CSS Units
CSS units are used to specify measurements and sizes in Cascading Style Sheets (CSS). They allow you to define lengths, distances, and other dimensions within a webpage. Here are some commonly used CSS units:
- Pixels (px): Pixels are the most basic unit of measurement in CSS. One pixel represents a single dot on a screen. Pixel values are fixed and do not scale with the user’s device or screen resolution.
- Percentage (%): Percentage units are relative to the parent element. For example, if you set a width of 50% on a child element inside a container, it will take up half of the width of the container.
- Viewport Units (vw, vh, vmin, vmax): Viewport units are relative to the size of the browser window. The available viewport units are:
- vw (viewport width): 1vw is equal to 1% of the width of the viewport.
- vh (viewport height): 1vh is equal to 1% of the height of the viewport.
- vmin: 1vmin is equal to the smaller value between 1vw and 1vh.
- vmax: 1vmax is equal to the larger value between 1vw and 1vh.
- Em (em): The em unit is relative to the font size of the element or its nearest parent with a font size defined. For example, if an element has a font size of 16px, 1em would be equal to 16px. If the font size of a parent element is 20px, 1em would be equal to 20px.
- Rem (rem): The rem unit is similar to the em unit, but it is relative to the root element’s font size (typically the
<html>
element). This makes it useful for creating scalable designs across the entire page, as it does not depend on nested elements. - Absolute Length Units (in, cm, mm, pt, pc): These units represent fixed physical lengths and are typically used for print stylesheets or specific cases where exact measurements are required. For example,
in
represents inches,cm
represents centimeters,mm
represents millimeters,pt
represents points, andpc
represents picas. - Flexible Length Units (fr): The fr unit is used in CSS Grid and CSS Flexbox layouts to distribute available space among multiple elements. It represents a fraction of the available space. For example, if an element has a width of 2fr and another has 1fr, the first element will take twice the space of the second.
These are just a few of the most commonly used CSS units. Each unit has its own purpose and use case, and understanding them allows you to create responsive and flexible designs in CSS.