Vue

HTML

<div id="app">
  <svg version="1.1">
    <rect x=0 y=0 width=100 height=100 fill="blue" stroke="red" :stroke-width="strokeWidth"/>
  </svg>
  <input type="number" v-model="strokeWidth" >
</div>

CSS

body {
  background: #20262E;
  padding: 20px;
  font-family: Helvetica;
}

#app {
  background: #fff;
  border-radius: 4px;
  padding: 20px;
  transition: all 0.2s;
}

li {
  margin: 8px 0;
}

h2 {
  font-weight: bold;
  margin-bottom: 15px;
}

del {
  color: rgba(0, 0, 0, 0.3);
}

Vue

new Vue({
  el: "#app",
  data: {
    strokeWidth: 1
  } 
})