.title {
  font-size: var(--font-size-2xl);
  font-weight: 700;
  letter-spacing: -0.5px;
  margin: 0;
  padding: 0;
}

.title a {
  color: var(--color-text-primary);
  text-decoration: none;
  transition: var(--transition-base);
  display: inline-block;
}

.title a:hover {
  transform: translateY(-1px);
  opacity: 0.9;
}

/* Design System - CSS Variables */
:root {
  /* Base Colors */
  --color-white: #ffffff;
  --color-black: #000000;
  --color-gray-100: #f5f5f5;
  --color-gray-200: #e5e5e5;
  --color-gray-300: #d4d4d4;
  --color-gray-400: #a3a3a3;
  --color-gray-500: #737373;
  --color-gray-600: #525252;
  --color-gray-700: #404040;
  --color-gray-800: #262626;
  --color-gray-900: #171717;

  /* Semantic Colors - Light Theme */
  --color-background: var(--color-white);
  --color-surface: var(--color-gray-100);
  --color-card: var(--color-white);
  --color-border: var(--color-gray-300);
  --color-text-primary: var(--color-black);
  --color-text-secondary: var(--color-gray-900);
  --color-text-muted: var(--color-gray-700);
  --color-accent: var(--color-black);
  --color-accent-hover: var(--color-gray-900);
  --color-error: var(--color-black);
  --color-success: var(--color-black);
  --color-focus-ring: rgba(0, 0, 0, 0.3);

  /* Spacing Scale - 4pt Grid */
  --space-1: 0.25rem; /* 4px */
  --space-2: 0.5rem; /* 8px */
  --space-3: 0.75rem; /* 12px */
  --space-4: 1rem; /* 16px */
  --space-5: 1.25rem; /* 20px */
  --space-6: 1.5rem; /* 24px */
  --space-8: 2rem; /* 32px */
  --space-10: 2.5rem; /* 40px */
  --space-12: 3rem; /* 48px */
  --space-16: 4rem; /* 64px */
  --space-20: 5rem; /* 80px */

  /* Typography */
  --font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto,
    "Helvetica Neue", Arial, sans-serif;
  --font-size-xs: 0.75rem; /* 12px */
  --font-size-sm: 0.875rem; /* 14px */
  --font-size-base: 1rem; /* 16px */
  --font-size-lg: 1.125rem; /* 18px */
  --font-size-xl: 1.25rem; /* 20px */
  --font-size-2xl: 1.5rem; /* 24px */
  --font-size-3xl: 1.875rem; /* 30px */

  /* Elevation */
  --elevation-0: 0;
  --elevation-1: 0 1px 3px rgba(0, 0, 0, 0.1), 0 1px 2px rgba(0, 0, 0, 0.06);
  --elevation-2: 0 3px 6px rgba(0, 0, 0, 0.1), 0 3px 6px rgba(0, 0, 0, 0.06);
  --elevation-4: 0 4px 8px rgba(0, 0, 0, 0.1), 0 4px 8px rgba(0, 0, 0, 0.06);

  /* Border Radius */
  --radius-sm: 0.25rem; /* 4px */
  --radius-md: 0.5rem; /* 8px */
  --radius-lg: 0.75rem; /* 12px */
  --radius-xl: 1rem; /* 16px */

  /* Transitions */
  --transition-fast: 150ms ease;
  --transition-base: 300ms ease;
  --transition-slow: 500ms ease;
}

/* Dark Theme */
.dark-theme {
  --color-background: var(--color-gray-900);
  --color-surface: var(--color-gray-800);
  --color-card: var(--color-gray-800);
  --color-border: var(--color-gray-600);
  --color-text-primary: var(--color-white);
  --color-text-secondary: var(--color-gray-100);
  --color-text-muted: var(--color-gray-300);
  --color-accent: var(--color-white);
  --color-accent-hover: var(--color-gray-100);
  --color-error: var(--color-white);
  --color-success: var(--color-white);
  --color-focus-ring: rgba(255, 255, 255, 0.4);
}

/* Reset and Base Styles */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  font-size: 16px;
  scroll-behavior: smooth; /* Changed to smooth for better user experience */
  -webkit-text-size-adjust: 100%;
}

body {
  font-family: var(--font-family);
  background: var(--color-background);
  color: var(--color-text-primary);
  line-height: 1.6;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  font-size: var(--font-size-base);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-rendering: optimizeSpeed;
  overflow-x: hidden;
}

