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%;
}