:root {
  --color-primary: #5B4CE0;
  --color-primary-dark: #4A3BC9;
  --color-secondary: #7C3AED;
  --color-accent: #A78BFA;
  --color-bg: #FAFBFC;
  --color-surface: #FFFFFF;
  --color-text: #1A1A2E;
  --color-text-muted: #4A5568;
  --color-text-subtle: #6B7280;
  --color-border: #E5E7EB;
  --color-success: #10B981;
  --color-error: #EF4444;
  
  --font-family: 'Heebo', -apple-system, BlinkMacSystemFont, sans-serif;
  
  --space-xs: 0.25rem;
  --space-sm: 0.5rem;
  --space-md: 1rem;
  --space-lg: 1.5rem;
  --space-xl: 2rem;
  --space-2xl: 3rem;
  --space-3xl: 4rem;
  
  --radius-sm: 0.375rem;
  --radius-md: 0.75rem;
  --radius-lg: 1rem;
  --radius-xl: 1.5rem;
  
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
  --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
  
  --transition-fast: 150ms ease;
  --transition-base: 250ms ease;
  --transition-slow: 350ms ease;
}

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

html {
  font-size: 16px;
  -webkit-text-size-adjust: 100%;
}

body {
  font-family: var(--font-family);
  font-weight: 400;
  line-height: 1.6;
  color: var(--color-text);
  background: var(--color-bg);
  min-height: 100vh;
  min-height: 100dvh;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

.page-wrapper {
  display: flex;
  flex-direction: column;
  min-height: 100vh;
  min-height: 100dvh;
}

/* Header */
.header {
  padding: var(--space-lg) var(--space-xl);
  background: var(--color-surface);
  border-block-end: 1px solid var(--color-border);
  position: sticky;
  top: 0;
  z-index: 100;
}

.logo {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  justify-content: center;
}

.logo-icon {
  width: 36px;
  height: 36px;
}

.logo-text {
  font-size: 1.375rem;
  font-weight: 600;
  background: linear-gradient(135deg, var(--color-primary), var(--color-secondary));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

/* Main */
.main {
  flex: 1;
  display: flex;
  align-items: flex-start;
  justify-content: center;
  padding: var(--space-xl);
  padding-block-start: var(--space-2xl);
}

.checkout-card {
  width: 100%;
  max-width: 600px;
  background: var(--color-surface);
  border-radius: var(--radius-xl);
  box-shadow: var(--shadow-xl);
  overflow: hidden;
  animation: cardSlideIn 0.4s ease-out;
}

@keyframes cardSlideIn {
  from {
    opacity: 0;
    transform: translateY(16px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@media (prefers-reduced-motion: reduce) {
  .checkout-card {
    animation: none;
  }
  
  .button-spinner {
    animation: none;
    opacity: 0;
  }
}

.card-header {
  background: linear-gradient(135deg, var(--color-primary), var(--color-secondary));
  padding: var(--space-xl);
  text-align: center;
  color: white;
}

.business-badge {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 56px;
  height: 56px;
  background: rgba(255, 255, 255, 0.2);
  border-radius: 50%;
  margin-block-end: var(--space-md);
  backdrop-filter: blur(10px);
}

.badge-icon {
  width: 28px;
  height: 28px;
}

.business-title {
  font-size: 1.125rem;
  font-weight: 400;
  margin-block-end: var(--space-xs);
}

.business-subtitle {
  font-size: 1.5rem;
  font-weight: 600;
}

/* Plan Section */
.plan-section {
  padding: var(--space-xl);
  border-block-end: 1px solid var(--color-border);
}

.plan-badge {
  display: inline-block;
  padding: var(--space-xs) var(--space-md);
  background: linear-gradient(135deg, var(--color-primary), var(--color-secondary));
  color: white;
  font-size: 0.75rem;
  font-weight: 500;
  border-radius: 999px;
  margin-block-end: var(--space-md);
}

.plan-badge:empty {
  display: none;
}

.plan-details {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: var(--space-md);
  margin-block-end: var(--space-lg);
}

.plan-title {
  font-size: 1.25rem;
  font-weight: 600;
  color: var(--color-text);
}

.plan-price {
  font-size: 1.75rem;
  font-weight: 600;
  color: var(--color-primary);
  unicode-bidi: isolate;
}

.plan-features {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: var(--space-sm);
}

.plan-features li {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  font-size: 0.9375rem;
  line-height: 1.5;
  color: var(--color-text-muted);
}

.plan-features li::before {
  content: '';
  display: inline-block;
  width: 20px;
  height: 20px;
  background: var(--color-success);
  border-radius: 50%;
  flex-shrink: 0;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24' fill='none' stroke='white' stroke-width='3'%3E%3Cpolyline points='20,6 9,17 4,12'/%3E%3C/svg%3E");
  background-size: 12px;
  background-position: center;
  background-repeat: no-repeat;
}

