Web Design Methodology

Universal patterns for building production-grade HTML/CSS. This skill covers implementation methodology — pair with web-design-patterns for specific component designs.

What You Produce

Production-ready HTML/CSS prototypes with:

Semantic CSS custom properties (tokens)
BEM-named components
Mobile-first responsive design
Accessible markup
Optional three-state dark mode

File Structure

prototype/
├── index.html
├── about.html
├── services.html
├── contact.html
├── favicon.svg
├── css/
│   ├── variables.css     # Tokens: colours, typography, spacing
│   ├── styles.css        # All component styles (BEM)
│   └── mobile-nav.css    # Mobile menu styles
├── js/
│   ├── theme.js          # Dark mode toggle (only if requested)
│   └── mobile-menu.js    # Hamburger menu
└── media/
    └── images/

Build order:

variables.css — tokens first
favicon.svg — simple SVG from brand colour
styles.css — all BEM components
mobile-nav.css — responsive navigation
JS files — from assets/ templates
index.html — homepage first
Inner pages — about, services, contact
Mobile check — verify at 375px

BEM Naming

Use Block-Element-Modifier naming. No exceptions.

/* Block */
.hero { }
.card { }
.nav { }

/* Element (child of block) */
.hero__title { }
.hero__subtitle { }
.hero__cta { }
.card__image { }
.card__content { }

/* Modifier (variation) */
.hero--split { }
.hero--minimal { }
.card--featured { }
.btn--primary { }
.btn--lg { }

Rules:

Blocks are standalone components
Elements are children, connected with __
Modifiers are variations, connected with --
Never nest more than one level: .hero__content__title is wrong
Never use element without its block: .card__image only inside .card

CSS Custom Properties

Use semantic tokens. Never hardcode colours, spacing, or typography values.

See references/css-variables-template.md for the complete token template.

/* Always this */
.card {
  background: var(--card);
  color: var(--card-foreground);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow-sm);
  padding: var(--space-6);
}

/* Never this */
.card {
  background: #ffffff;
  color: #333333;
  border: 1px solid #e5e5e5;
  border-radius: 8px;
  box-shadow: 0 1px 3px rgba(0,0,0,0.1);
  padding: 24px;
}

Dark Mode (Optional)

Dark mode is optional — only add if the brief requests it. Most business sites ship faster as light-only.

When to include:

Brief explicitly requests it
Tech/developer audiences (expected)
Portfolio/creative sites (aesthetic choice)

When to skip:

Trades, hospitality, professional services
When simplicity and fast shipping matter more

If Adding Dark Mode

Use class-based toggle, never CSS media queries.

/* Light mode (default) */
:root {
  --background: #F9FAFB;
  --foreground: #0F172A;
  --card: #FFFFFF;
  --card-foreground: #1E293B;
}

/* Dark mode (via .dark class on html) */
.dark {
  --background: #0F172A;
  --foreground: #F1F5F9;
  --card: #1E293B;
  --card-foreground: #F1F5F9;
}

Rules:

.dark class on <html>, toggled via JavaScript
NEVER use @media (prefers-color-scheme: dark) — JS handles system preference
Every background token needs a paired foreground token
Brand colours get lighter/more saturated in dark mode
Backgrounds: #0F172A to #1E293B range (not pure black)
Every text-on-background combo must pass WCAG AA (4.5:1)

Use assets/theme-toggle.js for the three-state toggle implementation.

Responsive Design

Mobile-first. Design for 375px, enhance upward.

Breakpoints

/* Base: 375px (mobile) — no media query needed */
@media (min-width: 640px) { /* sm — large phone */ }
@media (min-width: 768px) { /* md — tablet */ }
@media (min-width: 1024px) { /* lg — small desktop */ }
@media (min-width: 1440px) { /* xl — standard desktop */ }

Mobile Priorities

Phone number visible and tappable without scrolling
Primary CTA visible without scrolling
Navigation works via hamburger menu
Touch targets minimum 44x44px
No horizontal scrolling ever
Images scale properly (no overflow)

Wide Screen Constraints

.prose { max-width: 65ch; }
.hero__content { max-width: min(640px, 45vw); }
.container {
  max-width: 1280px;
  margin-inline: auto;
  padding-inline: var(--space-4);
}
.section { padding: clamp(3rem, 6vw, 6rem) 0; }

Use assets/mobile-nav.js for the hamburger menu implementation.

Typography Rules

Dramatic size contrast. Headlines 3-4x body size. clamp(2.5rem, 6vw, 5rem) for hero titles.
Weight variety. Mix 300 and 800 weights. Uniform weight is boring.
One display moment per page. One oversized word, one dramatic headline, one pull quote. Not three.
Left-align body text. Centre only for heroes and short statements. Never centre paragraphs.
Letter spacing on uppercase. Add letter-spacing: 0.05em minimum.

Colour Usage

The 80/20 rule:

80% neutral tones (backgrounds, text, cards)
15% secondary/muted brand tones
5% primary brand colour (CTAs, one accent per viewport)

If primary is on every heading, border, icon — nothing stands out.

Spacing System

Not uniform padding. Sections breathe differently:

/* Tight section (service list, FAQ) */
.section--compact { padding: clamp(2rem, 4vw, 4rem) 0; }

/* Standard section */
.section { padding: clamp(3rem, 6vw, 6rem) 0; }

/* Breathing room (editorial break, testimonial) */
.section--spacious { padding: clamp(4rem, 8vw, 10rem) 0; }

Shadow System

Element	Shadow
Cards at rest	`--shadow-sm`
Cards on hover	`--shadow-md`
Dropdowns	`--shadow-lg`
Modals	`--shadow-xl`

Not everything needs shadow. Use sparingly.

Icons

Use Lucide icons via inline SVG:

Size: 24px inline, 32-48px for feature blocks
Stroke width: 1.5 or 2 (consistent throughout)
Colour: currentColor (inherits text colour)
Each icon should communicate something specific

Accessibility

Non-negotiable:

Semantic HTML: <header>, <nav>, <main>, <section>, <footer>
Alt text: Meaningful for content images, empty for decorative
Contrast: 4.5:1 minimum (7:1 preferred)
Focus styles: Visible on all interactive elements
Skip link: First focusable element
Form labels: Associated with inputs
ARIA: aria-expanded on toggles, aria-label where needed

Performance

loading="lazy" on images below the fold
loading="eager" on hero image
<link rel="preconnect" href="https://fonts.googleapis.com"> in head
Keep CSS under 50KB total
No JavaScript frameworks — vanilla JS only

Anti-AI Patterns

These patterns signal "AI generated this" — avoid:

Hero → trust bar → 3 cards → features → stats → CTA → footer (the skeleton)
Every section has identical padding
All cards same size in perfect 3-column grid
Everything centred
Every section: heading + subheading + content (same rhythm)
Decorative elements with no purpose
"Learn More" as every CTA
Inter/Arial/system fonts with no typographic personality

Quality Checklist

Before marking complete:

Direction is clear — can describe aesthetic in one phrase
Typography makes a statement — not Inter/system
Colour is restrained — primary used sparingly
No two adjacent sections look the same
CTAs are specific — no "Learn More"
Mobile works — tested at 375px
Dark mode works (only if enabled) — every section checked
No hallucinated images — only real file paths
Would a designer claim this as their work?

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