🛠️ Weekend Project: CSS

The Brief

Your client is you. Build a small, good-looking educational microsite that explains a four-step problem-solving method — George Pólya's classic framework from his 1945 book How to Solve It. The topic is just a vehicle: it gives you exactly four repeatable content blocks (perfect for a card grid) plus a home page, so you can focus your energy on the CSS.

Minimum pages to produce:

The Build Roadmap

You'll ship in five milestones. Each one leaves you with something that works in the browser, so you're never more than one milestone away from a demoable site. Build in this order — later milestones lean on the design tokens and layout you set up first.

Notice the dotted line back to the start: that's Pólya's Review step. After a first pass, loop back and raise the weakest area rather than piling on new features.

Milestone 1 — Scaffold & Design Tokens

Goal: four HTML files that share one stylesheet, and a set of CSS custom properties (design tokens) so every color, radius, and shadow is defined in one place. Tokens are what make a site feel cohesive instead of assembled from random values.

Folder structure

polya-site/
├── index.html
├── steps.html
├── apply.html
├── about.html
└── css/
    └── style.css

Design tokens (top of style.css)

Define everything as variables on :root. Bonus: a dark-mode override costs almost nothing once your colors are tokens.

:root {
  /* Brand */
  --brand: #0070f3;
  --brand-2: #00c8ff;
  --gradient: linear-gradient(45deg, var(--brand), var(--brand-2));

  /* Surface & text */
  --bg: #f4f7fb;
  --surface: #ffffff;
  --ink: #1e293b;
  --ink-soft: #64748b;

  /* Shape & depth */
  --radius: 1rem;
  --shadow-sm: 0 5px 15px rgb(0 0 0 / 0.10);
  --shadow-lg: 0 20px 40px rgb(0 0 0 / 0.15);

  /* Rhythm */
  --space: clamp(1rem, 2vw, 2rem);
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0f172a;
    --surface: #1e293b;
    --ink: #e2e8f0;
    --ink-soft: #94a3b8;
    --shadow-sm: 0 5px 15px rgb(0 0 0 / 0.40);
    --shadow-lg: 0 20px 40px rgb(0 0 0 / 0.50);
  }
}

*, *::before, *::after { box-sizing: border-box; }

body {
  margin: 0;
  font-family: system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  color: var(--ink);
  background: var(--bg);
  line-height: 1.6;
}

Milestone 2 — Navigation & Hero

Goal: a shared sticky navigation bar that condenses on scroll, plus a glassmorphism hero on the home page with gradient-text heading.

Sticky, scroll-reactive nav

Put this markup at the top of every page (identical, so the site feels like one place). The .scrolled class is toggled by a tiny bit of JS.

<nav class="site-nav">
  <a class="site-brand" href="index.html">How to Solve It</a>
  <ul class="site-links">
    <li><a href="index.html">Home</a></li>
    <li><a href="steps.html">The Steps</a></li>
    <li><a href="apply.html">Apply It</a></li>
    <li><a href="about.html">About</a></li>
  </ul>
</nav>

.site-nav {
  position: sticky;
  top: 0;
  z-index: 100;
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 1rem;
  padding: 1rem var(--space);
  background: rgb(255 255 255 / 0.8);
  backdrop-filter: blur(10px);
  box-shadow: var(--shadow-sm);
  transition: padding 0.3s ease;
}
.site-nav.scrolled { padding-block: 0.4rem; }

.site-links {
  display: flex;
  gap: 1.5rem;
  list-style: none;
  margin: 0;
  padding: 0;
}
.site-links a {
  position: relative;
  color: var(--ink);
  text-decoration: none;
  font-weight: 500;
}
/* underline that grows from the left */
.site-links a::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: -4px;
  height: 2px;
  width: 0;
  background: var(--gradient);
  transition: width 0.3s ease;
}
.site-links a:hover::after,
.site-links a[aria-current="page"]::after { width: 100%; }

// tiny progressive enhancement — condense the nav after scrolling
const nav = document.querySelector('.site-nav');
window.addEventListener('scroll', () => {
  nav.classList.toggle('scrolled', window.scrollY > 40);
}, { passive: true });

Glassmorphism hero + gradient text

.hero {
  min-height: 70vh;
  display: grid;
  place-items: center;
  padding: var(--space);
  background: var(--gradient); /* swap for an image once you have one */
  background-size: cover;
  background-position: center;
}
.hero-card {
  max-width: 40rem;
  padding: clamp(1.5rem, 4vw, 3rem);
  text-align: center;
  border-radius: var(--radius);
  background: rgb(255 255 255 / 0.15);
  backdrop-filter: blur(10px);
  border: 1px solid rgb(255 255 255 / 0.25);
  box-shadow: var(--shadow-lg);
  transition: transform 0.3s ease, box-shadow 0.3s ease;
}
.hero-card:hover {
  transform: translateY(-10px);
  box-shadow: 0 30px 60px rgb(0 0 0 / 0.25);
}
.hero-title {
  margin: 0 0 0.5rem;
  font-size: clamp(2rem, 6vw, 3.5rem);
  /* gradient text: paint the gradient, then clip it to the glyphs */
  background: var(--gradient);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}

Milestone 3 — The 3D Flip Cards

Goal: the steps.html page shows Pólya's four steps as cards that flip in 3D to reveal detail on the back. This is the showpiece — get it crisp.

