/* ===========================
   CSS VARIABLES & ROOT STYLES
   =========================== */

:root {
  /* Colors - Light Mode */
  --color-primary: #3b82f6;
  --color-primary-dark: #1e40af;
  --color-primary-light: #dbeafe;
  --color-secondary: #10b981;
  --color-accent: #06b6d4;
  --color-bg: #f3f4f6;
  --color-bg-secondary: #ffffff;
  --color-text-primary: #111827;
  --color-text-secondary: #6b7280;
  --color-text-tertiary: #9ca3af;
  --color-border: #e5e7eb;
  --color-border-dark: #d1d5db;
  --color-success: #10b981;
  --color-warning: #f59e0b;
  --color-error: #ef4444;

  /* Typography */
  --font-primary: 'Lexend', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --font-secondary: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --font-weight-regular: 400;
  --font-weight-medium: 500;
  --font-weight-semibold: 600;
  --font-weight-bold: 700;

  /* Responsive Spacing */
  --spacing-xs: clamp(0.25rem, 0.5vw, 0.5rem);
  --spacing-sm: clamp(0.5rem, 1vw, 0.75rem);
  --spacing-md: clamp(0.75rem, 2vw, 1rem);
  --spacing-lg: clamp(1rem, 3vw, 1.5rem);
  --spacing-xl: clamp(1.5rem, 4vw, 2rem);
  --spacing-2xl: clamp(2rem, 5vw, 2.5rem);
  --spacing-3xl: clamp(2.5rem, 6vw, 3.5rem);
  --spacing-4xl: clamp(3rem, 8vw, 4.5rem);

  /* Border Radius */
  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 16px;

  /* Shadows - Optimized for light mode */
  --shadow-xs: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
  --shadow-sm: 0 1px 3px 0 rgba(0, 0, 0, 0.1), 0 1px 2px 0 rgba(0, 0, 0, 0.06);
  --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);

  /* Transitions & Animation */
  --transition-fast: 150ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-base: 250ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-slow: 350ms cubic-bezier(0.4, 0, 0.2, 1);
}

/* Dark Mode Variables - Refined */
:root[data-theme="dark"] {
  --color-bg: #0f172a;
  --color-bg-secondary: #1a2847;
  --color-text-primary: #f8fafc;
  --color-text-secondary: #cbd5e1;
  --color-text-tertiary: #94a3b8;
  --color-border: #334155;
  --color-border-dark: #475569;
  
  /* Shadows - Optimized for dark mode (reduced intensity) */
  --shadow-xs: 0 1px 2px 0 rgba(0, 0, 0, 0.3);
  --shadow-sm: 0 1px 3px 0 rgba(0, 0, 0, 0.35), 0 1px 2px 0 rgba(0, 0, 0, 0.25);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.35), 0 2px 4px -1px rgba(0, 0, 0, 0.2);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.35), 0 4px 6px -2px rgba(0, 0, 0, 0.15);
  --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.35), 0 10px 10px -5px rgba(0, 0, 0, 0.1);
  
  /* Ensure form controls render properly in dark mode */
  color-scheme: dark;
}

/* ===========================
   ANIMATIONS
   =========================== */

@keyframes fadeInUp {
  from {
    opacity: 0;
    transform: translateY(12px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes fadeIn {
  from {
    opacity: 0;
  }
  to {
    opacity: 1;
  }
}

@keyframes slideInDown {
  from {
    opacity: 0;
    transform: translateY(-12px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes pulse {
  0%, 100% {
    opacity: 1;
  }
  50% {
    opacity: 0.7;
  }
}

@keyframes glow {
  0%, 100% {
    box-shadow: 0 0 0 0 rgba(59, 130, 246, 0.3);
  }
  50% {
    box-shadow: 0 0 0 8px rgba(59, 130, 246, 0);
  }
}

@keyframes hardwareAccel {
  from {
    transform: translateZ(0);
  }
  to {
    transform: translateZ(0);
  }
}

@keyframes scaleIn {
  from {
    opacity: 0;
    transform: scale(0.95);
  }
  to {
    opacity: 1;
    transform: scale(1);
  }
}

