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  <div id="app">
    <div class="wrapper">
      <span class="title"><h3>Do It App</h3></span>
    <ul >
      <li v-for="(task, index) in tasks"  v-bind:class="{completed:task.selected}"  > 
        {{ task.todo }} (index: {{ index }}) <br>
        <button v-on:click.prevent="removeTask(index)" >Remove</button>
        <button v-on:click="$set(task, 'selected', !task.selected)">Completed</button>
            v-on:keyup.enter ="addTask"
            placeholder="&#xF044 What to do"




                /* reset */
* {
  margin: 0;

body {
  margin: 0;
  font-family: sans-serif;

main {
  width: 100vw;
  min-height: 100vh;
  display: flex;
  justify-content: center;
  align-items: center;

#app {
  background: linear-gradient(230deg, hsl(197, 58%, 19%), hsl(360, 0%, 20%) );
  color: #111111;
  text-align: center;
  min-width: 280px;
  margin: 0 auto;
  display: table;
  padding: 10px;
  border-radius: 23px 13px 33px;
  line-height: 1.4em;
  width: 60%;
  max-width: 900px;

.title {
  color: #ffffff;

.wrapper {
  text-align: left;

hr {
  border-top: 0;
  border-bottom: 1px solid #bbafaf;
ul {
  background-color: #fff;;
  max-width: 100%;
li {
  list-style: circle outside none;
  text-align: left;
  padding: 10px 0 30px;
  border-top: 1px solid hsl(197, 58%, 19%);
  word-wrap: break-word;
  max-width: 100%;
li:first-child {
  border-top: 0 solid hsl(197, 58%, 19%);
input {
  font-family: san-serif, FontAwesome;
  width: 100%;
  margin: 15px 0;
  padding: 8px 10px;
  outline: 0;
  font-size: 1em;
button {
  float: right;
  margin: 0 10px;
  padding: .4em;
  /*background-color: hsl(197, 58%, 19%);
  color: hsl(197, 100%, 100%);
  border-radius: 3px; doesn't work on botton*/
.completed {
  background: pink;



                new Vue({
    el: '#app',
    data () {
        return {
            tasks: [{index: 'eat sushi 🍣', todo: 'eat sush 🍣'},{index: 'study Vue.js', todo: 'study 💚 Vue.js'}],
            newTask: '',
            completedClass: null
    methods: {
        addTask() {
             if (this.newTask.length > 0) {
                this.tasks.push({index: this.newTask, todo: this.newTask}) //add the new task an object: property
                this.newTask = '';
            else {
                alert("You need to add some text")
        removeTask(index) {
            //this.$delete(this.tasks, index);
            var remove = confirm('This will delete the task and is not reversible');
            if (remove === true) {this.tasks.splice(index, 1);}
        completedClassClick() {