.tool-container {
  max-width: 1000px;
  margin: 0 auto;
}

/* Category Selection */
.category-section {
  background: var(--bg-primary);
  border-radius: var(--border-radius);
  padding: 2rem;
  box-shadow: var(--shadow);
  margin-bottom: 2rem;
}

.category-section h3 {
  color: var(--text-primary);
  margin-bottom: 1.5rem;
  font-size: 1.3rem;
  text-align: center;
}

.category-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(120px, 1fr));
  gap: 1rem;
}

.category-btn {
  background: var(--bg-secondary);
  border: 2px solid rgba(102, 126, 234, 0.2);
  border-radius: var(--border-radius);
  padding: 1rem 0.5rem;
  text-align: center;
  cursor: pointer;
  transition: var(--transition);
  color: var(--text-primary);
}

.category-btn:hover {
  border-color: var(--primary-color);
  transform: translateY(-2px);
  box-shadow: var(--shadow);
}

.category-btn.active {
  background: linear-gradient(135deg, var(--primary-color), var(--accent-color));
  color: white;
  border-color: var(--primary-color);
  box-shadow: var(--shadow);
}

.category-icon {
  font-size: 1.5rem;
  margin-bottom: 0.5rem;
}

.category-name {
  font-size: 0.9rem;
  font-weight: 600;
}

/* Converter Section */
.converter-section {
  background: var(--bg-primary);
  border-radius: var(--border-radius);
  padding: 2rem;
  box-shadow: var(--shadow);
  margin-bottom: 2rem;
}

.converter-section h3 {
  color: var(--text-primary);
  margin-bottom: 1.5rem;
  font-size: 1.3rem;
  text-align: center;
}

.converter-grid {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  gap: 1.5rem;
  align-items: center;
  margin-bottom: 2rem;
}

.converter-card {
  background: var(--bg-secondary);
  border-radius: var(--border-radius);
  padding: 1.5rem;
  border: 1px solid rgba(102, 126, 234, 0.1);
}

.card-header h4 {
  color: var(--text-primary);
  margin-bottom: 1rem;
  font-size: 1.1rem;
  text-align: center;
}

.converter-content {
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

.unit-select {
  width: 100%;
  padding: 0.75rem;
  border: 2px solid rgba(102, 126, 234, 0.2);
  border-radius: var(--border-radius);
  background: var(--bg-primary);
  color: var(--text-primary);
  font-size: 1rem;
  transition: var(--transition);
}

.unit-select:focus {
  outline: none;
  border-color: var(--primary-color);
  box-shadow: 0 0 0 3px rgba(102, 126, 234, 0.1);
}

.input-group {
  position: relative;
  display: flex;
  align-items: center;
}

.input-group input {
  width: 100%;
  padding: 0.75rem 4rem 0.75rem 1rem;
  border: 2px solid rgba(102, 126, 234, 0.2);
  border-radius: var(--border-radius);
  background: var(--bg-primary);
  color: var(--text-primary);
  font-size: 1.2rem;
  font-weight: 600;
  transition: var(--transition);
}

.input-group input:focus {
  outline: none;
  border-color: var(--primary-color);
  box-shadow: 0 0 0 3px rgba(102, 126, 234, 0.1);
}

.input-group input[readonly] {
  background: linear-gradient(135deg, rgba(102, 126, 234, 0.1), rgba(240, 147, 251, 0.1));
  cursor: default;
}

.unit-label {
  position: absolute;
  right: 1rem;
  top: 50%;
  transform: translateY(-50%);
  color: var(--text-secondary);
  font-size: 0.9rem;
  font-weight: 600;
  pointer-events: none;
}

/* Swap Button */
.swap-container {
  display: flex;
  justify-content: center;
  align-items: center;
}

.swap-btn {
  width: 50px;
  height: 50px;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--primary-color), var(--accent-color));
  border: none;
  color: white;
  cursor: pointer;
  transition: var(--transition);
  display: flex;
  align-items: center;
  justify-content: center;
  box-shadow: var(--shadow);
}

