REM units
html {
font-size: 6.25%; /* =1px */
/* Since most browsers have a default value of 16px. Alternatively, people quite often
use 62.5% instead and adjust children REM units accordingly. */
}
body {
font-size: 14rem; /* =14px */
}
h1 {
font-size: 24rem; /* =24px */
}
Default HTML font size: https://stackoverflow.com/questions/24542508/default-html-font-size
Even better approach: https://css-tricks.com/rems-ems/