:root {
  --primary: #2563EB;
  --primary-light: #3B82F6;
  --secondary: #10B981;
  --secondary-light: #34D399;
  --background: #FFFFFF;
  --surface: #F8FAFC;
  --text-primary: #1E293B;
  --text-secondary: #64748B;
  --border: #E2E8F0;
  --border-light: #F1F5F9;
  --shadow: rgba(0, 0, 0, 0.08);
  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 16px;
  --transition: all 0.3s ease;
}

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

html {
  font-size: 16px;
}

body {
  font-family: system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
  background: linear-gradient(135deg, #F8FAFC 0%, #E2E8F0 100%);
  color: var(--text-primary);
  line-height: 1.6;
  min-height: 100vh;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

.app-container {
  max-width: 480px;
  margin: 0 auto;
  min-height: 100vh;
  background: var(--background);
  box-shadow: 0 0 40px var(--shadow);
  display: flex;
  flex-direction: column;
}

.app-header {
  background: linear-gradient(135deg, var(--primary) 0%, var(--primary-light) 100%);
  color: white;
  padding: 2rem 1.5rem;
  text-align: center;
  position: relative;
  overflow: hidden;
}

.app-header::before {
  content: '';
  position: absolute;
  top: -50%;
  right: -50%;
  width: 100%;
  height: 200%;
  background: radial-gradient(circle, rgba(255,255,255,0.1) 0%, transparent 70%);
  animation: pulse 4s ease-in-out infinite;
}

@keyframes pulse {
  0%, 100% { transform: scale(1); opacity: 0.5; }
  50% { transform: scale(1.1); opacity: 0.3; }
}

.app-title {
  font-size: 1.75rem;
  font-weight: 700;
  margin-bottom: 0.5rem;
  position: relative;
  z-index: 1;
}

.app-subtitle {
  font-size: 0.875rem;
  opacity: 0.9;
  position: relative;
  z-index: 1;
}

.app-main {
  flex: 1;
  padding: 1.5rem;
  padding-bottom: 2rem;
}

.loan-type-section {
  margin-bottom: 1.5rem;
  position: relative;
}

.loan-type-tabs {
  display: flex;
  background: var(--surface);
  border-radius: var(--radius-md);
  padding: 4px;
  position: relative;
}

.tab-btn {
  flex: 1;
  padding: 0.75rem 1rem;
  border: none;
  background: transparent;
  color: var(--text-secondary);
  font-size: 0.9375rem;
  font-weight: 500;
  cursor: pointer;
  transition: var(--transition);
  position: relative;
  z-index: 1;
  border-radius: var(--radius-sm);
}

.tab-btn.active {
  color: var(--primary);
  background: var(--background);
  box-shadow: 0 2px 8px var(--shadow);
}

.tab-btn:hover:not(.active) {
  color: var(--text-primary);
}

.form-section {
  margin-bottom: 1.25rem;
  animation: fadeIn 0.3s ease;
}

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(10px); }
  to { opacity: 1; transform: translateY(0); }
}

.input-group {
  margin-bottom: 0.75rem;
}

.input-label {
  display: block;
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 0.5rem;
}

.input-wrapper {
  display: flex;
  align-items: center;
  background: var(--surface);
  border: 2px solid var(--border);
  border-radius: var(--radius-md);
  padding: 0 1rem;
  transition: var(--transition);
}

.input-wrapper:focus-within {
  border-color: var(--primary);
  box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}

.input-field {
  flex: 1;
  border: none;
  background: transparent;
  padding: 0.875rem 0;
  font-size: 1rem;
  color: var(--text-primary);
  outline: none;
}

.input-field::placeholder {
  color: var(--text-secondary);
  opacity: 0.5;
}

.input-suffix {
  color: var(--text-secondary);
  font-size: 0.875rem;
  font-weight: 500;
}

.range-field {
  width: 100%;
  height: 6px;
  background: var(--border);
  border-radius: 3px;
  outline: none;
  -webkit-appearance: none;
  appearance: none;
  margin-bottom: 0.5rem;
}

.range-field::-webkit-slider-thumb {
  -webkit-appearance: none;
  width: 24px;
  height: 24px;
  background: var(--primary);
  border-radius: 50%;
  cursor: pointer;
  box-shadow: 0 2px 8px rgba(37, 99, 235, 0.3);
  transition: var(--transition);
}

