Sketch: Minor fixes to Gutenberg implementation, including:

* Update selectors for button blocks, for better custom colour fallbacks.
* Correct button line height in editor, and border colours.

sketch/css/blocks.css

@@ -214,12 +214,9 @@ p.has-drop-cap:not(:focus)::first-letter {
 
 /* Buttons */
 
-.wp-block-button__link:not(.has-text-color) {
-	color: #999999;
-}
-
-.wp-block-button__link:not(.has-background) {
+.wp-block-button__link {
 	background: white;
+	color: #999999;
 }
 
 .wp-block-button .wp-block-button__link {

sketch/css/editor-blocks.css

@@ -501,6 +501,7 @@ p.has-drop-cap:not(:focus)::first-letter {
 	font-size: 16px;
 	font-weight: 400;
 	letter-spacing: 2px;
+	line-height: 24px;
 	padding: 10px 14px;
 	text-transform: uppercase;
 	-webkit-transition: all 0.3s ease-in-out;
@@ -509,6 +510,14 @@ p.has-drop-cap:not(:focus)::first-letter {
 	transition: all 0.3s ease-in-out;
 }
 
+.wp-block-button .editor-rich-text__tinymce.mce-content-body {
+	line-height: 24px;
+}
+
+.wp-block-button .wp-block-button__link.has-text-color {
+	border-color: currentColor;
+}
+
 .wp-block-button__link:hover,
 .wp-block-button__link:focus {
 	background: transparent;