@keyframes rotateIcon {
  from {
    transform: rotate(0deg) scale(1);
  }
  to {
    transform: rotate(180deg) scale(1);
  }
}

@keyframes slideDown {
  from {
    max-height: 0;
    opacity: 0;
    transform: translateY(-10px);
  }
  to {
    max-height: 500px;
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes countUp {
  from {
    opacity: 0.6;
  }
  to {
    opacity: 1;
  }
}

@keyframes shimmer {
  0% {
    background-position: -1000px 0;
  }
  100% {
    background-position: 1000px 0;
  }
}

/* ===========================
   GLOBAL STYLES
   =========================== */

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

html {
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-secondary);
  font-size: clamp(14px, 2vw, 16px);
  line-height: 1.6;
  color: var(--color-text-primary);
  background-color: var(--color-bg);
  transition: background-color var(--transition-slow), color var(--transition-slow);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  overflow-x: hidden;
}

/* Theme transition mode - smooth color changes */
html.theme-transition,
html.theme-transition *,
html.theme-transition *::before,
html.theme-transition *::after {
  transition: background-color var(--transition-slow), 
              border-color var(--transition-slow), 
              color var(--transition-slow),
              box-shadow var(--transition-slow) !important;
}

/* ===========================
   TYPOGRAPHY
   =========================== */

h1,
h2,
h3,
h4,
h5,
h6 {
  font-family: var(--font-primary);
  font-weight: var(--font-weight-bold);
  line-height: 1.25;
  margin-bottom: var(--spacing-md);
  letter-spacing: -0.02em;
}

h1 {
  font-size: clamp(28px, 6vw, 44px);
}

h2 {
  font-size: clamp(24px, 5vw, 36px);
}

h3 {
  font-size: clamp(20px, 4vw, 28px);
}

p {
  margin-bottom: var(--spacing-md);
  color: var(--color-text-secondary);
}

/* ===========================
   LAYOUT CONTAINERS
   =========================== */

.container {
  width: 100%;
  max-width: clamp(320px, 95vw, 1320px);
  margin: 0 auto;
  padding: 0 clamp(0.75rem, 3vw, 1.5rem);
}

/* ===========================
   HEADER STYLES
   =========================== */

.header {
  background-color: var(--color-bg-secondary);
  border-bottom: 1px solid var(--color-border);
  padding: clamp(1rem, 3vw, 1.5rem) 0;
  box-shadow: var(--shadow-xs);
  transition: all var(--transition-slow);
  animation: slideInDown var(--transition-slow);
  will-change: transform;
}

.header .container {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: var(--spacing-lg);
}

.header-content {
  flex: 1;
  min-width: 0;
}

.header-title {
  background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-accent) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  font-size: clamp(26px, 5vw, 42px);
  margin-bottom: clamp(0.25rem, 1vw, 0.5rem);
  animation: fadeInUp calc(var(--transition-slow) * 0.6);
  animation-fill-mode: both;
}

.header-subtitle {
  font-size: clamp(12px, 2vw, 15px);
  color: var(--color-text-secondary);
  margin-bottom: 0;
  animation: fadeInUp calc(var(--transition-slow) * 0.7);
  animation-fill-mode: both;
  animation-delay: 50ms;
}

.main {
  padding: var(--spacing-4xl) 0;
  min-height: calc(100vh - 200px);
  animation: fadeIn var(--transition-slow);
  animation-fill-mode: both;
  animation-delay: 100ms;
}

.footer {
  background-color: var(--color-bg-secondary);
  border-top: 1px solid var(--color-border);
  padding: var(--spacing-xl) 0;
  text-align: center;
  margin-top: var(--spacing-4xl);
  transition: all var(--transition-slow);
}

.footer-text {
  font-size: clamp(11px, 1.5vw, 13px);
  color: var(--color-text-tertiary);
  margin-bottom: 0;
}

