:root {
  --accent: #0070f3;
  --bg: #fff;
  --fg: #222;
  --maxW: 800px;
  --spacing: 1rem;
  --font-size: 18px; /* added */
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  padding: var(--spacing);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  font-size: var(--font-size); /* updated */
  line-height: 1.6;
  color: var(--fg);
  background: var(--bg);
}

.container {
  max-width: var(--maxW);
  margin: 0 auto;
  padding-bottom: var(--spacing);
}

header {
  text-align: center;
  margin-bottom: var(--spacing);
}

h1 {
  margin: var(--spacing) 0;
  font-size: 2rem;
}

nav ul {
  display: flex;
  flex-wrap: wrap;
  list-style: none;
  padding: 0;
  margin: var(--spacing) 0;
  justify-content: center;
}

nav li {
  margin: 0.5rem;
}

nav a {
  text-decoration: none;
  color: var(--fg);
  padding: 0.25rem 0.5rem;
  font-weight: 500;
}

nav a:hover,
nav a:focus {
  color: var(--accent);
  outline: none;
}

section {
  margin-top: calc(var(--spacing) * 2);
}

section h2 {
  font-size: 1.5rem;
  margin-bottom: 0.5rem;
}

img {
  max-width: 100%;
  height: auto;
  display: block;
  margin: var(--spacing) auto;
  border-radius: 4px;
}

@media (min-width: 600px) {
  nav ul {
    justify-content: space-around;
  }
}

/* Video embed */
.video-container {
  position: relative;
  width: 100%;
  padding-bottom: 56.25%;        /* 16:9 aspect ratio */
  margin: calc(var(--spacing) * 2) 0;
  border-radius: 4px;
  overflow: hidden;
}

.video-container video {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  display: block;
}