Bootstrap 5 Responsive Design: Breakpoint Settings and Multi-device Adaptation Guide

Responsive design enables webpages to adapt to multiple devices. Bootstrap 5 simplifies implementation through preset breakpoints and components, eliminating the need to write media queries from scratch. Its default six breakpoints (xs < 576px, sm ≥ 576px, md ≥ 768px, lg ≥ 992px, xl ≥ 1200px, xxl ≥ 1400px) serve as layout switching critical points. The core control methods include: 1) responsive utility classes (e.g., d-sm-block to display block-level elements at the sm breakpoint), which can control element visibility; 2) the grid system (row + col), where column widths are controlled by breakpoint prefixes (e.g., col-md-6 means occupying 6 columns above the medium screen). In practice, layouts are structured as single-column on mobile, two-column on tablets, and three-column on desktops. Images use img-fluid for adaptive scaling, and the navigation bar employs hamburger menus for mobile adaptation. Custom breakpoints can be configured via CSS variables. The core steps involve grid column layout, utility class control of visibility, image adaptation, and navigation collapse, simplifying responsive development.