/* ===== CSS Variables ===== */
:root {
  --primary-color: #3b82f6;
  --primary-hover: #2563eb;
  --secondary-color: #64748b;
  --error-color: #ef4444;
  --error-light: #fecaca;
  --success-color: #22c55e;
  --success-light: #bbf7d0;
  --warning-color: #f59e0b;
  --background-color: #f8fafc;
  --card-color: #ffffff;
  --text-color: #1e293b;
  --text-muted: #64748b;
  --border-color: #e2e8f0;
  --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -2px rgba(0, 0, 0, 0.1);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -4px rgba(0, 0, 0, 0.1);
  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 16px;
  --transition-fast: 150ms ease;
  --transition-normal: 250ms ease;
  --transition-slow: 350ms ease;
}

[data-theme="dark"] {
  --primary-color: #60a5fa;
  --primary-hover: #3b82f6;
  --secondary-color: #94a3b8;
  --error-color: #f87171;
  --error-light: #451a1a;
  --success-color: #4ade80;
  --success-light: #14532d;
  --warning-color: #fbbf24;
  --background-color: #0f172a;
  --card-color: #1e293b;
  --text-color: #f1f5f9;
  --text-muted: #94a3b8;
  --border-color: #334155;
  --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.3);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.4), 0 2px 4px -2px rgba(0, 0, 0, 0.3);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.5), 0 4px 6px -4px rgba(0, 0, 0, 0.4);
}

/* ===== Reset & Base ===== */
*,
*::before,
*::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  background-color: var(--background-color);
  color: var(--text-color);
  line-height: 1.6;
  min-height: 100vh;
  padding: 16px;
  transition: background-color var(--transition-normal), color var(--transition-normal);
}

/* ===== Container ===== */
.container {
  max-width: 960px;
  margin: 0 auto;
  background-color: var(--card-color);
  border-radius: var(--radius-lg);
  padding: 24px;
  box-shadow: var(--shadow-lg);
  transition: all var(--transition-normal);
}

/* ===== Typography ===== */
h1 {
  text-align: center;
  color: var(--text-color);
  font-size: clamp(1.5rem, 4vw, 2rem);
  font-weight: 700;
  margin-bottom: 8px;
  letter-spacing: -0.025em;
}

h2 {
  color: var(--text-color);
  font-size: 1.25rem;
  font-weight: 600;
}

p {
  color: var(--text-muted);
}

/* ===== Theme Toggle ===== */
.theme-toggle-container {
  display: flex;
  justify-content: flex-end;
  margin-bottom: 16px;
}

#theme-toggle {
  background: transparent;
  color: var(--text-muted);
  border: 1px solid var(--border-color);
  padding: 8px 16px;
  font-size: 14px;
  font-weight: 500;
  border-radius: var(--radius-md);
  cursor: pointer;
  transition: all var(--transition-fast);
  flex: none;
  min-width: auto;
}

#theme-toggle:hover {
  background-color: var(--border-color);
  color: var(--text-color);
  transform: none;
}

/* ===== Form Elements ===== */
textarea {
  width: 100%;
  min-height: 140px;
  padding: 16px;
  font-family: "SF Mono", "Monaco", "Menlo", "Consolas", monospace;
  font-size: 14px;
  line-height: 1.5;
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  resize: vertical;
  background-color: var(--card-color);
  color: var(--text-color);
  transition: all var(--transition-fast);
  box-shadow: var(--shadow-sm);
}

textarea:focus {
  outline: none;
  border-color: var(--primary-color);
  box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.15);
}

textarea::placeholder {
  color: var(--text-muted);
  opacity: 0.7;
}

/* ===== Controls ===== */
.controls {
  display: flex;
  gap: 12px;
  margin-bottom: 20px;
  flex-wrap: wrap;
}

button {
  background-color: var(--primary-color);
  color: white;
  padding: 12px 24px;
  border: none;
  border-radius: var(--radius-md);
  cursor: pointer;
  font-size: 15px;
  font-weight: 600;
  transition: all var(--transition-fast);
  flex: 1;
  min-width: 120px;
  box-shadow: var(--shadow-sm);
  position: relative;
  overflow: hidden;
}

button:hover:not(:disabled) {
  background-color: var(--primary-hover);
  transform: translateY(-1px);
  box-shadow: var(--shadow-md);
}

