/* HERO */
#home {
  min-height: 100vh;
  display: flex;
  align-items: center;
  padding: 8rem 4rem 4rem;
  position: relative;
  overflow: hidden;
}

.hero-grid {
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(rgba(0,229,255,0.04) 1px, transparent 1px),
    linear-gradient(90deg, rgba(0,229,255,0.04) 1px, transparent 1px);
  background-size: 60px 60px;
  mask-image: radial-gradient(ellipse 80% 80% at 50% 50%, black 20%, transparent 100%);
}

.hero-glow {
  position: absolute;
  width: 600px; height: 600px;
  background: radial-gradient(circle, rgba(124,58,237,0.15) 0%, transparent 70%);
  top: -100px; right: -100px;
  pointer-events: none;
}

.hero-glow2 {
  position: absolute;
  width: 400px; height: 400px;
  background: radial-gradient(circle, rgba(0,229,255,0.1) 0%, transparent 70%);
  bottom: 0; left: 10%;
  pointer-events: none;
}

.hero-content {
  position: relative;
  z-index: 1;
  max-width: 760px;
}

.hero-tag {
  display: inline-flex;
  align-items: center;
  gap: 0.6rem;
  font-family: var(--mono);
  font-size: 0.75rem;
  color: var(--accent);
  letter-spacing: 0.12em;
  text-transform: uppercase;
  margin-bottom: 1.5rem;
}

.hero-tag::before {
  content: '';
  display: block;
  width: 32px; height: 1px;
  background: var(--accent);
}

h1 {
  font-size: clamp(3rem, 7vw, 6rem);
  font-weight: 800;
  line-height: 1.0;
  letter-spacing: -0.02em;
  margin-bottom: 1.5rem;
}

h1 .line2 {
  color: transparent;
  -webkit-text-stroke: 1px rgba(255,255,255,0.25);
}

.hero-desc {
  font-size: 1.1rem;
  color: var(--muted);
  line-height: 1.7;
  max-width: 520px;
  margin-bottom: 2.5rem;
}

.hero-cta {
  display: flex;
  gap: 1rem;
  flex-wrap: wrap;
}

.btn-primary {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.85rem 2rem;
  background: var(--accent);
  color: #000;
  font-family: var(--mono);
  font-size: 0.8rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  text-decoration: none;
  transition: all 0.2s;
  clip-path: polygon(0 0, calc(100% - 10px) 0, 100% 10px, 100% 100%, 10px 100%, 0 calc(100% - 10px));
}

.btn-primary:hover {
  background: #fff;
  transform: translateY(-2px);
  box-shadow: 0 8px 30px rgba(0,229,255,0.3);
}

.btn-secondary {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.85rem 2rem;
  border: 1px solid var(--border);
  color: var(--text);
  font-family: var(--mono);
  font-size: 0.8rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  text-decoration: none;
  transition: all 0.2s;
}

.btn-secondary:hover {
  border-color: var(--accent);
  color: var(--accent);
}

/* SECTION BASE */
section { padding: 6rem 4rem; position: relative; z-index: 1; }

.section-label {
  display: flex;
  align-items: center;
  gap: 1rem;
  font-family: var(--mono);
  font-size: 0.7rem;
  color: var(--accent);
  letter-spacing: 0.15em;
  text-transform: uppercase;
  margin-bottom: 1rem;
}

.section-label::after {
  content: '';
  flex: 1;
  max-width: 80px;
  height: 1px;
  background: var(--accent);
  opacity: 0.4;
}

.section-title {
  font-size: clamp(2rem, 4vw, 3rem);
  font-weight: 800;
  letter-spacing: -0.02em;
  margin-bottom: 3rem;
}

/* COURSES SECTION (index) */
#slides { background: var(--bg2); }

.slides-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
  gap: 1.5rem;
}

.slide-card {
  background: var(--bg3);
  border: 1px solid var(--border);
  overflow: hidden;
  transition: all 0.3s;
  cursor: pointer;
  text-decoration: none;
  color: inherit;
  display: block;
}

.slide-card:hover {
  border-color: rgba(0,229,255,0.3);
  transform: translateY(-4px);
  box-shadow: 0 20px 40px rgba(0,0,0,0.4), 0 0 0 1px rgba(0,229,255,0.1);
}

.slide-thumb {
  width: 100%;
  aspect-ratio: 16/9;
  background: var(--bg);
  display: flex;
  align-items: center;
  justify-content: center;
  position: relative;
  overflow: hidden;
}

.slide-thumb-inner {
  width: 85%;
  height: 85%;
  border: 1px solid var(--border);
  display: flex;
  flex-direction: column;
  padding: 1rem;
  gap: 0.5rem;
}

.slide-line { height: 6px; background: rgba(0,229,255,0.15); border-radius: 2px; }
.slide-line.short { width: 55%; }
.slide-line.accent { background: rgba(0,229,255,0.5); width: 40%; }
.slide-dots { display: flex; gap: 4px; margin-top: auto; }
.slide-dot { width: 6px; height: 6px; border-radius: 50%; background: rgba(255,255,255,0.1); }
.slide-dot.on { background: var(--accent); }

.slide-overlay {
  position: absolute;
  inset: 0;
  background: rgba(0,229,255,0.05);
  display: flex;
  align-items: center;
  justify-content: center;
  opacity: 0;
  transition: opacity 0.2s;
}

