style.css

@import url('https://fonts.googleapis.com/css2?family=Roboto&display=swap');

body {
    height: 100vh;
    margin: 0;
    display: flex;
    justify-content: center;
    align-items: center;
    font-family: 'Roboto', sans-serif;
}

.container {
    width: 320px;
    height: 120px;
    background-color: rgba(201, 201, 201, 0.377);
    border-radius: 10px;
    display: flex;
    justify-content: center;
    align-items: center;
    flex-direction: column;
}

span {
    font-size: 30px;
    color: #1b1b1b;
}

.generateBtn{
    text-decoration: none;
    display: inline-block;
    margin: 10px 20px;
    padding: 10px 30px;
    position: relative;
    border: 2px solid #1b1b1b;
    color: #1b1b1b;
    font-size: 14px;
    transition: .4s;
    background-color: inherit;
    border-radius: 5px;
    cursor: pointer;
}

.generateBtn:after {
    content: "";
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    width: 100%;
    height: 100%;
    margin: auto;
    border: 2px solid rgba(0, 0, 0, 0);
    transition: .4s;
    border-radius: 5px;
  }
  .generateBtn:hover:after {
    border-color: #1b1b1b;
    width: calc(100% - 10px);
    height: calc(100% + 10px);
  }