Add styling options for the close icon

tp-dialog.js

@@ -41,6 +41,7 @@ class TpDialog extends EventHelpers(LitElement) {
           position: absolute;
           right: 4px;
           top: 5px;
+          z-index: 1;
           --tp-icon-width: 18px;
           --tp-icon-height: 18px;
         }
@@ -53,7 +54,7 @@ class TpDialog extends EventHelpers(LitElement) {
     return html`
       <dialog part="dialog">
         ${showClose ? html`
-          <div class="close-icon">
+          <div class="close-icon" part="close-icon">
             <tp-icon .icon=${this.icon ? this.icon : TpDialog.closeIcon} dialog-dismiss></tp-icon>
           </div>
         ` : null}