/* ===========================
   CARDS & SECTIONS
   =========================== */

.card {
  background-color: var(--color-bg-secondary);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: clamp(1rem, 4vw, 1.75rem);
  box-shadow: var(--shadow-sm);
  transition: all var(--transition-base);
  animation: fadeInUp var(--transition-base);
  animation-fill-mode: both;
  will-change: transform, box-shadow;
}

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

@media (hover: none) {
  .card:hover {
    transform: none;
  }
}

.card-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: var(--spacing-lg);
  flex-wrap: wrap;
  gap: var(--spacing-md);
}

.card-header h2 {
  margin-bottom: 0;
  flex: 1;
  min-width: 150px;
}

.section-title {
  font-size: clamp(22px, 4vw, 32px);
  margin-bottom: var(--spacing-2xl);
  color: var(--color-text-primary);
  animation: fadeInUp var(--transition-base);
  animation-fill-mode: both;
  animation-delay: 100ms;
}

.input-section {
  margin-bottom: var(--spacing-4xl);
  animation: fadeInUp var(--transition-base);
  animation-fill-mode: both;
}

.input-card {
  animation-delay: 150ms;
}

.stats-section,
.frequency-section,
.metrics-section {
  margin-bottom: var(--spacing-4xl);
}

.stats-section {
  animation: fadeInUp var(--transition-base);
  animation-fill-mode: both;
  animation-delay: 200ms;
}

.frequency-section .card {
  animation: fadeInUp var(--transition-base);
  animation-fill-mode: both;
  animation-delay: 300ms;
}

.metrics-section .card {
  animation: fadeInUp var(--transition-base);
  animation-fill-mode: both;
  animation-delay: 400ms;
}

/* ===========================
   TEXTAREA
   =========================== */

.textarea {
  width: 100%;
  min-height: clamp(240px, 50vh, 400px);
  padding: clamp(0.75rem, 3vw, 1rem);
  font-family: var(--font-secondary);
  font-size: clamp(14px, 2vw, 16px);
  line-height: 1.75;
  border: 2px solid var(--color-border);
  border-radius: var(--radius-md);
  background-color: var(--color-bg);
  color: var(--color-text-primary);
  resize: vertical;
  transition: all var(--transition-base);
  will-change: border-color, box-shadow;
}

.textarea:focus {
  outline: none;
  border-color: var(--color-primary);
  box-shadow: 0 0 0 4px var(--color-primary-light);
  animation: glow 2s infinite;
}

.textarea::placeholder {
  color: var(--color-text-tertiary);
  transition: color var(--transition-base);
}

.textarea:focus::placeholder {
  color: var(--color-text-tertiary);
  opacity: 0.6;
}

.char-count {
  margin-top: var(--spacing-md);
  font-size: clamp(12px, 1.5vw, 14px);
  color: var(--color-text-secondary);
  text-align: right;
  transition: color var(--transition-base);
}

/* ===========================
   STATISTICS GRID
   =========================== */

.stats-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(clamp(120px, 25vw, 200px), 1fr));
  gap: clamp(0.75rem, 2vw, 1.25rem);
  animation: fadeIn var(--transition-slow);
  animation-fill-mode: both;
  animation-delay: 250ms;
}

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

@media (min-width: 768px) {
  .stats-grid {
    grid-template-columns: repeat(4, 1fr);
  }
}

@media (max-width: 1024px) {
  .stats-grid {
    grid-template-columns: repeat(3, 1fr);
  }
}

@media (min-width: 1440px) {
  .stats-grid {
    grid-template-columns: repeat(5, 1fr);
  }
}

.stat-card {
  background: var(--color-bg-secondary);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: clamp(1rem, 3vw, 1.5rem);
  text-align: center;
  transition: all var(--transition-base);
  box-shadow: var(--shadow-xs);
  position: relative;
  overflow: hidden;
  will-change: transform, box-shadow;
  animation: fadeInUp var(--transition-base);
  animation-fill-mode: both;
}

.stat-card::before {
  content: '';
  position: absolute;
  inset: 0;
  background: linear-gradient(135deg, var(--color-primary-light) 0%, transparent 100%);
  opacity: 0;
  transition: opacity var(--transition-base);
  z-index: -1;
}

