fix(inputs): apply font-size variable to simple textbox (#853)

see kendo-angular/#1178

scss/input/_layout.scss

@@ -13,6 +13,7 @@
     $checkbox-dash-offset-x: $checkbox-border-width * 2 !default;
     $checkbox-dash-offset-y: ( $checkbox-size - $checkbox-dash-height ) / 2 !default;
 
+    $textbox-font-size: $font-size !default;
     $textbox-line-height: $form-line-height-em !default;
     // TODO: legacy, consider switching to 100%
     $textbox-default-width: $input-default-width !default;
@@ -29,6 +30,7 @@
         border-style: solid;
         outline: 0;
         font: inherit;
+        font-size: $textbox-font-size;
         line-height: $textbox-line-height;
         display: inline-flex;
         vertical-align: middle;
@@ -66,6 +68,7 @@
         color: inherit;
         background: none;
         font: inherit;
+        font-size: $textbox-font-size;
         flex: 1;
         display: flex;
         align-items: center;