Fixed line-height for textareas

no refs.
- Applied line-height for textareas with gh-input class. Having it applied all the textarea styles to textarea.gh-input caused bug in calculating the height of post titles in Koenig.

ghost/admin/app/styles/patterns/forms.css

@@ -168,8 +168,7 @@ select:focus {
     background: color-mod(var(--input-bg-color) l(-3%));
 }
 
-textarea,
-textarea.gh-input {
+textarea {
     width: 100%;
     height: auto;
     min-width: 250px;
@@ -180,6 +179,10 @@ textarea.gh-input {
     resize: vertical;
 }
 
+textarea.gh-input {
+    line-height: 1.5em;
+}
+
 
 /* Radio / Checkboxes
 /* ---------------------------------------------------------- */