:root {
  --primary-color: #1890ff;
  --success-color: #52c41a;
  --warning-color: #faad14;
  --danger-color: #ff4d4f;
  --text-color: #333;
  --text-secondary: #666;
  --bg-color: #f5f5f5;
  --card-bg: #fff;
  --border-color: #e8e8e8;
  --border-radius: 12px;
  --shadow: 0 2px 8px rgba(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;
  background-color: var(--bg-color);
  color: var(--text-color);
  min-height: 100vh;
}

.container {
  max-width: 480px;
  margin: 0 auto;
  padding: 16px;
}

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

.header h1 {
  font-size: 24px;
  color: var(--primary-color);
}

.tab-nav {
  display: flex;
  background-color: var(--card-bg);
  border-radius: var(--border-radius);
  margin-bottom: 16px;
  overflow: hidden;
  box-shadow: var(--shadow);
}

.tab-btn {
  flex: 1;
  padding: 14px;
  border: none;
  background: transparent;
  font-size: 16px;
  cursor: pointer;
  color: var(--text-secondary);
  transition: all 0.3s;
}

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

.tab-content {
  display: none;
}

.tab-content.active {
  display: block;
}

.refresh-btn-container {
  text-align: right;
  margin-bottom: 12px;
}

.stats-container {
  display: flex;
  justify-content: space-between;
  align-items: center;
  background-color: var(--card-bg);
  border-radius: var(--border-radius);
  padding: 16px;
  margin-bottom: 16px;
  box-shadow: var(--shadow);
}

.stat-item {
  flex: 1;
  text-align: center;
}

.stat-label {
  display: block;
  font-size: 13px;
  color: var(--text-secondary);
  margin-bottom: 4px;
}

.stat-value {
  display: block;
  font-size: 20px;
  font-weight: bold;
  color: var(--primary-color);
}

.stat-divider {
  width: 1px;
  height: 40px;
  background-color: var(--border-color);
}

.info-icon {
  display: inline-block;
  margin-left: 6px;
  font-size: 14px;
  color: var(--text-secondary);
  cursor: help;
  transition: color 0.2s;
  position: relative;
}

.info-icon:hover {
  color: var(--primary-color);
}

.tooltip {
  visibility: hidden;
  opacity: 0;
  position: absolute;
  bottom: 130%;
  left: 50%;
  transform: translateX(-50%);
  width: 240px;
  padding: 10px 14px;
  background-color: #333;
  color: white;
  font-size: 12px;
  line-height: 1.5;
  border-radius: 6px;
  text-align: left;
  z-index: 1000;
  transition: opacity 0.2s, visibility 0.2s;
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
}

.tooltip::after {
  content: '';
  position: absolute;
  top: 100%;
  left: 50%;
  transform: translateX(-50%);
  border-width: 6px;
  border-style: solid;
  border-color: #333 transparent transparent transparent;
}

.info-icon:hover .tooltip {
  visibility: visible;
  opacity: 1;
}

.fill-hint-btn {
  display: block;
  margin-top: 8px;
  padding: 0;
  border: none;
  background: transparent;
  color: var(--primary-color);
  font-size: 13px;
  cursor: pointer;
  text-align: left;
  transition: opacity 0.2s;
}

.fill-hint-btn:hover {
  opacity: 0.8;
  text-decoration: underline;
}

.term-selector-group {
  margin-bottom: 16px;
}

.term-selector-group label {
  display: block;
  font-size: 14px;
  color: var(--text-secondary);
  margin-bottom: 8px;
}

.term-selector {
  display: flex;
  align-items: center;
  gap: 12px;
}

.term-selector .form-input {
  flex: 1;
}

.term-separator {
  font-size: 16px;
  color: var(--text-secondary);
  font-weight: bold;
}

.cards-container {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.credit-card {
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  border-radius: var(--border-radius);
  padding: 20px;
  color: white;
  box-shadow: var(--shadow);
}

.card-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 20px;
}

.bank-name {
  font-size: 20px;
  font-weight: bold;
}

.card-body {
  display: flex;
  justify-content: space-between;
  gap: 16px;
}

.info-item {
  flex: 1;
}

.info-item .label {
  display: block;
  font-size: 12px;
  opacity: 0.8;
  margin-bottom: 4px;
}

.info-item .value {
  font-size: 18px;
  font-weight: bold;
}

.info-item .value.bill-amount {
  color: #ffeaa7;
}

.info-item .value.credit-limit {
  color: #81ecec;
}

.calculate-form {
  background-color: var(--card-bg);
  border-radius: var(--border-radius);
  padding: 20px;
  box-shadow: var(--shadow);
  margin-bottom: 16px;
}

.form-group {
  margin-bottom: 16px;
}

.form-group label {
  display: block;
  font-size: 14px;
  color: var(--text-secondary);
  margin-bottom: 8px;
}

.form-input {
  width: 100%;
  padding: 12px;
  border: 1px solid var(--border-color);
  border-radius: 8px;
  font-size: 16px;
  outline: none;
  transition: border-color 0.3s;
}

