Add part for styling

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@tp/tp-timeout-strip",
-  "version": "1.0.0",
+  "version": "1.0.1",
   "description": "",
   "main": "tp-timeout-strip.js",
   "scripts": {

tp-timeout-strip.js

@@ -43,7 +43,7 @@ class TpTimeoutStrip extends LitElement {
 
   render() {
     return html`
-      <div class="strip ${this.active ? 'active' : ''}" style="animation-duration: ${this.timeout}ms" @animationend=${this._onAnimationEnd}></div>
+      <div part="strip" class="strip ${this.active ? 'active' : ''}" style="animation-duration: ${this.timeout}ms" @animationend=${this._onAnimationEnd}></div>
     `;
   }