fix wrong rich-text-widget offset (#2033)

.rich-text-input { padding: 6px; }
messed up image & mathjax overlay positioning
because parent padding isn't added to absolute positioning px

ts/editor/FieldDescription.svelte

@@ -40,9 +40,6 @@ License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html
         opacity: 0.4;
         pointer-events: none;
 
-        /* same as in ContentEditable */
-        padding: 6px;
-
         /* stay a on single line */
         overflow-x: hidden;
         white-space: nowrap;

ts/editor/rich-text-input/RichTextInput.svelte

@@ -244,7 +244,7 @@ License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html
 <style lang="scss">
     .rich-text-input {
         position: relative;
-        padding: 6px;
+        margin: 6px;
     }
 
     .hidden {