The Ultimate Design & Creative Cheatsheet

/* ── Design Token Pattern for Colors ── */
:root {
  /* Primary palette */
  --color-primary-50:  #eff6ff;
  --color-primary-100: #dbeafe;
  --color-primary-500: #3b82f6;
  --color-primary-700: #1d4ed8;
  --color-primary-900: #1e3a5f;

  /* Semantic tokens */
  --color-bg:          #0f172a;
  --color-surface:     #1e293b;
  --color-border:      #334155;
  --color-text:        #f1f5f9;
  --color-text-muted:  #94a3b8;

  /* Feedback */
  --color-success: #22c55e;
  --color-warning: #f59e0b;
  --color-error:   #ef4444;
  --color-info:    #3b82f6;
}

/* ── Responsive Fluid Typography with clamp() ── */
:root {
  /* Fluid type scale based on 1rem = 16px */
  --font-display:  clamp(2rem, 5vw, 4rem);    /* 32-64px */
  --font-h2:       clamp(1.5rem, 3.5vw, 2.5rem); /* 24-40px */
  --font-h3:       clamp(1.25rem, 2.5vw, 1.75rem); /* 20-28px */
  --font-body:     clamp(1rem, 1.2vw, 1.125rem);   /* 16-18px */
  --font-small:    clamp(0.8rem, 1vw, 0.875rem);   /* 13-14px */
  --font-caption:  clamp(0.7rem, 0.8vw, 0.75rem);  /* 11-12px */
}

/* Line height & letter spacing best practices */
h1, h2 { line-height: 1.15; letter-spacing: -0.02em; }
h3, h4 { line-height: 1.3;  letter-spacing: -0.01em; }
body    { line-height: 1.6;  letter-spacing: 0; }
small, caption {
  line-height: 1.4;
  letter-spacing: 0.02em;
  text-transform: uppercase;
}

/* ── Flexbox vs Grid: When to Use Which ── */

/* Flexbox: Navbar / Toolbar */
.navbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  padding: 0 24px;
  height: 64px;
}

/* Grid: Dashboard Layout */
.dashboard {
  display: grid;
  grid-template-columns: 260px 1fr 300px;
  grid-template-rows: 64px 1fr;
  grid-template-areas:
    "sidebar header header"
    "sidebar main   aside";
  min-height: 100vh;
}

/* Grid: Auto-responsive card grid */
.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 24px;
}

/* Grid: Holy Grail Layout */
.page {
  display: grid;
  grid-template: auto 1fr auto / 200px 1fr 200px;
  grid-template-areas:
    "header header header"
    "nav    main   aside"
    "footer footer footer";
  min-height: 100vh;
}

// ── Lucide Icons in React ──
import { Search, Bell, Settings, ChevronRight } from 'lucide-react';

function Header() {
  return (
    <header className="flex items-center justify-between p-4">
      <Search size={20} strokeWidth={1.5} />
      <Bell size={20} className="text-gray-500" />
      <Settings size={20} />
      <ChevronRight size={16} />
    </header>
  );
}

// ── Heroicons (Tailwind ecosystem) ──
// npm install @heroicons/react
import { MagnifyingGlassIcon } from '@heroicons/react/24/outline';

function SearchBar() {
  return (
    <div className="relative">
      <MagnifyingGlassIcon className="absolute left-3 top-3 h-5 w-5" />
      <input type="text" className="pl-10 pr-4 py-2 border rounded" />
    </div>
  );
}

<!-- ── Responsive Image Strategy ── -->
<picture>
  <!-- AVIF for modern browsers -->
  <source
    srcset="hero.avif"
    type="image/avif"
  />
  <!-- WebP fallback -->
  <source
    srcset="hero.webp"
    type="image/webp"
  />
  <!-- JPEG fallback for old browsers -->
  <img
    src="hero.jpg"
    alt="Hero description"
    width="1200"
    height="600"
    loading="lazy"
    decoding="async"
    fetchpriority="high"
  />
</picture>

<!-- ── Art Direction with srcset ── -->
<img
  src="team-photo-small.jpg"
  srcset="team-photo-large.jpg 1024w,
          team-photo-medium.jpg 640w,
          team-photo-small.jpg 320w"
  sizes="(max-width: 640px) 100vw,
         (max-width: 1024px) 50vw,
         33vw"
  alt="Team working together"
  loading="lazy"
/>

/* ── Design Token: Animation System ── */
:root {
  /* Durations */
  --duration-instant:  100ms;
  --duration-fast:     150ms;
  --duration-normal:   200ms;
  --duration-slow:     300ms;
  --duration-slower:   500ms;

  /* Easing curves */
  --ease-default:     cubic-bezier(0.4, 0, 0.2, 1);
  --ease-in:          cubic-bezier(0.4, 0, 1, 1);
  --ease-out:         cubic-bezier(0, 0, 0.2, 1);
  --ease-in-out:      cubic-bezier(0.4, 0, 0.2, 1);
  --ease-spring:      cubic-bezier(0.34, 1.56, 0.64, 1);
  --ease-bounce:      cubic-bezier(0.68, -0.55, 0.27, 1.55);
}

/* Respects user motion preference */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    transition-duration: 0.01ms !important;
  }
}