$blue-600: #0f6eef and $spacing-sm: 1rem. They never change.--color-primary: #0f6eef. Different themes redefine these values—dark mode, high contrast, brand variants.var(--color-primry) (typo!) and the button renders with a transparent background. The bug reaches production.// ❌ BEFORE: LESS (2016)
@import (reference) '../../less/variables.less';
.pillar-button {
background: @color-interactive-primary; // Hardcoded reference
color: #ffffff; // Magic value (where did this come from?)
padding: 8px 16px; // Arbitrary numbers
font-size: 14px; // Not scaled responsively
&:hover {
background: darken(@color-interactive-primary, 10%); // Manual calculation
}
}
// ✅ AFTER: SCSS + Tokens (2025)
@use '../design/' as design;
$button-bg: design.$color-primary; // Validated token
$button-text: design.text-contrast($button-bg); // Auto-calculated contrast (WCAG)
.pros-button {
@include design.button-reset(); // Reusable mixin
background: $button-bg;
color: $button-text;
padding: design.$spacing-xs design.$spacing-sm; // Semantic spacing
border-radius: design.$radius-default; // Consistent radius
@include design.paragraph(1); // Typography mixin
&:hover {
background: design.resolve-hover($button-bg); // Intelligent hover (darkens bright, lightens dark)
}
}
prefers-color-scheme
|
Theme Type
|
Use Case
|
Implementation
|
|---|---|---|
|
High Contrast
|
Accessibility compliance (WCAG AAA)
|
Redefine color tokens with maximum contrast ratios (e.g., pure black #000 on pure white #fff)
|
|
Brand Variants
|
White-label products, regional customization
|
Swap --color-primary to client brand color, auto-generate contrast/hover states
|
|
Seasonal Themes
|
Marketing campaigns, special events
|
Temporary theme overrides applied at the application level
|
|
Reduced Motion
|
Accessibility for vestibular disorders
|
Respect prefers-reduced-motion media query, disable animations via CSS variables
|
// themes.scss - Theme definitions
$default: (
'primary': $blue-600, // #0f6eef
'surface-primary': $warm-0, // #ffffff
'text-standard': $warm-1000, // #3a3a3a
// ... 22+ semantic color assignments
);
$dark: (
'primary': $blue-500, // #3384f2 (lighter for dark bg)
'surface-primary': $warm-1000, // #1a1a1a (inverted)
'text-standard': $warm-0, // #ffffff (inverted)
// ... same semantic keys, different values
);
// Compiled CSS output
html > body {
--color-primary: #0f6eef;
--color-surface-primary: #ffffff;
--color-text-standard: #3a3a3a;
}
html > body.dark-mode {
--color-primary: #3384f2;
--color-surface-primary: #1a1a1a;
--color-text-standard: #ffffff;
}
// Theme switching in React (zero component changes)
function toggleTheme() {
document.body.classList.toggle('dark-mode');
// All components update instantly via CSS variables!
}
themes.scss$highContrast: (
'primary': #0000ff, // Pure blue
'surface-primary': #ffffff, // Pure white
'text-standard': #000000, // Pure black
// ... define all 22+ semantic tokens
);
html > body.high-contrast {
@include apply-theme($highContrast);
// Automatically creates:
// --color-primary: #0000ff
// --color-primary-contrast: #ffffff (auto-calculated)
// --color-primary-hover: #0000cc (auto-calculated)
}
document.body.classList.add('high-contrast');
var(--color-primary), not hardcoded values!(--color-primary) without knowing or caring what actual color value it holds. Themes redefine the values, not the semantics.#0f6eef here. Should this be design.$color-primary?"