html {
  background-image: url("/images/studbg.jpg");
  }
  
.main {
  border-color:black;
  border-style:solid;
  border-width:5px;
  width:79%;
  height:100%;
  
}

.box02{
background:url(images/back01.gif);
border:solid 1px #483b3c;
margin:1em auto; /* 中央寄せは0をautoに変更 */
padding:20px 0;
width:85%  /* 幅 */
}

.box-inner{
background:#fff;
border-bottom:2px dashed #c3c2ad;
border-top:2px dashed #c3c2ad;
box-shadow:0 4px 0 #fff,0 -4px 0 #fff;
padding:15px
}

body {
  font-family: "Inter", sans-serif;
  font-weight: 700;
  font-style: normal;
}

.links {
  background-color:purple;
  height:10%;
  width:80%;
  right:0px;
  top:0px;
  padding:0px;
  position: fixed;
  text-align:center;
}

.links a {
  background-color:grey;
  border: 3px solid red;
padding:15px;
text-align:center;
width:50%
}