.stat-card:hover::before {
  opacity: 0.05;
}

.stat-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-md);
  border-color: var(--color-primary-light);
}

@media (hover: none) {
  .stat-card:hover {
    transform: none;
  }
}

.stat-icon {
  font-size: clamp(24px, 5vw, 32px);
  margin-bottom: var(--spacing-sm);
  display: block;
  animation: fadeIn var(--transition-base);
  animation-fill-mode: both;
}

.stat-value {
  font-family: var(--font-primary);
  font-size: clamp(26px, 6vw, 40px);
  font-weight: var(--font-weight-bold);
  color: var(--color-primary);
  margin-bottom: var(--spacing-sm);
  display: block;
  animation: countUp var(--transition-fast);
  animation-fill-mode: both;
  letter-spacing: -0.01em;
}

.stat-label {
  font-size: clamp(11px, 1.5vw, 13px);
  color: var(--color-text-secondary);
  font-weight: var(--font-weight-medium);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  animation: fadeIn var(--transition-base);
  animation-fill-mode: both;
  animation-delay: 50ms;
}

/* Stagger animations for stat cards */
.stat-card:nth-child(1) { animation-delay: 290ms; }
.stat-card:nth-child(2) { animation-delay: 330ms; }
.stat-card:nth-child(3) { animation-delay: 370ms; }
.stat-card:nth-child(4) { animation-delay: 410ms; }
.stat-card:nth-child(5) { animation-delay: 450ms; }
.stat-card:nth-child(6) { animation-delay: 490ms; }
.stat-card:nth-child(7) { animation-delay: 530ms; }
.stat-card:nth-child(8) { animation-delay: 570ms; }
.stat-card:nth-child(9) { animation-delay: 610ms; }
.stat-card:nth-child(10) { animation-delay: 650ms; }

/* ===========================
   FREQUENCY ANALYSIS
   =========================== */

.frequency-container {
  display: grid;
  gap: var(--spacing-lg);
}

.frequency-top-10 h3,
.frequency-full h3 {
  font-size: clamp(18px, 3vw, 22px);
  margin-bottom: var(--spacing-lg);
  color: var(--color-text-primary);
  animation: fadeInUp var(--transition-base);
  animation-fill-mode: both;
}

.frequency-list,
.frequency-list-full {
  display: grid;
  gap: var(--spacing-md);
  animation: fadeIn var(--transition-base);
  animation-fill-mode: both;
  animation-delay: 50ms;
}

.frequency-item {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: clamp(0.75rem, 2vw, 1rem);
  background-color: var(--color-bg);
  border-radius: var(--radius-sm);
  border-left: 4px solid var(--color-primary);
  transition: all var(--transition-base);
  animation: slideInDown var(--transition-base);
  animation-fill-mode: both;
  will-change: transform, background-color;
}

.frequency-item:hover {
  background-color: var(--color-primary-light);
  transform: translateX(4px);
}

@media (hover: none) {
  .frequency-item:hover {
    transform: none;
  }
}

.frequency-item-word {
  font-family: var(--font-primary);
  font-weight: var(--font-weight-semibold);
  color: var(--color-primary);
  flex: 1;
  font-size: clamp(14px, 2vw, 16px);
  word-break: break-word;
}

.frequency-item-stats {
  display: flex;
  gap: clamp(0.75rem, 2vw, 1.25rem);
  align-items: center;
  font-size: clamp(12px, 1.5vw, 14px);
  flex-shrink: 0;
}

.frequency-item-count {
  background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-accent) 100%);
  color: white;
  padding: clamp(4px, 1vw, 6px) clamp(6px, 1.5vw, 8px);
  border-radius: 4px;
  font-weight: var(--font-weight-bold);
  min-width: 40px;
  text-align: center;
  transition: transform var(--transition-fast);
}

.frequency-item:hover .frequency-item-count {
  transform: scale(1.05);
}

.frequency-item-percentage {
  color: var(--color-text-secondary);
  min-width: 50px;
  text-align: right;
  font-size: clamp(12px, 1.5vw, 13px);
  font-weight: var(--font-weight-medium);
}

