/* =================================
   GLOBAL PAGE STYLING
================================= */

body {
  margin: 0;
  font-family: 'Segoe UI', Tahoma, sans-serif;
  background: #f1f5f9;
  color: #1e293b;
}

h3 {
  padding: 10px 20px;
  font-size: 13px;
  color: #64748b;
  margin: 0;
}

header {
  background: #0f172a;
  padding: 20px 28px;
  margin-bottom: 0;
}

header h1 {
  color: #f0f9ff;
  border-left-color: #38bdf8 !important;
}

main {
  max-width: 860px;
  margin: 0 auto;
  padding: 28px 24px 48px;
}

section {
  margin-bottom: 28px;
}

section h2 {
  font-size: 1rem;
  font-weight: 700;
  color: #0f172a;
  margin-bottom: 10px;
  padding-bottom: 6px;
  border-bottom: 1px solid #e2e8f0;
}

section p {
  font-size: 14px;
  line-height: 1.75;
  color: #475569;
}

code {
  background: #e2e8f0;
  padding: 2px 6px;
  border-radius: 4px;
  font-size: 13px;
  color: #0f172a;
}

/* =================================
   NAVIGATION BAR
================================= */

nav {
  display: flex;
  justify-content: space-between;
  align-items: center;
  background-color: #1e293b;
  padding: 14px 28px;
  border-bottom: 3px solid #0ea5e9;
}

nav .logo {
  font-size: 1.3rem;
  font-weight: bold;
  color: #38bdf8;
}

nav a {
  color: #e0f2fe;
  text-decoration: none;
  margin-left: 18px;
  font-weight: 500;
  font-size: 14px;
  transition: color 0.2s;
}

nav a:hover {
  color: #7dd3fc;
}

/* =================================
   GRID LAYOUT
================================= */

.container {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 16px;
  padding: 4px 0;
}

.item {
  background: #0f172a;
  color: #e0f2fe;
  padding: 28px;
  border-radius: 8px;
  text-align: center;
  font-weight: 600;
  font-size: 14px;
  box-shadow: 0 4px 12px rgba(0,0,0,0.15);
  transition: transform 0.25s ease, box-shadow 0.25s ease;
}

.item:hover {
  transform: translateY(-4px);
  box-shadow: 0 8px 20px rgba(0,0,0,0.25);
}

.item-4 { background: linear-gradient(135deg, #0369a1, #0ea5e9); }
.item-5 { background: linear-gradient(135deg, #065f46, #10b981); }
.item-6 { background: linear-gradient(135deg, #7c3aed, #a78bfa); }

/* =================================
   RESPONSIVE DESIGN
================================= */

@media (max-width: 900px) {
  .container {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (max-width: 600px) {
  nav {
    flex-direction: column;
    align-items: flex-start;
    gap: 10px;
  }

  .container {
    grid-template-columns: 1fr;
  }

  body {
    background: #e8f0fe;
  }
}

/* =================================
   FOOTER
================================= */

footer {
  text-align: center;
  padding: 20px;
  font-size: 13px;
  color: #94a3b8;
  border-top: 1px solid #e2e8f0;
}