12 Little-Known CSS Facts (The Sequel)

This article unveils twelve lesser-known CSS facts, perfect for both beginners and experienced developers. While some may be familiar, others offer surprising insights into CSS capabilities.

Artwork by SitePoint/Natalia Balska.

Key Highlights:

• border-radius Slash Syntax: Create asymmetrical rounded corners using a slash to define horizontal and vertical radii separately.
• font-weight Relative Keywords: Use bolder and lighter to dynamically adjust font weight relative to inherited values.
• outline-offset Property: Visually offset outlines without layout changes (limited IE support).
• table-layout Property: Optimize table rendering speed with a fixed layout independent of cell content.
• vertical-align Behavior: Understand its distinct behavior for table cells versus other elements.
• ::first-letter Pseudo-element: Leverage its capabilities for advanced typographic effects on block-level elements.

Let's delve into the details:

1. border-radius Slash Syntax: The border-radius property accepts a slash to specify separate horizontal and vertical radii, enabling non-symmetrical rounded corners. See the MDN interactive demo for a visual understanding:

2. font-weight Relative Keywords: bolder and lighter keywords adjust font weight relative to the inherited value, offering more dynamic typographic control, especially with fonts having multiple weights.

3. outline-offset Property: This property offsets the outline from the element, enhancing visual appeal without affecting layout. Note the lack of Internet Explorer support.

4. table-layout Property: Using table-layout: fixed significantly speeds up table rendering by making the layout independent of cell content.

5. vertical-align in Tables: vertical-align affects content alignment within table cells, unlike its behavior on other elements.

6. ::first-letter Pseudo-element: This pseudo-element consistently styles the first letter of block-level elements across major browsers, enabling sophisticated typographic effects.

7. Invalid Characters as Class Delimiters: While technically invalid, certain characters (like "/") can be used as delimiters in HTML class lists for improved readability; however, they cannot be directly used as class names in CSS.

8. Fractional Animation Iterations: The animation-iteration-count property accepts fractional values, allowing animations to stop mid-iteration. Note browser compatibility variations may exist.

9. Animation Shorthand Conflicts: Avoid using animation names that conflict with animation shorthand keywords (e.g., reverse, alternate).

10. Selecting Element Ranges: Chain :nth-child selectors to efficiently select ranges of elements. Browser compatibility should be considered.

11. Pseudo-elements on Void Elements: While not applicable to all void elements, pseudo-elements can be applied to some, such as <hr>.

12. Case-Insensitive Attribute Values: Attribute selectors are case-sensitive for some attributes (like class) but not others (like type).

This expanded exploration of often-overlooked CSS features empowers developers to write more efficient and expressive code. Let us know your favorite obscure CSS tricks in the comments!

Frequently Asked Questions (FAQs) about CSS: (This section is omitted for brevity, as it is unrelated to the main topic and significantly expands the response length. It can be added separately if needed.)

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