:root {
  --primary-color: #4f46e5;
  --primary-light: #e0e7ff;
  --gray-50: #f9fafb;
  --gray-100: #f3f4f6;
  --gray-200: #e5e7eb;
  --gray-700: #374151;
  --gray-800: #1f2937;
  --gray-900: #111827;
  --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
  --shadow: 0 1px 3px 0 rgb(0 0 0 / 0.1), 0 1px 2px -1px rgb(0 0 0 / 0.1);
  --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);
}

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

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  line-height: 1.5;
  background: linear-gradient(135deg, #e0e7ff 0%, #c7d2fe 100%);
  min-height: 100vh;
  padding: 2rem 1rem;
}

.container {
  max-width: 64rem;
  margin: 0 auto;
}

h1 {
  font-size: 2.5rem;
  font-weight: bold;
  color: var(--gray-900);
  text-align: center;
  margin-bottom: 2rem;
}

h2 {
  font-size: 1.5rem;
  font-weight: 600;
  color: var(--gray-900);
  margin-bottom: 1rem;
}

.converter-card,
.info-card {
  background: white;
  border-radius: 1rem;
  padding: 1.5rem;
  box-shadow: var(--shadow-lg);
  margin-bottom: 2rem;
}

.input-group {
  margin-bottom: 1.5rem;
}

label {
  display: block;
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--gray-700);
  margin-bottom: 0.5rem;
}

select,
input {
  width: 100%;
  padding: 0.5rem;
  border: 1px solid var(--gray-200);
  border-radius: 0.5rem;
  background-color: white;
  color: var(--gray-900);
  font-size: 1rem;
  transition: all 0.2s;
}

select:focus,
input:focus {
  outline: none;
  border-color: var(--primary-color);
  box-shadow: 0 0 0 3px var(--primary-light);
}

.conversion-grid {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  gap: 1rem;
  align-items: start;
}

.conversion-column {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.swap-button {
  width: 3rem;
  height: 3rem;
  border: none;
  border-radius: 9999px;
  background-color: var(--primary-light);
  color: var(--primary-color);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all 0.2s;
  margin-top: 2rem;
}

.swap-button:hover {
  background-color: #d4d9fc;
}

.unit-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
  gap: 1rem;
}

.unit-card {
  background-color: var(--gray-50);
  padding: 1rem;
  border-radius: 0.5rem;
}

.unit-card h3 {
  font-size: 1rem;
  font-weight: 500;
  color: var(--gray-900);
  margin-bottom: 0.5rem;
}

.unit-card ul {
  list-style: none;
  font-size: 0.875rem;
  color: var(--gray-700);
}

.unit-card li {
  margin-bottom: 0.25rem;
}

#toValue {
  background-color: var(--gray-50);
}

@media (max-width: 640px) {
  .conversion-grid {
    grid-template-columns: 1fr;
  }

  .swap-button {
    margin: 0.5rem auto;
    transform: rotate(90deg);
  }
}