/* Theme transition */
.theme-transition,
.theme-transition *,
.theme-transition *:before,
.theme-transition *:after {
  transition: background-color 0.3s ease, color 0.3s ease,
    border-color 0.3s ease !important;
  /* Specific transitions instead of 'all' to prevent unwanted persistence */
}

/* Screen Reader Only */
.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;
}

/* Focus Styles - WCAG 2.2 AA Compliance */
*:focus-visible {
  outline: 3px solid var(--color-focus-ring);
  outline-offset: 2px;
  border-radius: var(--radius-sm);
}

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

:focus:not(:focus-visible) {
  outline: none;
}

/* Skip to content link for keyboard users */
.skip-link {
  position: absolute;
  top: -40px;
  left: 0;
  background: var(--color-text-primary);
  color: var(--color-background);
  padding: var(--space-3);
  z-index: 100;
  transition: top 0.2s ease;
}

.skip-link:focus {
  top: 0;
}

/* Header */
.header {
  background: var(--color-surface);
  border-bottom: 1px solid var(--color-border);
  padding: var(--space-4) 0;
  position: sticky;
  top: 0;
  z-index: 100;
  backdrop-filter: blur(10px);
  box-shadow: var(--elevation-1);
}

.header-content {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 var(--space-6);
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 60px;
}

.title {
  font-size: var(--font-size-2xl);
  font-weight: 600;
  color: var(--color-text-primary);
  margin: 0;
}

.header-actions {
  display: flex;
  gap: var(--space-3);
}

.theme-toggle {
  background: var(--color-card);
  border: 1px solid var(--color-border);
  padding: var(--space-2);
  margin: 0;
  cursor: pointer;
  transition: var(--transition-base);
  position: relative;
  min-width: 40px;
  min-height: 40px;
  width: 40px;
  height: 40px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--color-accent);
  box-shadow: var(--elevation-1);
}

.theme-toggle:hover {
  transform: translateY(-2px);
  box-shadow: var(--elevation-2);
  background: var(--color-surface);
}

.theme-toggle:active {
  transform: translateY(0);
}

.theme-toggle::before,
.theme-toggle::after {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  border-radius: 50%;
  transition: var(--transition-base);
  opacity: 0;
  z-index: 0;
}

.theme-toggle::before {
  background: var(--color-text-primary);
  transform: scale(0.8);
}

.theme-toggle::after {
  border: 2px solid var(--color-text-primary);
  transform: scale(1.1);
}

.theme-toggle:hover::before {
  opacity: 1;
  transform: scale(1);
}

.theme-toggle:hover::after {
  opacity: 1;
  transform: scale(1);
}

.theme-toggle:hover {
  background: var(--color-text-primary);
  color: var(--color-background);
  border-color: var(--color-text-primary);
  transform: translateY(-2px);
}

.theme-toggle svg {
  width: var(--space-5);
  height: var(--space-5);
  stroke: var(--color-text-primary);
  stroke-width: 1.5;
  fill: none;
  transition: var(--transition-base);
  position: absolute;
  opacity: 0;
  transform: scale(0.5);
  z-index: 1;
}

.theme-toggle .moon-icon {
  opacity: 1;
  transform: scale(1);
}

.theme-toggle .sun-icon {
  opacity: 0;
  transform: scale(0.5);
}

.dark-theme .theme-toggle .moon-icon {
  opacity: 0;
  transform: scale(0.5);
}

.dark-theme .theme-toggle .sun-icon {
  opacity: 1;
  transform: scale(1);
}

.theme-toggle:hover svg {
  stroke: var(--color-background);
}

.dark-theme .theme-toggle:hover svg {
  stroke: var(--color-gray-900); /* Using gray-900 for better contrast */
}

.theme-toggle:hover {
  transform: translateY(-1px);
}

.theme-toggle:focus {
  outline: none;
}

.theme-toggle:focus-visible {
  outline: 2px solid var(--color-text-primary);
  outline-offset: 2px;
  border-radius: var(--radius-sm);
}

/* Main Content */
.main {
  flex: 1;
  padding: var(--space-12) 0;
}

.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 var(--space-6);
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--space-8);
  align-items: start;
}

