BOOTSTRAP

Bootstrap is the most popular front-end open-source CSS toolkit. It allows you to quickly design fast and responsive mobile-first web pages, without having to know the nitty-gritty of CSS.

Using Bootstrap, you can use extensive prebuilt interactive GUI components to create sites that are visually appealing on both desktop browsers and mobile devices, without touching a single line of CSS (although knowledge of CSS will allow you to finetune various aspects of the web pages). This is achieved by attaching pre-defined classes, possibly along with a few attributes, on HTML elements structured in specific ways.

Below is a starter template. If you're using compiled JavaScript, don't forget to include jQuery and Popper.js. You can also download Bootstrap to include it into your project without relying on the CDN:
      npm install bootstrap

RESETRUNFULL
<!doctype html><html lang="en">
  <head>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <link href="https://cdn.jsdelivr.net/npm/bootstrap@5.1.3/dist/css/bootstrap.min.css" rel="stylesheet" integrity="sha384-1BmE4kWBq78iYhFldvKuhfTAU6auU8tT94WrHftjDbrCEXSU1oBoqyl2QvZ6jIW3" crossorigin="anonymous">
    <title>Hello, world!</title>
  </head>
  <body>
    <h1>Hello, world!</h1>
    <script src="https://cdn.jsdelivr.net/npm/bootstrap@5.1.3/dist/js/bootstrap.bundle.min.js" integrity="sha384-ka7Sk0Gln4gmtz2MlQnikT1wXgYsOg+OMhuP+IlRH9sENBO0LRn5q+8nbTov4+1p" crossorigin="anonymous"></script>
  </body>
</html>