.swap-btn:hover {
  transform: rotate(180deg) scale(1.1);
  box-shadow: 0 4px 15px rgba(102, 126, 234, 0.3);
}

/* Formula Section */
.formula-section {
  margin-bottom: 2rem;
}

.formula-card {
  background: linear-gradient(135deg, rgba(102, 126, 234, 0.1), rgba(240, 147, 251, 0.1));
  border-radius: var(--border-radius);
  padding: 1.5rem;
  text-align: center;
  border: 1px solid rgba(102, 126, 234, 0.1);
}

.formula-card h4 {
  color: var(--text-primary);
  margin-bottom: 1rem;
  font-size: 1.1rem;
}

.formula-text {
  color: var(--text-secondary);
  font-size: 1rem;
  font-family: 'Courier New', monospace;
  background: var(--bg-secondary);
  padding: 1rem;
  border-radius: var(--border-radius);
  border: 1px solid rgba(102, 126, 234, 0.1);
}

/* Quick Conversions */
.quick-section, .common-section {
  background: var(--bg-primary);
  border-radius: var(--border-radius);
  padding: 2rem;
  box-shadow: var(--shadow);
  margin-bottom: 2rem;
}

.quick-section h3, .common-section h3 {
  color: var(--text-primary);
  margin-bottom: 1.5rem;
  font-size: 1.3rem;
  text-align: center;
}

.quick-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 1rem;
}

.quick-item {
  background: var(--bg-secondary);
  border: 1px solid rgba(102, 126, 234, 0.1);
  border-radius: var(--border-radius);
  padding: 1rem;
  text-align: center;
  cursor: pointer;
  transition: var(--transition);
}

.quick-item:hover {
  border-color: var(--primary-color);
  transform: translateY(-2px);
  box-shadow: var(--shadow);
}

.quick-value {
  font-size: 1.2rem;
  font-weight: 700;
  color: var(--primary-color);
  margin-bottom: 0.5rem;
}

.quick-label {
  color: var(--text-secondary);
  font-size: 0.9rem;
}

/* Common Conversions */
.common-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 1rem;
}

.common-item {
  background: var(--bg-secondary);
  border: 1px solid rgba(102, 126, 234, 0.1);
  border-radius: var(--border-radius);
  padding: 1rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
  transition: var(--transition);
}

.common-item:hover {
  border-color: var(--primary-color);
  box-shadow: var(--shadow);
}

.common-from {
  color: var(--text-primary);
  font-weight: 600;
}

.common-equals {
  color: var(--text-secondary);
  margin: 0 1rem;
}

.common-to {
  color: var(--primary-color);
  font-weight: 600;
}

/* Animations */
@keyframes valueUpdate {
  0% {
    transform: scale(1);
  }
  50% {
    transform: scale(1.05);
  }
  100% {
    transform: scale(1);
  }
}

.value-updating {
  animation: valueUpdate 0.3s ease-out;
}

/* Responsive Design */
@media (max-width: 768px) {
  .category-grid {
    grid-template-columns: repeat(4, 1fr);
  }
  
  .converter-grid {
    grid-template-columns: 1fr;
    gap: 1rem;
  }
  
  .swap-container {
    order: 3;
    margin-top: 1rem;
  }
  
  .swap-btn {
    transform: rotate(90deg);
  }
  
  .swap-btn:hover {
    transform: rotate(270deg) scale(1.1);
  }
  
  .quick-grid {
    grid-template-columns: repeat(2, 1fr);
  }
  
  .common-grid {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 480px) {
  .category-grid {
    grid-template-columns: repeat(2, 1fr);
  }
  
  .quick-grid {
    grid-template-columns: 1fr;
  }
  
  .common-item {
    flex-direction: column;
    text-align: center;
    gap: 0.5rem;
  }
  
  .common-equals {
    margin: 0;
  }
}