Fixed Positioning Issue with Anchors and UL Lists in Google Chrome and Opera

This article addresses a rendering issue observed in Google Chrome and Opera browsers where a fixed-position sidebar may disappear when clicking on anchor links within the page. The presence of

elements on the page exacerbates this issue.

Chrome Solution

Applying a -webkit-transform: translateZ(0) property to the fixed sidebar element resolves this problem in Chrome. This technique exploits the separation of repaint and CSS rendering when engaging 3D transformations, mitigating the display glitches.

#sidebar {
    -webkit-transform: translateZ(0);
}

Opera Solution

Addressing this issue in Opera requires a different approach. We employ an @keyframes animation to force continuous repaints on a CSS property that influences layout but has no practical impact on page appearance. In this case, we animate the margin-bottom property:

@keyframes noop {
  0%   { margin-bottom: 0; }
  100% { margin-bottom: 1em; }
}

#sidebar {
    animation: noop 1s infinite;
}

It's important to note that this solution isn't flawless. In some cases, a brief flicker may occur when the sidebar loses positioning and redraws quickly. Opera's intrinsic behavior between redraws is responsible for this issue.

Additional Considerations

Subsequent encounters with this bug have demonstrated frequent occurrences in cases where a 3D transform is already applied to the body or a parent element. This practice, often used to enforce GPU rendering, can lead to persistent rendering issues. Consider removing existing 3D transforms before implementing the solutions provided above.

Google Chrome and Opera now handle fixed positioning with improved stability. These fixes have demonstrated effectiveness in resolving the rendering issues associated with using UL elements on the page.