:root {
  --primary-color: #8e44ad;
  --secondary-color: #2ecc71;
  --accent-color: #f39c12;
  --background-color: #1a1a2e;
  --card-color: #16213e;
  --text-color: #e2e2e2;
  --border-color: #0f3460;
  --highlight-color: #ddf535;
  --input-bg: #0f3460;
  --button-add-color: #0d448a;
  --button-add-hover: #195cb1;
  --button-calc-color: #208647;
  --button-calc-hover: #29b55e;
}

* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

/* Add transitions only to interactive elements */
button,
input,
select,
.result-item {
  transition: all 0.3s ease;
}

body {
  font-family: 'Poppins', 'Roboto', sans-serif;
  background-color: var(--background-color);
  background-image: linear-gradient(135deg, #1a1a2e 0%, #16213e 100%);
  color: var(--text-color);
  margin: 0;
  padding: 0;
  line-height: 1.6;
  min-height: 100vh;
  background: radial-gradient(22% 18% at 28% 25%,#152755 99%,#0000 101%) 16px 16px/calc(2*16px) calc(2*16px), radial-gradient(25% 25% at 25% 25%,#0a1b48 99%,#0000 101%) 0 0/calc(2*16px) calc(2*16px), radial-gradient(50% 50%,#0c1753 98%,#0000) 0 0/16px 16px, repeating-conic-gradient(#031135 0 25%,#131e3c 0 50%) calc(.5*16px) 0/calc(2*16px) 16px;
}

.container {
  max-width: 1000px;
  margin: 0 auto;
  padding: 20px;
}

header {
  text-align: center;
  padding: 20px 0;
  position: relative;
}

.logo {
  font-size: 2.5rem;
  font-weight: 700;
  color: var(--text-color);
  text-transform: uppercase;
  letter-spacing: 2px;
  margin-bottom: 10px;
  text-shadow: 0 0 12px #000, 0 0 9px rgba(212, 233, 69, 0.65);
  background-color: #16213e;
  border-radius: 100em;
}

.logo span {
  color: var(--highlight-color);
}

.tagline {
  font-size: 1rem;
  color: var(--text-color);
  background-color: #16213e;
  border-radius: 100em;
  padding: 6px;
}

/* Calculator Card */
.calculator-card {
  background-color: var(--card-color);
  border-radius: 15px;
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.3);
  padding: 30px;
  margin-bottom: 30px;
  position: relative;
  overflow: hidden;
}

/* Product Type Selection */
.product-type-selection {
  margin-bottom: 25px;
}

.product-type-selection label {
  display: block;
  margin-bottom: 10px;
  font-weight: 600;
  color: var(--highlight-color);
}

.product-type-selection select {
  width: 100%;
  padding: 12px 15px;
  border-radius: 10px;
  background-color: var(--input-bg);
  border: 2px solid var(--border-color);
  color: var(--text-color);
  font-size: 16px;
  appearance: none;
  background-image: url("data:image/svg+xml;charset=UTF-8,%3csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24' fill='none' stroke='%23e2e2e2' stroke-width='2' stroke-linecap='round' stroke-linejoin='round'%3e%3cpolyline points='6 9 12 15 18 9'%3e%3c/polyline%3e%3c/svg%3e");
  background-repeat: no-repeat;
  background-position: right 15px center;
  background-size: 15px;
}

.product-type-selection select:focus {
  border-color: var(--highlight-color);
  outline: none;
  box-shadow: 0 0 0 3px rgba(233, 69, 96, 0.2);
}

.volume-preset-select {
  font-family: monospace;
  width: 100%;
  margin-bottom: 10px;
}

.custom-volume-inputs {
  display: flex;
  gap: 10px;
}

.custom-volume-inputs .volume-amount {
  flex: 2;
}

.custom-volume-inputs .volume-unit {
  flex: 1;
}

/* Product Rows */
.product-row {
  display: grid;
  grid-template-columns: 0.8fr 0.9fr 1fr 0.5fr 0.5fr 0.25fr;
  gap: 20px;
  position: relative;
  z-index: 1;
}

.product-header {
  font-weight: 600;
  color: var(--highlight-color);
  padding: 10px 0;
  border-bottom: 2px solid var(--border-color);
  margin-bottom: 20px;
  text-transform: uppercase;
  font-size: 0.9rem;
  letter-spacing: 1px;
}

.form-group {
  margin-bottom: 15px;
}

label {
  display: block;
  margin-bottom: 8px;
  font-weight: 500;
  font-size: 14px;
  color: var(--text-color);
}

input, select {
  width: 100%;
  padding: 12px 15px;
  border-radius: 10px;
  background-color: var(--input-bg);
  border: 2px solid var(--border-color);
  color: var(--text-color);
  font-size: 16px;
}

input:focus, select:focus {
  border-color: var(--highlight-color);
  outline: none;
  box-shadow: 0 0 0 3px rgba(233, 69, 96, 0.2);
}

/* Results Section */
.results {
  background-color: var(--card-color);
  border-radius: 15px;
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.3);
  padding: 30px;
  margin-top: 30px;
  position: relative;
  overflow: hidden;
}

.results::before {
  content: '';
  position: absolute;
  top: -50%;
  left: -50%;
  width: 200%;
  height: 200%;
  background: radial-gradient(circle, rgba(46, 204, 113, 0.1) 0%, rgba(22, 33, 62, 0) 70%);
  transform: rotate(30deg);
  z-index: 0;
}

