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ValidateHTML

Vendor Prefix Without Standard Property

Vendor prefixes (-webkit-, -moz-, -ms-) were used for experimental CSS features. When a feature becomes standard, you should include the unprefixed version as well. Using only the prefixed version means your CSS only works in specific browsers.

Why It Matters

A -webkit- only property works in Chrome and Safari but fails in Firefox. Most modern CSS properties no longer need prefixes, so using them alone is often unnecessary clutter.

Common Causes

  • Copying an old snippet that only includes the prefixed property and never the standard one.
  • Disabling or omitting Autoprefixer, so the unprefixed fallback is never generated.
  • Assuming a feature is still experimental when it has been standardized for years.

Code Examples

Bad CSS
.box {
  -webkit-border-radius: 8px;
  -moz-border-radius: 8px;
  /* missing standard property */

  -webkit-transition: all 0.3s;
  /* missing standard property */
}
Good CSS
.box {
  border-radius: 8px;      /* no prefix needed since 2012 */
  transition: all 0.3s;    /* no prefix needed since 2013 */
}

/* Only use prefixes when actually needed: */
.scroll {
  -webkit-overflow-scrolling: touch; /* still iOS-only */
}

How to Fix

  • 1Always include the standard (unprefixed) property AFTER the prefixed versions.
  • 2Most properties no longer need prefixes: border-radius, transition, transform, flexbox, grid.
  • 3Use Autoprefixer in your build process to add necessary prefixes automatically.
  • 4Check caniuse.com to see if a prefix is still needed for your browser targets.

Frequently Asked Questions

Should the prefixed or standard property come first?
List prefixed versions first and the standard, unprefixed property last. Source order breaks ties, so the modern property wins in browsers that support it while older engines fall back to their prefix.
Do I still need vendor prefixes in 2026?
Rarely. Mainstream properties like transform, transition, border-radius, flexbox, and grid have not needed prefixes for years. A few niche features, such as iOS overflow scrolling, still use one. Check caniuse to confirm.
What is the easiest way to manage prefixes?
Add Autoprefixer to your build (usually via PostCSS). You write the standard property, set a browserslist target, and it inserts exactly the prefixes those browsers require, with no manual upkeep.

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