color

Basic Syntax

p {
    color: #3b82f6;
}

.heading {
    color: rgb(255, 100, 50);
}

.accent {
    color: oklch(0.7 0.15 200);
}

Inherits to children. Change once on a parent, and all nested text updates.

color vs background-color

Two properties that always pair together.

.badge {
    color: #ffffff;            /* text color */
    background-color: #3b82f6; /* background fill */
    padding: 0.25rem 0.75rem;
    border-radius: 0.25rem;
}

color sets the foreground. background-color sets the background. You almost always set both together to guarantee readability.

Transparency with Alpha

Modern syntax uses a slash to separate the alpha channel.

/* Modern RGB with alpha */
.text {
    color: rgb(59 130 246 / 0.5);
}

/* HSL with alpha */
.text {
    color: hsl(217 91% 60% / 0.5);
}

/* 8-digit hex */
.text {
    color: #3b82f680;
}

Alpha values range from 0 (fully transparent) to 1 (fully opaque).

currentColor — Auto-Match Text

currentColor resolves to the value of the element's own color property. Perfect for icons and borders that should match text.

.button {
    color: #3b82f6;
    border: 2px solid currentColor;  /* matches text */
}

.icon {
    fill: currentColor;  /* SVG fills with text color */
}

.link:hover {
    color: #ef4444;
    border-bottom: 1px solid currentColor;  /* updates with color */
}

This is how Tailwind's icon libraries work — the icon inherits the surrounding text color.

Color Contrast — WCAG Rules

Contrast ratio is the difference in luminance between text and background. WCAG defines minimum ratios.

CSS Variables for Color Systems

The right way to manage a color palette across a site.

:root {
    --color-primary: #3b82f6;
    --color-success: #10b981;
    --color-danger: #ef4444;
    --color-text: #e2e8f0;
    --color-text-muted: #94a3b8;
    --color-bg: #020617;
}

.button {
    color: var(--color-primary);
    border: 1px solid var(--color-primary);
}

.error {
    color: var(--color-danger);
}

.muted {
    color: var(--color-text-muted);
}

Change one variable in :root and the entire site updates. This is how design systems work.