.slide-card:hover .slide-overlay { opacity: 1; }

.play-btn {
  width: 48px; height: 48px;
  border: 2px solid var(--accent);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--accent);
  font-size: 1.2rem;
}

.slide-info { padding: 1.2rem; }
.slide-meta { font-family: var(--mono); font-size: 0.68rem; color: var(--accent); letter-spacing: 0.1em; text-transform: uppercase; margin-bottom: 0.5rem; }
.slide-title { font-size: 1rem; font-weight: 700; margin-bottom: 0.4rem; }
.slide-desc { font-size: 0.85rem; color: var(--muted); line-height: 1.5; }

/* ARTICLES SECTION (index) */
#articles { background: var(--bg); }

.articles-list { display: flex; flex-direction: column; gap: 0; }

.article-item {
  display: flex;
  align-items: flex-start;
  gap: 2rem;
  padding: 2rem 0;
  border-bottom: 1px solid var(--border);
  text-decoration: none;
  color: inherit;
  transition: all 0.2s;
  position: relative;
}

.article-item::before {
  content: '';
  position: absolute;
  left: -4rem; top: 0; bottom: 0;
  width: 0;
  background: rgba(0,229,255,0.03);
  transition: width 0.3s;
}

.article-item:hover::before { width: calc(100% + 8rem); }

.article-num { font-family: var(--mono); font-size: 0.7rem; color: var(--muted); min-width: 2.5rem; padding-top: 0.3rem; }
.article-body { flex: 1; }

.article-tag {
  display: inline-block;
  font-family: var(--mono); font-size: 0.68rem;
  color: var(--accent2); letter-spacing: 0.1em; text-transform: uppercase;
  margin-bottom: 0.5rem;
}

.article-title { font-size: 1.2rem; font-weight: 700; margin-bottom: 0.5rem; transition: color 0.2s; }
.article-item:hover .article-title { color: var(--accent); }
.article-excerpt { font-size: 0.88rem; color: var(--muted); line-height: 1.6; }
.article-date { font-family: var(--mono); font-size: 0.7rem; color: var(--muted); white-space: nowrap; padding-top: 0.3rem; }
.article-arrow { font-size: 1.2rem; color: var(--muted); padding-top: 0.2rem; transition: all 0.2s; }
.article-item:hover .article-arrow { color: var(--accent); transform: translateX(4px); }

/* CONTACT SECTION (index) */
#contact { background: var(--bg2); display: flex; gap: 4rem; flex-wrap: wrap; }
.contact-left { flex: 1; min-width: 280px; }
.contact-right { flex: 1; min-width: 280px; }

.contact-desc { font-size: 1rem; color: var(--muted); line-height: 1.7; margin-bottom: 2.5rem; }
.contact-links { display: flex; flex-direction: column; gap: 1rem; }

.contact-link { display: flex; align-items: center; gap: 1rem; text-decoration: none; color: var(--text); transition: color 0.2s; }
.contact-link:hover { color: var(--accent); }

.contact-icon {
  width: 40px; height: 40px;
  border: 1px solid var(--border);
  display: flex; align-items: center; justify-content: center;
  font-size: 1rem; transition: all 0.2s;
}
.contact-link:hover .contact-icon { border-color: var(--accent); background: rgba(0,229,255,0.05); }
.contact-link-text { font-family: var(--mono); font-size: 0.85rem; }

.form-group { margin-bottom: 1.2rem; }
.form-group label {
  display: block; font-family: var(--mono); font-size: 0.7rem;
  color: var(--muted); letter-spacing: 0.1em; text-transform: uppercase; margin-bottom: 0.5rem;
}
.form-group input, .form-group textarea {
  width: 100%; background: var(--bg3); border: 1px solid var(--border);
  color: var(--text); font-family: var(--sans); font-size: 0.95rem;
  padding: 0.85rem 1rem; outline: none; transition: border-color 0.2s; resize: vertical;
}
.form-group input:focus, .form-group textarea:focus { border-color: rgba(0,229,255,0.4); }
.form-group textarea { min-height: 120px; }

/* ANIMATIONS */
@keyframes fadeUp {
  from { opacity: 0; transform: translateY(30px); }
  to   { opacity: 1; transform: translateY(0); }
}
.hero-tag  { animation: fadeUp 0.6s ease both 0.1s; }
h1         { animation: fadeUp 0.6s ease both 0.2s; }
.hero-desc { animation: fadeUp 0.6s ease both 0.35s; }
.hero-cta  { animation: fadeUp 0.6s ease both 0.5s; }

/* RESPONSIVE */
@media (max-width: 768px) {
  #home { padding: 6rem 1.5rem 3rem; }
  section { padding: 4rem 1.5rem 3rem; }
  .slides-grid { grid-template-columns: 1fr; }
  .hero-desc { font-size: 0.95rem; }
  .hero-cta { flex-direction: column; align-items: flex-start; }
  .btn-primary, .btn-secondary { width: 100%; justify-content: center; padding: 0.8rem 1.5rem; }
  .article-item { gap: 1rem; }
  .article-date { display: none; }
  #contact { flex-direction: column; gap: 2.5rem; }
  .contact-right { width: 100%; }
}

@media (max-width: 480px) {
  .article-num { display: none; }
  .article-item { gap: 0; }
  .section-title { font-size: 1.8rem; margin-bottom: 2rem; }
}