gecko-dev/servo/resources/servo.css

input                   { background: white; min-height: 1.0em; padding: 0em; padding-left: 0.25em; padding-right: 0.25em; border: solid lightgrey 1px; color: black; white-space: nowrap; text-align: left; }
textarea                { background: white; min-height: 1.0em; padding: 0em; padding-left: 0.25em; padding-right: 0.25em; border: solid lightgrey 1px; color: black; white-space: pre; }
input::selection,
textarea::selection     { background: rgba(176, 214, 255, 1.0); color: black; }
button,
input[type="button"],
input[type="submit"],
input[type="reset"]     { background: lightgrey; border-top: solid 1px #EEEEEE; border-left: solid 1px #CCCCCC; border-right: solid 1px #999999; border-bottom: solid 1px #999999; text-align: center; vertical-align: middle; color: black; }
input[type="hidden"]    { display: none !important }
input[type="checkbox"],
input[type="radio"]     { font-family: monospace !important; border: none !important; background: transparent; }

input[type="checkbox"]::before { display: inline-block; border: solid currentcolor 1px; content: ""; padding: 0; width: 1em; height: 1em; text-align: center; }
input[type="checkbox"]:checked::before { content: "✓"; }
input[type="checkbox"]:indeterminate::before { content: "-"; }
input[type="radio"]::before { display: inline-block; border: solid currentcolor 1px; content: ""; padding: 0; width: 1em; height: 1em; border-radius: 50%; text-align: center; }
input[type="radio"]:checked::before { content: "●"; line-height: 1em; }

select                        { border-style: solid; border-width: 1px; background: white; }
select[multiple]              { padding: 0em 0.25em; }
select:not([multiple])        { padding: 0.25em 0.5em; border-radius: 6px; }
select:not([multiple])::after { content: ""; display: inline-block; border-width: 5.2px 3px 0 3px; border-style: solid; border-color: currentcolor transparent transparent transparent; margin-left: 0.5em; }
select:not([multiple]) option           { display: none !important; }
select:not([multiple]) option[selected] { display: inline !important; }
select[multiple] option                 { display: block !important; }
select[multiple] option[selected]       { background-color: grey; color: white; }
select[multiple]:focus option[selected] { background-color: darkblue; }

td[align="left"]    { text-align: left; }
td[align="center"]  { text-align: center; }
td[align="right"]   { text-align: right; }

center { text-align: -servo-center; }

input:not([type=radio i]):not([type=checkbox i]):not([type=reset i]):not([type=button i]):not([type=submit i]),
textarea {
  cursor: text;
  overflow: hidden;
  -servo-overflow-clip-box: content-box;
}

// https://html.spec.whatwg.org/multipage/rendering.html#the-details-and-summary-elements
details {
  display: block;
}
details::-servo-details-summary {
  margin-left: 40px;
  display: list-item;
  list-style: disclosure-closed;
}
details[open]::-servo-details-summary {
  list-style: disclosure-open;
}
details::-servo-details-content {
  margin-left: 40px;
  overflow: hidden;
  display: none;
}
details[open]::-servo-details-content {
  display: block;
}