/* Card Component System */
.card {
  background: var(--color-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-xl);
  padding: var(--space-8);
  box-shadow: var(--elevation-1);
  transition: var(--transition-base);
}

.card--interactive:hover {
  box-shadow: var(--elevation-2);
  transform: translateY(-1px);
}

.card--flat {
  box-shadow: none;
  border-radius: var(--radius-md);
}

/* Cards Implementation */
.input-card,
.qr-card {
  background: var(--color-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-xl);
  padding: var(--space-8);
  box-shadow: var(--elevation-1);
  transition: var(--transition-base);
}

.input-card:hover,
.qr-card:hover {
  box-shadow: var(--elevation-2);
  transform: translateY(-1px);
}

.section-title {
  font-size: var(--font-size-xl);
  font-weight: 600;
  color: var(--color-text-primary);
  margin-bottom: var(--space-6);
  display: flex;
  align-items: center;
  gap: var(--space-2);
}

/* Input Section */
.input-wrapper {
  position: relative;
  margin-bottom: var(--space-4);
}

.content-input {
  width: 100%;
  min-height: 120px;
  height: fit-content;
  max-height: 60vh; 
  padding: var(--space-4);
  padding-right: calc(var(--space-4) + 44px);
  border: 2px solid var(--color-border);
  border-radius: var(--radius-lg);
  background: var(--color-card);
  color: var(--color-text-primary);
  font-family: var(--font-family);
  font-size: var(--font-size-base);
  line-height: 1.5;
  resize: vertical;
  overflow-y: auto;
}

.content-input:focus {
  border-color: var(--color-accent);
  box-shadow: 0 0 0 3px var(--color-focus-ring);
}

.content-input::placeholder {
  color: var(--color-text-muted);
}

.clear-btn {
  position: absolute;
  bottom: var(--space-3);
  right: var(--space-3);
  background: transparent;
  border: none;
  width: 28px;
  height: 28px;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  color: var(--color-text-muted);
  transition: var(--transition-base);
  z-index: 1;
  opacity: 0.5;
}

.clear-btn:hover {
  background: transparent;
  color: var(--color-text-primary);
  opacity: 1;
  transform: scale(1);
}

.clear-btn svg,
.share-btn svg,
.copy-btn svg,
.download-btn svg,
.mobile-download-btn svg {
  width: var(--space-5);
  height: var(--space-5);
  stroke: currentColor;
  stroke-width: 2;
  fill: none;
  opacity: 1;
}

.clear-btn svg {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  transition: var(--transition-base);
}

.clear-btn .paste-icon {
  stroke-width: 1.75;
}

.clear-btn .clear-icon {
  stroke-width: 1.5;
}

.clear-btn:hover svg {
  transform: translate(-50%, -50%) scale(1.1);
}

.input-hint {
  color: var(--color-text-muted);
  font-size: var(--font-size-sm);
  line-height: 1.4;
  margin-bottom: var(--space-3);
}

.input-stats {
  display: flex;
  justify-content: flex-end;
  margin-top: var(--space-2);
}

.char-count {
  color: var(--color-text-muted);
  font-size: var(--font-size-xs);
  font-weight: 500;
}

/* QR Section */
.qr-display {
  margin: var(--space-8) 0;
  display: flex;
  justify-content: center;
  align-items: center;
  aspect-ratio: 1;
  min-height: 320px;
  max-height: 512px;
  width: 100%;
  position: relative;
  transition: height var(--transition-base);
  background: var(--color-surface);
  border-radius: var(--radius-lg);
  overflow: hidden;
}

.qr-placeholder {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--space-4);
  color: var(--color-text-muted);
  padding: var(--space-8);
}

.qr-placeholder svg {
  width: 3rem;
  height: 3rem;
  opacity: 0.5;
}

.qr-placeholder p {
  font-size: var(--font-size-sm);
  text-align: center;
}

.qr-image {
  border-radius: var(--radius-lg);
  background: white;
  box-shadow: var(--elevation-2);
  width: 100%;
  height: 100%;
  object-fit: contain;
  padding: var(--space-4);
  transition: all var(--transition-base);
}

.qr-loading {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--space-4);
  color: var(--color-text-muted);
  padding: var(--space-8);
}

.loading-spinner {
  width: 2rem;
  height: 2rem;
  border: 2px solid var(--color-border);
  border-top: 2px solid var(--color-text-primary);
  border-radius: 50%;
  animation: spin 1s linear infinite;
}

