Are class names in CSS selectors case sensitive?
Yes, CSS class selectors are case-sensitive. These two might look like siblings, but they get treated like complete strangers: .menuItem versus .menuitem.
Example:
Getting to the crux of case sensitivity
HTML and CSS: A tale of two sensitivities
Strangely enough, HTML class names and CSS class selectors don't share the same viewpoint on cases. In CSS, class selectors are case-sensitive. But when it comes to HTML, class names are actually case-insensitive. Confused much? Let's go deeper.
The fuss about CSS properties
By default, CSS properties, values, pseudo-classes, and element names are case-insensitive. So whether you're shouting in all caps (e.g. DISPLAY: BLOCK;) or whispering in lowercase (e.g. display: block;), CSS hears you just fine.
The Document Object Model and quirks mode
The DOM (Document Object Model) in browsers can influence the way your CSS behaves. Most modern browsers adhere to a standard mode, which treats selectors as case-sensitive. However, the quirks mode throws a wrench into the works by treating all selectors as case-insensitive.
The future of CSS and case insensitivity
There's a glimmer of hope for those seeking case insensitivity in CSS selectors. Selectors Level 4, which is still in draft, proposes the ability to make attribute searches case-insensitive using the "i" flag, like so: [class~="SelfCatering" i].
Case Sensitive CSS classes:
💂♀️ Maggie: Very specific, only responds to "Maggie". 👱♀️ maggie: Different entity, only responds to "maggie".
Case Insensitive:
👮♀️Charlie: Equally responds to both "Charlie" and "charlie".
## Developer's guide: navigating case sensitivity
### Consistency is king
Inconsistencies can make code maintenance a nightmare and ruin your weekend plans. Be that **mindful developer** who sticks to consistent class naming in both your HTML and CSS.
### Embrace modern doctypes
Don't let your HTML live in the past. Use a **modern HTML doctype**, because consistency across all browsers is what we're all about.
### Mind the language-specific rules
Are you a **polyglot** programmer dealing with languages like **XML** that are **case-sensitive?** Make sure to remember these language-specific rules and quirks.
### Be future-proof
Get acquainted with the **Selectors Level 4** proposal, and be that developer who's always prepared for the future.
## Potential gotchas and how to tackle them
### Different browsers, different rules
Browsers can sometimes be that pesky kid who refuses to follow the rules. Make sure you **test thoroughly** across different browsers to ensure a consistent experience.
### Team chaos
When working in teams, maintaining a common **CSS naming convention** can save you from mixed-up class names and a lot of heartache.
### Dynamic fails
Handling **dynamically generated class names** can be tricky. Ensure that your JavaScript or server-side languages match the cases used in your CSS.
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