Three properties do the heavy lifting: perspective on the container gives depth, transform-style: preserve-3d lets the two faces live in the same 3D space, and backface-visibility: hidden stops the back from showing through the front.

<div class="flip" tabindex="0">
  <div class="flip-inner">
    <div class="flip-face flip-front">
      <span class="flip-num">1</span>
      <h3>Understand</h3>
    </div>
    <div class="flip-face flip-back">
      <p>Name what's known, unknown, and the goal — in your own words.</p>
    </div>
  </div>
</div>

.flip {
  width: 100%;
  aspect-ratio: 3 / 4;
  perspective: 1000px; /* depth of the 3D scene */
}
.flip-inner {
  position: relative;
  width: 100%;
  height: 100%;
  transform-style: preserve-3d;
  transition: transform 0.8s cubic-bezier(0.2, 0.8, 0.2, 1);
}
/* flip on hover AND keyboard focus for accessibility */
.flip:hover .flip-inner,
.flip:focus-visible .flip-inner { transform: rotateY(180deg); }

.flip-face {
  position: absolute;
  inset: 0;
  display: grid;
  place-content: center;
  gap: 0.5rem;
  padding: 1.5rem;
  border-radius: var(--radius);
  backface-visibility: hidden;
  box-shadow: var(--shadow-sm);
}
.flip-front { background: var(--surface); }
.flip-back {
  background: var(--brand);
  color: #fff;
  transform: rotateY(180deg); /* pre-rotate so it faces us after the flip */
}
.flip-num {
  font-size: 4rem;
  font-weight: 800;
  line-height: 1;
  background: var(--gradient);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}

Milestone 4 — Content Grid & Effects

Goal: the apply.html page uses an auto-fitting responsive grid of example cards, each with a lift-on-hover, a gradient top-bar that wipes in, and an image that de-saturates until you hover it.

Responsive grid with zero media queries

auto-fit plus minmax() gives you a grid that reflows on its own — one column on a phone, several on a wide screen — without a single breakpoint.

.examples {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(16rem, 1fr));
  gap: var(--space);
  padding: var(--space);
}
.example {
  position: relative;
  overflow: hidden;
  border-radius: var(--radius);
  background: var(--surface);
  box-shadow: var(--shadow-sm);
  transition: transform 0.3s ease, box-shadow 0.3s ease;
}
.example:hover {
  transform: translateY(-10px) scale(1.02);
  box-shadow: var(--shadow-lg);
}
/* accent bar that wipes in from the left */
.example::before {
  content: "";
  position: absolute;
  inset: 0 0 auto 0;
  height: 5px;
  background: var(--gradient);
  transform: scaleX(0);
  transform-origin: left;
  transition: transform 0.3s ease;
}
.example:hover::before { transform: scaleX(1); }

/* filter: desaturate until hover */
.example img {
  width: 100%;
  height: 12rem;
  object-fit: cover;
  filter: grayscale(60%);
  transition: filter 0.3s ease;
}
.example:hover img { filter: grayscale(0%); }

Milestone 5 — Polish, A11y & Ship

Goal: take the working site from "it functions" to "it's finished." This is Pólya's Review step — the difference between a demo and a portfolio piece.

Respect reduced motion

Some users get motion sickness from big transitions. Honor their OS setting — this one media query is the single most important accessibility upgrade for an effects-heavy site.

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.001ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.001ms !important;
    scroll-behavior: auto !important;
  }
}

Provide fallbacks for backdrop-filter

Where a browser lacks backdrop-filter, a plain translucent background still reads fine. Detect support and enhance rather than assume.

.hero-card { background: rgb(255 255 255 / 0.6); } /* readable fallback */

@supports (backdrop-filter: blur(10px)) {
  .hero-card {
    background: rgb(255 255 255 / 0.15);
    backdrop-filter: blur(10px);
  }
}

Final polish pass

• Check color contrast — body text should hit WCAG AA (4.5:1). Gradient text over a busy image is the usual offender.
• Tab through every page with the keyboard: can you reach and trigger every interactive element? Is the focus outline visible?
• Run Lighthouse and WAVE; fix anything red.
• Test at 360 px, 768 px, and 1280 px widths.

What Good Looks Like

Use this bar to grade yourself honestly. "Good" isn't "used the most effects" — it's restraint plus polish. A calm site with three effects done cleanly beats a noisy one with ten done sloppily.

Ship Checklist

Before you call it done, walk this list top to bottom. Each item maps to a milestone above.

Summary & Quiz

📚 Further Reading

• MDN — CSS reference
• CSS-Tricks Almanac
• Pólya — How to Solve It (overview)
• web.dev — prefers-reduced-motion

🚀 What's Next?

You've squeezed everything out of hand-tuned CSS layout and effects. Next module we graduate to a modern layout engine built for exactly this kind of one-dimensional arrangement: Flexbox Layout Concepts. Much of the nav and card work you just did by hand gets dramatically simpler with it.