*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

html { scroll-behavior: smooth; }

:root {
  --bg: #eaf3fc;
  --bg2: #dbe9f8;
  --bg3: #1c2330;
  --cyan: #1565c0;
  --cyan2: #0d47a1;
  --ink: #142a44;
  --muted: #4a6178;
  --border: #c7dbf0;
  --card: #ffffff;
  --green: #3fb950;
  --orange: #ff7b54;
  --purple: #a371f7;
  --yellow: #f0b429;
}

body {
  font-family: 'Space Grotesk', sans-serif;
  background: var(--bg);
  color: var(--ink);
  min-height: 100vh;
  overflow-x: hidden;
  line-height: 1.6;
}

.grid-bg {
  position: fixed;
  inset: 0;
  background-image: radial-gradient(rgba(21, 101, 192, 0.05) 1px, transparent 1px);
  background-size: 32px 32px;
  pointer-events: none;
  z-index: 0;
}

nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 2.5rem;
  height: 64px;
  background: rgba(234, 243, 252, 0.85);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border);
}

.nav-logo {
  display: flex;
  align-items: center;
  gap: 10px;
  text-decoration: none;
}

.logo-text {
  font-size: 1.4rem;
  font-weight: 700;
  color: var(--ink);
  letter-spacing: -0.4px;
}

.logo-text span { color: var(--cyan); }

.logo-ai {
  margin-left: 2px;
  font-weight: 800;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 2rem;
}

.nav-links a {
  color: var(--muted);
  text-decoration: none;
  font-size: 0.9rem;
  font-weight: 500;
  transition: color 0.15s;
}

.nav-links a:hover,
.nav-links a.active { color: var(--cyan); }

.btn-start {
  background: var(--cyan);
  color: #fff;
  padding: 8px 20px;
  border-radius: 8px;
  font-weight: 700;
  font-size: 0.88rem;
  text-decoration: none;
  transition: background 0.15s, transform 0.1s;
}

.btn-start:hover {
  background: var(--cyan2);
  transform: translateY(-1px);
}

.menu-toggle {
  display: none;
  background: none;
  border: none;
  color: var(--ink);
  font-size: 1.5rem;
  cursor: pointer;
}

.hero {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: 7.5rem 2rem 4rem;
  position: relative;
  z-index: 1;
}

.hero::before {
  content: '';
  position: absolute;
  inset: 0;
  background: radial-gradient(ellipse 80% 60% at 50% 0%, rgba(21, 101, 192, 0.08) 0%, transparent 70%);
  pointer-events: none;
}

.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  background: rgba(21, 101, 192, 0.08);
  border: 1px solid rgba(21, 101, 192, 0.2);
  color: var(--cyan);
  padding: 6px 16px;
  border-radius: 100px;
  font-size: 0.8rem;
  font-family: 'Space Mono', monospace;
  margin-bottom: 2rem;
  letter-spacing: 0.5px;
}

.hero h1 {
  font-size: clamp(2.4rem, 6vw, 4.8rem);
  font-weight: 700;
  line-height: 1.08;
  letter-spacing: -2px;
  margin-bottom: 1.5rem;
  max-width: 860px;
}

.hero h1 .cyan { color: var(--cyan); }

.hero-sub {
  font-size: 1.05rem;
  color: var(--muted);
  line-height: 1.75;
  max-width: 620px;
  margin: 0 auto 2.5rem;
}

.hero-actions {
  display: flex;
  gap: 0.8rem;
  flex-wrap: wrap;
  justify-content: center;
  margin-bottom: 3.5rem;
}

.btn-primary {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  background: var(--cyan);
  color: #fff;
  padding: 12px 24px;
  border-radius: 8px;
  font-weight: 700;
  font-size: 0.92rem;
  text-decoration: none;
  transition: background 0.15s;
  border: none;
  cursor: pointer;
}

.btn-primary:hover { background: var(--cyan2); }

.btn-outline {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  background: transparent;
  color: var(--ink);
  padding: 12px 24px;
  border-radius: 8px;
  font-weight: 600;
  font-size: 0.92rem;
  text-decoration: none;
  border: 1px solid var(--border);
  transition: border-color 0.15s, color 0.15s;
}