.empty-state {
  text-align: center;
  padding: var(--spacing-xl);
  color: var(--color-text-tertiary);
  font-style: italic;
  animation: fadeIn var(--transition-base);
  animation-fill-mode: both;
}

/* ===========================
   ADVANCED METRICS
   =========================== */

.metrics-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(clamp(200px, 30vw, 280px), 1fr));
  gap: var(--spacing-lg);
  margin-bottom: var(--spacing-xl);
}

.metric-item {
  background-color: var(--color-bg);
  padding: clamp(0.75rem, 2vw, 1rem);
  border-radius: var(--radius-sm);
  border: 1px solid var(--color-border);
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: var(--spacing-md);
  transition: all var(--transition-base);
  animation: fadeInUp var(--transition-base);
  animation-fill-mode: both;
  will-change: background-color, border-color;
}

.metric-item:hover {
  border-color: var(--color-primary-light);
  background-color: var(--color-primary-light);
}

@media (hover: none) {
  .metric-item:hover {
    background-color: var(--color-bg);
  }
}

.metric-label {
  font-weight: var(--font-weight-semibold);
  color: var(--color-text-secondary);
  font-size: clamp(12px, 1.5vw, 14px);
}

.metric-value {
  font-family: var(--font-primary);
  font-size: clamp(18px, 3vw, 24px);
  font-weight: var(--font-weight-bold);
  color: var(--color-secondary);
  letter-spacing: -0.01em;
}

.keyword-density {
  background-color: var(--color-bg);
  padding: clamp(0.75rem, 3vw, 1.25rem);
  border-radius: var(--radius-sm);
  margin-bottom: var(--spacing-lg);
  border: 1px solid var(--color-border);
  transition: all var(--transition-base);
}

.keyword-density h3 {
  font-size: clamp(16px, 2.5vw, 20px);
  margin-bottom: var(--spacing-md);
}

.keyword-density-list {
  display: grid;
  gap: clamp(0.5rem, 1vw, 0.75rem);
}

.keyword-item {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: clamp(0.5rem, 1.5vw, 0.75rem) clamp(0.75rem, 2vw, 1rem);
  background-color: var(--color-bg-secondary);
  border-radius: 4px;
  border-left: 3px solid var(--color-secondary);
  transition: all var(--transition-fast);
  animation: fadeInUp var(--transition-base);
  animation-fill-mode: both;
  will-change: transform;
}

.keyword-item:hover {
  transform: translateX(4px);
  border-left-color: var(--color-accent);
}

@media (hover: none) {
  .keyword-item:hover {
    transform: none;
  }
}

.keyword-name {
  font-weight: var(--font-weight-semibold);
  color: var(--color-text-primary);
  font-size: clamp(13px, 1.5vw, 15px);
}

.keyword-percentage {
  font-size: clamp(12px, 1.5vw, 13px);
  color: var(--color-text-secondary);
  font-weight: var(--font-weight-medium);
}

/* ===========================
   BUTTONS
   =========================== */

.btn {
  padding: clamp(0.5rem, 1.5vw, 0.75rem) clamp(1rem, 2vw, 1.25rem);
  border: none;
  border-radius: var(--radius-sm);
  font-family: var(--font-secondary);
  font-size: clamp(13px, 1.5vw, 15px);
  font-weight: var(--font-weight-semibold);
  cursor: pointer;
  transition: all var(--transition-base);
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--spacing-sm);
  white-space: nowrap;
  user-select: none;
  will-change: transform, box-shadow, background-color;
  position: relative;
  overflow: hidden;
}

.btn::before {
  content: '';
  position: absolute;
  inset: 0;
  background: rgba(255, 255, 255, 0);
  transition: background var(--transition-fast);
  z-index: 0;
}

.btn:active::before {
  background: rgba(255, 255, 255, 0.2);
}

.btn-primary {
  background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-accent) 100%);
  color: white;
  box-shadow: var(--shadow-sm);
}

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

.btn-primary:active {
  transform: translateY(0);
}

.btn-secondary {
  background-color: var(--color-bg);
  color: var(--color-text-primary);
  border: 1px solid var(--color-border);
}

