:root {
  --primary: #445283;
  --secondary: #8A94A9;
  --background: #E3E5E7;
  --white: #ffffff;
}

html {
  scroll-behavior: smooth;
}

body {
  font-family: Arial, sans-serif;
  background: var(--background);
  color: var(--primary);
}

/* HEADINGS */
h1, h3 {
  text-align: center;
  padding: 1rem;
}

/* NAVIGATION (MOBILE FIRST - CLEAN) */
.sub-nav {
  position: sticky;
  top: 0;
  background: var(--secondary);
  padding: 0.75rem;
  z-index: 1000;
}

.sub-nav ul {
  display: flex;
  overflow-x: auto;
  gap: 10px;
  list-style: none;
  padding: 0;
}

.sub-nav a {
  color: white;
  text-decoration: none;
  padding: 8px 12px;
  background: rgba(255,255,255,0.2);
  border-radius: 20px;
  white-space: nowrap;
  font-weight: bold;
}

/* CONTAINER */
.container {
  width: 90%;
  margin: auto;
}

/* HERO */
.hero img {
  width: 100%;
  aspect-ratio: 3 / 1;
  object-fit: cover;
}

.hero-text {
  text-align: center;
  padding: 1rem;
}

/* PEN SECTIONS */
.pen-block {
  margin: 3rem 0;
  text-align: center;
}

.pen-block img {
  max-width: 400px;
  margin: 1rem auto;
}

/* CONTENT BOXES */
.content-section {
  background: white;
  padding: 1rem;
  border-left: 5px solid var(--primary);
  border-radius: 8px;
}

.content-section p {
  line-height: 1.6;
}

/* GRID (FIXED BREAKPOINTS) */
.pen-grid {
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

@media (min-width: 768px) {
  .pen-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (min-width: 1024px) {
  .pen-grid {
    grid-template-columns: repeat(4, 1fr);
  }

  .container {
    width: 80%;
  }
}
.nav-links {
  display: none;
  flex-direction: column;
  gap: 1rem;
}

.nav-links.active {
  display: flex;
}

.nav-header {
  font-size: 2rem;
  cursor: pointer;
}

/* Desktop */
@media (min-width: 768px) {
  .nav-header {
    display: none;
  }

  .nav-links {
    display: flex;
    flex-direction: row;
    justify-content: center;
  }
}

h3 {
  text-align: center;
}

body {
  font-family: 'Inter', sans-serif;
}

.rating {
  font-size: 1.5rem;
  color: gold;
  margin: 0.5rem 0;
}

.usability {
  display: flex;
  justify-content: center;
  padding: 3rem 1rem;
}

.usability-box {
  background: white;
  max-width: 700px;
  width: 100%;
  padding: 2rem;
  border-radius: 12px;
  box-shadow: 0 4px 12px rgba(0,0,0,0.1);
}

/* Keep text readable */
.usability-box h2,
.usability-box h3 {
  text-align: center;
}

.usability-box p,
.usability-box li {
  text-align: left;
  line-height: 1.6;
}

.nav-links {
  display: none;
}

.nav-links.active {
  display: flex;
}