/* ============================================
   HEIC Viewer — Main Stylesheet
   Professional, clean, conversion-optimized design
   ============================================ */

/* --- CSS Variables --- */
:root {
  --color-primary: #2563EB;
  --color-primary-hover: #1D4ED8;
  --color-primary-light: #DBEAFE;
  --color-primary-bg: #EFF6FF;
  --color-success: #059669;
  --color-success-bg: #ECFDF5;
  --color-warning: #D97706;
  --color-warning-bg: #FFFBEB;
  --color-error: #DC2626;
  --color-error-bg: #FEF2F2;

  --color-bg: #FFFFFF;
  --color-bg-secondary: #F8FAFC;
  --color-bg-tertiary: #F1F5F9;
  --color-surface: #FFFFFF;
  --color-border: #E2E8F0;
  --color-border-hover: #CBD5E1;

  --color-text: #0F172A;
  --color-text-secondary: #475569;
  --color-text-tertiary: #94A3B8;
  --color-text-inverse: #FFFFFF;

  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.07), 0 2px 4px -2px rgba(0, 0, 0, 0.05);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.08), 0 4px 6px -4px rgba(0, 0, 0, 0.04);
  --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 8px 10px -6px rgba(0, 0, 0, 0.04);

  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 16px;
  --radius-xl: 20px;
  --radius-2xl: 24px;

  --font-sans: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
  --font-mono: 'SF Mono', 'Fira Code', 'Fira Mono', 'Roboto Mono', monospace;

  --transition: 200ms cubic-bezier(0.4, 0, 0.2, 1);
}

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

html {
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
}

body {
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.6;
  color: var(--color-text);
  background: var(--color-bg);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

img {
  max-width: 100%;
  height: auto;
  display: block;
}

a {
  color: var(--color-primary);
  text-decoration: none;
}

a:hover {
  text-decoration: underline;
}

.container {
  width: 100%;
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 24px;
}

/* --- Header --- */
.header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(255, 255, 255, 0.85);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border-bottom: 1px solid var(--color-border);
}

.header .container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 64px;
}

.logo {
  display: flex;
  align-items: center;
  gap: 10px;
  text-decoration: none;
}

.logo:hover {
  text-decoration: none;
}

.logo-icon {
  flex-shrink: 0;
}

.logo-text {
  font-size: 20px;
  font-weight: 700;
  color: var(--color-text);
  letter-spacing: -0.02em;
}

.logo-highlight {
  color: var(--color-primary);
  font-weight: 600;
}

.nav {
  display: flex;
  align-items: center;
  gap: 4px;
}

.nav-link {
  padding: 8px 14px;
  font-size: 14px;
  font-weight: 500;
  color: var(--color-text-secondary);
  border-radius: var(--radius-sm);
  transition: all var(--transition);
}

.nav-link:hover {
  color: var(--color-text);
  background: var(--color-bg-tertiary);
  text-decoration: none;
}

/* --- Hero Section --- */
.hero {
  padding: 80px 0 60px;
  text-align: center;
}

.hero-content {
  max-width: 720px;
  margin: 0 auto;
}

.hero-title {
  font-size: clamp(32px, 5vw, 48px);
  font-weight: 800;
  line-height: 1.15;
  letter-spacing: -0.03em;
  color: var(--color-text);
  margin-bottom: 16px;
}

.gradient-text {
  background: linear-gradient(135deg, #2563EB 0%, #7C3AED 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero-subtitle {
  font-size: 18px;
  color: var(--color-text-secondary);
  line-height: 1.7;
  margin-bottom: 40px;
}

.hero-subtitle strong {
  color: var(--color-text);
}

/* --- Upload Zone --- */
.upload-wrapper {
  max-width: 680px;
  margin: 0 auto;
}

.upload-zone {
  position: relative;
  padding: 48px 24px;
  border: 2px dashed var(--color-border);
  border-radius: var(--radius-xl);
  background: var(--color-bg-secondary);
  cursor: pointer;
  transition: all 300ms cubic-bezier(0.4, 0, 0.2, 1);
}

.upload-zone:hover {
  border-color: var(--color-primary);
  background: var(--color-primary-bg);
  transform: translateY(-1px);
  box-shadow: var(--shadow-md);
}

.upload-zone.drag-over {
  border-color: var(--color-primary);
  background: var(--color-primary-bg);
  transform: scale(1.01);
  box-shadow: var(--shadow-lg);
}

