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

:root {
  --color-canvas: #FFFFFF;
  --color-ink: #0F0F0F;
  --color-graphite: #606060;
  --color-mist: #E5E5E5;
  --color-smoke: #F5F5F5;
  --color-surface: #F9F9F9;
  --color-sidebar: #FAFAFA;
  --color-red: #FF0000;
  --color-red-hover: #CC0000;
  --color-red-light: #FFF5F5;
  --color-red-gradient: linear-gradient(45deg, #FF0000, #FF00A8);
  --color-success: #16A34A;
  --color-error: #DC2626;
  --sidebar-width: 240px;
  --header-height: 56px;
  --radius-pill: 18px;
  --radius-card: 8px;
  --font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Arial, sans-serif;
}

[data-theme="dark"] {
  --color-canvas: #121212;
  --color-ink: #E8E8E8;
  --color-graphite: #A0A0A0;
  --color-mist: #333;
  --color-smoke: #1E1E1E;
  --color-surface: #252525;
  --color-sidebar: #1A1A1A;
  --color-red: #FF3333;
  --color-red-hover: #FF5555;
  --color-red-light: #2A1515;
  --color-success: #22C55E;
  --color-error: #EF4444;
}

html { font-size: 14px; }

body {
  font-family: var(--font-family);
  color: var(--color-ink);
  background: var(--color-canvas);
  line-height: 1.5;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  transition: background 0.2s, color 0.2s;
}

a { color: var(--color-ink); text-decoration: none; }
a:hover { color: var(--color-red); }

:focus-visible {
  outline: 2px solid var(--color-red);
  outline-offset: 2px;
}

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

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

/* === SKIP TO CONTENT === */
.skip-to-content {
  position: absolute;
  top: -1000px;
  left: 8px;
  z-index: 1000;
  padding: 10px 20px;
  background: var(--color-red);
  color: #fff;
  font-weight: 600;
  border-radius: 0 0 var(--radius-pill) var(--radius-pill);
  font-size: 0.9rem;
}

.skip-to-content:focus {
  top: 0;
}

/* === HEADER === */
.site-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: var(--header-height);
  background: var(--color-canvas);
  border-bottom: 1px solid var(--color-mist);
  display: flex;
  align-items: center;
  padding: 0 16px;
  z-index: 100;
  transition: background 0.2s, border-color 0.2s;
}

.site-logo {
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--color-ink);
}

.site-logo:hover { color: var(--color-ink); }

.logo-mark {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 32px;
  height: 32px;
  background: var(--color-red);
  color: #fff;
  border-radius: 50%;
  font-size: 1rem;
  font-weight: 800;
}

.sidebar-toggle {
  display: none;
  background: none;
  border: none;
  font-size: 1.5rem;
  cursor: pointer;
  padding: 8px;
  margin-right: 8px;
  color: var(--color-ink);
}

/* === HEADER DARK MODE TOGGLE === */
.dark-toggle {
  background: none;
  border: 1px solid var(--color-mist);
  cursor: pointer;
  font-size: 1rem;
  padding: 6px 10px;
  border-radius: var(--radius-pill);
  margin-left: auto;
  color: var(--color-graphite);
  transition: background 0.15s, border-color 0.15s;
  line-height: 1;
}

.dark-toggle:hover {
  background: var(--color-smoke);
  border-color: var(--color-red);
}

/* === SIDEBAR === */
.sidebar {
  position: fixed;
  top: var(--header-height);
  left: 0;
  width: var(--sidebar-width);
  height: calc(100vh - var(--header-height));
  background: var(--color-sidebar);
  border-right: 1px solid var(--color-mist);
  overflow-y: auto;
  z-index: 50;
  padding: 12px 0;
  transition: background 0.2s, border-color 0.2s;
}

.sidebar::-webkit-scrollbar { width: 6px; }
.sidebar::-webkit-scrollbar-thumb { background: var(--color-mist); border-radius: 3px; }

