• CSS
  • Your first website: Styling the content
  • Challenge: Styling a biography page
  • Combinators
  • Sizing items in CSS
  • Styling tables
  • Challenge: A cool-looking box
  • Styling links
  • Introduction to CSS layout
  • CSS grid layout
  • CSS reference
  • Modules
    1. CSS basic user interface
    2. CSS cascading and inheritance
    3. CSS conditional rules
    4. CSS display
    5. CSS fonts
    6. CSS images
    7. CSS masking
    8. CSS namespaces
    9. CSS paged media
    10. CSS ruby layout
    11. CSS scroll-driven animations
    12. CSS shapes
    13. CSS text decoration
    14. CSS view transitions
    15. -moz-float-edge Non-standard Deprecated
    16. -moz-force-broken-image-icon Non-standard Deprecated
    17. -moz-image-region Non-standard
    18. -moz-orient Non-standard
    19. -moz-user-focus Non-standard Deprecated
    20. -moz-user-input Non-standard Deprecated
  • -webkit-*
    1. -webkit-border-before Non-standard
    2. -webkit-box-reflect Non-standard
    3. -webkit-mask-box-image Non-standard
    4. -webkit-mask-composite Non-standard
    5. -webkit-mask-position-x Non-standard
    6. -webkit-mask-position-y Non-standard
    7. -webkit-mask-repeat-x Non-standard
    8. -webkit-mask-repeat-y Non-standard
    9. -webkit-tap-highlight-color Non-standard
    10. -webkit-text-security Non-standard
    11. -webkit-touch-callout Non-standard
  • align-items
  • anchor-name Experimental
  • animation-*
    1. animation-direction
    2. animation-name
    3. animation-range Experimental
    4. animation-range-end Experimental
    5. animation-range-start Experimental
    6. animation-timeline Experimental
    7. backdrop-filter
    8. background-blend-mode
    9. background-origin
    10. background-repeat
    11. border-block
    12. border-block-end-style
    13. border-block-start-style
    14. border-bottom
    15. border-bottom-style
    16. border-end-end-radius
    17. border-image-repeat
    18. border-inline
    19. border-inline-end-style
    20. border-inline-start-style
    21. border-left
    22. border-radius
    23. border-right-width
    24. border-style
    25. border-top-right-radius
    26. bottom
    27. box-*
      1. box-align Non-standard Deprecated
      2. box-direction Non-standard Deprecated
      3. box-flex Non-standard Deprecated
      4. box-flex-group Non-standard Deprecated
      5. box-lines Non-standard Deprecated
      6. box-ordinal-group Non-standard Deprecated
      7. box-orient Non-standard Deprecated
      8. box-pack Non-standard Deprecated
      9. break-before
      10. clear
      11. clip-*
        1. clip Deprecated
        2. color-interpolation
        3. column-fill
        4. column-rule-style
        5. columns
        6. contain-*
          1. contain-intrinsic-inline-size
          2. container-name
          3. counter-increment
          4. cx
          5. display
          6. field-sizing Experimental
          7. fill-*
            1. filter
            2. flex-*
              1. flex-flow
              2. float
              3. font-family
              4. font-optical-sizing
              5. font-smooth Non-standard
              6. font-stretch Deprecated
              7. font-synthesis-position Experimental
              8. font-variant
              9. font-variant-emoji
              10. font-variation-settings
              11. grid
              12. grid-auto-rows
              13. grid-row
              14. grid-template-areas
              15. height
              16. image-orientation
              17. image-resolution Experimental
            3. inset-block
            4. inset-inline-end
            5. interpolate-size Experimental
            6. justify-self
          8. line-break
          9. line-height-step Experimental
        7. list-*
          1. list-style-type
        8. margin-*
          1. margin-block-start
          2. margin-inline-start
          3. margin-trim Experimental
