The from keyword for color functions (color(), hsl(), oklch(), etc.) creates a new color based on a given color by modifying the values of the input color. Also known as relative color syntax (RCS).

The backdrop-filter CSS property applies graphical effects such as blurring or color shifting to the area behind an element.

The @starting-style CSS at-rule sets the starting values for properties that are transitioning when the target element's style is first updated.

The / notation in content CSS property values adds alternative text to generated content. For example, the content: url('upvote-icon.svg') / 'Upvote' declaration adds accessible 'Upvote' text to the SVG icon. Also known as alternate text.

The round(), mod(), and rem() CSS functions compute rounded values and the remainder after division.

The light-dark() CSS function accepts two colors and uses one depending on the current color scheme.

The writing-mode CSS property orients form elements (such as radio buttons, progress bars, or select menus) vertically when the writing mode is vertical-lr or vertical-rl. The direction CSS property sets whether inputs flow from top to bottom or bottom to top.