.btn-outline:hover {
  border-color: var(--cyan);
  color: var(--cyan);
}

.stats {
  display: flex;
  align-items: center;
  gap: 2.5rem;
  justify-content: center;
  flex-wrap: wrap;
}

.stat { text-align: center; }

.stat-num {
  font-size: 1.8rem;
  font-weight: 700;
  letter-spacing: -1px;
}

.stat-num span { color: var(--cyan); }

.stat-label {
  font-size: 0.75rem;
  color: var(--muted);
  font-family: 'Space Mono', monospace;
  text-transform: uppercase;
  letter-spacing: 1px;
  margin-top: 3px;
}

.stat-divider {
  width: 1px;
  height: 40px;
  background: var(--border);
}

.section {
  padding: 5rem 2.5rem;
  max-width: 1200px;
  margin: 0 auto;
  position: relative;
  z-index: 1;
}

.section-label {
  font-size: 0.72rem;
  font-family: 'Space Mono', monospace;
  color: var(--cyan);
  text-transform: uppercase;
  letter-spacing: 2.5px;
  margin-bottom: 0.8rem;
}

.section-title {
  font-size: clamp(1.6rem, 3.5vw, 2.4rem);
  font-weight: 700;
  letter-spacing: -0.5px;
  margin-bottom: 0.6rem;
}

.section-sub {
  font-size: 0.95rem;
  color: var(--muted);
  line-height: 1.7;
  max-width: 560px;
}

.courses-header {
  display: flex;
  justify-content: space-between;
  align-items: flex-end;
  margin-bottom: 2.5rem;
  flex-wrap: wrap;
  gap: 1rem;
}

.featured {
  background: linear-gradient(135deg, rgba(21, 101, 192, 0.06) 0%, rgba(163, 113, 247, 0.06) 100%);
  border: 1px solid var(--border);
  border-radius: 16px;
  padding: 2.5rem;
  display: grid;
  grid-template-columns: 1.2fr 0.8fr;
  gap: 2rem;
  margin-bottom: 2rem;
  align-items: center;
}

.featured-label {
  font-size: 0.68rem;
  font-family: 'Space Mono', monospace;
  color: var(--cyan);
  text-transform: uppercase;
  letter-spacing: 2px;
  margin-bottom: 0.6rem;
}

.featured-title {
  font-size: 1.6rem;
  font-weight: 700;
  letter-spacing: -0.3px;
  margin-bottom: 0.5rem;
}

.featured-sub {
  font-size: 0.9rem;
  color: var(--muted);
  line-height: 1.65;
  margin-bottom: 1.2rem;
}

.featured-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin-bottom: 1.2rem;
}

.tag {
  font-size: 0.72rem;
  font-family: 'Space Mono', monospace;
  padding: 4px 10px;
  border-radius: 100px;
  border: 1px solid var(--border);
  color: var(--muted);
}

.featured-visual {
  background: var(--bg3);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 1.5rem;
  font-family: 'Space Mono', monospace;
  font-size: 0.82rem;
  line-height: 1.8;
  color: #c9d1d9;
}

.code-kw { color: #c792ea; }
.code-fn { color: #82aaff; }
.code-st { color: #c3e88d; }
.code-cm { color: #546e7a; font-style: italic; }

.courses-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(270px, 1fr));
  gap: 1.2rem;
}

.course-card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 1.5rem;
  text-decoration: none;
  display: flex;
  flex-direction: column;
  gap: 1rem;
  transition: border-color 0.2s, transform 0.2s, box-shadow 0.2s;
}

.course-card:hover {
  border-color: rgba(21, 101, 192, 0.3);
  transform: translateY(-3px);
  box-shadow: 0 12px 40px rgba(0, 0, 0, 0.3);
}

.card-top {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.card-icon {
  width: 44px;
  height: 44px;
  border-radius: 10px;
  display: grid;
  place-items: center;
  font-size: 1.3rem;
}

.card-badge {
  font-size: 0.66rem;
  font-family: 'Space Mono', monospace;
  padding: 3px 8px;
  border-radius: 4px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.badge-beginner { background: rgba(63, 185, 80, 0.15); color: var(--green); }
.badge-intermediate { background: rgba(255, 123, 84, 0.15); color: var(--orange); }
.badge-advanced { background: rgba(163, 113, 247, 0.15); color: var(--purple); }