.sidebar-section { margin-bottom: 8px; }

.sidebar-heading {
  padding: 8px 20px 4px;
  font-size: 0.65rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--color-graphite);
  font-weight: 600;
}

.sidebar-link {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 8px 20px;
  font-size: 0.9rem;
  color: var(--color-graphite);
  transition: background 0.15s, color 0.15s, border-color 0.15s;
  border-left: 3px solid transparent;
}

.sidebar-link:hover {
  background: var(--color-smoke);
  color: var(--color-ink);
}

.sidebar-link.active {
  background: var(--color-red-light);
  color: var(--color-red);
  border-left-color: var(--color-red);
  font-weight: 500;
}

.sidebar-link .icon {
  width: 20px;
  text-align: center;
  font-size: 1rem;
  flex-shrink: 0;
}

.sidebar-coming {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 8px 20px;
  font-size: 0.85rem;
  color: var(--color-mist);
  pointer-events: none;
}

.sidebar-coming .badge {
  font-size: 0.6rem;
  background: var(--color-mist);
  color: var(--color-graphite);
  padding: 1px 6px;
  border-radius: 8px;
  margin-left: auto;
}

/* === MAIN CONTENT === */
.main-content {
  margin-left: var(--sidebar-width);
  margin-top: var(--header-height);
  min-height: calc(100vh - var(--header-height));
  padding: 32px 40px 60px;
  flex: 1;
}

/* === HERO SECTION === */
.hero {
  text-align: center;
  padding: 48px 0 40px;
  max-width: 720px;
  margin: 0 auto;
}

.hero h1 {
  font-size: 2.4rem;
  font-weight: 800;
  line-height: 1.15;
  margin-bottom: 12px;
  letter-spacing: -0.02em;
}

.hero h1 .highlight {
  background: var(--color-red-gradient);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero p {
  font-size: 1.1rem;
  color: var(--color-graphite);
  margin-bottom: 28px;
  line-height: 1.6;
}

.hero-stats {
  display: flex;
  justify-content: center;
  gap: 40px;
  margin-top: 24px;
}

.hero-stat {
  text-align: center;
}

.hero-stat-value {
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--color-red);
}

.hero-stat-label {
  font-size: 0.8rem;
  color: var(--color-graphite);
  margin-top: 2px;
}

/* === BREADCRUMB === */
.breadcrumb {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 0.8rem;
  color: var(--color-graphite);
  margin-bottom: 20px;
  flex-wrap: wrap;
}

.breadcrumb a { color: var(--color-graphite); }
.breadcrumb a:hover { color: var(--color-red); }
.breadcrumb .sep { color: var(--color-mist); }
.breadcrumb .current { color: var(--color-ink); font-weight: 500; }

/* === TOOL HEADER === */
.tool-header {
  margin-bottom: 28px;
}

.tool-header h1 {
  font-size: 1.6rem;
  font-weight: 700;
  margin-bottom: 6px;
}

.tool-header p {
  color: var(--color-graphite);
  font-size: 1rem;
}

/* === CONVERTER WIDGET === */
.converter-widget {
  background: var(--color-canvas);
  border: 1px solid var(--color-mist);
  border-radius: var(--radius-card);
  padding: 32px;
  margin-bottom: 32px;
  max-width: 600px;
  transition: background 0.2s, border-color 0.2s;
}

.drop-zone {
  border: 2px dashed var(--color-mist);
  border-radius: var(--radius-card);
  padding: 48px 24px;
  text-align: center;
  cursor: pointer;
  transition: border-color 0.2s, background 0.2s, transform 0.2s;
  position: relative;
}

.drop-zone:hover,
.drop-zone.drag-over {
  border-color: var(--color-red);
  background: var(--color-red-light);
}

.drop-zone.drop-success {
  border-color: var(--color-success);
  background: #F0FDF4;
  transform: scale(1.02);
}

