html body {
  margin: 0;
  padding: 0;
  overflow: hidden;
}

main {
  height: 100vh;
  display: grid;
  grid-template-columns: 10% 2fr 1fr;
  grid-template-rows: 10% auto 10%;
}

h1 {
  grid-column: 2 / 3;
}

#container {
  border: 1px solid green;
  grid-column: 2 / 3;
  grid-row: 2 / 3;
}

#parent {
  border: 1px solid blue;
  height: 300px;
  width: 300px;
  position: absolute;
}

#context {
  border: 1px solid red;
  height: 100px;
  width: 100px;
  position: fixed;
}

#options {
  grid-column: 3 / 4;
  grid-row: 1 /3;
  padding: 1em;
}

form > label {
  display: flex;
  background-color: white;
}

form > label > span {
  flex: 1;
}

form > label > select {
  margin-left: 8px;
}