        9. marker-*
          1. marker-start
        10. mask-*
          1. mask-border-outset
          2. mask-border-width
          3. mask-mode
          4. mask-size
          5. math-shift Experimental
          6. max-inline-size
          7. min-inline-size
          8. object-position
          9. offset-*
            1. offset-path
            2. order
            3. outline-offset
            4. overflow-anchor
            5. overflow-wrap
            6. overlay Experimental
            7. overscroll-*
              1. overscroll-behavior-x
              2. padding-block-end
              3. padding-inline-end
              4. padding-top
            8. page-*
              1. page-break-after Deprecated
              2. page-break-before Deprecated
              3. page-break-inside Deprecated
            9. place-content
            10. position
            11. position-anchor Experimental
            12. position-area Experimental
            13. position-try Experimental
            14. position-try-fallbacks Experimental
            15. position-try-order Experimental
            16. position-visibility Experimental
          10. resize
          11. ruby-align
          12. scale
          13. scroll-*
            1. scroll-margin-block-end
            2. scroll-margin-inline-end
            3. scroll-margin-top
            4. scroll-padding-block-start
            5. scroll-padding-inline-start
            6. scroll-snap-align
            7. scroll-timeline Experimental
            8. scroll-timeline-axis Experimental
            9. scroll-timeline-name Experimental
          14. scrollbar-*
            1. shape-image-threshold
            2. speak-as Experimental
            3. stroke-dasharray
            4. stroke-miterlimit
            5. table-layout
            6. text-*
              1. text-box
              2. text-decoration
              3. text-decoration-skip Experimental
              4. text-emphasis
              5. text-indent
              6. text-rendering
              7. text-size-adjust Experimental
              8. text-spacing-trim Experimental
              9. text-wrap
              10. timeline-scope Experimental
              11. transform-box
              12. transition-behavior
              13. transition-timing-function
            7. user-modify Non-standard Deprecated
            8. view-timeline Experimental
            9. view-timeline-axis Experimental
            10. view-timeline-inset Experimental
            11. view-timeline-name Experimental
            12. white-space-collapse
            13. word-break
            14. y
            15. Attribute selectors
            16. Universal selectors
          15. Combinators
            1. Column combinator Experimental
            2. Selector list
            3. :-moz-broken Non-standard Deprecated
            4. :-moz-drag-over Non-standard
            5. :-moz-first-node Experimental Non-standard
            6. :-moz-handler-blocked Non-standard
            7. :-moz-handler-crashed Non-standard
            8. :-moz-handler-disabled Non-standard
            9. :-moz-last-node Experimental Non-standard
            10. :-moz-loading Non-standard
            11. :-moz-locale-dir(ltr) Non-standard
            12. :-moz-locale-dir(rtl) Non-standard
            13. :-moz-only-whitespace Non-standard
            14. :-moz-submit-invalid Non-standard
            15. :-moz-suppressed Non-standard
            16. :-moz-user-disabled Non-standard
            17. :-moz-window-inactive Non-standard
          16. :blank Experimental
          17. :current Experimental
          18. :disabled
          19. :first-child
          20. :focus-within
        11. :has()
        12. :hover
        13. :is()
        14. :left
        15. :local-link Experimental
        16. :nth-child()
        17. :only-child
        18. :out-of-range
        19. :placeholder-shown
        20. :read-write
