Shadcn Layouts

shadcn/Tailwind Layouts

Help generate shadcn/Tailwind components that render correctly the first time. Most agent-generated UI fails due to missing mental models about how CSS layout works—not syntax errors, but assumption gaps.

When to Use This Skill

Use this skill when:

• Creating shadcn/Tailwind layouts
• Debugging height/scroll issues
• Fixing flex/grid problems
• Setting up full-page app shells

Do NOT use this skill when:

• Writing backend code
• Working on non-Tailwind CSS projects
• Designing (use frontend-design first)

Core Principle

CSS layout flows from constraints. Height flows down from explicit ancestors. Width flows up from content. Agents fail because they apply classes without understanding the constraint chain.

Critical Mental Models

Model 1: Height Inheritance Chain

h-full means height: 100%. 100% of what? 100% of the parent's computed height.

BROKEN (chain incomplete):<html>                        <!-- no height -->  <body>                      <!-- no height -->    <div class="h-full">      <!-- 100% of nothing = 0 -->
WORKING (chain complete):<html class="h-full">         <!-- 100% of viewport -->  <body class="h-full">       <!-- 100% of html -->    <div class="h-full">      <!-- 100% of body = works -->

Rule: Trace from element up to <html>. Every ancestor needs explicit height, OR use viewport units (h-screen) to break the chain.

Model 2: Flex Overflow Gotcha

Flex children have implicit min-height: auto, preventing shrinking below content size.

// BROKEN (won't scroll)<div className="flex flex-col h-screen">  <main className="flex-1 overflow-y-auto">  {/* Can't shrink! */}
// WORKING (scrolls correctly)<div className="flex flex-col h-screen">  <main className="flex-1 overflow-y-auto min-h-0">  {/* Can shrink */}

Rule: Flex children that scroll need min-h-0. Children that shouldn't shrink need shrink-0.

Model 3: Grid Parent/Child Separation

Grid is defined on the parent. Children just occupy cells.

// BROKEN<div className="grid-cols-3">           {/* Missing 'grid'! */}
// WORKING<div className="grid grid-cols-3">      {/* 'grid' enables grid-cols-* */}

Rule: flex or grid must be declared on parent before direction/template classes work.

Model 4: Scroll Container Dimensions

Scroll containers need explicit dimensions to know when to scroll.

// BROKEN (never scrolls)<ScrollArea>  {/* No height constraint */}
// WORKING (flex-constrained)<div className="flex flex-col h-screen">  <ScrollArea className="flex-1 min-h-0">

Diagnostic States

SL1: Height Chain Broken

Symptoms: Elements collapse, h-full not working Fix: Trace to html, add heights or use h-screen

SL2: Flex Overflow Blocked

Symptoms: Scroll doesn't work, content overflows Fix: Add min-h-0 to flex children that scroll

SL3: Grid Structure Wrong

Symptoms: Items stack vertically instead of columns Fix: Ensure grid grid-cols-* on parent

SL4: Styles Not Applying

Symptoms: Unstyled components, colors wrong Fix: Check Tailwind content paths, CSS variables in globals.css

SL5: Component Dependencies Missing

Symptoms: "Module not found", functionality broken Fix: npx shadcn add [component], install peer deps

Common Layout Patterns

Full-Page App Shell

// layout.tsx<html lang="en" className="h-full">  <body className="h-full">{children}</body></html>
// page.tsx<div className="flex h-full">  <aside className="w-64 shrink-0 border-r overflow-y-auto">    <nav>...</nav>  </aside>  <main className="flex-1 min-w-0 overflow-y-auto">    {children}  </main></div>

Dashboard with Header

<div className="flex flex-col h-screen">  <header className="h-16 shrink-0 border-b">...</header>  <div className="flex flex-1 min-h-0">    <aside className="w-64 shrink-0 border-r overflow-y-auto">...</aside>    <main className="flex-1 min-w-0 overflow-y-auto p-6">      {children}    </main>  </div></div>

Card Grid

<div className="grid grid-cols-1 md:grid-cols-2 lg:grid-cols-3 gap-6">  {items.map(item => (    <Card key={item.id}>      <CardHeader><CardTitle>{item.title}</CardTitle></CardHeader>      <CardContent>{item.content}</CardContent>    </Card>  ))}</div>

Anti-Patterns

The Height Assumption

Using h-full without verifying ancestor chain. Fix: Trace to html. Use h-screen to break chain.

The Overflow Ignorance

Adding overflow-y-auto without min-h-0 on flex children. Fix: Flex children need min-h-0 to shrink.

The Import Guess

Guessing import paths like shadcn/ui. Fix: Check components.json for alias. Usually @/components/ui/*.

The Flat Compound

Flattening compound components (Dialog without DialogTrigger/DialogContent). Fix: Maintain required nesting structure.

Pre-Generation Checklist

• Import alias known (@/components/ui/*)
• html has h-full
• body has h-full or min-h-full
• Scroll containers have explicit height
• Flex scroll children have min-h-0
• Fixed elements have shrink-0

Related Skills

• frontend-design - Design decisions before implementation
• react-pwa - PWA features for React apps