Textbook: Update table spacing, button borders, in editor to match front-end.

textbook/assets/css/editor-blocks.css

@@ -457,9 +457,9 @@ p.has-drop-cap:not(:focus)::first-letter {
 	border-collapse: collapse;
 }
 
-.wp-block-table th {
-	padding-bottom: 0;
-	padding-top: 0;
+.editor-styles-wrapper .wp-block-table th {
+	padding-bottom: 0.25em;
+	padding-top: 0.25em;
 }
 
 .wp-block-table th,
@@ -539,6 +539,10 @@ p.has-drop-cap:not(:focus)::first-letter {
 	color: #fff;
 }
 
+.wp-block-button .wp-block-button__link.has-text-color {
+	border-color: currentColor;
+}
+
 /* Separator */
 
 .wp-block-separator {