* {
  padding: 0;
  margin: 0;
  box-sizing: border-box;
}
html {
  font-family: sans-serif;
}

body {
  height: 100%;
}

[layout]:focus {
  background: black !important;
  outline: none !important;
}
[layout]:focus * {
  border-color: gold !important;
}

[layout] {
  transition: all 0.5s;
  width: 100%;
  align-items: stretch;
  padding: 1rem;
  height: 100vh;
  border: 4px solid black;
}

[layout] > * {
  border: 2px solid rgba(0, 0, 0, 0.5);
  justify-self: center;
  width: 100%;
  overflow: hidden;
}

.selected * {
  border-color: gold !important;
}
[br] {
  border-right: 2px solid rgba(0, 0, 0, 0.5) !important;
}
[bb] {
  border-bottom: 2px solid rgba(0, 0, 0, 0.5) !important;
}
[gap="none"] > * {
  border: none;
  border-left: 2px solid rgba(0, 0, 0, 0.5);
  border-top: 2px solid rgba(0, 0, 0, 0.5);
}