.btn-secondary:hover {
  background-color: var(--color-border);
  border-color: var(--color-border-dark);
  transform: translateY(-1px);
}

.btn-secondary:active {
  transform: translateY(0);
}

.btn-sm {
  padding: clamp(0.375rem, 1vw, 0.5rem) clamp(0.75rem, 1.5vw, 0.875rem);
  font-size: clamp(12px, 1.5vw, 13px);
}

.action-buttons {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(160px, 1fr));
  gap: clamp(0.75rem, 2vw, 1rem);
  margin-top: var(--spacing-lg);
  animation: fadeInUp var(--transition-base);
  animation-fill-mode: both;
  animation-delay: 100ms;
}

/* ===========================
   TOGGLES & CHECKBOXES
   =========================== */

.toggle-label {
  display: inline-flex;
  align-items: center;
  gap: var(--spacing-sm);
  cursor: pointer;
  font-size: clamp(13px, 1.5vw, 14px);
  font-weight: var(--font-weight-medium);
  color: var(--color-text-primary);
  user-select: none;
  transition: all var(--transition-base);
  padding: var(--spacing-sm);
  border-radius: var(--radius-sm);
}

.toggle-label:hover {
  color: var(--color-primary);
  background-color: var(--color-primary-light);
}

@media (hover: none) {
  .toggle-label:hover {
    background-color: transparent;
  }
}

.toggle-label input[type="checkbox"] {
  width: 18px;
  height: 18px;
  cursor: pointer;
  accent-color: var(--color-primary);
  transition: all var(--transition-fast);
}

.toggle-label input[type="checkbox"]:checked {
  transform: scale(1.05);
}

.theme-toggle {
  background: none;
  border: none;
  font-size: clamp(20px, 4vw, 28px);
  cursor: pointer;
  transition: all var(--transition-base);
  padding: clamp(0.5rem, 1.5vw, 0.75rem);
  border-radius: var(--radius-sm);
  will-change: transform;
  animation: fadeIn var(--transition-base);
}

.theme-toggle:hover {
  transform: scale(1.1) rotate(15deg);
}

@media (hover: none) {
  .theme-toggle:hover {
    transform: none;
  }
}

.theme-toggle:active {
  transform: scale(0.95);
}

/* ===========================
   ABOUT SECTION
   =========================== */

.about-section {
  margin-bottom: var(--spacing-4xl);
  animation: fadeInUp var(--transition-base);
  animation-fill-mode: both;
  animation-delay: 500ms;
}

.about-content {
  max-width: 800px;
  margin: 0 auto;
}

.about-content h2 {
  font-size: clamp(28px, 5vw, 42px);
  margin-bottom: var(--spacing-3xl);
  color: var(--color-text-primary);
  animation: fadeInUp var(--transition-base);
  animation-fill-mode: both;
  animation-delay: 520ms;
}

.about-paragraph {
  margin-bottom: var(--spacing-xl);
  animation: fadeInUp var(--transition-base);
  animation-fill-mode: both;
}

.about-paragraph:nth-child(2) {
  animation-delay: 540ms;
}

.about-paragraph:nth-child(3) {
  animation-delay: 560ms;
}

.about-paragraph:nth-child(4) {
  animation-delay: 580ms;
}

.about-paragraph:nth-child(5) {
  animation-delay: 600ms;
}

.about-paragraph:nth-child(6) {
  animation-delay: 620ms;
}

.about-paragraph p {
  font-size: clamp(15px, 2vw, 16px);
  line-height: 1.8;
  color: var(--color-text-secondary);
  margin-bottom: 0;
}

.about-paragraph p strong {
  color: var(--color-text-primary);
  font-weight: var(--font-weight-semibold);
}

.about-disclaimer {
  background-color: var(--color-bg);
  border-left: 4px solid var(--color-primary);
  padding: var(--spacing-lg);
  border-radius: var(--radius-sm);
  margin-top: var(--spacing-2xl);
  animation: fadeInUp var(--transition-base);
  animation-fill-mode: both;
  animation-delay: 640ms;
}

