/* ============================================================
   HIENPHAN.VN — courses.css
   Trang liệt kê khoá học
   ============================================================ */

/* ---------- Nav active link ---------- */
.nav-links a.active {
  color: var(--mauve);
  font-weight: 700;
}
.nav-links a.active::after {
  width: 100%;
}

/* ============================================================
   COURSES HERO
   ============================================================ */
.courses-hero {
  min-height: 360px;
  padding-top: 80px;
  padding-bottom: 4rem;
  background: var(--gradient-blush);
  display: flex;
  align-items: center;
  position: relative;
  overflow: clip; /* clip decorative orbs without creating scroll container */
}
.courses-hero::before {
  content: '';
  position: absolute;
  top: -120px; right: -80px;
  width: 480px; height: 480px;
  border-radius: 50%;
  background: radial-gradient(circle, rgba(217,215,247,0.35) 0%, transparent 70%);
  pointer-events: none;
}
.courses-hero::after {
  content: '';
  position: absolute;
  bottom: -80px; left: -60px;
  width: 320px; height: 320px;
  border-radius: 50%;
  background: radial-gradient(circle, rgba(200,96,42,0.08) 0%, transparent 70%);
  pointer-events: none;
}
.courses-hero-inner {
  position: relative;
  z-index: 1;
}
.courses-hero h1 {
  margin-bottom: 1rem;
  color: var(--purple-dark);
  letter-spacing: -0.01em;
  line-height: 1.2;
}
.courses-hero h1 span {
  background: linear-gradient(135deg, #C8602A 0%, #D97035 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}
.courses-hero-sub {
  font-size: clamp(0.92rem, 1.4vw, 1.05rem);
  color: var(--text-muted);
  max-width: 640px;
  line-height: 1.8;
  margin-bottom: 2rem;
}
.courses-hero-stats {
  display: flex;
  gap: 2.5rem;
  flex-wrap: wrap;
}
.courses-hero-stat {
  display: flex;
  flex-direction: column;
  gap: 2px;
}
.courses-hero-stat-num {
  font-family: var(--font-serif);
  font-size: 1.7rem;
  font-weight: 700;
  color: var(--mauve);
  line-height: 1;
}
.courses-hero-stat-label {
  font-size: 0.8rem;
  font-weight: 600;
  letter-spacing: 0.05em;
  color: var(--text-muted);
  text-transform: uppercase;
}

/* ============================================================
   TAB SWITCHER
   ============================================================ */
.courses-tabs-section {
  background: var(--white);
  padding: 2.5rem 0 0;
  position: sticky;
  top: 72px;
  z-index: 100;
  border-bottom: 1px solid rgba(217,215,247,0.4);
}
.courses-tabs {
  display: flex;
  gap: 0.5rem;
  padding-bottom: 0;
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
  scrollbar-width: none;
}
.courses-tabs::-webkit-scrollbar { display: none; }
.courses-tab-btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 0.6rem 1.4rem;
  border-radius: 50px;
  font-family: var(--font-sans);
  font-size: 0.9rem;
  font-weight: 600;
  cursor: pointer;
  border: 2px solid transparent;
  background: var(--blush);
  color: var(--text-muted);
  transition: all 0.3s ease;
  position: relative;
  bottom: -1px;
}
.courses-tab-btn:hover {
  color: var(--purple-dark);
  border-color: var(--lavender-mid);
}
.courses-tab-btn.active {
  background: var(--white);
  color: var(--purple-dark);
  border-color: var(--lavender-mid);
  border-bottom-color: var(--white);
  box-shadow: 0 -4px 16px rgba(217,215,247,0.25);
}
.courses-tab-btn .tab-badge {
  display: inline-block;
  padding: 1px 8px;
  border-radius: 50px;
  font-size: 0.72rem;
  font-weight: 700;
  background: var(--gradient-cta);
  color: #fff;
}

/* ============================================================
   COURSES SECTION WRAPPER
   ============================================================ */
.courses-section {
  padding: 4rem 0 5rem;
  background: var(--white);
}
.courses-section-title {
  margin-bottom: 2.5rem;
}
.courses-section-title .section-label {
  margin-bottom: 0.5rem;
}

/* ============================================================
   COURSES GRID
   ============================================================ */
.courses-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 2rem;
}

