Media Queries

Overview

Media queries are a CSS feature that allows you to apply styles based on the characteristics of the device or viewport.

Basic Syntax

@media (condition) {
    /* CSS rules */
}

Common Media Features

Feature	Description	Example
min-width	Minimum viewport width	@media (min-width: 768px)
max-width	Maximum viewport width	@media (max-width: 600px)
orientation	Portrait or landscape	@media (orientation: landscape)
prefers-color-scheme	Light or dark mode preference	@media (prefers-color-scheme: dark)

Breakpoint Strategy

Mobile-First Approach (Recommended)

Start with mobile styles, then add complexity for larger screens:

/* Base styles (mobile) */
.grid {
    display: grid;
    grid-template-columns: 1fr;
    gap: 1rem;
}

/* Tablet (768px and up) */
@media (min-width: 768px) {
    .grid {
        grid-template-columns: 1fr 1fr;
    }
}

/* Desktop (1024px and up) */
@media (min-width: 1024px) {
    .grid {
        grid-template-columns: 1fr 1fr 1fr;
    }
}

Common Breakpoints

Size	Width	Devices
Small	< 576px	Phones (portrait)
Medium	576px - 768px	Phones (landscape), small tablets
Large	768px - 1024px	Tablets
XL	1024px - 1200px	Laptops, desktops
XXL	> 1200px	Large desktops

Combining Conditions

/* AND - both conditions must be true */
@media (min-width: 768px) and (orientation: landscape) {
    /* Tablet in landscape */
}

/* OR - either condition */
@media (max-width: 600px), (orientation: portrait) {
    /* Small screen OR portrait orientation */
}

Example in BBj

rem Inject responsive CSS
css$ = "@media (min-width: 600px) {"
css$ = css$ + "  .my-window { grid-template-columns: auto 1fr auto 1fr; }"
css$ = css$ + "}"
css$ = css$ + "@media (min-width: 900px) {"
css$ = css$ + "  .my-window { grid-template-columns: repeat(3, auto 1fr); }"
css$ = css$ + "}"

web! = BBjAPI().getWebManager()
web!.injectStyle(css$)

Testing Media Queries

In Browser Developer Tools

1. Open Developer Tools (F12)
2. Click the device emulation icon
3. Select "Responsive" mode
4. Drag handles to resize viewport
5. Watch layout change at breakpoints

Exercise: Media Queries

Run DWCTraining/10_AdvancedResponsive/MediaQueries.bbj to experiment with responsive layouts.