.upload-zone.has-files {
  border-style: solid;
  border-color: var(--color-primary);
  background: var(--color-bg);
  padding: 16px 24px;
  border-radius: var(--radius-lg) var(--radius-lg) 0 0;
  cursor: default;
}

.upload-zone.has-files:hover {
  transform: none;
  box-shadow: none;
}

.upload-icon {
  margin-bottom: 16px;
  display: flex;
  justify-content: center;
}

.upload-title {
  font-size: 20px;
  font-weight: 600;
  color: var(--color-text);
  margin-bottom: 8px;
}

.upload-hint {
  font-size: 15px;
  color: var(--color-text-secondary);
  margin-bottom: 12px;
}

.upload-formats {
  display: inline-block;
  padding: 4px 14px;
  font-size: 12px;
  font-weight: 600;
  color: var(--color-primary);
  background: var(--color-primary-light);
  border-radius: 999px;
  letter-spacing: 0.05em;
}

/* --- Progress Bar --- */
.progress-bar {
  margin-top: 24px;
  display: none;
}

.progress-bar.active {
  display: block;
}

.progress-track {
  width: 100%;
  height: 6px;
  background: var(--color-bg-tertiary);
  border-radius: 999px;
  overflow: hidden;
}

.progress-fill {
  height: 100%;
  background: linear-gradient(90deg, #2563EB, #7C3AED);
  border-radius: 999px;
  width: 0%;
  transition: width 300ms ease;
}

.progress-text {
  display: block;
  margin-top: 8px;
  font-size: 13px;
  color: var(--color-text-secondary);
  text-align: center;
}

/* --- Results Area --- */
.results {
  animation: slideUp 400ms cubic-bezier(0.4, 0, 0.2, 1);
}

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

.results-toolbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 12px;
  padding: 16px 20px;
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-top: none;
  border-radius: 0 0 var(--radius-lg) var(--radius-lg);
  scroll-margin-top: 80px;
}

.toolbar-left {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 16px;
  flex-wrap: wrap;
  flex: 1 1 100%;
}

.toolbar-right {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  flex: 1 1 100%;
}

.file-count {
  font-size: 14px;
  font-weight: 600;
  color: var(--color-text);
  white-space: nowrap;
}

/* --- Quality Control --- */
.quality-control {
  display: flex;
  align-items: center;
  gap: 8px;
}

.quality-control label {
  font-size: 13px;
  font-weight: 500;
  color: var(--color-text-secondary);
  white-space: nowrap;
}

.quality-control input[type="range"] {
  width: 100px;
  height: 4px;
  -webkit-appearance: none;
  appearance: none;
  background: var(--color-bg-tertiary);
  border-radius: 999px;
  outline: none;
  cursor: pointer;
}

.quality-control input[type="range"]::-webkit-slider-thumb {
  -webkit-appearance: none;
  width: 16px;
  height: 16px;
  border-radius: 50%;
  background: var(--color-primary);
  cursor: pointer;
  border: 2px solid white;
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.15);
  transition: transform var(--transition);
}

.quality-control input[type="range"]::-webkit-slider-thumb:hover {
  transform: scale(1.15);
}

.quality-value {
  font-size: 13px;
  font-weight: 600;
  color: var(--color-primary);
  min-width: 36px;
}

/* --- Format Toggle --- */
.format-toggle {
  display: flex;
  background: var(--color-bg-tertiary);
  border-radius: var(--radius-sm);
  padding: 3px;
}

.format-btn {
  padding: 6px 14px;
  font-size: 13px;
  font-weight: 600;
  border: none;
  background: none;
  color: var(--color-text-secondary);
  border-radius: 4px;
  cursor: pointer;
  transition: all var(--transition);
  font-family: inherit;
}

.format-btn.active {
  background: var(--color-surface);
  color: var(--color-primary);
  box-shadow: var(--shadow-sm);
}

.format-btn:hover:not(.active) {
  color: var(--color-text);
}

.format-btn[data-format="both"].active {
  background: linear-gradient(135deg, #2563EB, #7C3AED);
  color: white;
  box-shadow: var(--shadow-sm);
}

/* --- Dual Format Download Buttons --- */
.file-card-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  align-items: center;
}

.btn-download-jpg {
  background: var(--color-success) !important;
  color: white !important;
}

.btn-download-jpg:hover {
  background: #047857 !important;
}

.btn-download-png {
  background: var(--color-primary) !important;
  color: white !important;
}