[data-theme="dark"] .drop-zone.drop-success {
  background: #0A2A10;
}

.drop-zone-icon {
  font-size: 2.5rem;
  margin-bottom: 12px;
}

.drop-zone-icon .success-check {
  display: none;
  color: var(--color-success);
}

.drop-zone.drop-success .drop-zone-icon .default-icon {
  display: none;
}

.drop-zone.drop-success .drop-zone-icon .success-check {
  display: inline;
}

.drop-zone-text {
  font-size: 0.95rem;
  color: var(--color-graphite);
}

.drop-zone-text strong {
  color: var(--color-red);
}

.drop-zone-hint {
  font-size: 0.8rem;
  color: var(--color-mist);
  margin-top: 8px;
}

.drop-zone input[type="file"] {
  position: absolute;
  inset: 0;
  opacity: 0;
  cursor: pointer;
}

.file-info {
  display: none;
  align-items: center;
  gap: 12px;
  padding: 14px 16px;
  background: var(--color-smoke);
  border-radius: var(--radius-card);
  margin-top: 16px;
}

.file-info.show { display: flex; }

.file-info-name {
  flex: 1;
  font-weight: 500;
  font-size: 0.9rem;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.file-info-size {
  color: var(--color-graphite);
  font-size: 0.8rem;
}

.file-info-remove {
  background: none;
  border: none;
  cursor: pointer;
  color: var(--color-graphite);
  font-size: 1.1rem;
  padding: 4px;
}

.file-info-remove:hover { color: var(--color-red); }

.converter-controls {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-top: 20px;
  flex-wrap: wrap;
}

.converter-controls label {
  font-size: 0.85rem;
  font-weight: 500;
  color: var(--color-graphite);
}

.converter-controls select {
  padding: 8px 14px;
  border: 1px solid var(--color-mist);
  border-radius: var(--radius-pill);
  font-size: 0.9rem;
  background: var(--color-canvas);
  color: var(--color-ink);
  cursor: pointer;
  outline: none;
  min-width: 120px;
  transition: background 0.2s, border-color 0.2s, color 0.2s;
}

.converter-controls select:focus {
  border-color: var(--color-red);
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 10px 24px;
  border: none;
  border-radius: var(--radius-pill);
  font-size: 0.9rem;
  font-weight: 600;
  cursor: pointer;
  transition: background 0.15s, transform 0.1s;
  font-family: inherit;
}

.btn:active { transform: scale(0.97); }

.btn-primary {
  background: var(--color-red);
  color: #fff;
}

.btn-primary:hover { background: var(--color-red-hover); }

.btn-primary:disabled {
  background: var(--color-mist);
  color: var(--color-graphite);
  cursor: not-allowed;
}

.btn-secondary {
  background: var(--color-smoke);
  color: var(--color-ink);
  border: 1px solid var(--color-mist);
}

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

.btn-success {
  background: var(--color-success);
  color: #fff;
}

.btn-success:hover { background: #15803D; }

/* === CONVERTER RESULT === */
.converter-result {
  display: none;
  margin-top: 20px;
  padding: 16px;
  background: #F0FDF4;
  border: 1px solid #BBF7D0;
  border-radius: var(--radius-card);
}

.converter-result.show { display: block; }

.converter-result.success { background: #F0FDF4; border-color: #BBF7D0; }
[data-theme="dark"] .converter-result.success { background: #0A2A10; border-color: #166534; }

  .converter-result.error { background: #FEF2F2; border-color: #FECACA; }
  [data-theme="dark"] .converter-result.error { background: #2A1010; border-color: #7F1D1D; }
.converter-result-message {
  font-size: 0.9rem;
  margin-bottom: 12px;
}

.converter-result .btn { margin-top: 8px; }

/* === PROGRESS === */
.progress-bar {
  display: none;
  margin-top: 16px;
  height: 4px;
  background: var(--color-smoke);
  border-radius: 2px;
  overflow: hidden;
}

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

.progress-bar-fill {
  height: 100%;
  background: var(--color-red-gradient);
  width: 0%;
  transition: width 0.3s;
  border-radius: 2px;
}

