position: sticky The key to implementing a sticky navigation bar or sidebar is to correctly set positioning properties and understand usage restrictions. 1. It must be used with top, bottom, left or right, and the parent container cannot have properties such as overflow: hidden, transform or filter; 2. When used in the navigation bar, z-index and background colors must be set to ensure visibility and readability, and pay attention to the hierarchical relationship of multiple sticky elements and content occlusion issues; 3. When implementing the sidebar, you need to set the top value and height: fit-content to prevent the screen from being full, and scrolling support should be added if necessary; 4. Pay attention to compatibility. Mainstream browsers have good support, but IE does not support it, and alternatives are required to avoid common style traps. Only by mastering these key points can you ensure sticky works as expected.

Using CSS's position: sticky to implement sticky navigation bar or sidebar is a practical and not difficult to implement. It allows an element to "stick" on the screen when scrolling a page, such as common top navigation or side menus. The key is to understand its usage conditions and limitations, otherwise it is easy to "how it doesn't take effect".

1. Basic grammar and necessary conditions

position: sticky looks simple, but must be used with top , bottom , left or right , otherwise it will fail. For example:

 .sticky-nav {
  position: sticky;
  top: 0;
}

After writing this way, .sticky-nav will be fixed to the screen when scrolling to 0px from the top.
But note:

• It must have a clear positioning value (such as top: 0 ) and cannot just write position: sticky .
• The parent container cannot be overflow: hidden or transform , filter and other attributes, otherwise sticky will be disabled.
• The sticky element is positioned relative to the most recent scrolling ancestor element, rather than the entire page.

2. Common practices used on the navigation bar

The top navigation bar is the most common application scenario. You can put it at the top of the page so that it is always visible while scrolling:

 <nav class="sticky-nav">...</nav>

 .sticky-nav {
  position: sticky;
  top: 0;
  z-index: 1000;
  background: white;
}

z-index is added to prevent being covered by other content, and the background color is to make the content readable (especially when scrolling).
In practice, you may encounter:

• When the page has multiple sticky elements, they are overwritten in turn
• The contents below the navigation bar may be blocked, you can use margin-top to adjust the spacing.

3. How to achieve sticky effect in the sidebar

In addition to top navigation, the sidebar can also be fixed with sticky. Structurally, there is usually a left area plus the main content area:

 <div class="container">
  <aside class="sidebar">This is the sidebar</aside>
  <main class="content">Main content</main>
</div>

The corresponding CSS can be written like this:

 .sidebar {
  position: sticky;
  top: 20px; /* Start to fix at a certain distance from the top*/
  height: fit-content; /* Prevent the screen height from being full*/
}

This way, when the user scrolls the page, the sidebar stops at the right position and does not exceed the content height.
Tips:

• Add max-height and overflow-y: auto to .sidebar to keep scrolling under long content
• Pay attention to the layout width to avoid sticky elements affecting the main content layout

4. Compatibility and precautions

Although mainstream browsers support position: sticky , it is not applicable in older versions (such as IE). If you need to be compatible with these environments, you may have to use JavaScript to simulate or consider alternatives.

Some other places that are prone to pitfalls:

• Forgot to set top or left , resulting in invalid
• The parent container has been set to overflow: hidden , sticky is invalid
• The scroll container is not the viewport itself (such as scrolling inside a div), and sticky behavior will be different

Basically that's it. The key to using position: sticky is to figure out the context and style limitations it depends on. It looks simple, but if the details are not handled properly, problems will be easily arise.

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