/* Payment Action Section */
.payment-action {
  padding: var(--space-xl);
  background: linear-gradient(180deg, var(--color-bg) 0%, var(--color-surface) 100%);
  text-align: center;
}

.pay-button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-sm);
  width: 100%;
  max-width: 360px;
  padding: var(--space-lg) var(--space-xl);
  background: linear-gradient(135deg, var(--color-primary), var(--color-secondary));
  color: white;
  font-family: var(--font-family);
  font-size: 1.125rem;
  font-weight: 600;
  border: none;
  border-radius: var(--radius-lg);
  cursor: pointer;
  transition: transform var(--transition-fast), box-shadow var(--transition-fast), opacity var(--transition-fast);
  box-shadow: 0 4px 14px rgba(91, 76, 224, 0.4);
}

.pay-button:hover:not(:disabled) {
  transform: translateY(-2px);
  box-shadow: 0 6px 20px rgba(91, 76, 224, 0.5);
}

.pay-button:active:not(:disabled) {
  transform: translateY(0);
}

.pay-button:disabled {
  opacity: 0.8;
  cursor: not-allowed;
}

.pay-button.loading {
  pointer-events: none;
}

.pay-button-icon {
  width: 24px;
  height: 24px;
  flex-shrink: 0;
}

.button-spinner {
  width: 20px;
  height: 20px;
  border: 2px solid rgba(255, 255, 255, 0.3);
  border-block-start-color: white;
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
  flex-shrink: 0;
}

@keyframes spin {
  to { transform: rotate(360deg); }
}

.payment-note {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-xs);
  margin-block-start: var(--space-lg);
  font-size: 0.875rem;
  color: var(--color-text-subtle);
}

.note-icon {
  width: 16px;
  height: 16px;
  color: var(--color-success);
  flex-shrink: 0;
}

/* Error State */
.error-state {
  padding: var(--space-3xl) var(--space-xl);
  text-align: center;
}

.error-icon {
  width: 64px;
  height: 64px;
  color: var(--color-error);
  margin-block-end: var(--space-lg);
}

.error-title {
  font-size: 1.5rem;
  font-weight: 600;
  color: var(--color-text);
  margin-block-end: var(--space-sm);
}

.error-message {
  font-size: 1rem;
  color: var(--color-text-muted);
  max-width: 320px;
  margin-inline: auto;
  line-height: 1.6;
}

/* Footer */
.footer {
  padding: var(--space-lg) var(--space-xl);
  background: var(--color-surface);
  border-block-start: 1px solid var(--color-border);
  text-align: center;
}

.security-badge {
  display: inline-flex;
  align-items: center;
  gap: var(--space-sm);
  padding: var(--space-sm) var(--space-lg);
  background: var(--color-bg);
  border-radius: var(--radius-md);
  font-size: 0.875rem;
  color: var(--color-text-muted);
  margin-block-end: var(--space-md);
}

.lock-icon {
  width: 16px;
  height: 16px;
  color: var(--color-success);
}

.footer-brand {
  font-size: 0.8125rem;
  color: var(--color-text-subtle);
}

/* Responsive */
@media (max-width: 640px) {
  .main {
    padding: var(--space-md);
    padding-block-start: var(--space-lg);
  }
  
  .checkout-card {
    border-radius: var(--radius-lg);
  }
  
  .card-header {
    padding: var(--space-lg);
  }
  
  .business-badge {
    width: 48px;
    height: 48px;
  }
  
  .badge-icon {
    width: 24px;
    height: 24px;
  }
  
  .business-title {
    font-size: 1rem;
  }
  
  .business-subtitle {
    font-size: 1.25rem;
  }
  
  .plan-section {
    padding: var(--space-lg);
  }
  
  .plan-details {
    flex-direction: column;
    align-items: flex-start;
    gap: var(--space-sm);
  }
  
  .plan-title {
    font-size: 1.125rem;
  }
  
  .plan-price {
    font-size: 1.5rem;
  }
  
  .payment-action {
    padding: var(--space-lg);
  }
  
  .pay-button {
    padding: var(--space-md) var(--space-lg);
    font-size: 1rem;
  }
  
  .footer {
    padding: var(--space-md);
  }
  
  .security-badge {
    font-size: 0.8125rem;
    padding: var(--space-xs) var(--space-md);
  }
}

@media (max-width: 360px) {
  html {
    font-size: 14px;
  }
  
  .header {
    padding: var(--space-md);
  }
  
  .logo-icon {
    width: 32px;
    height: 32px;
  }
  
  .logo-text {
    font-size: 1.25rem;
  }
}

/* Focus styles for accessibility */
*:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: 2px;
}

/* Hide content visually but keep accessible */
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}