.range-field::-webkit-slider-thumb:hover {
  transform: scale(1.1);
  box-shadow: 0 4px 12px rgba(37, 99, 235, 0.4);
}

.range-field::-moz-range-thumb {
  width: 24px;
  height: 24px;
  background: var(--primary);
  border-radius: 50%;
  cursor: pointer;
  border: none;
  box-shadow: 0 2px 8px rgba(37, 99, 235, 0.3);
}

.range-display {
  display: flex;
  align-items: baseline;
  margin-left: 1rem;
  white-space: nowrap;
}

.range-value {
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--primary);
}

.range-unit {
  font-size: 0.875rem;
  color: var(--text-secondary);
  margin-left: 0.25rem;
}

.range-labels {
  display: flex;
  justify-content: space-between;
  font-size: 0.75rem;
  color: var(--text-secondary);
  margin-top: 0.5rem;
}

.rate-presets {
  display: flex;
  gap: 0.5rem;
  margin-top: 0.75rem;
  flex-wrap: wrap;
}

.preset-btn {
  padding: 0.5rem 0.875rem;
  border: 1px solid var(--border);
  background: var(--surface);
  color: var(--text-secondary);
  font-size: 0.8125rem;
  font-weight: 500;
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: var(--transition);
}

.preset-btn:hover {
  border-color: var(--primary);
  color: var(--primary);
}

.preset-btn.active {
  background: var(--primary);
  border-color: var(--primary);
  color: white;
}

.repayment-toggle {
  display: flex;
  gap: 0.75rem;
}

.toggle-btn {
  flex: 1;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.5rem;
  padding: 1rem;
  border: 2px solid var(--border);
  background: var(--surface);
  border-radius: var(--radius-md);
  cursor: pointer;
  transition: var(--transition);
}

.toggle-btn:hover {
  border-color: var(--primary-light);
}

.toggle-btn.active {
  border-color: var(--primary);
  background: rgba(37, 99, 235, 0.05);
}

.toggle-icon {
  font-size: 1.5rem;
}

.toggle-text {
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--text-primary);
}

.calculate-btn {
  width: 100%;
  padding: 1rem;
  background: linear-gradient(135deg, var(--primary) 0%, var(--primary-light) 100%);
  color: white;
  border: none;
  border-radius: var(--radius-md);
  font-size: 1.0625rem;
  font-weight: 600;
  cursor: pointer;
  transition: var(--transition);
  box-shadow: 0 4px 12px rgba(37, 99, 235, 0.3);
  margin-top: 1rem;
}

.calculate-btn:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 20px rgba(37, 99, 235, 0.4);
}

.calculate-btn:active {
  transform: scale(0.98);
}

.results-section {
  margin-top: 2rem;
  animation: slideUp 0.4s ease;
}

@keyframes slideUp {
  from { opacity: 0; transform: translateY(20px); }
  to { opacity: 1; transform: translateY(0); }
}

.results-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 1rem;
}

.results-title {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--text-primary);
}

.repayment-type-badge {
  padding: 0.375rem 0.875rem;
  background: var(--primary);
  color: white;
  font-size: 0.8125rem;
  font-weight: 600;
  border-radius: 20px;
}

.summary-cards {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 0.75rem;
  margin-bottom: 1.5rem;
}

.summary-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 1rem;
  text-align: center;
  transition: var(--transition);
}

.summary-card:hover {
  transform: translateY(-2px);
  box-shadow: 0 4px 12px var(--shadow);
}

.summary-card.primary {
  grid-column: span 2;
  background: linear-gradient(135deg, var(--primary) 0%, var(--primary-light) 100%);
  color: white;
  border: none;
}

.summary-card.primary .card-label {
  color: rgba(255, 255, 255, 0.9);
}

.summary-card.primary .card-value {
  color: white;
  font-size: 2rem;
}

.card-label {
  font-size: 0.8125rem;
  color: var(--text-secondary);
  margin-bottom: 0.25rem;
}

.card-value {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--text-primary);
  transition: all 0.3s ease;
}

.card-value.interest {
  color: var(--secondary);
}

.card-value.monthly {
  color: var(--primary);
}

.card-unit {
  font-size: 0.75rem;
  color: var(--text-secondary);
  margin-top: 0.125rem;
}