.btn-download-png:hover {
  background: var(--color-primary-hover) !important;
}

/* --- Buttons --- */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 10px 18px;
  font-size: 14px;
  font-weight: 600;
  border: none;
  border-radius: var(--radius-md);
  cursor: pointer;
  transition: all var(--transition);
  font-family: inherit;
  white-space: nowrap;
}

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

.btn-primary:hover {
  background: var(--color-primary-hover);
  box-shadow: var(--shadow-md);
  transform: translateY(-1px);
}

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

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

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

.btn-icon {
  padding: 8px;
  border-radius: var(--radius-sm);
  background: none;
  border: 1px solid transparent;
  cursor: pointer;
  color: var(--color-text-secondary);
  transition: all var(--transition);
}

.btn-icon:hover {
  background: var(--color-bg-tertiary);
  color: var(--color-text);
  border-color: var(--color-border);
}

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

.file-card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  overflow: hidden;
  transition: all var(--transition);
}

.file-card:hover {
  box-shadow: var(--shadow-lg);
  border-color: var(--color-primary-light);
}

.file-card-preview {
  position: relative;
  width: 100%;
  aspect-ratio: 4/3;
  background: var(--color-bg-tertiary);
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: hidden;
  cursor: pointer;
}

.file-card-preview img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  transition: transform 300ms ease;
}

.file-card:hover .file-card-preview img {
  transform: scale(1.03);
}

.file-card-preview .loading-spinner {
  width: 32px;
  height: 32px;
  border: 3px solid var(--color-border);
  border-top-color: var(--color-primary);
  border-radius: 50%;
  animation: spin 600ms linear infinite;
}

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

.file-card-overlay {
  position: absolute;
  inset: 0;
  background: rgba(0, 0, 0, 0);
  display: flex;
  align-items: center;
  justify-content: center;
  transition: background var(--transition);
}

.file-card-preview:hover .file-card-overlay {
  background: rgba(0, 0, 0, 0.3);
}

.file-card-overlay .zoom-icon {
  opacity: 0;
  transform: scale(0.8);
  transition: all var(--transition);
  color: white;
}

.file-card-preview:hover .file-card-overlay .zoom-icon {
  opacity: 1;
  transform: scale(1);
}

.file-card-error {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 8px;
  color: var(--color-error);
  font-size: 13px;
}

.file-card-body {
  padding: 14px 16px;
}

.file-card-name {
  font-size: 14px;
  font-weight: 600;
  color: var(--color-text);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
  margin-bottom: 6px;
}

.file-card-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  font-size: 12px;
  color: var(--color-text-secondary);
  margin-bottom: 12px;
}

.file-card-meta span {
  display: flex;
  align-items: center;
  gap: 4px;
}

.file-card-actions {
  display: flex;
  gap: 8px;
}

.file-card-actions .btn {
  flex: 1;
  justify-content: center;
  padding: 8px 12px;
  font-size: 13px;
}

.file-card-actions .btn-download {
  background: var(--color-primary);
  color: var(--color-text-inverse);
}

.file-card-actions .btn-download:hover {
  background: var(--color-primary-hover);
}

.file-card-actions .btn-preview {
  background: var(--color-bg-tertiary);
  color: var(--color-text-secondary);
}

.file-card-actions .btn-preview:hover {
  background: var(--color-border);
  color: var(--color-text);
}

.file-card-size-saved {
  font-size: 11px;
  color: var(--color-success);
  font-weight: 500;
}

/* --- Empty State --- */
.empty-state {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: 60px 20px;
  color: var(--color-text-tertiary);
}

.empty-state.hidden {
  display: none;
}

.empty-icon {
  margin-bottom: 16px;
  opacity: 0.5;
}

.empty-text {
  font-size: 15px;
}

/* --- Trust Bar --- */
.trust-bar {
  padding: 24px 0;
  background: var(--color-bg-secondary);
  border-top: 1px solid var(--color-border);
  border-bottom: 1px solid var(--color-border);
}

.trust-items {
  display: flex;
  justify-content: center;
  flex-wrap: wrap;
  gap: 32px;
}

.trust-item {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 14px;
  font-weight: 500;
  color: var(--color-text-secondary);
}

/* --- Features Section --- */
.features {
  padding: 100px 0;
}

.section-title {
  font-size: clamp(28px, 4vw, 36px);
  font-weight: 800;
  text-align: center;
  letter-spacing: -0.02em;
  margin-bottom: 12px;
}

.section-subtitle {
  font-size: 17px;
  color: var(--color-text-secondary);
  text-align: center;
  max-width: 500px;
  margin: 0 auto 56px;
}