.result-item {
  background-color: rgba(15, 52, 96, 0.5);
  border-radius: 10px;
  padding: 20px;
  margin-bottom: 15px;
  position: relative;
  z-index: 1;
  border: 4px solid var(--secondary-color);
}

.result-item.best-value {
  background-color: rgba(46, 204, 113, 0.2);
  transform: scale(1.02);
  box-shadow: 0 5px 15px rgba(0, 0, 0, 0.2);
  border: 4px solid var(--secondary-color);
}

.result-item.best-value::before {
  content: "Best Value";
  position: absolute;
  top: -10px;
  right: 10px;
  background-color: var(--secondary-color);
  color: white;
  padding: 5px 12px;
  border-radius: 20px;
  font-size: 12px;
  font-weight: bold;
  text-transform: uppercase;
  letter-spacing: 1px;
}

.result-product {
  font-weight: 600;
  margin-bottom: 10px;
  font-size: 1.1rem;
  color: var(--text-color);
}

.result-details {
  display: flex;
  justify-content: space-between;
  margin-bottom: 15px;
  font-size: 0.9rem;
  color: var(--text-color);
  opacity: 0.8;
}

.result-value {
  font-size: 28px;
  font-weight: 700;
  text-align: center;
  margin: 20px 0;
  color: var(--highlight-color);
  text-shadow: 0 0 10px rgba(233, 69, 96, 0.3);
}

.unit-selector {
  text-align: right;
  margin-bottom: 20px;
  position: relative;
  z-index: 1;
}

.unit-selector select {
  width: auto;
  padding: 8px 16px;
  background-color: rgba(15, 52, 96, 0.7);
  border: 2px solid var(--border-color);
  color: var(--text-color);
  border-radius: 20px;
  font-size: 14px;
}

.calculate-button {
  display: block;
  width: 100%;
  padding: 15px;
  background-color: var(--button-calc-color);
  color: white;
  border: none;
  border-radius: 10px;
  font-size: 18px;
  font-weight: 600;
  cursor: pointer;
  margin-top: 25px;
  text-transform: uppercase;
  letter-spacing: 1px;
  position: relative;
  overflow: hidden;
  z-index: 1;
}

.calculate-button:hover {
  background-color: var(--button-calc-hover);
  transform: translateY(-2px);
  box-shadow: 0 5px 15px rgba(135, 233, 69, 0.4);
}

.calculate-button::after {
  content: '';
  position: absolute;
  top: 0;
  left: -100%;
  width: 100%;
  height: 100%;
  background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.2), transparent);
  transition: 0.5s;
  z-index: -1;
}

.calculate-button:hover::after {
  left: 100%;
}

.no-results {
  text-align: center;
  padding: 30px;
  font-style: italic;
  color: var(--text-color);
  opacity: 0.7;
}

/* Footer */
footer {
  text-align: center;
  margin-top: 50px;
  padding: 20px 0;
  color: var(--text-color);
  opacity: 0.7;
  font-size: 14px;
}

/* Animations */
@keyframes fadeIn {
  from {
    opacity: 0;
    transform: translateY(20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes pulse {
  from {
    transform: scale(1);
    text-shadow: 0 0 10px rgba(233, 69, 96, 0.3);
  }
  to {
    transform: scale(1.05);
    text-shadow: 0 0 20px rgba(233, 69, 96, 0.6);
  }
}

.result-item.best-value .result-value {
  animation: pulse 1.5s infinite alternate;
}

/* Responsive Design */
@media (max-width: 768px) {
  .container {
    padding: 15px;
  }
  
  .calculator-card, .results {
    padding: 20px;
  }
  
  .product-row {
    grid-template-columns: 1fr 1fr;
    gap: 15px;
  }
  
  .logo {
    font-size: 2rem;
  }
  
  .result-value {
    font-size: 24px;
  }
}

@media (max-width: 480px) {
  .product-row {
    grid-template-columns: 1fr;
    gap: 10px;
  }
  
  .logo {
    font-size: 1.8rem;
  }
  
  .calculate-button {
    padding: 12px;
    font-size: 16px;
  }
}

/* Row Management Buttons */
.add-row-button {
  display: block;
  width: 100%;
  padding: 12px;
  margin: 20px 0;
  background-color: var(--button-add-color);
  color: white;
  border: none;
  border-radius: 10px;
  font-size: 16px;
  font-weight: 500;
  cursor: pointer;
  transition: background-color 0.3s ease;
}

.add-row-button:hover {
  background-color: var(--button-add-hover);
}

.delete-row-button {
  background: none;
  border: none;
  color: var(--highlight-color);
  font-size: 18px;
  cursor: pointer;
  opacity: 0.7;
  transition: opacity 0.3s ease;
  height: 47px;
}

.delete-row-button:hover {
  opacity: 1;
}

.cost-metrics {
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 20px;
  font-size: 24px;
  font-weight: 700;
}

.cost-per-unit, .units-per-cost {
  text-align: center;
}

.cost-per-unit {
  border-right: 2px solid rgba(255, 255, 255, 0.1);
  padding-right: 20px;
}

.units-per-cost {
  padding-left: 20px;
}

.metric-label {
  font-size: 12px;
  color: inherit;
  opacity: 0.8;
  margin-top: 4px;
  font-weight: normal;
}