#btn1 {
    position: relative;
    display: inline-block;
    padding: 15px 40px;
    font-size: 18px;
    color: white;
    background: linear-gradient(90deg, #ff416c, #ff4b2b);
    border: none;
    border-radius: 8px;
    cursor: pointer;
    overflow: hidden;
    transition: 0.3s;
  }

  #btn1::before {
    content: "";
    position: absolute;
    top: 0;
    left: -100%;
    width: 300%;
    height: 100%;
    background: linear-gradient(90deg, #ff416c, #ff4b2b, #ff416c);
    transition: transform 0.8s ease-in-out;
  }

  #btn1:hover::before {
    transform: translateX(100%);
  }