/* ============================================================
   COURSE CARD
   ============================================================ */
.course-card {
  background: var(--white);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-card);
  border: 1px solid rgba(217,215,247,0.4);
  overflow: hidden;
  display: flex;
  flex-direction: column;
  transition: all 0.4s cubic-bezier(0.4, 0, 0.2, 1);
}
.course-card:hover {
  transform: translateY(-6px);
  box-shadow: 0 20px 60px rgba(217,215,247,0.55);
  border-color: var(--lavender-mid);
}

/* Thumbnail */
.course-card-thumb {
  position: relative;
  height: 200px;
  overflow: hidden;
  flex-shrink: 0;
}
.course-card-thumb-inner {
  width: 100%;
  height: 100%;
  background: linear-gradient(135deg, #D9D7F7 0%, #B8B5EF 40%, #9B98E8 100%);
  display: flex;
  align-items: center;
  justify-content: center;
  transition: transform 0.5s ease;
}
.course-card-thumb-inner.thumb-coral {
  background: linear-gradient(135deg, #fde8d8 0%, #f5c4a0 40%, #e8a070 100%);
}
.course-card-thumb-inner.thumb-navy {
  background: linear-gradient(135deg, #c8d0e8 0%, #a0adcc 40%, #6878a8 100%);
}
.course-card:hover .course-card-thumb-inner {
  transform: scale(1.05);
}
.thumb-icon {
  font-size: 3.5rem;
  opacity: 0.45;
  user-select: none;
}

/* Tag / Badge */
.course-card-tag {
  position: absolute;
  top: 1rem;
  left: 1rem;
  padding: 4px 12px;
  border-radius: 50px;
  font-size: 0.72rem;
  font-weight: 700;
  letter-spacing: 0.04em;
  text-transform: uppercase;
}
.course-card-tag.tag-online {
  background: rgba(217,215,247,0.92);
  color: var(--purple-dark);
  border: 1px solid rgba(217,215,247,0.6);
}
.course-card-tag.tag-offline {
  background: rgba(200,96,42,0.88);
  color: #fff;
}

/* Card body */
.course-card-body {
  padding: 1.5rem;
  display: flex;
  flex-direction: column;
  flex: 1;
  gap: 0.75rem;
}
.course-title {
  font-family: var(--font-serif);
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--purple-dark);
  line-height: 1.35;
  margin: 0;
}
.course-desc {
  font-size: 0.875rem;
  color: var(--text-muted);
  line-height: 1.7;
  flex: 1;
}

/* Meta row */
.course-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem 1rem;
  padding: 0.6rem 0;
  border-top: 1px solid rgba(217,215,247,0.35);
  border-bottom: 1px solid rgba(217,215,247,0.35);
}
.course-meta-item {
  display: flex;
  align-items: center;
  gap: 5px;
  font-size: 0.78rem;
  font-weight: 600;
  color: var(--text-muted);
}
.course-meta-icon {
  font-size: 0.85rem;
  opacity: 0.7;
}

/* Price */
.course-price {
  display: flex;
  align-items: baseline;
  gap: 0.75rem;
}
.course-price-original {
  font-size: 0.85rem;
  color: var(--text-muted);
  text-decoration: line-through;
  opacity: 0.7;
}
.course-price-sale {
  font-family: var(--font-serif);
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--mauve);
}

/* CTA button */
.course-cta-btn {
  display: block;
  width: 100%;
  text-align: center;
  padding: 0.7rem 1rem;
  border-radius: 50px;
  background: var(--gradient-dark);
  color: #fff;
  font-family: var(--font-sans);
  font-size: 0.9rem;
  font-weight: 600;
  transition: all 0.35s ease;
  border: none;
  cursor: pointer;
  letter-spacing: 0.01em;
  margin-top: auto;
}
.course-cta-btn:hover {
  background: var(--gradient-cta);
  transform: translateY(-2px);
  box-shadow: 0 8px 24px rgba(200,96,42,0.35);
  color: #fff;
}

