body {
  background-image: url(https://dangoweb.ga/wave.png); /* Background Image */
  color: white; /* Text color */
  text-align:center /* Center blocks */
}

html-col {
  color: orangered /* Text color */
}

css-col {
  color: blue /* Text color */
}

highlight {
  background-color: black; /* Background color */
  border: 10px solid black; /* Border size, design, color */
  border-radius: 10px /* Rounded border */
}

hidden {
  opacity: 0.5
}