Dark Mode & Theming Systems | prefers-color-scheme & Scalable Themes
Learn how to implement dark mode and scalable theming systems using prefers-color-scheme, CSS variables, and reusable design tokens.
Dark Mode & Theming Systems | prefers-color-scheme & Scalable Themes
Dark mode is no longer a feature.
It is an expectation.
Modern UI systems must support multiple themes without duplicating CSS
or creating override chaos.
This lesson explains how dark mode and theming systems actually work
using prefers-color-scheme , CSS variables, and scalable theme logic
with live editable examples .
Why Dark Mode Is a System Problem
Dark mode is not just inverting colors.
It affects:
Contrast and readability Shadows and elevation Borders and dividers States and feedback Info!
If dark mode is handled with overrides, the architecture will not scale.
prefers-color-scheme (The Foundation)
The prefers-color-scheme media query lets CSS detect the user’s system theme.
Basic Dark Mode Example ✏️ Edit ▶ Run <div class="box">System Theme</div>
<style>
.box {
padding: 24px;
border-radius: 16px;
background: #ffffff;
color: #0f172a;
}
@media (prefers-color-scheme: dark) {
.box {
background: #020617;
color: #e5e7eb;
}
}
</style&g…
