.program-explorer-section {
  --pe-bg: #ffffff;
  --pe-sidebar-bg: #f4f6fb;
  --pe-content-bg: #fdfbf7;
  --pe-border: #e5e7eb;
  --pe-text: #1f2937;
  --pe-muted: #6b7280;
  --pe-primary: #2563eb;
  --pe-primary-soft: #e0ecff;
  --pe-shadow: 0 1px 2px rgba(16, 24, 40, .04), 0 4px 12px rgba(16, 24, 40, .06);
  --pe-radius: 14px;
  --pe-sidebar-w: clamp(260px, 22vw, 320px);

  box-sizing: border-box;
  display: grid;
  grid-template-columns: var(--pe-sidebar-w) minmax(0, 1fr);
  gap: 0;
  width: 100%;
  max-width: 1600px;
  margin: 0 auto;
  height: min(85vh, 900px);
  background: var(--pe-bg);
  border: 1px solid var(--pe-border);
  border-radius: var(--pe-radius);
  overflow: hidden;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  color: var(--pe-text);
}
.program-explorer-section *,
.program-explorer-section *::before,
.program-explorer-section *::after { box-sizing: border-box; }

/* ---------- Sidebar ---------- */
.program-explorer-section .program-sidebar {
  background: var(--pe-sidebar-bg);
  border-right: 1px solid var(--pe-border);
  overflow-y: auto;
  overflow-x: hidden;
  padding: 20px 0;
  min-width: 0;
}
.program-explorer-section .program-sidebar__title {
  font-size: 13px;
  font-weight: 700;
  letter-spacing: .12em;
  text-transform: uppercase;
  color: var(--pe-muted);
  margin: 0 20px 12px;
}
.program-explorer-section .program-sidebar__list {
  list-style: none;
  margin: 0;
  padding: 0;
}
.program-explorer-section .program-category {
  position: relative;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 8px;
  width: 100%;
  padding: 12px 20px;
  background: transparent;
  border: 0;
  border-left: 3px solid transparent;
  text-align: left;
  font: inherit;
  font-size: 12px;
  color: var(--pe-text);
  cursor: pointer;
  transition: background .18s, color .18s, border-color .18s;
}
.program-explorer-section .program-category:hover { background: rgba(37, 99, 235, .06); }
.program-explorer-section .program-category:focus-visible {
  outline: 2px solid var(--pe-primary);
  outline-offset: -2px;
}
.program-explorer-section .program-category.is-active {
  background: var(--pe-primary-soft);
  color: var(--pe-primary);
  font-weight: 600;
  border-left-color: var(--pe-primary);
}
.program-explorer-section .program-category__chevron { opacity: 0; transition: opacity .18s; }
.program-explorer-section .program-category.is-active .program-category__chevron { opacity: 1; }

/* ---------- Content ---------- */
.program-explorer-section .program-content {
  background: var(--pe-content-bg);
  overflow-y: auto;
  overflow-x: hidden;
  padding: 28px 28px 40px;
  min-width: 0;
}
.program-explorer-section .program-content__header { margin-bottom: 20px; }
.program-explorer-section .program-content__heading {
  margin: 0 0 6px;
  font-size: clamp(20px, 2vw, 24px);
  font-weight: 700;
  color: #b45309;
}
.program-explorer-section .program-content__subtitle {
  margin: 0;
  color: var(--pe-muted);
  font-size: 14px;
}

/* ---------- Grid ---------- */
.program-explorer-section .program-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 20px;
}