.about-disclaimer p {
  font-size: clamp(13px, 1.5vw, 14px);
  color: var(--color-text-tertiary);
  margin-bottom: 0;
  line-height: 1.7;
}

/* Scroll animation support */
.about-paragraph {
  opacity: 0;
  transform: translateY(20px);
}

.about-paragraph.in-view {
  animation: fadeInUp var(--transition-base) forwards;
}

.about-disclaimer {
  opacity: 0;
  transform: translateY(20px);
}

.about-disclaimer.in-view {
  animation: fadeInUp var(--transition-base) forwards;
  animation-delay: 100ms;
}

/* ===========================
   RESPONSIVE DESIGN SYSTEM
   =========================== */

/* 320px - Small Phones */
@media (max-width: 320px) {
  :root {
    font-size: 14px;
  }

  .stats-grid {
    grid-template-columns: 1fr;
  }

  .container {
    padding: 0 0.5rem;
  }
}

/* 320px - 480px - Large Phones */
@media (max-width: 480px) {
  .header .container {
    flex-direction: column;
    align-items: flex-start;
  }

  .theme-toggle {
    align-self: flex-start;
  }

  .textarea {
    min-height: clamp(200px, 40vh, 300px);
  }

  .stats-grid {
    grid-template-columns: repeat(2, 1fr);
    gap: 0.75rem;
  }

  .metrics-grid {
    grid-template-columns: 1fr;
  }

  .frequency-item-stats {
    flex-direction: column;
    align-items: flex-end;
    gap: 0.5rem;
  }

  .action-buttons {
    grid-template-columns: 1fr;
  }

  .card {
    padding: 1rem;
  }

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

/* 481px - 768px - Tablets */
@media (min-width: 481px) and (max-width: 768px) {
  .stats-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .metrics-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .action-buttons {
    grid-template-columns: repeat(2, 1fr);
  }
}

/* 769px - 1024px - Small Laptops */
@media (min-width: 769px) and (max-width: 1024px) {
  .stats-grid {
    grid-template-columns: repeat(3, 1fr);
  }

  .metrics-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

/* 1025px - 1440px - Desktops */
@media (min-width: 1025px) and (max-width: 1440px) {
  .stats-grid {
    grid-template-columns: repeat(4, 1fr);
  }

  .metrics-grid {
    grid-template-columns: repeat(3, 1fr);
  }

  .action-buttons {
    grid-template-columns: repeat(2, 1fr);
  }
}

/* 1441px+ - Large Monitors */
@media (min-width: 1441px) {
  .stats-grid {
    grid-template-columns: repeat(5, 1fr);
  }

  .metrics-grid {
    grid-template-columns: repeat(4, 1fr);
  }

  .action-buttons {
    grid-template-columns: repeat(2, 1fr);
  }

  .container {
    max-width: 1360px;
  }
}

/* ===========================
   ACCESSIBILITY
   =========================== */

button:focus-visible,
input:focus-visible,
textarea:focus-visible,
a:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: 2px;
}

/* Reduced Motion Support */
@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }

  .card,
  .stat-card,
  .frequency-item,
  .keyword-item {
    animation: none;
  }

  .header {
    animation: none;
  }
}

/* High Contrast Support */
@media (prefers-contrast: more) {
  :root {
    --color-border: #000000;
    --color-border-dark: #000000;
  }

  .stat-card {
    border-width: 2px;
  }

  .card {
    border-width: 2px;
  }
}

/* Dark Mode Support */
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    color-scheme: dark;
  }
}

/* Touch Device Optimizations */
@media (hover: none) and (pointer: coarse) {
  .btn {
    padding: clamp(0.625rem, 2vw, 0.875rem) clamp(1.125rem, 2.5vw, 1.5rem);
  }

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

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

/* Print Styles */
@media print {
  .header,
  .footer,
  .theme-toggle,
  .btn {
    display: none;
  }

  body {
    background-color: white;
    color: black;
  }

  .card {
    page-break-inside: avoid;
  }
}