/* =====================================================================
 * bienac — trang danh sách hiện tượng vật lý
 * ===================================================================== */

.ph-page { padding-top: 90px; }
.ph-section { max-width: 1100px; }
.site-nav .nav-active { color: var(--cyan); }

/* ------------------------------------------------------ Chú giải -- */
.ph-legend {
  margin-top: 22px;
  display: flex;
  flex-wrap: wrap;
  gap: 8px 10px;
}
.ph-chip {
  font-size: 0.72rem;
  font-weight: 600;
  letter-spacing: 0.04em;
  color: var(--text-dim);
  border: 1px solid var(--glass-border);
  background: var(--glass);
  border-radius: 999px;
  padding: 4px 12px 4px 9px;
  display: inline-flex;
  align-items: center;
  gap: 7px;
}
.ph-chip::before {
  content: '';
  width: 9px;
  height: 9px;
  border-radius: 50%;
  background: var(--c);
  box-shadow: 0 0 8px var(--c);
}

/* -------------------------------------------------------- Lưới -- */
.ph-grid {
  margin-top: 30px;
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: 18px;
}

.ph-card {
  display: flex;
  flex-direction: column;
  text-align: left;
  padding: 0;
  overflow: hidden;
  font-family: var(--font);
  color: var(--text);
  background: var(--glass);
  border: 1px solid var(--glass-border);
  border-radius: 16px;
  cursor: pointer;
  transition: transform 0.18s ease, box-shadow 0.22s ease, border-color 0.22s ease;
}
.ph-card:hover,
.ph-card:focus-visible {
  transform: translateY(-4px);
  border-color: var(--c);
  box-shadow: 0 0 22px color-mix(in srgb, var(--c) 45%, transparent),
              0 14px 30px rgba(0, 0, 0, 0.45);
  outline: none;
}
.ph-card.active {
  border-color: var(--c);
  box-shadow: 0 0 0 1px var(--c),
              0 0 26px color-mix(in srgb, var(--c) 55%, transparent);
}

.ph-preview {
  position: relative;
  display: flex;
  align-items: center;
  justify-content: center;
  height: 116px;
}
.ph-preview::after {
  content: '';
  position: absolute;
  inset: 0;
  background: radial-gradient(circle at 50% 120%,
              color-mix(in srgb, var(--c) 40%, transparent), transparent 70%);
}
.ph-icon {
  position: relative;
  font-size: 2.6rem;
  filter: drop-shadow(0 4px 14px rgba(0, 0, 0, 0.5));
}

.ph-body {
  display: flex;
  flex-direction: column;
  gap: 7px;
  padding: 16px 18px 18px;
}
.ph-tag {
  align-self: flex-start;
  font-size: 0.66rem;
  font-weight: 600;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  color: var(--c);
  border: 1px solid color-mix(in srgb, var(--c) 45%, transparent);
  border-radius: 999px;
  padding: 2px 9px;
}
.ph-name {
  font-size: 1.18rem;
  font-weight: 800;
  color: var(--c);
  text-shadow: 0 0 14px color-mix(in srgb, var(--c) 45%, transparent);
}
.ph-desc {
  font-size: 0.9rem;
  line-height: 1.6;
  color: var(--text-dim);
}
.ph-cta {
  margin-top: 4px;
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--text);
  opacity: 0.7;
  transition: opacity 0.2s ease;
}
.ph-card:hover .ph-cta,
.ph-card.active .ph-cta { opacity: 1; color: var(--c); }

/* ------------------------------------------- "Đang xem" toast -- */
.ph-now {
  position: fixed;
  left: 50%;
  bottom: 24px;
  transform: translate(-50%, 30px);
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 10px 18px;
  font-size: 0.9rem;
  color: var(--text);
  background: rgba(8, 14, 24, 0.9);
  border: 1px solid var(--glass-border);
  border-radius: 999px;
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  box-shadow: 0 12px 30px rgba(0, 0, 0, 0.5);
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.3s ease, transform 0.3s ease;
  z-index: 60;
}
.ph-now.show {
  opacity: 1;
  transform: translate(-50%, 0);
}
.ph-now-label { color: var(--text-dim); }
.ph-now-name { font-weight: 700; color: var(--cyan); }

@media (prefers-reduced-motion: reduce) {
  .ph-card, .ph-card:hover { transition: none; transform: none; }
  .ph-now { transition: none; }
}