/* ============================================================
   OFFLINE BANNER
   ============================================================ */
.offline-banner-section {
  padding: 4rem 0 5rem;
  background: var(--white);
}
.offline-banner {
  background: var(--gradient-dark);
  border-radius: var(--radius-lg);
  padding: 3.5rem clamp(2rem, 5vw, 4.5rem);
  position: relative;
  overflow: hidden;
  display: flex;
  align-items: center;
  gap: 3rem;
}
.offline-banner::before {
  content: '';
  position: absolute;
  top: -100px; right: -100px;
  width: 400px; height: 400px;
  border-radius: 50%;
  background: radial-gradient(circle, rgba(217,215,247,0.12) 0%, transparent 65%);
  pointer-events: none;
}
.offline-banner::after {
  content: '';
  position: absolute;
  bottom: -80px; left: 20%;
  width: 300px; height: 300px;
  border-radius: 50%;
  background: radial-gradient(circle, rgba(200,96,42,0.12) 0%, transparent 65%);
  pointer-events: none;
}
.offline-banner-content {
  flex: 1;
  position: relative;
  z-index: 1;
}
.offline-banner-badge {
  display: inline-block;
  padding: 5px 16px;
  border-radius: 50px;
  background: rgba(217,215,247,0.18);
  border: 1px solid rgba(217,215,247,0.3);
  color: var(--lavender-mid);
  font-size: 0.72rem;
  font-weight: 700;
  letter-spacing: 0.15em;
  text-transform: uppercase;
  margin-bottom: 1rem;
}
.offline-banner h2 {
  color: #fff;
  font-size: clamp(1.3rem, 2.5vw, 2rem);
  margin-bottom: 0.75rem;
  line-height: 1.3;
}
.offline-banner-sub {
  color: rgba(255,255,255,0.72);
  font-size: 0.95rem;
  line-height: 1.75;
  margin-bottom: 1.5rem;
  max-width: 520px;
}

/* Price big */
.offline-price-area {
  display: flex;
  align-items: center;
  gap: 1.25rem;
  flex-wrap: wrap;
  margin-bottom: 1.5rem;
}
.offline-price-big {
  font-family: var(--font-serif);
  font-size: clamp(1.8rem, 3vw, 2.4rem);
  font-weight: 700;
  color: var(--mauve);
  line-height: 1;
}
.offline-price-label {
  font-size: 0.78rem;
  color: rgba(255,255,255,0.55);
  line-height: 1.5;
}
.offline-status-badge {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 5px 14px;
  border-radius: 50px;
  background: rgba(200,96,42,0.25);
  border: 1px solid rgba(200,96,42,0.5);
  color: #ffb882;
  font-size: 0.78rem;
  font-weight: 700;
  letter-spacing: 0.05em;
}

/* Banner CTA col */
.offline-banner-cta {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 1rem;
  flex-shrink: 0;
  position: relative;
  z-index: 1;
  min-width: 200px;
}
.offline-cta-btn {
  display: inline-block;
  padding: 0.85rem 2rem;
  border-radius: 50px;
  background: var(--gradient-cta);
  color: #fff;
  font-family: var(--font-sans);
  font-size: 1rem;
  font-weight: 700;
  text-align: center;
  transition: all 0.35s ease;
  box-shadow: 0 8px 28px rgba(200,96,42,0.45);
  white-space: nowrap;
}
.offline-cta-btn:hover {
  transform: translateY(-3px);
  box-shadow: 0 16px 40px rgba(200,96,42,0.55);
  color: #fff;
}
.offline-cta-note {
  font-size: 0.75rem;
  color: rgba(255,255,255,0.45);
  text-align: center;
  line-height: 1.5;
}

/* ============================================================
   WHY LEARN WITH HIEN — 3 pillars
   ============================================================ */
.courses-why-section {
  padding: 5rem 0;
  background: var(--gradient-blush);
}
.courses-why-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 2rem;
  margin-top: 2.5rem;
}
.why-card {
  background: var(--white);
  border-radius: var(--radius-md);
  padding: 2rem 1.75rem;
  box-shadow: var(--shadow-card);
  border: 1px solid rgba(217,215,247,0.35);
  transition: all 0.35s ease;
  text-align: center;
}
.why-card:hover {
  transform: translateY(-4px);
  box-shadow: 0 16px 48px rgba(217,215,247,0.5);
}
.why-card-icon {
  font-size: 2.2rem;
  margin-bottom: 1rem;
  display: block;
  line-height: 1;
}
.why-card-title {
  font-family: var(--font-serif);
  font-size: 1.05rem;
  font-weight: 700;
  color: var(--purple-dark);
  margin-bottom: 0.6rem;
}
.why-card-desc {
  font-size: 0.875rem;
  color: var(--text-muted);
  line-height: 1.7;
}