/* === TOAST NOTIFICATION === */
.toast {
  position: fixed;
  top: 16px;
  right: 16px;
  z-index: 10000;
  padding: 12px 20px;
  border-radius: var(--radius-card);
  font-size: 0.9rem;
  font-weight: 500;
  color: #fff;
  box-shadow: 0 4px 16px rgba(0,0,0,0.15);
  transform: translateX(120%);
  transition: transform 0.3s ease;
  max-width: 360px;
  pointer-events: none;
}

.toast.toast-show {
  transform: translateX(0);
}

.toast-success { background: var(--color-success); }
.toast-error { background: var(--color-error); }
.toast-info { background: #333; }
[data-theme="dark"] .toast-info { background: #555; }

/* === CONTENT SECTIONS (SEO) === */
.content-section {
  max-width: 720px;
  margin-bottom: 36px;
}

.content-section h2 {
  font-size: 1.3rem;
  font-weight: 700;
  margin-bottom: 12px;
  padding-bottom: 8px;
  border-bottom: 2px solid var(--color-smoke);
}

.content-section h3 {
  font-size: 1.05rem;
  font-weight: 600;
  margin: 20px 0 8px;
}

.content-section p {
  color: var(--color-graphite);
  line-height: 1.7;
  margin-bottom: 12px;
}

.content-section ul, .content-section ol {
  color: var(--color-graphite);
  padding-left: 20px;
  margin-bottom: 12px;
  line-height: 1.7;
}

.content-section li { margin-bottom: 6px; }

.how-it-works {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 20px;
  margin: 20px 0;
}

.how-step {
  text-align: center;
  padding: 20px 16px;
  border: 1px solid var(--color-mist);
  border-radius: var(--radius-card);
}

.how-step-num {
  width: 32px;
  height: 32px;
  background: var(--color-red);
  color: #fff;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  font-size: 0.85rem;
  margin: 0 auto 10px;
}

.how-step h3 {
  font-size: 0.95rem;
  margin-bottom: 6px;
  border: none;
  padding: 0;
}

.how-step p {
  font-size: 0.85rem;
  margin: 0;
}

/* === FORMAT TABLE === */
.format-table {
  width: 100%;
  border-collapse: collapse;
  margin: 16px 0;
  font-size: 0.9rem;
}

.format-table th {
  text-align: left;
  padding: 10px 14px;
  background: var(--color-smoke);
  font-weight: 600;
  border-bottom: 2px solid var(--color-mist);
}

.format-table td {
  padding: 10px 14px;
  border-bottom: 1px solid var(--color-smoke);
}

.format-table tr:hover td { background: var(--color-smoke); }

/* === FAQ === */
.faq-list {
  margin: 16px 0;
}

.faq-item {
  border: 1px solid var(--color-smoke);
  border-radius: var(--radius-card);
  margin-bottom: 8px;
  overflow: hidden;
}

.faq-question {
  display: flex;
  align-items: center;
  justify-content: space-between;
  width: 100%;
  padding: 14px 18px;
  background: none;
  border: none;
  font-size: 0.95rem;
  font-weight: 600;
  text-align: left;
  cursor: pointer;
  color: var(--color-ink);
  font-family: inherit;
  transition: background 0.15s;
}

.faq-question:hover { background: var(--color-smoke); }

.faq-question .arrow {
  transition: transform 0.2s;
  font-size: 0.8rem;
  color: var(--color-graphite);
}

.faq-question.open .arrow { transform: rotate(180deg); }

.faq-answer {
  display: none;
  padding: 0 18px 14px;
  font-size: 0.9rem;
  color: var(--color-graphite);
  line-height: 1.7;
}

.faq-answer.open { display: block; }

/* === RELATED TOOLS === */
.related-tools {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(180px, 1fr));
  gap: 12px;
  margin: 16px 0;
}

