How are Decimal Places Handled in CSS Widths (Percentage vs. Pixels)?

Decimal Precision in CSS Widths

In CSS, widths can be specified using either percentages, pixels, or other units. As you're working with decimal fractions in widths, a common question arises: are decimal places respected?

Consider the following CSS declarations:

.percentage {
  width: 49.5%;
}

.pixel {
  width: 122.5px;
}

Percentage Widths

In the case of percentage widths, decimal places are indeed respected. This means elements with a width of "49.5%" will occupy exactly half of their parent container. This precision is crucial for precise and consistent layouts, especially when dealing with fractional widths.

#outer {
    width: 200px;
}

#first {
    width: 50%;
    height: 20px;
    background-color: red;
}

#second {
    width: 50.5%;
    height: 20px;
    background-color:green;
}

#third {
    width: 51%;
    height: 20px;
    background-color:blue;
}

In this example, the "first" div occupies exactly half of the "outer" div's width, the "second" div occupies 50.5%, and the "third" div occupies 51%.

Pixel Widths

However, when using pixel widths, fractional values are truncated to the nearest integer. This means that a width of "122.5px" will be rendered as "122px" in most browsers. This is because pixel values represent discrete points, and there is no direct mapping for fractional values.

In summary, decimal places in percentage widths are respected, providing precise control over element sizes. However, pixel widths truncate fractional values to the nearest integer. Understanding this distinction is crucial for accurate and consistent CSS designs.

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