/* ======================================= */
/* PERIODIC TABLE EXPLORER - MODERN GRADIENT STYLE */
/* ======================================= */
.periodic-card {
  max-width: 1400px;
  margin: 0 auto;
  padding: 35px;
  background: linear-gradient(145deg, var(--card-bg) 0%, var(--secondary-bg) 100%);
  border: 1px solid var(--border-color);
  border-radius: 20px;
  box-shadow: 
    0 20px 60px rgba(0, 0, 0, 0.5),
    0 0 0 1px rgba(255, 255, 255, 0.05) inset;
  color: var(--text-color);
  position: relative;
  overflow: hidden;
  box-sizing: border-box;
}

.periodic-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  background: linear-gradient(90deg, var(--accent-purple), var(--accent-blue), var(--accent-purple));
  background-size: 200% 100%;
  animation: periodicGradientShift 3s ease infinite;
}

@keyframes periodicGradientShift {
  0%, 100% { background-position: 0% 50%; }
  50% { background-position: 100% 50%; }
}

.periodic-card h1 {
  color: var(--text-primary);
  font-size: 2rem;
  margin-bottom: 8px;
  text-align: center;
  font-weight: 700;
  letter-spacing: -0.5px;
}

.periodic-card .intro {
  text-align: center;
  color: var(--text-secondary);
  font-size: 0.9rem;
  margin-bottom: 25px;
  font-weight: 400;
  line-height: 1.6;
}

/* Legend */
.periodic-card .legend {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 12px 16px;
  padding: 20px;
  margin-bottom: 25px;
  border: 2px solid var(--border-dark);
  background: var(--overlay-medium);
  border-radius: 12px;
  box-shadow: inset 0 2px 8px rgba(0, 0, 0, 0.25);
}

.periodic-card .legend-item {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 0.9rem;
  color: var(--text-primary);
  cursor: pointer;
  padding: 8px 12px;
  background: var(--overlay-dark);
  border-radius: 8px;
  border: 2px solid var(--border-dark);
  transition: all 0.2s ease;
  font-weight: 500;
}

.periodic-card .legend-item:hover {
  background: var(--overlay-light);
  border-color: var(--accent-purple);
  transform: translateY(-2px);
  box-shadow: 0 4px 12px rgba(147, 51, 234, 0.3);
}

.periodic-card .legend-item input[type="checkbox"] {
  appearance: none;
  margin: 0;
  width: 18px;
  height: 18px;
  border: 2px solid var(--border-dark);
  border-radius: 4px;
  cursor: pointer;
  background: var(--overlay-dark);
  display: inline-block;
  position: relative;
  transition: all 0.2s ease;
  flex-shrink: 0;
}

.periodic-card .legend-item input[type="checkbox"]:hover {
  border-color: var(--accent-purple);
}

.periodic-card .legend-item input[type="checkbox"]:checked {
  background: linear-gradient(135deg, var(--accent-purple) 0%, var(--accent-purple-dark) 100%);
  border-color: var(--accent-purple);
}

.periodic-card .legend-item input[type="checkbox"]:checked::after {
  content: "✓";
  position: absolute;
  top: -2px;
  left: 2px;
  font-size: 0.85rem;
  color: white;
  font-weight: 700;
}

.periodic-card .color-box {
  width: 18px;
  height: 18px;
  border-radius: 6px;
  flex-shrink: 0;
  border: 2px solid rgba(0, 0, 0, 0.3);
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.3);
  transition: all 0.2s ease;
}

.periodic-card .legend-item:hover .color-box {
  transform: scale(1.1);
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.4);
}

/* Grid */
.periodic-card .periodic-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(85px, 1fr));
  gap: 12px;
  margin-bottom: 30px;
}

.periodic-card .element-cell {
  background: var(--overlay-dark);
  border: 2px solid var(--border-dark);
  border-radius: 10px;
  text-align: center;
  padding: 12px 8px;
  cursor: pointer;
  transition: all 0.2s ease;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  min-height: 85px;
  position: relative;
  overflow: hidden;
  backdrop-filter: blur(10px);
}