.features-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
  gap: 24px;
}

.feature-card {
  padding: 32px;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-xl);
  transition: all var(--transition);
}

.feature-card:hover {
  border-color: var(--color-primary-light);
  box-shadow: var(--shadow-lg);
  transform: translateY(-2px);
}

.feature-icon {
  width: 56px;
  height: 56px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--color-primary-bg);
  border-radius: var(--radius-lg);
  margin-bottom: 20px;
}

.feature-card h3 {
  font-size: 18px;
  font-weight: 700;
  margin-bottom: 8px;
}

.feature-card p {
  font-size: 15px;
  color: var(--color-text-secondary);
  line-height: 1.6;
}

/* --- How It Works --- */
.how-it-works {
  padding: 100px 0;
  background: var(--color-bg-secondary);
}

.steps {
  display: flex;
  align-items: flex-start;
  justify-content: center;
  gap: 16px;
  flex-wrap: wrap;
  margin-top: 56px;
}

.step {
  flex: 1;
  min-width: 220px;
  max-width: 300px;
  text-align: center;
  padding: 40px 24px;
  background: var(--color-surface);
  border-radius: var(--radius-xl);
  border: 1px solid var(--color-border);
  transition: all var(--transition);
}

.step:hover {
  box-shadow: var(--shadow-lg);
  transform: translateY(-2px);
}

.step-number {
  width: 48px;
  height: 48px;
  display: flex;
  align-items: center;
  justify-content: center;
  margin: 0 auto 20px;
  background: var(--color-primary);
  color: var(--color-text-inverse);
  font-size: 20px;
  font-weight: 700;
  border-radius: 50%;
}

.step h3 {
  font-size: 17px;
  font-weight: 700;
  margin-bottom: 8px;
}

.step p {
  font-size: 14px;
  color: var(--color-text-secondary);
  line-height: 1.6;
}

.step-arrow {
  display: flex;
  align-items: center;
  padding-top: 64px;
}

/* --- FAQ Section --- */
.faq {
  padding: 100px 0;
}

.faq-list {
  max-width: 760px;
  margin: 56px auto 0;
}

.faq-item {
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  margin-bottom: 12px;
  overflow: hidden;
  transition: all var(--transition);
}

.faq-item[open] {
  border-color: var(--color-primary-light);
  box-shadow: var(--shadow-md);
}

.faq-question {
  padding: 20px 24px;
  font-size: 16px;
  font-weight: 600;
  cursor: pointer;
  list-style: none;
  display: flex;
  align-items: center;
  justify-content: space-between;
  user-select: none;
  transition: color var(--transition);
}

.faq-question::-webkit-details-marker {
  display: none;
}

.faq-question::after {
  content: '';
  width: 20px;
  height: 20px;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='20' height='20' viewBox='0 0 20 20' fill='none'%3E%3Cpath d='M5 7.5L10 12.5L15 7.5' stroke='%2394A3B8' stroke-width='2' stroke-linecap='round' stroke-linejoin='round'/%3E%3C/svg%3E");
  background-size: contain;
  transition: transform var(--transition);
  flex-shrink: 0;
}

.faq-item[open] .faq-question::after {
  transform: rotate(180deg);
}

.faq-item[open] .faq-question {
  color: var(--color-primary);
}

.faq-answer {
  padding: 0 24px 20px;
  font-size: 15px;
  color: var(--color-text-secondary);
  line-height: 1.7;
}

.faq-answer strong {
  color: var(--color-text);
}

/* --- Footer --- */
.footer {
  padding: 60px 0 32px;
  background: var(--color-bg-secondary);
  border-top: 1px solid var(--color-border);
}

.footer-content {
  display: flex;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 40px;
  margin-bottom: 40px;
}

.footer-brand {
  max-width: 280px;
}

.footer-tagline {
  font-size: 14px;
  color: var(--color-text-secondary);
  margin-top: 12px;
  line-height: 1.6;
}

.footer-links {
  display: flex;
  gap: 60px;
  flex-wrap: wrap;
}

.footer-col h4 {
  font-size: 14px;
  font-weight: 700;
  color: var(--color-text);
  margin-bottom: 14px;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.footer-col a {
  display: block;
  font-size: 14px;
  color: var(--color-text-secondary);
  margin-bottom: 10px;
  transition: color var(--transition);
}

.footer-col a:hover {
  color: var(--color-primary);
  text-decoration: none;
}

.footer-bottom {
  padding-top: 24px;
  border-top: 1px solid var(--color-border);
  text-align: center;
  font-size: 13px;
  color: var(--color-text-tertiary);
}

