Use a theme color in a component

The convention every component in this codebase follows, and the mistakes that only show up in one of the two themes.

The convention

Reference the CSS variable as a Tailwind arbitrary value, never a hardcoded hex or a bare Tailwind palette color for anything that should adapt to the theme:

<div className="rounded-lg border border-[var(--border-color)] bg-[var(--surface-color)] p-4">
    <p className="text-[var(--text-color)]">Title</p>
    <p className="text-[var(--text-gray-color)]">Secondary text</p>
</div>

This works because Tailwind's arbitrary-value syntax (bg-[var(--x)]) emits background-color: var(--x) literally — the browser resolves --x at render time from whichever [data-theme] block is active (see guide 1), so the component itself needs zero theme-awareness: no useTheme() call, no conditional class, no re-render on theme change.

The token vocabulary (what to reach for)

Every token in global.css, and what it's for — reach for the existing one that matches your case rather than inventing a new one (see guide 2 for when a new token is actually warranted):

Mistakes that only break one theme

• A hardcoded hex copied from a design mock. bg-[#101113] matches --bg-color-hover in dark mode exactly, and is silently wrong (a near-black box on a light page) the moment someone switches to light. If you're tempted to hardcode a value you got from inspecting the dark theme, there's almost always an existing token for it — check the table above first.
• A bare Tailwind palette class for anything meant to adapt, e.g. text-gray-400 instead of text-[var(--text-gray-color)] — it renders the same gray in both themes instead of the theme-tuned value, usually ending up too light to read on the light background or too dark to read on the dark one. Tailwind palette classes are still correct for something that's supposed to stay the same color regardless of theme — the fixed-hue swatches in resources/js/utils/colors.ts (project/label colors, e.g. a red project badge is the same red in both themes) are exactly that case; a project's own chosen color is part of its identity, not part of the interface chrome that theme tokens exist to control.
• prefers-color-scheme media queries in component CSS. That's the mechanism emails use, which have no JavaScript and can't set data-theme — the app itself should never branch on the media query directly, only on resolvedTheme (and even that should be rare; almost everything should just be a CSS variable reference).

Previewing both themes without touching your OS setting

Pick dark/light explicitly in Account settings → Preferences — that's exactly what bypasses system's OS-following behavior (see guide 1's resolveTheme()) and lets you see either theme regardless of your actual OS appearance setting.

Tests

No dedicated "uses the right token" test exists or is expected per component — a component test verifying its rendered className contains the expected var(--...) reference (as resources/js/Components/Molecules/Alert/Alert.test.tsx's 'renders an icon styled for the %s intent' does, asserting toHaveClass('text-[var(--success-color)]') etc.) is the right level of coverage; there's no broader lint rule catching a hardcoded hex today.