.periodic-card .element-cell::before {
  content: '';
  position: absolute;
  top: 50%;
  left: 50%;
  width: 0;
  height: 0;
  border-radius: 50%;
  background: rgba(255, 255, 255, 0.1);
  transform: translate(-50%, -50%);
  transition: width 0.6s, height 0.6s;
}

.periodic-card .element-cell:hover::before {
  width: 300px;
  height: 300px;
}

.periodic-card .element-cell:hover {
  transform: translateY(-4px) scale(1.05);
  box-shadow: 0 8px 20px rgba(0, 0, 0, 0.4);
  background: var(--overlay-medium);
  z-index: 10;
}

.periodic-card .element-cell .number {
  display: block;
  font-size: 0.75rem;
  color: var(--text-secondary);
  margin-bottom: 4px;
  font-weight: 600;
}

.periodic-card .element-cell .symbol {
  font-size: 1.8rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 4px;
  text-shadow: 0 2px 4px rgba(0, 0, 0, 0.3);
}

.periodic-card .element-cell .name {
  font-size: 0.65rem;
  color: var(--text-secondary);
  font-weight: 500;
  text-transform: capitalize;
}

/* Info Panel - Hidden by default, shown in modal */
.periodic-card .element-info {
  display: none;
}

/* Modal styling */
.periodic-card .periodic-modal-overlay {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: rgba(0, 0, 0, 0.8);
  backdrop-filter: blur(8px);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 9999;
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.3s ease;
  padding: 20px;
}

.periodic-card .periodic-modal-overlay.visible {
  opacity: 1;
  pointer-events: all;
}

.periodic-card .periodic-modal {
  background: linear-gradient(145deg, var(--card-bg) 0%, var(--secondary-bg) 100%);
  border: 2px solid var(--border-color);
  border-radius: 16px;
  padding: 30px;
  max-width: 700px;
  width: 100%;
  max-height: 85vh;
  overflow-y: auto;
  box-shadow: 0 20px 60px rgba(0, 0, 0, 0.8);
  transform: scale(0.9) translateY(20px);
  transition: all 0.3s ease;
  position: relative;
}

.periodic-card .periodic-modal-overlay.visible .periodic-modal {
  transform: scale(1) translateY(0);
}

.periodic-card .periodic-modal::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  background: linear-gradient(90deg, var(--accent-purple), var(--accent-blue), var(--accent-purple));
  background-size: 200% 100%;
  animation: periodicGradientShift 3s ease infinite;
  border-radius: 16px 16px 0 0;
}

.periodic-card .periodic-modal-close {
  position: absolute;
  top: 20px;
  right: 20px;
  width: 36px;
  height: 36px;
  border: none;
  background: var(--overlay-dark);
  border: 2px solid var(--border-dark);
  border-radius: 8px;
  color: var(--text-primary);
  font-size: 1.5rem;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all 0.2s ease;
  z-index: 10;
}

.periodic-card .periodic-modal-close:hover {
  background: linear-gradient(135deg, #ef4444 0%, #dc2626 100%);
  border-color: #ef4444;
  color: white;
  transform: rotate(90deg);
  box-shadow: 0 4px 12px rgba(239, 68, 68, 0.4);
}

.periodic-card .periodic-modal-content {
  margin-top: 10px;
}

.periodic-card .periodic-modal h2 {
  margin-top: 0;
  margin-bottom: 20px;
  font-size: 1.8rem;
  font-weight: 700;
  border-bottom: 2px solid var(--border-dark);
  padding-bottom: 12px;
  padding-right: 40px;
}

.periodic-card .periodic-modal p {
  margin: 12px 0;
  line-height: 1.6;
  color: var(--text-secondary);
  font-size: 0.95rem;
}

.periodic-card .periodic-modal p strong {
  color: var(--accent-blue);
  font-weight: 600;
  margin-right: 6px;
  display: inline-block;
  min-width: 160px;
}