        21. :scope
        22. :target
        23. :target-within Experimental
        24. :visited
        25. ::-moz-color-swatch Non-standard
        26. ::-moz-focus-inner Experimental Non-standard
        27. ::-moz-list-bullet Experimental Non-standard
        28. ::-moz-list-number Experimental Non-standard
        29. ::-moz-meter-bar Non-standard
        30. ::-moz-progress-bar Experimental Non-standard
        31. ::-moz-range-progress Non-standard
        32. ::-moz-range-thumb Non-standard
        33. ::-moz-range-track Non-standard
      12. ::-webkit-*
        1. ::-webkit-inner-spin-button Non-standard
        2. ::-webkit-meter-bar Non-standard Deprecated
        3. ::-webkit-meter-even-less-good-value Non-standard
        4. ::-webkit-meter-inner-element Non-standard
        5. ::-webkit-meter-optimum-value Non-standard
        6. ::-webkit-meter-suboptimum-value Non-standard
        7. ::-webkit-progress-bar Non-standard
        8. ::-webkit-progress-inner-element Non-standard
        9. ::-webkit-progress-value Non-standard
        10. ::-webkit-scrollbar Non-standard
        11. ::-webkit-search-cancel-button Non-standard
        12. ::-webkit-search-results-button Non-standard
        13. ::-webkit-slider-runnable-track Non-standard
        14. ::-webkit-slider-thumb Non-standard
      13. ::cue
      14. ::first-line
      15. ::part()
      16. ::spelling-error
      17. ::view-transition-image-pair
      18. @color-profile
      19. @document Non-standard Deprecated
      20. @import
      21. @namespace
      22. @position-try Experimental
      23. @supports
      24. -moz-image-rect Non-standard Deprecated
      25. anchor-size() Experimental
      26. anchor() Experimental
      27. attr()
      28. calc-size() Experimental
      29. color-mix()
      30. cos()
      31. cubic-bezier()
      32. element() Experimental
      33. fit-content()
      34. hwb()
      35. inset()
      36. lch()
      37. log()
      38. min()
      39. oklch()
      40. palette-mix() Experimental
      41. scale3d()
      42. scroll() Experimental
      43. sin()
      44. steps()
      45. translateZ()
      46. view() Experimental
      47. <angle-percentage>
      48. <blend-mode>
      49. <color-interpolation-method>
      50. <custom-ident>
      51. <display-inside>
      52. <display-outside>
      53. <frequency-percentage>
      54. <hex-color>
      55. <image>
      56. <line-style>
      57. <overflow>
      58. <position-area> Experimental
      59. <resolution>
      60. <shape> Deprecated
      61. <time-percentage>
      62. Guides
      63. Animations
        1. Box alignment in block layout
        2. Introduction to the CSS basic box model
        3. Using relative colors
        4. Basic concepts of multi-column layout
        5. Handling content breaks in multi-column layout
      64. Conditional rules
        1. Using container size and style queries
      65. CSSOM view
        1. Introduction to formatting contexts
        2. Basic concepts of flexbox
        3. Controlling ratios of flex items along the main axis
        4. Variable fonts guide
      66. Grid
        1. Grid template areas
        2. Grids, logical values, and writing modes
        3. Masonry layout Experimental
      67. Images
        1. Basic concepts of logical properties and values
        2. Using CSS math functions
      68. Media queries
        1. Printing
      69. Nesting style rules
        1. Understanding z-index
      70. Scroll snap
        1. Basic shapes with shape-outside
        2. Using CSS transitions
      71. Center an element
      72. List group with badges
      73. Color picker tool
      74. Learn more
      75. See full compatibility
  • The @import at-rule is used to import style rules from other valid stylesheets. An @import rule must be defined at the top of the stylesheet, before any other at-rule (except @layer) and style declarations, or it will be ignored.