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

button:disabled {
  background-color: var(--border-color);
  color: var(--text-muted);
  cursor: not-allowed;
  transform: none;
  opacity: 0.6;
}

button.loading::after {
  content: "";
  position: absolute;
  width: 16px;
  height: 16px;
  border: 2px solid transparent;
  border-top-color: currentColor;
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
  margin-left: 8px;
}

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

#stop-btn {
  background-color: var(--error-color);
}

#stop-btn:hover:not(:disabled) {
  background-color: #dc2626;
}

#clear-btn {
  background-color: var(--secondary-color);
}

#clear-btn:hover:not(:disabled) {
  background-color: #475569;
}

/* ===== Progress Bar ===== */
.progress-container {
  margin: 24px 0;
  border-radius: var(--radius-lg);
  height: 8px;
  overflow: hidden;
  background-color: var(--border-color);
}

#progress-bar {
  height: 100%;
  background: linear-gradient(90deg, var(--primary-color), var(--success-color));
  width: 0%;
  transition: width var(--transition-normal);
  border-radius: var(--radius-lg);
}

/* ===== Statistics ===== */
.stats {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 12px;
  margin: 24px 0;
}

.stat-card {
  background: linear-gradient(135deg, var(--card-color) 0%, var(--border-color) 100%);
  border-radius: var(--radius-md);
  padding: 16px;
  text-align: center;
  border: 1px solid var(--border-color);
  transition: all var(--transition-fast);
}

.stat-card:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
}

.stat-card h3 {
  margin: 0 0 8px 0;
  font-size: 12px;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--text-muted);
}

.stat-card span {
  font-size: 28px;
  font-weight: 700;
  color: var(--text-color);
  display: block;
  transition: transform var(--transition-fast);
}

.stat-card span.counter-update {
  animation: pulse 0.3s ease;
}

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

/* ===== Results Grid ===== */
.results {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 16px;
  margin-top: 24px;
}

/* ===== Result Cards ===== */
.result-card {
  background-color: var(--card-color);
  border-radius: var(--radius-md);
  padding: 16px;
  border: 1px solid var(--border-color);
  box-shadow: var(--shadow-sm);
  transition: all var(--transition-fast);
  opacity: 0;
  transform: translateY(10px);
}

.result-card.fade-in {
  animation: fadeInUp var(--transition-normal) forwards;
}

.result-card.visible {
  opacity: 1;
  transform: translateY(0);
}

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

.result-card:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
}

.result-card.live {
  border-left: 4px solid var(--success-color);
  background: linear-gradient(90deg, var(--success-light) 0%, var(--card-color) 20%);
}

.result-card.dead {
  border-left: 4px solid var(--error-color);
  background: linear-gradient(90deg, var(--error-light) 0%, var(--card-color) 20%);
}

.result-card.invalid {
  border-left: 4px solid var(--secondary-color);
}

/* Card Header */
.card-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 12px;
}

.card-type-badge {
  font-size: 11px;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  padding: 4px 8px;
  border-radius: var(--radius-sm);
  background-color: var(--border-color);
  color: var(--text-muted);
}

.card-type-badge.visa {
  background-color: #1a1f71;
  color: white;
}

.card-type-badge.mastercard {
  background-color: #eb001b;
  color: white;
}

.card-type-badge.amex {
  background-color: #006fcf;
  color: white;
}

.card-type-badge.discover {
  background-color: #ff6000;
  color: white;
}

.status-badge {
  font-size: 11px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  padding: 4px 10px;
  border-radius: var(--radius-sm);
}

.status-badge.live {
  background-color: var(--success-light);
  color: var(--success-color);
}