/* ---------- Card ---------- */
.program-explorer-section .program-card {
  position: relative;
  display: flex;
  flex-direction: column;
  background: #fff;
  border: 1px solid var(--pe-border);
  border-radius: 12px;
  padding: 18px;
  box-shadow: var(--pe-shadow);
  transition: transform .2s ease, box-shadow .2s ease, border-color .2s;
  min-width: 0;
}
.program-explorer-section .program-card:hover {
  transform: translateY(-3px);
  border-color: #cfd8ea;
  box-shadow: 0 6px 20px rgba(16, 24, 40, .1);
}
.program-explorer-section .program-card__logo {
  height: 34px;
  display: flex;
  align-items: center;
  font-weight: 700;
  color: #374151;
  font-size: 14px;
  margin-bottom: 14px;
  letter-spacing: .02em;
}
.program-explorer-section .program-card__logo span {
  padding: 4px 8px;
  background: #f3f4f6;
  border-radius: 6px;
  font-size: 12px;
}
.program-explorer-section .program-card__title {
  margin: 0 0 8px;
  font-size: 15px;
  font-weight: 600;
  line-height: 1.4;
  color: var(--pe-text);
}
.program-explorer-section .program-card__desc {
  margin: 0 0 16px;
  font-size: 13px;
  color: var(--pe-muted);
  line-height: 1.5;
  flex: 1;
}
.program-explorer-section .program-card__footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 8px;
  margin-top: auto;
}
.program-explorer-section .program-card__duration {
  font-size: 12px;
  color: var(--pe-muted);
  font-weight: 500;
}
.program-explorer-section .program-card__badge {
  font-size: 11px;
  font-weight: 700;
  padding: 4px 10px;
  border-radius: 999px;
  color: #fff;
  letter-spacing: .02em;
}
.program-explorer-section .program-card__badge--popular { background: linear-gradient(90deg, #f59e0b, #f97316); }
.program-explorer-section .program-card__badge--trending { background: linear-gradient(90deg, #10b981, #059669); }
.program-explorer-section .program-card__badge--new { background: linear-gradient(90deg, #3b82f6, #06b6d4); }
.program-explorer-section .program-card__cta {
  margin-top: 14px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 9px 14px;
  border-radius: 8px;
  border: 1px solid var(--pe-primary);
  background: #fff;
  color: var(--pe-primary);
  font-weight: 600;
  font-size: 13px;
  cursor: pointer;
  transition: background .18s, color .18s;
}
.program-explorer-section .program-card__cta:hover { background: var(--pe-primary); color: #fff; }
.program-explorer-section .program-card__cta:focus-visible { outline: 2px solid var(--pe-primary); outline-offset: 2px; }

/* ---------- Tablet ---------- */
@media (min-width: 768px) and (max-width: 1199px) {
  .program-explorer-section {
    --pe-sidebar-w: clamp(220px, 26vw, 280px);
    height: min(85vh, 820px);
  }
  .program-explorer-section .program-content { padding: 22px; }
  .program-explorer-section .program-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 16px;
  }
}

/* ---------- Mobile ---------- */
@media (max-width: 767px) {
  .program-explorer-section {
    display: flex;
    flex-direction: column;
    height: auto;
    max-height: none;
    border-radius: 10px;
  }
  .program-explorer-section .program-sidebar {
    border-right: 0;
    border-bottom: 1px solid var(--pe-border);
    padding: 12px 0;
    overflow: hidden;
  }
  .program-explorer-section .program-sidebar__title {
    margin: 0 14px 8px;
    font-size: 11px;
  }
  .program-explorer-section .program-sidebar__list {
    display: flex;
    gap: 8px;
    padding: 4px 14px 8px;
    overflow-x: auto;
    overflow-y: hidden;
    scroll-snap-type: x proximity;
    -webkit-overflow-scrolling: touch;
  }
  .program-explorer-section .program-sidebar__list::-webkit-scrollbar { height: 4px; }
  .program-explorer-section .program-category {
    flex: 0 0 auto;
    padding: 10px 14px;
    border: 1px solid var(--pe-border);
    border-radius: 999px;
    background: #fff;
    scroll-snap-align: start;
    min-height: 40px;
  }
  .program-explorer-section .program-category.is-active {
    background: var(--pe-primary);
    color: #fff;
    border-color: var(--pe-primary);
  }
  .program-explorer-section .program-category__chevron { display: none; }
  .program-explorer-section .program-content {
    padding: 18px 14px 28px;
    overflow: visible;
  }
  .program-explorer-section .program-grid {
    grid-template-columns: 1fr;
    gap: 14px;
  }
}

@media (max-width: 480px) {
  .program-explorer-section .program-content__heading { font-size: 18px; }
  .program-explorer-section .program-card { padding: 16px; }
}