The short answer is: Yes, you will need to use CSS for React. There are different ways that you can incorporate CSS into your React app, including using inline styles, using a Css-in-Jss approach, or using a pre-processor such as Sass.
React is an open source JavaScript library created by Facebook that is used to build user interfaces. It was designed to make developing complex UIs easier, and it has become one of the most popular frameworks for web development. React is a component-based architecture, meaning developers can break their UI into smaller pieces, or components, and build reusable logic that can be used across projects.
React also comes with a styling language called JSX, which is a JavaScript-like syntax that makes it easy to write HTML-like markup language directly in React components. JSX is not a replacement for CSS, however, as it does not have the same functions as a CSS stylesheet. React developers will often use embedded styles in their JSX code, but this does not provide the same efficiency and flexibility as an actual CSS stylesheet.
As such, when building an app with React, you will need to write CSS to define how the React components should be stylized. This can be done by writing your own custom CSS stylesheets and linking them to your React components. You can also use a pre-processor such as Sass or Less to easily create and maintain complex sets of styles.
Inline styles are another way to provide styling to React components. This involves writing styling directly in the JSX code and applying those styles to the elements. This approach is best used for simple styling, as more complex styling will become hard to maintain.
A more modern approach to styling React components is CSS-in-JS, which uses JavaScript objects to style components instead of separate stylesheets. This approach can improve the performance of an application, as the styles are already available in the same JavaScript bundle being loaded by the browser, eliminating the need to make an additional network request. It also allows for greater flexibility and customization, as styles can be defined and updated quickly without needing to rewrite entire stylesheets.
As you can see, CSS is an important part of React, and you will need to incorporate it in your projects in one way or another. Whether you prefer to write your own CSS stylesheets or use a pre-processor such as Sass or Less, or use inline styles or the CSS-in-JS approach, there is an option available to suit your needs. No matter which approach you take, make sure that your applications are well-styled and easily maintainable in the long term.