@keyframes spin {
  0% {
    transform: rotate(0deg);
  }
  100% {
    transform: rotate(360deg);
  }
}

.qr-loading p {
  font-size: var(--font-size-sm);
  text-align: center;
}

/* Button System */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-2);
  padding: var(--space-3) var(--space-4);
  border-radius: var(--radius-md);
  font-size: var(--font-size-base);
  font-weight: 500;
  cursor: pointer;
  transition: var(--transition-base);
  min-width: 44px;
  min-height: 44px;
}

.btn--primary {
  background: var(--color-text-primary);
  color: var(--color-background);
  border: none;
}

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

.btn--icon {
  padding: var(--space-3);
  border-radius: var(--radius-md);
}

.btn:hover:not(:disabled) {
  transform: translateY(-1px);
}

.btn--primary:hover:not(:disabled) {
  background: var(--color-text-secondary);
  box-shadow: var(--elevation-2);
}

.btn--secondary:hover:not(:disabled) {
  background: var(--color-text-primary);
  color: var(--color-background);
  border-color: var(--color-text-primary);
}

.btn:disabled {
  opacity: 0.5;
  cursor: not-allowed;
  transform: none;
}

/* QR Actions */
.qr-actions {
  display: flex;
  flex-direction: column;
  gap: var(--space-4);
  align-items: center;
}

.primary-cta {
  composes: btn btn--primary;
  padding: var(--space-4) var(--space-8);
  border-radius: var(--radius-lg);
}

.primary-cta:hover:not(:disabled) {
  background: var(--color-text-secondary);
  transform: translateY(-1px);
  box-shadow: var(--elevation-2);
}

.primary-cta:disabled {
  opacity: 0.5;
  cursor: not-allowed;
  transform: none;
}

.primary-cta svg {
  width: var(--space-4);
  height: var(--space-4);
}

.secondary-actions {
  display: flex;
  gap: var(--space-3);
}

.share-btn,
.copy-btn {
  background: transparent;
  border: 1px solid var(--color-border);
  color: var(--color-text-secondary);
  padding: var(--space-3) var(--space-4);
  border-radius: var(--radius-md);
  cursor: pointer;
  font-size: var(--font-size-sm);
  display: flex;
  align-items: center;
  gap: var(--space-2);
  transition: var(--transition-base);
  min-width: 44px;
  min-height: 44px;
}

.share-btn:hover:not(:disabled),
.copy-btn:hover:not(:disabled) {
  background: var(--color-text-primary);
  color: var(--color-background);
  border-color: var(--color-text-primary);
}

.share-btn:disabled,
.copy-btn:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

.share-btn svg,
.copy-btn svg {
  width: var(--space-4);
  height: var(--space-4);
}

/* Mobile Bottom Bar */
.mobile-bottom-bar {
  display: none;
  position: fixed;
  bottom: 0;
  left: 0;
  right: 0;
  background: var(--color-surface);
  border-top: 1px solid var(--color-border);
  padding: var(--space-4) var(--space-6);
  z-index: 50;
  box-shadow: var(--elevation-4);
}

.mobile-download-btn {
  width: 100%;
  background: var(--color-text-primary);
  color: var(--color-background);
  border: none;
  padding: var(--space-4);
  border-radius: var(--radius-lg);
  cursor: pointer;
  font-weight: 500;
  font-size: var(--font-size-base);
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-2);
  transition: var(--transition-base);
  min-height: 44px;
}

.mobile-download-btn:hover:not(:disabled) {
  background: var(--color-text-secondary);
}

.mobile-download-btn:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

.mobile-download-btn svg {
  width: var(--space-4);
  height: var(--space-4);
}

/* Responsive Design - Mobile First */
/* <576px - Single column, hide helper text, mobile bottom bar */
@media (max-width: 575px) {
  .header-content {
    padding: 0 var(--space-4);
  }

  .title {
    font-size: var(--font-size-xl);
  }

  .main {
    padding: var(--space-8) 0;
    padding-bottom: calc(
      var(--space-8) + 80px
    ); /* Account for mobile bottom bar */
  }

