html {

  box-sizing: border-box;

}

*, *:before, *:after {

  box-sizing: inherit;

}

body {

  margin: 0;

  height: 100vh;

  overflow: hidden;

}

.top-nav {

  height: 40px;

  border-bottom: 1px solid #eee;

  padding: 5px;

}

.main-area {

  position: absolute;

  top: 40px;

  bottom: 0;

  left: 0;

  width: 100vw;

}

.viewer-container {

  width: 100%;

  height: 100%;

}