advance.css

@charset "UTF-8";
@import url('base.css'); @import "theme.css" layer(utilities);
@import url("landscape.css") screen and (orientation: landscape);

@namespace author url(http://www.xkeshav.com);

/* this is pre defined variable and this :root {} must be escaped, 
:root {
  --black: hsl(0, 0%, 0%);
}  
*/

@media (prefers-color-scheme: dark) {
  :root {
    --accent-color: hsl(225, 31%, 96%);
    --background-color: hsl(0, 2%, 20%);
  }
}

@container (width > 400px) and (width > 800px) or (orientation: portrait) {
  input[type='radio']:checked + label {
    text-decoration-color: Black;
  }
}

* {
  font-size: 18px;
  background-color: hsl(270 60% 70%);
}

.profile > #image {
  animation: 3s infinite alternate flash;
}

.author:is(h1)::before {
  content: 'publisher', 'Keshav Mohta';
  background-color: whitesmoke !important;
}

@page {
  size: landscape;
  margin: 20%;
  background-color: #1a10;
  @top-left {
    border-color: red;
  }
}

.class ~ .red {
  border-color: red;
}

/* unicode selector */
.♫ {
  display: block;
  background: #eee;
}

#© { /* matches the element with id="©" */
  caret-color: burlywood;
} 

::grammar-error {
  border-color: darkgoldenrod;
}

@keyframes flash {
  from, 0% {
    border-color: hwb(hue rgb(116, 59, 59) #666);
  }

  50%, 80% {
    background-color: rgba(100%, 50%, 0%, 0.1);
  }
}