style-index.css

body {
  background: #2d2828;
  color: #fff;
  font-family: sans-serif;
}
a {
  color: #fff;
}
iframe {
  /* outline: 1px solid red; */
}
.container {
  display: flex;
}
.sidenav {
  width: 300px;
}
.sidenav-link {
  display: block;
  text-decoration: none;
  height: 50px;
  line-height: 50px;
  border-bottom: 1px solid gray;
}
.main {
  margin-left: 30px;
}
.tablist {
  width: 100%;
  height: 50px;
}