CSS entries starting with “R”

Every CSS entry starting with R, grouped by kind. Pseudo-classes, pseudo-elements and types are filed by their first letter, ignoring the leading :, :: or <.

Name	Description
Color
`rebeccapurple`	Named colour #663399.
`red`	Named colour #ff0000.
`rosybrown`	Named colour #bc8f8f.
`royalblue`	Named colour #4169e1.
Descriptor
`range`	An @counter-style descriptor: the values the style can represent.
`result`	An @function descriptor: the value the custom function returns.
Function
`radial-gradient()`	An image of colours radiating out from a centre as a circle or ellipse.
`random()`	A random value between a minimum and a maximum.
`ray()`	A straight motion path at an angle, for offset-path.
`rect()`	A rectangle given by its edge positions from the top and left.
`referrer-policy()`	url() modifier setting the referrer policy for the request.
`rem()`	The remainder of a division, with the sign of the dividend.
`repeat()`	Repeats a pattern of grid tracks a set number of times or as many as fit.
`repeating-conic-gradient()`	A conic gradient whose stops repeat, for rays and checkerboards.
`repeating-linear-gradient()`	A linear gradient whose stops repeat, for stripes.
`repeating-radial-gradient()`	A radial gradient whose stops repeat, for concentric rings.
`rgb()`	An sRGB colour from red, green and blue channels, with optional alpha.
`rgba()`	Legacy alias of rgb() with the same arguments.
`rotate()`	Turns a box clockwise around its transform origin.
`rotate3d()`	Rotates a box around an arbitrary 3D axis.
`rotateX()`	Rotates a box around the x axis.
`rotateY()`	Rotates a box around the y axis.
`rotateZ()`	Rotates a box around the z axis, like rotate().
`round()`	Rounds a value to a multiple of a step.
Keyword
`revert`	Roll back to the previous cascade origin, such as the browser's style.
`revert-layer`	Roll back to the value from the previous cascade layer.
`revert-rule`	Use the value the property would have without the current rule.
Media feature
`resolution`	The pixel density of the output device.
Property
`r`	The radius of an SVG circle.
`reading-flow`	Makes focus and reading order follow a flex or grid layout's visual order.
`reading-order`	Moves an item within its container's reading flow.
`resize`	Gives an element a handle the user can drag to resize it.
`right`	The distance of a positioned box from the right of its containing block.
`rotate`	Rotates a box in 2D or around a 3D axis.
`row-gap`	The space between rows of a grid or lines of a flex container.
`row-rule`	Shorthand for the width, style and colour of lines between rows.
`row-rule-break`	Whether row rules break into segments where gaps intersect.
`row-rule-color`	The colour of lines drawn between rows.
`row-rule-inset`	Shorthand for the cap and junction insets of row rules.
`row-rule-inset-cap`	Insets of row rule ends at the container edges.
`row-rule-inset-cap-end`	Inset of a row rule end at the container edge.
`row-rule-inset-cap-start`	Inset of a row rule start end at the container edge.
`row-rule-inset-end`	Inset of the end of each row rule segment.
`row-rule-inset-junction`	Insets of row rule ends where they meet other rules.
`row-rule-inset-junction-end`	Inset of a row rule end where it meets other rules.
`row-rule-inset-junction-start`	Inset of a row rule start end where it meets other rules.
`row-rule-inset-start`	Inset of the start end of each row rule segment.
`row-rule-style`	The line style of rules drawn between rows.
`row-rule-visibility-items`	Which row gap segments get a rule, based on neighbouring items.
`row-rule-width`	The thickness of lines drawn between rows.
`ruby-align`	How ruby text and its base are spread when their lengths differ.
`ruby-overhang`	Whether a wide ruby annotation may hang over neighbouring text.
`ruby-position`	Whether ruby annotations sit over or under the base text.
`rule`	Sets column-rule and row-rule together to draw lines in every gap.
`rule-break`	Sets column-rule-break and row-rule-break together.
`rule-color`	Sets column-rule-color and row-rule-color together.
`rule-inset`	Sets every cap and junction inset of column and row rules together.
`rule-inset-cap`	Sets the cap insets of column and row rules together.
`rule-inset-end`	Sets the end insets of column and row rules together.
`rule-inset-junction`	Sets the junction insets of column and row rules together.
`rule-inset-start`	Sets the start insets of column and row rules together.
`rule-overlap`	Whether row or column rules are painted on top where they cross.
`rule-style`	Sets column-rule-style and row-rule-style together.
`rule-visibility-items`	Sets column-rule-visibility-items and row-rule-visibility-items together.
`rule-width`	Sets column-rule-width and row-rule-width together.
`rx`	The horizontal radius of an SVG ellipse or rounded rect corner.
`ry`	The vertical radius of an SVG ellipse or rounded rect corner.
Pseudo-class
`:read-only`	Matches elements the user cannot edit.
`:read-write`	Matches editable inputs, textareas and contenteditable elements.
`:required`	Matches form controls that must have a value before submitting.
`:right`	In @page, matches right-hand pages of a double-sided document.
`:root`	Matches the root element of the document, html in HTML.
Type
`<ratio>`	Two numbers separated by a slash, such as an aspect ratio.
`<relative-size>`	larger or smaller: one step from the parent's font size.
`<resolution>`	The pixel density of a device or image.
Unit
`rad`	Radians; a full circle is 2 pi.
`rcap`	The cap height of the root element's font.
`rch`	The advance width of the digit 0 in the root element's font.
`rem`	The root element's font size.
`rex`	The x-height of the root element's font.
`ric`	The ic unit measured on the root element.
`rlh`	The root element's line height.