/* --- Toast Notifications --- */
.toast-container {
  position: fixed;
  bottom: 24px;
  right: 24px;
  z-index: 1000;
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.toast {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 14px 20px;
  background: var(--color-surface);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-xl);
  border: 1px solid var(--color-border);
  font-size: 14px;
  font-weight: 500;
  color: var(--color-text);
  animation: toastIn 300ms cubic-bezier(0.4, 0, 0.2, 1);
  min-width: 280px;
  max-width: 400px;
}

.toast.success {
  border-left: 3px solid var(--color-success);
}

.toast.error {
  border-left: 3px solid var(--color-error);
}

.toast.removing {
  animation: toastOut 200ms cubic-bezier(0.4, 0, 0.2, 1) forwards;
}

@keyframes toastIn {
  from {
    opacity: 0;
    transform: translateX(100%) scale(0.95);
  }
  to {
    opacity: 1;
    transform: translateX(0) scale(1);
  }
}

@keyframes toastOut {
  from {
    opacity: 1;
    transform: translateX(0) scale(1);
  }
  to {
    opacity: 0;
    transform: translateX(100%) scale(0.95);
  }
}

/* --- Lightbox / Modal --- */
.modal-overlay {
  position: fixed;
  inset: 0;
  z-index: 1000;
  background: rgba(0, 0, 0, 0.85);
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 24px;
  animation: fadeIn 200ms ease;
  cursor: pointer;
}

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

.modal-content {
  max-width: 90vw;
  max-height: 90vh;
  cursor: default;
  animation: zoomIn 300ms cubic-bezier(0.4, 0, 0.2, 1);
}

@keyframes zoomIn {
  from { transform: scale(0.9); opacity: 0; }
  to { transform: scale(1); opacity: 1; }
}

.modal-content img {
  max-width: 90vw;
  max-height: 85vh;
  object-fit: contain;
  border-radius: var(--radius-md);
}

.modal-close {
  position: absolute;
  top: 20px;
  right: 20px;
  width: 40px;
  height: 40px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: rgba(255, 255, 255, 0.1);
  border: 1px solid rgba(255, 255, 255, 0.2);
  border-radius: 50%;
  color: white;
  font-size: 20px;
  cursor: pointer;
  transition: background var(--transition);
}

.modal-close:hover {
  background: rgba(255, 255, 255, 0.2);
}

/* --- Selection mode for delete --- */
.file-card.selected {
  border-color: var(--color-error);
  box-shadow: 0 0 0 2px rgba(220, 38, 38, 0.2);
}

/* --- File Type Badge --- */
.file-type-badge {
  position: absolute;
  top: 8px;
  left: 8px;
  padding: 3px 8px;
  font-size: 11px;
  font-weight: 700;
  letter-spacing: 0.03em;
  border-radius: 4px;
  z-index: 2;
  pointer-events: none;
  backdrop-filter: blur(4px);
  -webkit-backdrop-filter: blur(4px);
}

.file-type-badge.heic {
  background: rgba(37, 99, 235, 0.85);
  color: white;
}

.file-type-badge.livp {
  background: rgba(124, 58, 237, 0.85);
  color: white;
}

.file-type-badge.heif {
  background: rgba(5, 150, 105, 0.85);
  color: white;
}

/* --- Responsive --- */
@media (max-width: 768px) {
  .header .container {
    height: 56px;
  }

  .nav-link {
    padding: 6px 8px;
    font-size: 13px;
  }

  .hero {
    padding: 48px 0 40px;
  }

  .upload-zone {
    padding: 36px 16px;
  }

  .results-toolbar {
    flex-direction: column;
    align-items: stretch;
  }

  .toolbar-left {
    flex-direction: column;
    align-items: center;
    gap: 12px;
  }

  .toolbar-right {
    justify-content: center;
  }

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

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

  .steps {
    flex-direction: column;
    align-items: center;
  }

  .step {
    max-width: 100%;
  }

  .step-arrow {
    transform: rotate(90deg);
    padding-top: 0;
    padding: 8px 0;
  }

  .trust-items {
    gap: 16px;
  }

  .trust-item {
    font-size: 13px;
  }

  .footer-content {
    flex-direction: column;
    gap: 32px;
  }

  .footer-links {
    gap: 32px;
  }
}

@media (max-width: 480px) {
  .container {
    padding: 0 16px;
  }

  .hero-title {
    font-size: 28px;
  }

  .hero-subtitle {
    font-size: 16px;
  }

  .logo-text {
    font-size: 17px;
  }

  .section-title {
    font-size: 24px;
  }

  .toast-container {
    left: 16px;
    right: 16px;
    bottom: 16px;
  }

  .toast {
    min-width: auto;
    max-width: 100%;
  }
}

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

.visually-hidden {
  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 --- */
:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: 2px;
}