  .container {
    padding: 0 var(--space-4);
    gap: var(--space-6);
  }

  .input-card,
  .qr-card {
    padding: var(--space-6);
  }

  .content-input {
    min-height: 120px;
    max-height: 40vh; /* Smaller viewport height for mobile */
    padding: var(--space-4);
  }

  .qr-display {
    min-height: fit-content;
  }

  .input-hint {
    display: none;
  }

  .secondary-actions {
    display: none;
  }

  .mobile-bottom-bar {
    display: block;
  }
  
  /* Improve touch targets for mobile */
  button, 
  .btn,
  input[type="button"],
  input[type="submit"] {
    min-height: 44px;
    min-width: 44px;
  }
  
  /* Adjust font sizes for better readability on small screens */
  html {
    font-size: 14px;
  }
}

/* 576-767px - Single column, hide helper text */
@media (min-width: 576px) and (max-width: 767px) {
  .header-content {
    padding: 0 var(--space-5);
  }

  .main {
    padding: var(--space-10) 0;
  }

  .container {
    padding: 0 var(--space-5);
    gap: var(--space-6);
  }

  .input-card,
  .qr-card {
    padding: var(--space-6);
  }

  .input-hint {
    display: none;
  }

  .secondary-actions {
    display: none;
  }
}

/* 768-991px - Two columns 50/50, show all elements */
@media (min-width: 768px) and (max-width: 991px) {
  .container {
    grid-template-columns: 1fr 1fr;
    gap: var(--space-8);
  }

  .qr-image {
    max-width: 320px;
    max-height: 320px;
  }

  .content-input {
    max-height: calc(
      320px - var(--space-8) * 2
    ); /* match QR dimensions minus padding */
  }

  .qr-actions {
    flex-direction: row;
    justify-content: center;
  }

  .secondary-actions {
    display: flex;
  }
}

/* 992-1199px - Two columns 40/60 */
@media (min-width: 992px) and (max-width: 1199px) {
  .container {
    grid-template-columns: 2fr 3fr;
    gap: var(--space-10);
  }

  .qr-image {
    max-width: 384px;
    max-height: 384px;
  }

  .content-input {
    max-height: calc(
      384px - var(--space-8) * 2
    ); /* match QR dimensions minus padding */
  }

  .qr-actions {
    flex-direction: row;
    justify-content: center;
  }
}

/* ≥1200px - Two columns 35/65 */
@media (min-width: 1200px) {
  .container {
    grid-template-columns: 7fr 13fr;
    gap: var(--space-12);
  }

  .qr-image {
    max-width: 512px;
    max-height: 512px;
  }

  .content-input {
    max-height: calc(
      512px - var(--space-8) * 2
    ); /* match QR dimensions minus padding */
  }

  .qr-actions {
    flex-direction: row;
    justify-content: center;
  }
}

/* Animation for QR code fade-in */
@keyframes fadeIn {
  from {
    opacity: 0;
    transform: scale(0.95);
  }
  to {
    opacity: 1;
    transform: scale(1);
  }
}

.qr-image.fade-in {
  animation: fadeIn var(--transition-base);
  animation-fill-mode: none; /* Ensures animation state doesn't persist */
}

/* Error handling styles */
.content-input.error {
  border-color: var(--color-error);
  box-shadow: 0 0 0 3px var(--color-focus-ring);
}

/* Success feedback */
.success-feedback {
  color: var(--color-success);
  font-size: var(--font-size-sm);
  margin-top: var(--space-2);
}

/* High contrast mode support */
@media (prefers-contrast: high) {
  :root {
    --color-border: #000000;
    --color-text-muted: #000000;
  }
}

/* Reduced motion support */
@media (prefers-reduced-motion: reduce) {
  * {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
}

/* Print Styles */
@media print {
  body {
    background: white;
    color: black;
  }
  
  .header,
  .input-card,
  .mobile-bottom-bar,
  .qr-actions,
  .theme-toggle {
    display: none !important;
  }
  
  .container {
    display: block;
    padding: 0;
  }
  
  .qr-card {
    width: 100%;
    box-shadow: none;
    border: none;
    margin: 0 auto;
  }
  
  .qr-display {
    display: flex;
    justify-content: center;
    align-items: center;
    height: auto;
  }
  
  .qr-image {
    max-width: 80%;
    height: auto;
  }
  
  /* Add URL after links */
  a[href]:after {
    content: " (" attr(href) ")";
  }
}