wagtail/client/scss/elements/_elements.scss

*,
::before,
::after {
  // Reset border styles so tailwinds default border class works as expected
  // https://tailwindcss.com/docs/preflight#border-styles-are-reset-globally
  border-width: 0;
  border-style: solid;
  // Set all elements to inherit their parent’s (border-box) box-sizing.
  box-sizing: inherit;
}

::before,
::after {
  --tw-content: '';
}

// Default to LTR if `dir` is not set.
:root,
:host,
[dir='ltr'] {
  // Flips the direction based on whether the UI is LTR or RTL. Used for:
  // - `transform` / `background-position` declarations for layout
  // - icons mirroring.
  // - Any other styles built with physical properties or values to mirror for RTL languages.
  --w-direction-factor: 1;
}

[dir='rtl'] {
  --w-direction-factor: -1;
}

html {
  height: 100%;
  // Set the whole admin to border-box by default.
  box-sizing: border-box;
  // Display viewport overscroll areas in a theme-appropriate color.
  background-color: theme('colors.surface-page');
}

body {
  overflow-x: hidden;
  position: relative;

  &:after {
    content: '';
    position: fixed;
    transition:
      visibility 0s linear 0s,
      opacity 0.2s ease-out;
    background: theme('colors.white-50');
    width: 100%;
    height: 100%;
    top: 0;
    inset-inline-start: 0;
    z-index: 5;
    opacity: 0;
    visibility: hidden;
  }
}

hr {
  border: 1px solid theme('colors.border-furniture');
  border-width: 1px 0 0;
  margin: 1.5em 0;
}

// general image style
img {
  max-width: 100%;
  height: auto;
}