CSS one-liner to improve form elements

The CSS `accent-color` property lets you theme native form elements like checkboxes, radio buttons, range sliders, and progress bars with a single line of CSS. Set it on the `html` element or any container, and it cascades down as an inherited property. The browser automatically handles contrast ratios, choosing appropriate foreground colors (e.g., white checkmarks on dark backgrounds) without requiring custom-built components.