    Syntax

    css
    @import url;
    @import url layer;
    @import url layer(layer-name);
    @import url layer(layer-name) supports(supports-condition);
    @import url layer(layer-name) supports(supports-condition) list-of-media-queries;
    @import url layer(layer-name) list-of-media-queries;
    @import url supports(supports-condition);
    @import url supports(supports-condition) list-of-media-queries;
    @import url list-of-media-queries;
    

    where:

    url

    Is a <url> type representing the location of the resource to import. The URL may be absolute or relative.

    list-of-media-queries

    Is a comma-separated list of media queries, which specify the media-dependent conditions for applying the CSS rules defined in the linked URL. If the browser does not support any of these queries, it does not load the linked resource.

    layer-name

    Is the name of a cascade layer into which the contents of the linked resource are imported.

    supports-condition

    Indicates the feature(s) that the browser must support in order for the stylesheet to be imported. If the browser does not conform to the conditions specified in the supports-condition, it may not fetch the linked stylesheet, and even if downloaded through some other path, will not load it. The syntax of supports() is almost identical to that described in @supports, and that topic can be used as a more complete reference.

    Use @import together with the layer keyword or layer() function to import external style sheets (from frameworks, widget stylesheets, libraries, etc.) into layers.

    Description

    Imported rules must come before all other types of rules, except @layer statements.

    css
    * {
      margin: 0;
      padding: 0;
    }
    /* more styles */
    @import url("my-imported-styles.css");
    

    As the @import at-rule is declared after the styles it is invalid and hence ignored.

    css
    @import url("my-imported-styles.css");
    * {
      margin: 0;
      padding: 0;
    }
    /* more styles */
    

    The @import rule is not a conditional group at-rules.

    So that media queries after the URL. In the absence of any media query, the import is not conditional on the media used. Specifying all for the list-of-media-queries has the same effect.

    Similarly, user agents can use the supports() function in an @import at-rule to only fetch resources if a particular feature set is (or is not) supported. This allows authors to take advantage of recently introduced CSS features, while providing graceful fallbacks for older browser versions. Note that the conditions in the supports() function of an @import at-rule can be obtained in JavaScript using CSSImportRule.supportsText.

    The @import rule can also be used to create a <string> ][ '.' [ supports( ] ) ?

    <url()> =
    url( |
    * )

    <supports-condition> =
    not <supports-in-parens> * *

    <supports-in-parens> =
    ( <supports-condition> ) <declaration> )

    Examples

    Importing CSS rules

    css
    @import "custom.css";
    @import url("chrome://communicator/skin/");
    

    The two examples above show how to specify the url as a <string> and as a url() function.

    Importing CSS rules conditional on media queries

    css
    @import url("fine-print.css") print;
    @import url("bluish.css") print, screen;
    @import "common.css" screen;
    @import url("landscape.css") screen and (orientation: landscape);
    

    The @import rules in the above examples show media-dependent conditions that will need to be true before the linked CSS rules are applied. So for instance, the last @import rule will load the landscape.css stylesheet only on a screen device in landscape orientation.

    Importing CSS rules conditional on feature support

    css
    @import url("gridy.css") supports(display: grid) screen and (max-width: 400px);
    @import url("flexy.css") supports((not (display: grid)) and (display: flex))
      screen and (max-width: 400px);
    

    The @import rules above illustrate how you might import a layout that uses a grid if display: grid is supported, and otherwise imports CSS that uses display: flex. While you can only have one supports() statement, you can combine any number of feature checks with not, and, and or. However, you must use parenthesis to define precedence when you mix them, e.g. supports((..) or (..) and not (..)) is invalid, but supports((..) or ((..) and (not (..)))) is valid. Note that if you just have a single declaration then you don't need to wrap it in additional parentheses: this is shown in the first example above.

    The examples above show support conditions using basic declaration syntax. You can also specify CSS functions in supports(), and it will evaluate to true if they are supported and can be evaluated on the user-agent. For example, the code below shows an @import that is conditional on both child combinators (selector()) and the font-tech() function:

    css
    @import url("whatever.css")
    supports((selector(h2 > p)) and (font-tech(color-COLRv1)));
    

    Importing CSS rules into a cascade layer

    css
    @import "theme.css" layer(utilities);
    

    In the above example, a cascade layer named utilities is created and it will include rules from the imported stylesheet theme.

    css
    @import url(headings.css) layer(default);
    @import url(links.css) layer(default);
    
    @layer default {
      audio[controls] {
        display: block;
      }
    }
    

    In the above example, the rules in headings.css and links.css stylesheets cascade within the same layer as the audio[controls] rule.

    css
    @import "theme.css" layer();
    @import "style.css" layer;
    

    This is an example of creating two separate unnamed cascade layers and importing the linked rules into each one separately. A cascade layer declared without a name is an unnamed cascade layer. Unnamed cascade layers are finalized when created: they do not provide any means for re-arranging or adding styles and they cannot be referenced from outside.

    Specifications

    Specification
    CSS Cascading and Inheritance Level 5
    # at-import

    Browser compatibility

    BCD tables only load in the browser

    See also