.card-title {
  font-size: 1.05rem;
  font-weight: 700;
  color: var(--ink);
  line-height: 1.35;
}

.card-desc {
  font-size: 0.83rem;
  color: var(--muted);
  line-height: 1.65;
  flex: 1;
}

.card-meta {
  display: flex;
  align-items: center;
  gap: 1rem;
  font-size: 0.75rem;
  color: var(--muted);
  font-family: 'Space Mono', monospace;
  border-top: 1px solid var(--border);
  padding-top: 0.9rem;
}

.card-link {
  font-size: 0.82rem;
  color: var(--cyan);
  font-weight: 600;
}

.why-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(240px, 1fr));
  gap: 1.2rem;
  margin-top: 2rem;
}

.why-card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 1.5rem;
}

.why-icon {
  font-size: 1.5rem;
  margin-bottom: 0.8rem;
}

.why-card h3 {
  font-size: 1rem;
  margin-bottom: 0.5rem;
}

.why-card p {
  font-size: 0.86rem;
  color: var(--muted);
  line-height: 1.65;
}

.about-wrap {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 2.5rem;
  align-items: center;
  margin-top: 2rem;
}

.about-panel {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 16px;
  padding: 2rem;
}

.about-panel h3 {
  font-size: 1.2rem;
  margin-bottom: 0.8rem;
}

.about-panel p {
  color: var(--muted);
  font-size: 0.92rem;
  line-height: 1.75;
  margin-bottom: 0.8rem;
}

.about-list {
  list-style: none;
  margin-top: 1rem;
}

.about-list li {
  padding: 0.55rem 0;
  border-bottom: 1px solid var(--border);
  font-size: 0.88rem;
  color: var(--muted);
}

.about-list li strong { color: var(--ink); }

.contact-section {
  background: linear-gradient(180deg, transparent, rgba(21, 101, 192, 0.04));
  border-top: 1px solid var(--border);
  border-bottom: 1px solid var(--border);
}

.contact-box {
  max-width: 720px;
  margin: 2rem auto 0;
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 16px;
  padding: 2rem;
}

.contact-form {
  display: grid;
  gap: 1rem;
  margin-top: 1.5rem;
}

.contact-form label {
  display: grid;
  gap: 0.4rem;
  font-size: 0.82rem;
  color: var(--muted);
}

.contact-form input,
.contact-form select,
.contact-form textarea {
  background: var(--bg2);
  border: 1px solid var(--border);
  color: var(--ink);
  padding: 12px 14px;
  border-radius: 8px;
  font-family: inherit;
  font-size: 0.92rem;
  outline: none;
}

.contact-form input:focus,
.contact-form select:focus,
.contact-form textarea:focus {
  border-color: rgba(21, 101, 192, 0.4);
}

.contact-form textarea { min-height: 110px; resize: vertical; }

.form-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1rem;
}

footer {
  border-top: 1px solid var(--border);
  padding: 3rem 2.5rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 1rem;
  max-width: 1200px;
  margin: 0 auto;
  position: relative;
  z-index: 1;
}

.footer-copy { font-size: 0.82rem; color: var(--muted); }

.footer-links {
  display: flex;
  gap: 1.5rem;
}

.footer-links a {
  font-size: 0.82rem;
  color: var(--muted);
  text-decoration: none;
  transition: color 0.15s;
}

.footer-links a:hover { color: var(--cyan); }

@media (max-width: 900px) {
  .featured { grid-template-columns: 1fr; }
  .about-wrap { grid-template-columns: 1fr; }
}

@media (max-width: 768px) {
  nav { padding: 0 1.2rem; }

  .nav-links {
    display: none;
    position: absolute;
    top: 64px;
    left: 0;
    right: 0;
    flex-direction: column;
    align-items: stretch;
    gap: 0;
    background: var(--bg2);
    border-bottom: 1px solid var(--border);
    padding: 0.5rem 0;
  }

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

  .nav-links a {
    padding: 0.9rem 1.2rem;
    border-bottom: 1px solid var(--border);
  }

  .menu-toggle { display: block; }

  .btn-start { display: none; }

  .hero { padding: 5rem 1.2rem 3rem; }

  .section { padding: 3rem 1.2rem; }

  .stat-divider { display: none; }

  .form-row { grid-template-columns: 1fr; }
}