.form-input:focus {
  border-color: var(--primary-color);
}

.input-group {
  display: flex;
  gap: 8px;
}

.input-group .form-input {
  flex: 1;
}

.form-row {
  display: flex;
  gap: 12px;
}

.form-row .form-group {
  flex: 1;
}

.btn {
  padding: 10px 16px;
  border: none;
  border-radius: 8px;
  font-size: 14px;
  cursor: pointer;
  transition: all 0.3s;
}

.btn-small {
  padding: 8px 12px;
  font-size: 13px;
}

.btn-large {
  width: 100%;
  padding: 14px;
  font-size: 16px;
  font-weight: bold;
}

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

.btn-primary:hover {
  background-color: #40a9ff;
}

.btn-secondary {
  background-color: var(--border-color);
  color: var(--text-color);
}

.btn-secondary:hover {
  background-color: #d9d9d9;
}

.result-container {
  margin-top: 16px;
}

.result-card {
  background-color: var(--card-bg);
  border-radius: var(--border-radius);
  padding: 20px;
  box-shadow: var(--shadow);
}

.result-card.best-option {
  border: 2px solid var(--success-color);
}

.result-header {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 20px;
}

.badge {
  background-color: var(--success-color);
  color: white;
  padding: 4px 12px;
  border-radius: 20px;
  font-size: 12px;
  font-weight: bold;
}

.result-header .bank-name {
  font-size: 18px;
  font-weight: bold;
  color: var(--text-color);
}

.rate-display {
  text-align: center;
  margin-bottom: 20px;
  padding: 20px;
  background: linear-gradient(135deg, var(--primary-color), #40a9ff);
  border-radius: 12px;
  color: white;
}

.rate-value {
  display: block;
  font-size: 36px;
  font-weight: bold;
}

.rate-label {
  display: block;
  font-size: 14px;
  opacity: 0.9;
}

.details {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 12px;
}

.detail-item {
  padding: 12px;
  background-color: var(--bg-color);
  border-radius: 8px;
}

.detail-item .label {
  display: block;
  font-size: 12px;
  color: var(--text-secondary);
  margin-bottom: 4px;
}

.detail-item .value {
  font-size: 16px;
  font-weight: bold;
  color: var(--text-color);
}

.loading {
  text-align: center;
  padding: 40px;
  color: var(--text-secondary);
}

.no-result {
  text-align: center;
  padding: 40px;
  color: var(--text-secondary);
  background-color: var(--card-bg);
  border-radius: var(--border-radius);
  box-shadow: var(--shadow);
}

.result-section {
  margin-top: 16px;
}

.result-title {
  font-size: 20px;
  font-weight: bold;
  color: var(--primary-color);
  margin-bottom: 16px;
  text-align: center;
}

.options-container {
  display: flex;
  flex-direction: column;
  gap: 12px;
  margin-bottom: 16px;
}

.option-card {
  background-color: var(--card-bg);
  border-radius: var(--border-radius);
  padding: 16px;
  box-shadow: var(--shadow);
  border: 2px solid transparent;
  transition: all 0.3s;
}

.option-card.best {
  border-color: var(--success-color);
  background: linear-gradient(135deg, rgba(82, 196, 26, 0.05), rgba(82, 196, 26, 0.02));
}

.option-header {
  display: flex;
  align-items: center;
  gap: 8px;
  margin-bottom: 12px;
  flex-wrap: wrap;
}

.option-number {
  font-size: 16px;
  font-weight: bold;
  color: var(--text-secondary);
}

.option-bank {
  font-size: 16px;
  font-weight: bold;
  color: var(--text-color);
}

.option-type {
  font-size: 14px;
  color: var(--text-secondary);
  padding: 2px 8px;
  background-color: var(--bg-color);
  border-radius: 4px;
}

.best-badge {
  font-size: 12px;
  font-weight: bold;
  color: white;
  background-color: var(--success-color);
  padding: 2px 8px;
  border-radius: 4px;
}

.option-body {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 12px;
}

.option-detail {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.detail-label {
  font-size: 13px;
  color: var(--text-secondary);
}

.detail-value {
  font-size: 15px;
  font-weight: bold;
  color: var(--text-color);
}

.detail-value.rate {
  color: var(--primary-color);
}

.total-section {
  background-color: var(--card-bg);
  border-radius: var(--border-radius);
  padding: 16px;
  box-shadow: var(--shadow);
  border-top: 3px solid var(--primary-color);
}

.total-title {
  font-size: 16px;
  font-weight: bold;
  color: var(--primary-color);
  margin-bottom: 12px;
}

.total-details {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 12px;
}

.total-detail {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.total-label {
  font-size: 14px;
  color: var(--text-secondary);
}

.total-value {
  font-size: 16px;
  font-weight: bold;
  color: var(--text-color);
}

.total-value.rate {
  color: var(--primary-color);
}

@media (min-width: 640px) {
  .option-body {
    grid-template-columns: repeat(4, 1fr);
  }
  
  .total-details {
    grid-template-columns: repeat(4, 1fr);
  }
}

@media (min-width: 768px) {
  .container {
    max-width: 640px;
    padding: 24px;
  }
}

@media (min-width: 1024px) {
  .container {
    max-width: 720px;
  }
}