Shortest dark mode in CSS

darkMode.css

/* https://dev.to/akhilarjun/one-line-dark-mode-using-css-24li */

html[theme='dark-mode'] {
    /* Inverse the colors of all HTML elements */
    filter: invert(1) hue-rotate(180deg);
}
html[theme='dark-mode'] img {
    /* Inverse the images back to normal */
    filter: invert(1) hue-rotate(180deg);
}
html {
    /* Animate the transition so it doesn't flash */
    transition: color 300ms, background-color 300ms;
}