Difference between px, rem, em units

There are two types of units in CSS:

• Absolute units: px
• Relative units: em, rem, %, vh

Absolute units don't change, while relative units are flexible and change based on context.

Let's dive into the most popular of them: px, em, and rem.

Pixels (px)

Pixels (px) are a common unit of measurement in web design. They are fixed and useful for maintaining consistent sizing of certain elements. However, they can pose problems for responsive sites.

/* 100px is the width and height of the element */
.element {
    width: 100px;
    height: 100px;
}

Use px for small, fixed-size elements like borders, icons. Not for typography or layout.

Relative EM (em)

The em unit is relative to the font size of its closest parent element.

/* 1.5em is the font size of the element */
.element {
    font-size: 1.5em;
}

Root REM (rem)

REM is similar to EM, but always relative to the root element (HTML tag).

Relative units like %, em, and rem are better for responsive design and accessibility standards.