.status-badge.dead {
  background-color: var(--error-light);
  color: var(--error-color);
}

/* Card Number */
.card-number {
  font-family: "SF Mono", "Monaco", "Menlo", "Consolas", monospace;
  font-size: 16px;
  font-weight: 600;
  margin-bottom: 12px;
  color: var(--text-color);
  letter-spacing: 0.05em;
}

/* Card Details */
.card-details {
  display: flex;
  gap: 16px;
}

.detail-item {
  display: flex;
  flex-direction: column;
}

.detail-label {
  font-size: 11px;
  font-weight: 500;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--text-muted);
  margin-bottom: 2px;
}

.detail-value {
  font-size: 14px;
  font-weight: 600;
  color: var(--text-color);
}

.reason {
  font-size: 12px;
  color: var(--text-muted);
  margin-top: 12px;
  padding-top: 12px;
  border-top: 1px solid var(--border-color);
}

/* ===== Notifications ===== */
.notification {
  position: fixed;
  bottom: 24px;
  right: 24px;
  padding: 16px 24px;
  border-radius: var(--radius-md);
  background-color: var(--card-color);
  color: var(--text-color);
  box-shadow: var(--shadow-lg);
  border: 1px solid var(--border-color);
  font-weight: 500;
  z-index: 1000;
  opacity: 0;
  transform: translateY(20px) scale(0.95);
  transition: all var(--transition-normal);
}

.notification.show {
  opacity: 1;
  transform: translateY(0) scale(1);
}

.notification.success {
  border-left: 4px solid var(--success-color);
}

.notification.warning {
  border-left: 4px solid var(--warning-color);
}

.notification.info {
  border-left: 4px solid var(--primary-color);
}

/* ===== SEO Content ===== */
.seo-content {
  margin-top: 32px;
  padding: 24px;
  background-color: var(--card-color);
  border-radius: var(--radius-md);
  border: 1px solid var(--border-color);
}

.seo-content h2 {
  text-align: left;
  margin-bottom: 16px;
}

.seo-content p {
  line-height: 1.7;
  margin-bottom: 12px;
}

.seo-content ul {
  padding-left: 24px;
  margin: 16px 0;
}

.seo-content li {
  margin-bottom: 8px;
  color: var(--text-muted);
}

/* ===== Responsive Design ===== */
@media (max-width: 768px) {
  body {
    padding: 12px;
  }

  .container {
    padding: 16px;
    border-radius: var(--radius-md);
  }

  h1 {
    font-size: 1.5rem;
  }

  .stats {
    grid-template-columns: repeat(2, 1fr);
    gap: 8px;
  }

  .stat-card {
    padding: 12px;
  }

  .stat-card span {
    font-size: 24px;
  }

  .controls {
    flex-direction: column;
  }

  button {
    min-width: 100%;
  }

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

  .result-card {
    padding: 12px;
  }

  .card-number {
    font-size: 14px;
  }

  .card-details {
    flex-wrap: wrap;
    gap: 8px;
  }

  .notification {
    left: 16px;
    right: 16px;
    bottom: 16px;
  }
}

@media (max-width: 480px) {
  .stats {
    grid-template-columns: repeat(2, 1fr);
  }

  .stat-card h3 {
    font-size: 10px;
  }

  .stat-card span {
    font-size: 20px;
  }

  .card-header {
    flex-direction: column;
    align-items: flex-start;
    gap: 8px;
  }

  textarea {
    min-height: 120px;
    font-size: 13px;
  }
}

/* ===== Accessibility ===== */
@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation: none !important;
    transition: none !important;
  }
}

/* ===== Focus States ===== */
button:focus-visible,
textarea:focus-visible,
#theme-toggle:focus-visible {
  outline: 2px solid var(--primary-color);
  outline-offset: 2px;
}

/* ===== Print Styles ===== */
@media print {
  .theme-toggle-container,
  .controls,
  .progress-container {
    display: none;
  }

  .container {
    box-shadow: none;
    border: 1px solid #ccc;
  }
}