v0 keeps using the wrong colors. Here's the fix.

v0 is impressive. You describe a UI and it builds it. A pricing page in thirty seconds. A dashboard layout in a minute. The components are clean, the code is production-ready, the design is polished.

But the colors are wrong. Every time.

v0 uses its own color palette. Zinc backgrounds. Slate text. Blue primaries. It looks good — in a generic, seen-this-on-every-shadcn-site way. But it looks nothing like your brand. And correcting it prompt by prompt is tedious.

Why v0 ignores your colors

v0 doesn't read your project files. Unlike Claude Code or Cursor, it doesn't index your workspace. It doesn't know what's in your repo. Every conversation starts with zero context about your design system.

When you say "build me a hero section," v0 makes its best guess at colors. That guess is based on shadcn/ui defaults and common design patterns. The result is competent but generic. It has no way to know you use warm terracotta instead of cool slate.

Even when you include hex codes in your prompt — "use #FC6911 as the primary" — v0 applies it inconsistently. It might use it on a button but fall back to defaults for borders, backgrounds, and secondary text. One hex code doesn't communicate a system.

The system instructions fix

v0 supports system instructions. This is text that persists across your entire conversation, providing context before every prompt. And it's where your palette belongs.

Instead of pasting hex codes into individual prompts, you paste your structured palette into v0's system instructions once. Every component v0 generates in that conversation uses your colors. Roles, values, contrast rules — all of it.

Here's the format that works:

• Start with a clear directive: "Use only these colors in all generated components"
• List each color with its role and hex value
• Include usage descriptions so v0 knows what each color does
• Add rules about what combinations to use and avoid
• Include CSS variables so v0 generates semantic code, not hardcoded values

The exact prompt pattern

Paste this structure into v0's system instructions (adapted with your actual palette values):

• Background (#F5DBC1) — Use for page backgrounds, card surfaces, modal backdrops. This is the default canvas.
• Ink (#2D1B0E) — Use for headings, body text, primary content. This is the readable text color.
• Accent (#FC6911) — Use for buttons, CTAs, links, active states. Sparingly. Never as body text.
• Support (#8B6F47) — Use for secondary text, captions, metadata, timestamps.
• Neutral (#A39484) — Use for borders, dividers, disabled states, subtle backgrounds.

Then add the rules:

• Never use colors outside this palette
• Never use accent as body text — insufficient contrast for small text
• Use ink-colored text on accent buttons, not white
• Use CSS variables: --color-bg, --color-text, --color-primary, --color-secondary, --color-muted

Now say "build me a pricing page" and watch v0 use your actual brand. Background is warm, not white. Text is your ink, not gray-900. Buttons are your accent, not blue-600. The entire output is on brand.

Before and after

Without palette instructions:

• v0 generates a pricing page with bg-white, text-zinc-900, border-zinc-200
• CTA buttons are bg-blue-600 text-white
• Secondary text is text-zinc-500
• Looks like a shadcn template. Functional but brandless.

With palette in system instructions:

• v0 generates with bg-[var(--color-bg)], text-[var(--color-text)]
• CTA buttons use bg-[var(--color-primary)] text-[var(--color-text)]
• Secondary text uses text-[var(--color-secondary)]
• Looks like your brand. Ready to ship.

Same tool. Same prompt. The only difference is thirty seconds of setup.

Where to get the palette data

You need structured palette data with roles, values, and rules. You could write it by hand, but computing contrast ratios and formatting tokens is busywork.

Paletter generates the exact format v0 needs. Upload an image or build a palette from scratch, export as COLORS.md, and copy the relevant sections into v0's system instructions. The roles, values, contrast data, and rules are all pre-formatted.

If you also use Claude Code or Cursor, the same COLORS.md file works in your project root for those tools. One palette, every AI tool. See the full v0 integration guide for advanced patterns.

Make it stick

Save your system instructions. v0 persists system instructions within a conversation. But when you start a new chat, you need to paste them again. Keep your palette prompt saved somewhere accessible — a note, a snippet, a file on your desktop.

Start every v0 session with the palette. Before your first component prompt, paste the palette into system instructions. Every component in that session will be on brand.

Be specific in follow-ups. If v0 drifts, reference the roles by name: "use the accent color here, not blue." Role names are more effective than hex codes because v0 maps them back to the system instructions.