<div class="container">
  <button type="button">✅点击我开始，然后按键盘的"tab"键💯</button>
  <button type="button">✅我先获得焦点💯</button>
  <button type="button" tabindex="-1">🚫我无法获得焦点(显式设置了tabindex="-1")</button>
  <button type="button">✅我是最后一个获得焦点💯</button></div>

@import 'https://fonts.googleapis.com/css?family=Share+Tech+Mono';

@import 'https://cdnjs.cloudflare.com/ajax/libs/font-awesome/4.7.0/css/font-awesome.min.css';

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

body {
    width: 100vw;
    min-height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
    background-image: url('https://s3-us-west-2.amazonaws.com/s.cdpn.io/1376484/jess-harding-lqT6NAmTaiY-unsplash.jpg'),radial-gradient(#28a3dd, #0d7751);
    background-size: cover;
    background-position: center;
    font-family: "Share Tech Mono", monospace;
    font-size: 2rem;
    background-blend-mode: multiply,screen, overlay;
}

.container {
    position: relative;
    background-size: cover;
    background-position: center;
    backdrop-filter: blur(20px);
    background-color: rgba(255, 255, 255, 0.5);
    border-radius: 5px;
    padding:2vw;
    box-sizing: border-box;
    box-shadow: 0 1px 3px rgba(0, 0, 0, 0.12), 0 1px 2px rgba(0, 0, 0, 0.24);
    transition: .3s ease;
    margin: 3vw;
    display: flex;
    flex-direction: column;
}

button {
  display: inline-flex;
  font-size: 16px;
  font-weight: 700;
  border-radius: 5px;
  transition: background .3s;
  padding: 4vh 6vh;
  background: #11a8ab;
  border: none 0;
  color: #fff;
  align-items: center;
  justify-content: center;
  margin: 1vh;
}

button:hover {
  background: #0F9295;
}

button:focus,
button:active {
    box-shadow: inset 0 0 3px  3px #f36;
}