.periodic-card .periodic-modal img {
  max-width: 100%;
  border-radius: 12px;
  margin-top: 20px;
  border: 2px solid var(--border-dark);
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.3);
  transition: all 0.3s ease;
}

.periodic-card .periodic-modal img:hover {
  transform: scale(1.02);
  border-color: var(--accent-purple);
  box-shadow: 0 8px 20px rgba(147, 51, 234, 0.4);
}

/* Scrollbar voor modal */
.periodic-card .periodic-modal::-webkit-scrollbar {
  width: 10px;
}

.periodic-card .periodic-modal::-webkit-scrollbar-track {
  background: var(--overlay-dark);
  border-radius: 5px;
}

.periodic-card .periodic-modal::-webkit-scrollbar-thumb {
  background: var(--accent-purple);
  border-radius: 5px;
}

.periodic-card .periodic-modal::-webkit-scrollbar-thumb:hover {
  background: var(--accent-purple-dark);
}

/* Responsive */
@media (max-width: 1200px) {
  .periodic-card {
    max-width: 100%;
  }

  .periodic-card .periodic-grid {
    grid-template-columns: repeat(auto-fit, minmax(75px, 1fr));
    gap: 10px;
  }
}

@media (max-width: 768px) {
  .periodic-card {
    padding: 20px 12px;
    border-radius: 16px;
  }

  .periodic-card h1 {
    font-size: 1.5rem;
    margin-bottom: 6px;
  }

  .periodic-card .intro {
    font-size: 0.85rem;
    margin-bottom: 20px;
  }

  .periodic-card .legend {
    padding: 16px;
    gap: 8px 12px;
  }

  .periodic-card .legend-item {
    padding: 6px 10px;
    font-size: 0.85rem;
  }

  .periodic-card .legend-item input[type="checkbox"] {
    width: 16px;
    height: 16px;
  }

  .periodic-card .color-box {
    width: 16px;
    height: 16px;
  }

  .periodic-card .periodic-grid {
    grid-template-columns: repeat(auto-fit, minmax(65px, 1fr));
    gap: 8px;
    margin-bottom: 20px;
  }

  .periodic-card .element-cell {
    padding: 10px 6px;
    min-height: 75px;
  }

  .periodic-card .element-cell .symbol {
    font-size: 1.4rem;
  }

  .periodic-card .element-cell .number {
    font-size: 0.7rem;
  }

  .periodic-card .element-cell .name {
    font-size: 0.6rem;
  }

  .periodic-card .element-info {
    padding: 20px;
    min-height: 200px;
  }

  .periodic-card .element-info h2 {
    font-size: 1.3rem;
    margin-bottom: 12px;
  }

  .periodic-card .element-info p {
    font-size: 0.9rem;
    margin: 8px 0;
  }
}

@media (max-width: 480px) {
  .periodic-card {
    padding: 16px 10px;
  }

  .periodic-card h1 {
    font-size: 1.3rem;
  }

  .periodic-card .intro {
    font-size: 0.8rem;
  }

  .periodic-card .legend {
    padding: 12px;
  }

  .periodic-card .legend-item {
    padding: 5px 8px;
    font-size: 0.8rem;
  }

  .periodic-card .periodic-grid {
    grid-template-columns: repeat(auto-fit, minmax(55px, 1fr));
    gap: 6px;
  }

  .periodic-card .element-cell {
    padding: 8px 4px;
    min-height: 65px;
  }

  .periodic-card .element-cell .symbol {
    font-size: 1.2rem;
  }

  .periodic-card .element-cell .number {
    font-size: 0.65rem;
  }

  .periodic-card .element-cell .name {
    font-size: 0.55rem;
  }

  .periodic-card .element-info {
    padding: 16px;
    min-height: 180px;
  }

  .periodic-card .element-info h2 {
    font-size: 1.2rem;
  }

  .periodic-card .element-info p {
    font-size: 0.85rem;
  }
}