<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>
  <p class="p">Кнопка</p>
</body>
<style>
  @import url(https://fonts.googleapis.com/css?family=Montserrat:100,200,300,regular,500,600,700,800,900,100italic,200italic,300italic,italic,500italic,600italic,700italic,800italic,900italic);
  .p{
    color: white;
    font-family: Montserrat;
    padding: 15px 45px;
    background: #000;
    display: flex;
    justify-content: center;
    align-items: center;
    width:100px;
    clip-path: polygon(88% 0%, 100% 50%, 88% 100%, 0% 100%, 12% 50%, 0% 0%);
    
  }
</style>
</html>

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External JavaScript

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