HTML & CSS · The Box Model · Lesson 9 of 25

Backgrounds and Borders

Concept

Backgrounds and Borders

background-color, background-image, and border-radius let you style a box's fill and corners.

border-radius can take a single value for uniform corners, or up to four values to round each corner independently — a value of 50% on a square element makes it a perfect circle.

By the end of this lesson

Explain the core idea behind Backgrounds and Borders.
Predict output before running a change.
Test one realistic and one unusual input.
Use the result to make the next decision.

How to study this page

1. Read one concept.
2. Change the example.
3. Run, compare, and explain.
4. Complete the challenge below.

Syntax

.selector {
  background-color: color;
  background-image: url("image.jpg");
  border-radius: 12px;
}

ExampleRunnable

.card {
  background-color: #e7f8f1;
  border-radius: 12px;
}

Try it Yourself »

A circular avatar

.avatar {
  width: 48px;
  height: 48px;
  border-radius: 50%;
}

Self-check before continuing

Without looking at the example, describe what changes when you modify one input in Backgrounds and Borders. Then reopen the editor and prove your explanation with a small test.

You are ready to continue when you can predict, test, and explain the result.

Your turn

Style a card with a soft background color and rounded corners.

Loading editor…

Console

Output will appear here...