/* ============================================
   Dark Mode
   ============================================ */
[data-theme="dark"] {
  --color-primary: #3B82F6;
  --color-primary-hover: #60A5FA;
  --color-primary-light: #1E3A5F;
  --color-primary-bg: #0F172A;
  --color-success: #10B981;
  --color-success-bg: #064E3B;
  --color-warning: #F59E0B;
  --color-warning-bg: #451A03;
  --color-error: #EF4444;
  --color-error-bg: #450A0A;
  --color-bg: #0F172A;
  --color-bg-secondary: #1E293B;
  --color-bg-tertiary: #334155;
  --color-surface: #1E293B;
  --color-border: #334155;
  --color-border-hover: #475569;
  --color-text: #F1F5F9;
  --color-text-secondary: #94A3B8;
  --color-text-tertiary: #64748B;
  --color-text-inverse: #FFFFFF;
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.2);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.3), 0 2px 4px -2px rgba(0, 0, 0, 0.2);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.4), 0 4px 6px -4px rgba(0, 0, 0, 0.2);
  --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.5), 0 8px 10px -6px rgba(0, 0, 0, 0.3);
}

[data-theme="dark"] .header {
  background: rgba(15, 23, 42, 0.85);
}

[data-theme="dark"] .logo-icon rect {
  fill: var(--color-primary);
}

/* --- Theme Toggle --- */
.theme-toggle {
  width: 36px;
  height: 36px;
  display: flex;
  align-items: center;
  justify-content: center;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  background: none;
  cursor: pointer;
  color: var(--color-text-secondary);
  font-size: 16px;
  transition: all var(--transition);
  flex-shrink: 0;
}

.theme-toggle:hover {
  border-color: var(--color-primary);
  color: var(--color-primary);
  background: var(--color-primary-bg);
}

/* --- Language Switcher --- */
.lang-switcher {
  position: relative;
  flex-shrink: 0;
}

.lang-current {
  display: flex;
  align-items: center;
  gap: 6px;
  padding: 6px 12px;
  font-size: 13px;
  font-weight: 600;
  color: var(--color-text-secondary);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  background: none;
  cursor: pointer;
  font-family: inherit;
  transition: all var(--transition);
}

.lang-current:hover {
  border-color: var(--color-primary);
  color: var(--color-primary);
}

.lang-current svg {
  width: 14px;
  height: 14px;
  transition: transform var(--transition);
}

.lang-dropdown {
  position: absolute;
  top: 100%;
  right: 0;
  margin-top: 6px;
  min-width: 140px;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-lg);
  opacity: 0;
  visibility: hidden;
  transform: translateY(-4px);
  transition: all var(--transition);
  z-index: 200;
  overflow: hidden;
}

.lang-dropdown.open {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}

.lang-option {
  display: flex;
  align-items: center;
  gap: 8px;
  width: 100%;
  padding: 10px 14px;
  font-size: 13px;
  font-weight: 500;
  color: var(--color-text-secondary);
  background: none;
  border: none;
  cursor: pointer;
  font-family: inherit;
  transition: all var(--transition);
  text-align: left;
}

.lang-option:hover {
  background: var(--color-bg-tertiary);
  color: var(--color-text);
}

.lang-option.active {
  color: var(--color-primary);
  background: var(--color-primary-bg);
  font-weight: 600;
}

.lang-flag {
  font-size: 16px;
}

/* --- Back to Top Button --- */
.back-to-top {
  position: fixed;
  bottom: 28px;
  right: 28px;
  z-index: 99;
  width: 44px;
  height: 44px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--color-primary);
  color: white;
  border: none;
  border-radius: 50%;
  cursor: pointer;
  box-shadow: var(--shadow-lg);
  transition: all var(--transition);
  opacity: 0;
  visibility: hidden;
  transform: translateY(8px);
}

.back-to-top.visible {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}

.back-to-top:hover {
  background: var(--color-primary-hover);
  transform: translateY(-2px);
  box-shadow: var(--shadow-xl);
}

.back-to-top:active {
  transform: translateY(0);
}

/* --- Converter CTA Button (in-section) --- */
.converter-cta {
  text-align: center;
  margin-top: 24px;
}

