @@ input[type="checkbox"] {
     overflow: auto;
 }
 #close-bottom {
-    width: 18%;
+    max-width: 3rem;
     margin-left: 1rem;
     background: var(--background);
     border: var(--border-15);
@@ -493,6 +493,9 @@ input[type="checkbox"] {
     padding-top: 0!important;
     padding-bottom: 1rem;
 }
+#popup-imagePicker #popup-buttons {
+    padding-top: 1rem;
+}
 /* adapt the page according to screen size */
 @media screen and (min-width: 2300px) {
     html {