Improve input padding, fix #18237.

app/assets/stylesheets/framework/forms.scss

@@ -76,6 +76,7 @@ label {
 .form-control {
   @include box-shadow(none);
   border-radius: 3px;
+  padding: $gl-vert-padding $gl-input-padding;
 }
 
 .select-wrapper {

app/assets/stylesheets/framework/selects.scss

@@ -8,7 +8,7 @@
     background: #fff;
     border-color: $input-border;
     height: 35px;
-    padding: $gl-vert-padding $gl-btn-padding;
+    padding: $gl-vert-padding $gl-input-padding;
     font-size: $gl-font-size;
     line-height: 1.42857143;
     border-radius: $border-radius-base;

app/assets/stylesheets/framework/variables.scss

@@ -57,6 +57,7 @@ $code_line_height: 1.5;
  */
 $gl-padding: 16px;
 $gl-btn-padding: 10px;
+$gl-input-padding: 10px;
 $gl-vert-padding: 6px;
 $gl-padding-top: 10px;