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why we use padding-top instead of height to maintain aspect ratio

Using padding-top: 56.4% is a common technique to maintain a responsive aspect ratio for an element, particularly useful for elements like videos or images that need to scale with the width of their container while preserving their aspect ratio. This technique is based on the "intrinsic ratio" method, which leverages the fact that padding percentages are based on the width of the containing block.

Why padding-top Instead of height

  1. Percentage Padding Relative to Width:

    • Padding percentages are calculated based on the width of the containing block. Therefore, padding-top: 56.4% sets the padding-top to 56.4% of the width of the container, creating a proportional relationship between width and height that maintains the aspect ratio.
    • If you use height: 56.4%, it sets the height relative to the height of the containing block, which doesn't maintain the aspect ratio based on width.

  2. Responsive Design:

    • Using padding-top ensures that as the width of the container changes, the height will adjust proportionally, keeping the aspect ratio consistent.
    • This is crucial for responsive design where the container width might change based on different screen sizes or orientations.

Example

Here's an example to illustrate the use of padding-top: 56.4%:

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Responsive Aspect Ratio</title>
    <style>
        .aspect-ratio-box {
            position: relative;
            width: 100%;
            padding-top: 56.4%; /* 16:9 aspect ratio */
            background: lightgray;
        }
        .aspect-ratio-box iframe class='youtube-video' {
            position: absolute;
            top: 0;
            left: 0;
            width: 100%;
            height: 100%;
        }
    </style>
</head>
<body>
    <div class="aspect-ratio-box">
        <iframe src="https://www.example.com" frameborder="0"></iframe>
    </div>
</body>
</html>

Explanation:

Published on: Jul 30, 2024, 12:14 PM  
 

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