.comparison-section {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 1rem;
  margin-bottom: 1.5rem;
}

.comparison-title {
  font-size: 0.9375rem;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 0.75rem;
}

.comparison-table {
  width: 100%;
}

.comparison-header,
.comparison-row {
  display: grid;
  grid-template-columns: 2fr 1.5fr 1.5fr 1.5fr;
  gap: 0.5rem;
  padding: 0.5rem 0;
}

.comparison-header {
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--text-secondary);
  border-bottom: 1px solid var(--border);
}

.comparison-row {
  font-size: 0.875rem;
  border-bottom: 1px solid var(--border-light);
}

.comparison-row:last-child {
  border-bottom: none;
}

.comparison-col {
  text-align: center;
}

.comparison-col.method {
  font-weight: 600;
  color: var(--text-primary);
  text-align: left;
}

.comparison-col.highlight {
  color: var(--secondary);
  font-weight: 600;
}

.detail-tabs {
  display: flex;
  background: var(--surface);
  border-radius: var(--radius-md);
  padding: 4px;
  margin-bottom: 1rem;
}

.detail-tab-btn {
  flex: 1;
  padding: 0.625rem 1rem;
  border: none;
  background: transparent;
  color: var(--text-secondary);
  font-size: 0.875rem;
  font-weight: 500;
  cursor: pointer;
  transition: var(--transition);
  border-radius: var(--radius-sm);
}

.detail-tab-btn.active {
  color: var(--primary);
  background: var(--background);
  box-shadow: 0 2px 8px var(--shadow);
}

.detail-tab-btn:hover:not(.active) {
  color: var(--text-primary);
}

.detail-table-container {
  overflow-x: auto;
  border-radius: var(--radius-md);
  border: 1px solid var(--border);
}

.detail-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.8125rem;
  min-width: 500px;
}

.detail-table thead {
  background: var(--surface);
  position: sticky;
  top: 0;
}

.detail-table th {
  padding: 0.875rem 0.5rem;
  text-align: right;
  font-weight: 600;
  color: var(--text-secondary);
  border-bottom: 2px solid var(--border);
  white-space: nowrap;
}

.detail-table th:first-child {
  text-align: center;
  padding-left: 1rem;
}

.detail-table td {
  padding: 0.75rem 0.5rem;
  text-align: right;
  color: var(--text-primary);
  border-bottom: 1px solid var(--border-light);
  white-space: nowrap;
}

.detail-table td:first-child {
  text-align: center;
  font-weight: 600;
  color: var(--text-secondary);
  padding-left: 1rem;
}

.detail-table tbody tr:nth-child(even) {
  background: var(--surface);
}

.detail-table tbody tr:hover {
  background: rgba(37, 99, 235, 0.05);
}

.detail-table tbody tr.highlight {
  background: rgba(37, 99, 235, 0.1);
}

.detail-table tbody tr.highlight td {
  color: var(--primary);
  font-weight: 600;
}

.detail-table .principal {
  color: var(--primary);
}

.detail-table .interest {
  color: var(--secondary);
}

.app-footer {
  text-align: center;
  padding: 1.5rem;
  background: var(--surface);
  border-top: 1px solid var(--border);
  margin-top: auto;
}

.footer-text {
  font-size: 0.8125rem;
  color: var(--text-secondary);
  margin-bottom: 0.25rem;
}

.footer-version {
  font-size: 0.75rem;
  color: var(--text-secondary);
  opacity: 0.7;
}

@media (max-width: 480px) {
  .app-container {
    max-width: 100%;
    box-shadow: none;
  }

  .app-header {
    padding: 1.5rem 1rem;
  }

  .app-title {
    font-size: 1.5rem;
  }

  .app-main {
    padding: 1rem;
  }

  .summary-card.primary .card-value {
    font-size: 1.75rem;
  }

  .detail-table {
    font-size: 0.75rem;
  }

  .detail-table th,
  .detail-table td {
    padding: 0.625rem 0.375rem;
  }

  .comparison-header,
  .comparison-row {
    grid-template-columns: 1.5fr 1fr 1fr 1fr;
    font-size: 0.75rem;
  }
}