CSS only theme toggles are possible by utilizing a checkbox and placing the body content below the checkbox in a container element. Then adding a transparent la

CSS only theme toggles are possible by utilizing a checkbox and placing the body content below the checkbox in a container element. Then adding a transparent label element that controls the checkbox state somewhere else on the page and styling a pseudo-button however one likes below the label. Then in CSS setting both the prefers-color-scheme media queries but also configuring how the colors should react when the checkbox state is changed. So if a user has prefers-color-scheme:light then when the theme switcher is clicked it styles the page the opposite (example selector: .theme-switch:checked ~ .pagebody). Can also add such styling as a default outside of media queries, too, for browsers that don't recognize prefers-color-scheme. Saving the state across pages however requires some JS but just wanted to comment that CSS-only toggles are possible.