body {
    background-image: url('ntu.jpg');
    background-size: cover;
    background-attachment: fixed;
    background-repeat: no-repeat;
    background-color: #f4f0f0;
    color: #ffffff;
}
body {
    margin: 0;
    padding: 0;
    font-family: Arial, sans-serif;
}
/* === removing default button style ===*/
.button {
    margin: 0;
    height: auto;
    background: transparent;
    padding: 0;
    border: none;
    cursor: pointer;
  }
  
  /* button styling */
  .button {
    --border-right: 6px;
    --text-stroke-color: rgba(255,255,255,0.6);
    --animation-color: #da7e15;
    --fs-size: 2em;
    letter-spacing: 3px;
    text-decoration: none;
    font-size: var(--fs-size);
    font-family: "Arial";
    position: relative;
    text-transform: uppercase;
    color: transparent;
    -webkit-text-stroke: 1px var(--text-stroke-color);
  }
  .button-container {
    position: fixed;
    top: 20px; /* 距离页面顶部的距离 */
  }
  /* this is the text, when you hover on button */
  .hover-text {
    position: absolute;
    -webkit-box-sizing: border-box;
            box-sizing: border-box;
    content: attr(data-text);
    color: var(--animation-color);
    width: 0%;
    inset: 0;
    border-right: var(--border-right) solid var(--animation-color);
    overflow: hidden;
    -webkit-transition: 0.5s;
    transition: 0.5s;
    -webkit-text-stroke: 1px var(--animation-color);
  }
  .button-container {
    position: fixed;
    top: 20px; /* 距离页面顶部的距离 */
    left: 50%; /* 水平居中 */
    transform: translateX(-50%); /* 居中处理 */
  }
  

  


  /* hover */
  .button:hover .hover-text {
    width: 100%;
    -webkit-filter: drop-shadow(0 0 23px var(--animation-color));
            filter: drop-shadow(0 0 23px var(--animation-color))
  }