Svelte Guideline: Styling — Tailwind v4 uses Vite plugin not config file. Description: No tailwind.config.ts; configure in app.css with @theme blocks. Do: @theme inline { --radius: 0.625rem; --color-primary: #ff7a76; }. Don't: Creating tailwind.config.ts in Tailwind v4. Good Example: @import 'tailwindcss'; @theme inline { ... }. Bad Example: module.exports = { theme: { extend: {} } }. Severity: High. Docs: https://tailwindcss.com/docs/v4.