transitions w3schools code example
Example 1: html transition
html.color-theme-in-transition,
html.color-theme-in-transition *,
html.color-theme-in-transition *:before,
html.color-theme-in-transition *:after {
transition: all 750ms !important;
transition-delay: 0 !important;
}
Example 2: Using CSS transitions
div {
transition: <property> <duration> <timing-function> <delay>;
}