.converter-cta .btn-converter {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 12px 28px;
  font-size: 15px;
  font-weight: 600;
  color: var(--color-text-inverse);
  background: var(--color-primary);
  border: none;
  border-radius: var(--radius-md);
  cursor: pointer;
  font-family: inherit;
  transition: all var(--transition);
  text-decoration: none;
}

.converter-cta .btn-converter:hover {
  background: var(--color-primary-hover);
  box-shadow: var(--shadow-md);
  transform: translateY(-2px);
  text-decoration: none;
  color: var(--color-text-inverse);
}

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

/* --- Contact Email Card --- */
.contact-email-card {
  text-align: center;
  padding: 40px;
  background: var(--color-bg);
  border: 2px solid var(--color-primary-light);
  border-radius: var(--radius-xl);
  margin-top: 24px;
}

.contact-email-card .email-icon {
  width: 64px;
  height: 64px;
  display: flex;
  align-items: center;
  justify-content: center;
  margin: 0 auto 20px;
  background: var(--color-primary-bg);
  border-radius: 50%;
}

.contact-email-card .email-address {
  display: inline-block;
  font-size: 22px;
  font-weight: 700;
  color: var(--color-primary);
  margin-bottom: 8px;
  text-decoration: none;
  transition: color var(--transition);
}

.contact-email-card .email-address:hover {
  color: var(--color-primary-hover);
}

.contact-email-card .email-note {
  font-size: 14px;
  color: var(--color-text-secondary);
  max-width: 400px;
  margin: 0 auto;
}

/* --- Nav controls group (lang + theme) --- */
.nav-controls {
  display: flex;
  align-items: center;
  gap: 8px;
  margin-left: 16px;
}

/* --- Responsive for new elements --- */
@media (max-width: 768px) {
  .back-to-top {
    bottom: 20px;
    right: 20px;
    width: 40px;
    height: 40px;
  }

  .contact-email-card {
    padding: 28px 20px;
  }

  .contact-email-card .email-address {
    font-size: 18px;
  }

  .nav-controls {
    margin-left: 8px;
    gap: 4px;
  }

  .lang-current {
    padding: 4px 8px;
    font-size: 12px;
  }
}

/* --- Print styles --- */
@media print {
  .header, .footer, .toast-container, .upload-zone {
    display: none;
  }
}

/* ============================================
   Page Templates (About, Contact, Blog, Legal)
   ============================================ */

/* --- Page Hero (smaller than main hero) --- */
.page-hero {
  padding: 60px 0 40px;
  text-align: center;
  background: var(--color-bg-secondary);
  border-bottom: 1px solid var(--color-border);
}

.page-hero-title {
  font-size: clamp(28px, 4vw, 42px);
  font-weight: 800;
  letter-spacing: -0.02em;
  color: var(--color-text);
  margin-bottom: 8px;
}

.page-hero-subtitle {
  font-size: 16px;
  color: var(--color-text-secondary);
  max-width: 600px;
  margin: 0 auto;
}

/* --- Page Content --- */
.page-content {
  padding: 60px 0;
}

.page-content-inner {
  max-width: 760px;
  margin: 0 auto;
}

.page-content h2 {
  font-size: 24px;
  font-weight: 700;
  color: var(--color-text);
  margin: 40px 0 16px;
  letter-spacing: -0.01em;
}

.page-content h2:first-child {
  margin-top: 0;
}

.page-content h3 {
  font-size: 18px;
  font-weight: 600;
  color: var(--color-text);
  margin: 28px 0 12px;
}

.page-content p {
  font-size: 15px;
  line-height: 1.8;
  color: var(--color-text-secondary);
  margin-bottom: 16px;
}

.page-content ul, .page-content ol {
  margin: 0 0 16px 20px;
  font-size: 15px;
  line-height: 1.8;
  color: var(--color-text-secondary);
}

.page-content li {
  margin-bottom: 8px;
}

.page-content strong {
  color: var(--color-text);
}

.page-content a {
  color: var(--color-primary);
  text-decoration: underline;
}

.page-content a:hover {
  color: var(--color-primary-hover);
}

.page-content .last-updated {
  font-size: 13px;
  color: var(--color-text-tertiary);
  margin-top: 40px;
  padding-top: 16px;
  border-top: 1px solid var(--color-border);
}

/* --- Breadcrumbs --- */
.breadcrumbs {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 13px;
  color: var(--color-text-tertiary);
  margin-bottom: 8px;
}

