Error Handling

CSS is designed to be fault-tolerant - errors do not break the page. The browser simply ignores invalid rules and continues parsing.

<p class="error-demo">Invalid CSS is ignored; valid CSS still works</p>

.error-demo {
color: #059669;
font-size: 1.125rem;
font-weight: bold;

/* This is invalid - the browser ignores it */
colr: #ff0000;

/* This is also invalid */
background-colour: hotpink;

/* This property does not exist */
super-style: amazing;
}

What Happens with Errors

/* Valid declaration */
color: #333;

/* Invalid property name - whole line ignored */
colr: #333;

/* Invalid value - declaration ignored */
color: burple;

/* Invalid selector - entire rule ignored */
@unknown-rule { }

Fallback Strategy

Provide fallback values for newer properties:

.element {
  /* Fallback for older browsers */
  background: #6366f1;

  /* Modern browsers use this */
  background: linear-gradient(135deg, #6366f1, #ec4899);
}

Common CSS Errors

Because of this fault tolerance, CSS is safe to use with progressive enhancement - newer features degrade gracefully in older browsers.