Styling in React Using Styled Components

Introduction

Styling React applications can be done in multiple ways. While CSS files and CSS Modules work well, modern React applications often use Styled Components to write CSS directly inside JavaScript.

Styled Components allow developers to create component-based styles with dynamic behavior, better maintainability, and no class name conflicts.

In this article, you will learn what Styled Components are, how they work, how to use them in React, examples, advantages, limitations, interview questions, and SEO details.

What Are Styled Components?

Styled Components is a popular CSS-in-JS library for React.

It allows you to:

• Write CSS inside JavaScript files
• Scope styles to components automatically
• Apply dynamic styles using props
• Avoid global CSS conflicts

Each styled component is a React component with its own styles.

Installing Styled Components

To use Styled Components, install the package:

npm install styled-components

or

yarn add styled-components

Basic Styled Component Example

import styled from "styled-components";

const Title = styled.h1`
  color: blue;
  font-size: 24px;
`;

function App() {
  return <Title>Styled Components in React</Title>;
}

export default App;

In this example:

• styled.h1 creates a styled heading
• CSS is written using template literals
• Styles apply only to this component

Creating Styled Buttons

const Button = styled.button`
  background-color: green;
  color: white;
  padding: 10px 16px;
  border: none;
  cursor: pointer;
`;

function App() {
  return <Button>Click Me</Button>;
}

Dynamic Styling Using Props

Styled Components allow styles to change based on props.

const Button = styled.button`
  background-color: ${(props) => (props.primary ? "blue" : "gray")};
  color: white;
  padding: 10px;
`;

function App() {
  return <Button primary>Submit</Button>;
}

This makes conditional styling clean and readable.

Extending Styled Components

You can extend an existing styled component.

const PrimaryButton = styled(Button)`
  background-color: darkblue;
`;

This helps reuse styles across components.

Styling Based on State

function App() {
  const [active, setActive] = React.useState(false);

  const Box = styled.div`
    padding: 20px;
    background-color: ${active ? "black" : "white"};
    color: ${active ? "white" : "black"};
  `;

  return (
    <Box onClick={() => setActive(!active)}>
      Click to Toggle Style
    </Box>
  );
}

Styled Components vs CSS Modules

Advantages of Styled Components

• Automatic scoping
• No class name conflicts
• Dynamic styling with props
• Better component encapsulation

Limitations of Styled Components

• Adds extra dependency
• Slight runtime performance cost
• Not ideal for very large static stylesheets

Best Practices

• Use Styled Components for reusable UI components
• Avoid overusing dynamic styles
• Keep styles small and readable
• Combine with CSS Modules when needed

Interview Questions and Answers

1. What are Styled Components?

Styled Components is a CSS-in-JS library that allows writing component-scoped CSS inside JavaScript files.

2. How do Styled Components prevent class name conflicts?

They generate unique class names automatically at runtime.

3. Can Styled Components use props?

Yes, props can be used to apply dynamic styles.

4. Are Styled Components better than CSS?

They are better for dynamic, component-based styling but not always ideal for large static styles.

5. Do Styled Components support media queries?

Yes, all CSS features including media queries are supported.