<h1><b>color-mix()</b> is <u>awesome.</u></h1>

:root {
  /* change me! */
  --brand: #0af; 
  
  /* very dark brand blue */
  --text1: color-mix(var(--brand) 25%, black);
  --text2: color-mix(var(--brand) 40%, black);
  
  /* very bright brand white */
  --surface1: color-mix(var(--brand) 5%, white);
  
  /*  https://web.dev/prefers-color-scheme/  */
  color-scheme: light dark;
}

@media (prefers-color-scheme: dark) {
  :root {
    --text1: color-mix(var(--brand) 15%, white);
    --text2: color-mix(var(--brand) 40%, white);
    --surface1: color-mix(var(--brand) 5%, black);
  }
}

h1 {
  font-size: 10vmin;
  font-weight: 300;
}

b {
  color: var(--text2);
  font-family: ui-monospace, monospace;
}

u {
  text-decoration-color: var(--brand);
  text-underline-offset: .25ex;
}

html {
  block-size: 100%;
  inline-size: 100%;
}

body {
  color: var(--text1);
  background: var(--surface1);
  min-block-size: 100%;
  min-inline-size: 100%;
  margin: 0;
  box-sizing: border-box;
  display: grid;
  place-content: center;
  font-family: system-ui, sans-serif;
}