html, body {
  box-sizing: border-box;
  background-color: #fff;
 /* max-width: 500px;*/
  /*margin: auto;*/
  /*padding: 5px;*/
  margin: 0;
  padding: 0;
  top: 0;
  bottom: 0;
  min-height: 100%;
  font-family: "Trebuchet MS", "Lucida Grande", "Lucida Sans Unicode", "Lucida Sans", Tahoma, sans-serif;
  color: #000;
  -webkit-text-size-adjust: 100%;
}

body {
  /*position: relative;*/
  height: 100%;
}

a:link {
    color: #000;
}

a:visited {
    color: #000;
}

a:hover {
    color: #000;
}

a:active {
    color: #0ff;
}

#canvas_ {
  cursor: crosshair;
  border: 1px solid #000000;
  
  z-index: 2;
  pointer-events: auto;
  position: absolute;
  top: 0px;
  left: 0px;
  /*bottom: 0;*/
  
  /*width: 100%;*/
  height: 100%;

  display: block;   /* this is IMPORTANT! */
  
  padding: 0px;
  margin: 0px;
  box-sizing: border-box;
  /*width: 100vw;
  height: 100vh;*/
}

#wrapper {
  /*width: 100%;*/
  /*height: 100%;*/
  width: 100vw;
  height: 100vh;
  padding:0;
  margin:0;
  box-sizing: border-box;
  border: 5px solid red;
}

.overlay {
  height: 100%;
  width: 100%;
  position: fixed;
  z-index: 1;
  top: 0;
  left: 0;
  background-color: rgb(0,0,0);
  background-color: rgba(0,0,0, 0.3);
  overflow-x: hidden;
  transition: 0.5s;
}

.overlay-content {
  position: relative;
  top: 25%;
  width: 100%;
  text-align: center;
  margin-top: 30px;
}

.overlay a {
  padding: 8px;
  text-decoration: none;
  font-size: 36px;
  color: #818181;
  display: block;
  transition: 0.3s;
}

.overlay a:hover, .overlay a:focus {
  color: #f1f1f1;
}

.overlay .closebtn {
  position: absolute;
  top: 20px;
  right: 45px;
  font-size: 60px;
}

@media screen and (max-height: 450px) {
  .overlay a {font-size: 20px}
  .overlay .closebtn {
  font-size: 40px;
  top: 15px;
  right: 35px;
  }
}