.breadcrumbs a {
  color: var(--color-text-secondary);
  text-decoration: none;
}

.breadcrumbs a:hover {
  color: var(--color-primary);
}

.breadcrumbs .sep {
  user-select: none;
}

/* --- Blog Listing --- */
.blog-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(340px, 1fr));
  gap: 24px;
  max-width: 960px;
  margin: 0 auto;
}

.blog-card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: 28px;
  transition: all var(--transition);
  display: flex;
  flex-direction: column;
}

.blog-card:hover {
  box-shadow: var(--shadow-lg);
  border-color: var(--color-primary-light);
  transform: translateY(-2px);
}

.blog-card-date {
  font-size: 12px;
  color: var(--color-text-tertiary);
  margin-bottom: 8px;
}

.blog-card-title {
  font-size: 18px;
  font-weight: 700;
  color: var(--color-text);
  margin-bottom: 10px;
  line-height: 1.4;
}

.blog-card-title a {
  color: inherit;
  text-decoration: none;
}

.blog-card-title a:hover {
  color: var(--color-primary);
}

.blog-card-excerpt {
  font-size: 14px;
  color: var(--color-text-secondary);
  line-height: 1.6;
  flex: 1;
}

.blog-card-more {
  display: inline-block;
  font-size: 13px;
  font-weight: 600;
  color: var(--color-primary);
  margin-top: 14px;
}

.blog-card-more:hover {
  text-decoration: underline;
}

.blog-card-tag {
  display: inline-block;
  padding: 3px 10px;
  font-size: 11px;
  font-weight: 600;
  border-radius: 999px;
  background: var(--color-primary-bg);
  color: var(--color-primary);
  margin-bottom: 12px;
}

/* --- Contact Form --- */
.contact-form {
  margin-top: 24px;
}

.form-group {
  margin-bottom: 20px;
}

.form-group label {
  display: block;
  font-size: 14px;
  font-weight: 600;
  color: var(--color-text);
  margin-bottom: 6px;
}

.form-group input,
.form-group textarea,
.form-group select {
  width: 100%;
  padding: 12px 16px;
  font-size: 15px;
  font-family: var(--font-sans);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  background: var(--color-bg);
  color: var(--color-text);
  transition: border-color var(--transition);
}

.form-group input:focus,
.form-group textarea:focus,
.form-group select:focus {
  outline: none;
  border-color: var(--color-primary);
  box-shadow: 0 0 0 3px var(--color-primary-light);
}

.form-group textarea {
  resize: vertical;
  min-height: 120px;
}

/* --- Responsive --- */
@media (max-width: 768px) {
  .page-hero {
    padding: 40px 0 32px;
  }

  .page-content {
    padding: 40px 0;
  }

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

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

.visually-hidden {
  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 --- */
:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: 2px;
}

/* Social Share Buttons */
.social-share {
  display: flex;
  gap: 12px;
  margin: 32px 0;
  padding: 20px 0;
  border-top: 1px solid var(--color-border);
  border-bottom: 1px solid var(--color-border);
  align-items: center;
  justify-content: center;
}
.social-share-label {
  font-size: 14px;
  font-weight: 600;
  color: var(--color-text-secondary);
  margin-right: 8px;
}
.social-share-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
  border-radius: 10px;
  background: var(--color-bg-secondary);
  color: var(--color-text-secondary);
  text-decoration: none;
  transition: all 0.2s;
  border: 1px solid var(--color-border);
}
.social-share-btn:hover {
  transform: translateY(-2px);
  box-shadow: 0 4px 12px rgba(0,0,0,0.1);
}
.social-share-btn.twitter:hover { background: #1DA1F2; color: white; border-color: #1DA1F2; }
.social-share-btn.facebook:hover { background: #1877F2; color: white; border-color: #1877F2; }
.social-share-btn.linkedin:hover { background: #0A66C2; color: white; border-color: #0A66C2; }
.social-share-btn.wechat:hover { background: #07C160; color: white; border-color: #07C160; }

/* Try Converter Section */
.try-converter-section {
  padding: 60px 0;
  background: var(--color-bg-secondary);
  text-align: center;
}
.try-converter-inner h3 {
  font-size: 24px;
  font-weight: 700;
  margin-bottom: 8px;
  color: var(--color-text);
}
.try-converter-inner p {
  font-size: 16px;
  color: var(--color-text-secondary);
  margin-bottom: 24px;
}

[data-theme="dark"] .social-share-btn {
  background: var(--color-bg-tertiary);
}