style.css

* {
  font-family: 'Source Code Pro', monospace;
  color: white;
}
body {
  background: #181818;
  overflow-x: hidden;
}
#top {
  position: fixed;
  top: 0px;
  left: 0px;
  width: 100%;
  height: 100px;
  background: #282828;
  z-index: 1;
  overflow: hidden;
}
.menu {
  height: 80px;
  margin: 10px 10px 10px 10px;
  border: none;
  background: rgb(0, 128, 128, 0.25);
  cursor: pointer;
  padding-left: 20px;
  padding-right: 20px;
  transition: background 0.4s;
  border-radius: 3px;
  font-size: 16px;
}
.menu:hover {
  background: rgb(0, 0, 0, 0.25);
  text-decoration: underline;
}
.right {
  float: right;
}
.left {
  float: left;
}
#promotion {
  position: absolute;
  top: 200px;
  left: 100px;
  width: calc(100% - 200px);
}
#promotion-div {
  background-image: linear-gradient(to bottom right, #181818, rgb(0,128,128,0.25));
  padding: 1px 50px;
}
h1 {
  font-size: 50px;
}
#promotion button {
  margin: 50px 0px;
}

#shadow {
        position: fixed;
        top: 0px;
        left: 0px;
        height: 100%;
        width: 100%;
        background: rgb(0, 0, 0, 0.3);
        z-index: 10;
        visibility: hidden;
      }
      #message {
        position: fixed;
        top: 50%;
        left: 50%;
        width: 400px;
        height: 250px;
        padding: 20px;
        margin: -145px -220px;
        z-index: 11;
        border-radius: 3px;
        background: #282828;
        visibility: hidden;
      }
      #message-text {
        width: 100%;
        height: 170px;
        overflow-y: auto;
        overflow-x: hidden;
        line-height: 2;
        overflow: auto;
      }
      #message button {
        margin-top: 10px;
        float: right;
        height: 40px;
        background: rgb(0, 128, 128, 0.25);
        font-size: 16px;
        border-radius: 3px;
        border: none;
        transition: background 0.4s;
        padding-left: 20px;
        padding-right: 20px;
      }
      #message button:hover {
        background: rgb(0, 0, 0, 0.25);
        text-decoration: underline;
        cursor: pointer;
      }
      
input {
  width: 100%;
  font-size: 16px;
  background: transparent;
  border: none;
  border-bottom: 2px solid white;
  opacity: 0.8;
  outline: none;
}
input:hover {
  opacity: 0.9;
}
input:focus {
  opacity: 1;
}
.link {
  cursor: pointer;
  user-select: none;
  -webkit-user-select: none;
}
.link:hover {
  text-decoration: underline;
}