/* =====================
   GLOBAL RESET & BASE
===================== */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

:root {
  --primary: #0f172a;
  --accent: #2563eb;
  --bg: #f8fafc;
  --text: #1e293b;
  --muted: #64748b;
  --card: #ffffff;
  --border: #e5e7eb;
}

body {
  font-family: 'Inter', sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.7;
}

a {
  color: var(--accent);
  text-decoration: none;
}

img {
  max-width: 100%;
  display: block;
  border-radius: 14px;
}

/* =====================
   LAYOUT
===================== */
.container {
  max-width: 1200px;
  margin: auto;
  padding: 0 20px;
}

.grid-3 {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 30px;
}

/* =====================
   HEADER & NAVIGATION
===================== */
.site-header {
  background: #ffffff;
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  z-index: 1000;
}

.header-flex {
  display: flex;
  justify-content: space-between;
  align-items: center;
  height: 72px;
}

.logo a {
  font-weight: 800;
  font-size: 1.2rem;
  color: var(--primary);
}

.main-nav ul {
  list-style: none;
  display: flex;
  align-items: center;
  gap: 24px;
}

.main-nav li {
  position: relative;
  font-weight: 500;
}

.main-nav span {
  cursor: pointer;
}

/* =====================
   MEGA MENU
===================== */
.has-mega:hover .mega-menu {
  display: grid;
}

.mega-menu {
  display: none;
  position: absolute;
  top: 60px;
  left: 0;
  background: #ffffff;
  border: 1px solid var(--border);
  box-shadow: 0 30px 60px rgba(0,0,0,0.12);
  padding: 30px;
  grid-template-columns: repeat(5, 1fr);
  gap: 30px;
  width: 900px;
  border-radius: 18px;
}

.mega-column h4 {
  font-size: 0.95rem;
  margin-bottom: 12px;
  color: var(--primary);
}

.mega-column a {
  display: block;
  font-size: 0.85rem;
  margin-bottom: 8px;
  color: var(--muted);
}

.mega-column a:hover {
  color: var(--accent);
}

/* =====================
   HERO
===================== */
.hero {
  padding: 100px 0;
  background: linear-gradient(135deg, #1e293b, #020617);
  color: #ffffff;
  text-align: center;
}

.hero h1 {
  font-size: 3rem;
  font-weight: 800;
  max-width: 800px;
  margin: auto;
}

.hero p {
  margin: 20px auto 30px;
  max-width: 720px;
  color: #cbd5f5;
}

.btn-primary {
  display: inline-block;
  padding: 14px 34px;
  background: var(--accent);
  color: #ffffff;
  border-radius: 999px;
  font-weight: 600;
}

/* =====================
   TOPIC CARDS
===================== */
.topics {
  padding: 80px 0;
}

.topic-card {
  background: var(--card);
  padding: 20px;
  border-radius: 22px;
  box-shadow: 0 20px 40px rgba(0,0,0,0.08);
  transition: transform 0.3s ease;
}

.topic-card:hover {
  transform: translateY(-6px);
}

.topic-card h2 {
  font-size: 1.25rem;
  margin: 14px 0 8px;
}

.topic-card p {
  font-size: 0.9rem;
  color: var(--muted);
}

.topic-card a {
  display: inline-block;
  margin-top: 12px;
  font-weight: 600;
}

/* =====================
   FOOTER
===================== */
.site-footer {
  background: #020617;
  color: #94a3b8;
  padding: 70px 0 30px;
  margin-top: 80px;
}

.footer-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 40px;
  margin-bottom: 30px;
}

.site-footer h4 {
  color: #ffffff;
  margin-bottom: 12px;
}

.site-footer a {
  display: block;
  color: #94a3b8;
  font-size: 0.9rem;
  margin-bottom: 6px;
}

.site-footer a:hover {
  color: #ffffff;
}

.site-footer p {
  font-size: 0.9rem;
}

copyright {
  text-align: center;
  font-size: 0.8rem;
  color: #64748b;
}

/* =====================
   RESPONSIVE
===================== */
@media (max-width: 900px) {
  .mega-menu {
    width: 100%;
    grid-template-columns: repeat(2, 1fr);
  }

  .hero h1 {
    font-size: 2.2rem;
  }
}