Why Do Percentage Paddings on Flex Item Children Break the Parent Flex Container?

Why Percentage Padding Breaks Flex Items

Consider a scenario where a

element is styled as a flex item. Inside this
are several
• elements that are not flex items. When percentage paddings are applied to the
• elements, the
  element breaks into multiple lines. However, when fixed paddings (e.g., 30px) are used, the
  remains on a single line.

  To understand this behavior, we delve into the calculation involved with percentage paddings. Percentage padding values are relative to the width of the containing block. However, the width of the containing block is determined by its content.

  In this case, the width of the

  is calculated based on the content of its
  • elements. To obtain this width, we use the following code:

    console.log(document.querySelector('ul').offsetWidth);

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    The complexity lies in the fact that we cannot determine the percentage padding values before calculating the width. Hence, we first calculate the width based on the content.

    Therefore, when percentage paddings are used, the browser struggles to determine the width of the containing block, resulting in the multi-line behavior. In contrast, with fixed paddings, the width is explicitly defined, eliminating this issue.

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