Use CSS Global Styles BootStrap in, we can not define your own CSS styles of.
Responsive Images
<!DOCTYPE html> <html lang="en"> <head> <meta charset="utf-8"> <meta http-equiv="X-UA-Compatible" content="IE=edge"> <meta name="viewport" content="width=device-width, initial-scale=1"> <title>Bootstrap CSS全局样式</title> <link href="./BootStrap_3.3.7_libs/css/bootstrap.min.css" rel="stylesheet"> < Script the src = "./ the jQuery / jQuery-3.2.1.min.js" > </ Script > < Script the src = "./ BootStrap_3.3.7_libs / JS / bootstrap.min.js" > </ Script > < / head > < body > <-! picture using CSS BootStrap of global style in the -> <-! <h3> using CSS global styles BootStrap of pictures </ h3> -> < img src = " ./img/banner_3.jpg " class =" IMG-responsive " Alt =" responsive Image " > <-! square with rounded corners -> <img src="./img/banner_3.jpg" alt="Responsive image" class="img-rounded"> <!-- 圆形 --> <img src="./img/banner_3.jpg" alt="Responsive image" class="img-circle"> <!-- 方角方形 --> <img src="./img/banner_3.jpg" alt="Responsive image" class="img-thumbnail"> </body> </html>
For details, please see: Global CSS styles