/* ============================================================
   CTA STRIP DARK
   ============================================================ */
.courses-cta-strip {
  background: var(--gradient-dark);
  padding: 4rem 0;
  text-align: center;
  position: relative;
  overflow: hidden;
}
.courses-cta-strip::before {
  content: '';
  position: absolute;
  top: 50%; left: 50%;
  transform: translate(-50%, -50%);
  width: 600px; height: 600px;
  border-radius: 50%;
  background: radial-gradient(circle, rgba(217,215,247,0.08) 0%, transparent 65%);
  pointer-events: none;
}
.courses-cta-strip h2 {
  color: #fff;
  margin-bottom: 0.75rem;
  position: relative;
  z-index: 1;
}
.courses-cta-strip p {
  color: rgba(255,255,255,0.65);
  margin-bottom: 2rem;
  font-size: 0.95rem;
  position: relative;
  z-index: 1;
}
.courses-cta-strip-btn {
  display: inline-block;
  padding: 0.85rem 2.2rem;
  border-radius: 50px;
  background: var(--gradient-cta);
  color: #fff;
  font-family: var(--font-sans);
  font-size: 1rem;
  font-weight: 700;
  transition: all 0.35s ease;
  box-shadow: 0 8px 28px rgba(200,96,42,0.4);
  position: relative;
  z-index: 1;
}
.courses-cta-strip-btn:hover {
  transform: translateY(-3px);
  box-shadow: 0 16px 42px rgba(200,96,42,0.55);
  color: #fff;
}

/* ============================================================
   SECTION HIDDEN (tab toggle)
   ============================================================ */
.courses-panel {
  display: none;
}
.courses-panel.active {
  display: block;
}

/* ============================================================
   REVEAL ON SCROLL
   ============================================================ */
.reveal-on-scroll {
  opacity: 0;
  transform: translateY(28px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}
.reveal-on-scroll.revealed {
  opacity: 1;
  transform: translateY(0);
}

/* ============================================================
   RESPONSIVE — 900px (tablet)
   ============================================================ */
@media (max-width: 900px) {
  .courses-grid {
    grid-template-columns: repeat(2, 1fr);
  }
  .courses-why-grid {
    grid-template-columns: repeat(2, 1fr);
  }
  .offline-banner {
    flex-direction: column;
    align-items: flex-start;
    gap: 2rem;
  }
  .offline-banner-cta {
    align-items: flex-start;
    min-width: unset;
    width: 100%;
  }
  .offline-cta-btn {
    width: 100%;
  }
  .nav-links {
    position: fixed;
    top: 72px; left: 0; right: 0;
    background: rgba(238,237,254,0.98);
    backdrop-filter: blur(20px);
    flex-direction: column;
    padding: 1.5rem 2rem 2rem;
    gap: 1.4rem;
    border-bottom: 1px solid rgba(217,215,247,0.3);
    transform: translateY(-110%);
    transition: transform 0.4s cubic-bezier(0.4, 0, 0.2, 1);
    z-index: 999;
    align-items: flex-start;
  }
  .nav-links.open { transform: translateY(0); }
  .nav-toggle { display: flex; }
}

/* ============================================================
   RESPONSIVE — 600px (mobile)
   ============================================================ */
@media (max-width: 600px) {
  .courses-hero {
    min-height: unset;
    padding-top: 90px;
    padding-bottom: 2.5rem;
  }
  .courses-hero-stats {
    gap: 1.5rem;
  }
  .courses-grid {
    grid-template-columns: 1fr;
  }
  .courses-why-grid {
    grid-template-columns: 1fr;
  }
  .offline-banner {
    padding: 2rem 1.5rem;
  }
  .offline-price-area {
    flex-direction: column;
    align-items: flex-start;
    gap: 0.75rem;
  }
  .courses-tabs {
    gap: 0.35rem;
  }
  .courses-tab-btn {
    font-size: 0.82rem;
    padding: 0.5rem 1rem;
  }
  .courses-tabs-section {
    top: 64px;
  }
}