npm i element-ui -S

import Vue from 'vue';
import ElementUI from 'element-ui';
import 'element-ui/lib/theme-chalk/index.css';
import App from './App.vue';
 
Vue.use(ElementUI);
 
new Vue({
 el: '#app',
 render: h => h(App)
});

<el-button :style="selfstyle">默认按钮</el-button>
<script>
 export default {
 data() {
  return {
  selfstyle: {
   color: "white",
   marginTop: "10px",
   width: "100px",
   backgroundColor: "cadetblue"
  }
  };
 }
 }
</script>

<el-button :class="[selfbutton]">默认按钮</el-button>
<script>
 export default {
 data() {
  return {
  selfbutton: "self-button"
  };
 }
 }
</script>
<style lang="stylus" rel="stylesheet/stylus" scoped>
 .self-button {
 color: white;
 margin-top: 10px;
 width: 100px;
 background-Color: cadetblue;
 }
</style>

<el-button>和下面的el-button效果一样</el-button>
<el-button :class="[selfbutton]">默认按钮</el-button>
<script>
 import './button.css'
 export default {}
</script>
<style lang="stylus" rel="stylesheet/stylus" scoped></style>
 
/* button.css */ 
.el-button {
 color: white;
 margin-top: 10px;
 width: 100px;
 background-Color: cadetblue;
}
 
.self-button {
 color: white;
 margin-top: 10px;
 width: 100px;
 background-Color: cadetblue;
}
 
.self-button:hover {
 color: black;
 background-Color: whitesmoke;
}

npm install element-react -S
npm install element-theme-default -S

import React from 'react';
import ReactDOM from 'react-dom';
import { Button } from 'element-react';
 
import 'element-theme-default';
 
ReactDOM.render(<Button type="primary">Hello</Button>, document.getElementById('app'));

import { Button } from 'element-react';
 
function app(){
 render() {
 const style = {
  color: "white",
  marginTop: "10px",
  width: "100px",
  backgroundColor: "cadetblue"
 }
 return(
       <div>
       <Button style={style}>Hello</Button>
      </div>
 );
 }
}

import '../style/button.css'
import { Button } from 'element-react';
 
function App(){
 render() {
 return(
  <div>
              <Button>和下面的Button效果一样</Button>
      <Button className="self-button">Hello</Button>
   </div>
 );
 }
}
 
/* button.css */
.el-button {
 color: white!important;
 margin-top: 10px!important;
 width: 100px!important;
 background-Color: cadetblue!important;
}
 
.self-button {
 color: white!important;
 margin-top: 10px!important;
 width: 100px!important;
 background-Color: cadetblue!important;
}
 
.self-button:hover {
 color: black!important;
 background-Color: whitesmoke!important;
}