html {
  font-size: 16px;
  font-family: sans-serif;
}
body {
  margin: 0;
  background: #1E1E1E;
  color: #999999;
}
header {
  background-color: #1E1E1E;
  opacity: 0.8;
  background-image:  repeating-linear-gradient(45deg, #666666 25%, transparent 25%, transparent 75%, #666666 75%, #666666), repeating-linear-gradient(45deg, #666666 25%, #1E1E1E 25%, #1E1E1E 75%, #666666 75%, #666666);
  background-position: 0 0, 10px 10px;
  background-size: 20px 20px;
  padding: 0 1rem;
}
.header-center {
  display: flex;
  justify-content: space-between;
  align-items: center;
  width: 70%;
  height: 100px;
  margin: 0 auto;
  color: #fff;
}
.header-center h1 {
  margin: 0;
}
nav {
  display: flex;
  flex-direction: column;
  height: 100%;
  align-items: center;
  justify-content: space-around;
}
main {
  padding: 1rem;
}
a, a:visited {
  text-decoration: none;
  color: #ffffff;
}
a:active, a:hover {
  color: #888888;
}
div.input-line {
  display: flex;
  flex-wrap: wrap;
  gap: 1rem;
  margin-bottom: 1rem;
  align-items: center;
}
div.input-unit {
  display: flex;
  flex: 1;
  gap: 0.5rem;
}
span.button-label {
  height: 40px;
  width: 6rem;
  display: inline-flex;
  align-items: center;
}
button {
  cursor: pointer;
  background-color: #e7e7e7;
  border: none;
  height: 40px;
  width: 100px;
}
button:disabled {
  cursor: default;
}
button:not(:disabled):hover {
  background-color: #555555;
  color: white;
}
select {
  border: none;
  background-color: #e7e7e7;
  height: 40px;
  width: 120px;
  padding-left: 0.5rem;
}
code, pre {
  font-family: monospace;
  display: block;
  overflow-x: auto;
  padding: 0.5em;
  background: #282828;
  color: #ebdbb2;
}
#game {
  display: block;
  width: 80%;
  height: calc(100vh - 150px);
  margin: 0 auto;
  border: 1px solid white;
  background-color: black;
}

@media (max-width: 700px) {
  html {
    font-size: 32px;
  }
  body {
    font-size: 0.75rem;
  }
  .header-center {
    width: auto;
    margin: 0;
  }
  .header-center h1 {
    display: none;
  }
  nav {
    flex-direction: row;
    justify-content: space-between;
    width: 100%;
  }
}