.related-tool-card {
  display: block;
  padding: 14px 18px;
  border: 1px solid var(--color-mist);
  border-radius: var(--radius-card);
  font-size: 0.9rem;
  font-weight: 500;
  transition: border-color 0.15s, background 0.15s;
}

.related-tool-card:hover {
  border-color: var(--color-red);
  background: var(--color-red-light);
  color: var(--color-red);
}

.related-tool-card .desc {
  display: block;
  font-size: 0.8rem;
  font-weight: 400;
  color: var(--color-graphite);
  margin-top: 2px;
}

/* === PRIVACY BANNER === */
.privacy-banner {
  background: var(--color-smoke);
  border: 1px solid var(--color-mist);
  border-radius: var(--radius-card);
  padding: 16px 20px;
  margin-bottom: 28px;
  display: flex;
  align-items: center;
  gap: 12px;
  font-size: 0.85rem;
  color: var(--color-graphite);
}

.privacy-banner .icon { font-size: 1.3rem; flex-shrink: 0; }

/* === TOOL GRID (landing page) === */
.tool-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 16px;
  margin: 20px 0;
}

.tool-card {
  display: block;
  padding: 20px;
  border: 1px solid var(--color-mist);
  border-radius: var(--radius-card);
  transition: border-color 0.15s, background 0.15s;
}

.tool-card:hover {
  border-color: var(--color-red);
  background: var(--color-red-light);
}

.tool-card-icon {
  font-size: 1.5rem;
  margin-bottom: 8px;
}

.tool-card-title {
  font-size: 1rem;
  font-weight: 600;
  margin-bottom: 4px;
}

.tool-card-desc {
  font-size: 0.85rem;
  color: var(--color-graphite);
  line-height: 1.5;
}

.tool-card .badge-new {
  display: inline-block;
  font-size: 0.6rem;
  background: var(--color-red);
  color: #fff;
  padding: 1px 6px;
  border-radius: 8px;
  margin-left: 6px;
  vertical-align: middle;
}

/* === SECTION HEADING === */
.section-heading {
  font-size: 1.2rem;
  font-weight: 700;
  margin: 36px 0 16px;
  padding-bottom: 8px;
  border-bottom: 2px solid var(--color-smoke);
}

/* === FOOTER === */
.site-footer {
  margin-left: var(--sidebar-width);
  margin-top: auto;
  background: var(--color-smoke);
  border-top: 1px solid var(--color-mist);
  padding: 32px 40px;
  transition: background 0.2s, border-color 0.2s;
}

.footer-content {
  max-width: 960px;
  margin: 0 auto;
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 16px;
}

.footer-copy {
  color: var(--color-graphite);
  font-size: 0.8rem;
}

.footer-links {
  display: flex;
  gap: 20px;
}

.footer-links a {
  color: var(--color-graphite);
  font-size: 0.8rem;
}

.footer-links a:hover { color: var(--color-red); }

/* === RESPONSIVE === */
@media (max-width: 900px) {
  .sidebar {
    transform: translateX(-100%);
    transition: transform 0.25s ease, background 0.2s;
  }

  .sidebar.open {
    transform: translateX(0);
    box-shadow: 4px 0 20px rgba(0,0,0,0.1);
  }

  .sidebar-toggle { display: block; }

  .main-content {
    margin-left: 0;
    padding: 24px 20px 40px;
  }

  .site-footer {
    margin-left: 0;
    padding: 24px 20px;
  }

  .hero h1 { font-size: 1.8rem; }
  .hero-stats { gap: 20px; flex-wrap: wrap; }
  .how-it-works { grid-template-columns: 1fr; }
  .tool-grid { grid-template-columns: 1fr; }
  .converter-widget { padding: 20px; }
  .related-tools { grid-template-columns: 1fr 1fr; }
}

@media (max-width: 480px) {
  .hero h1 { font-size: 1.4rem; }
  .hero p { font-size: 0.95rem; }
  .converter-controls { flex-direction: column; align-items: stretch; }
  .converter-controls select { width: 100%; }
  .btn { justify-content: center; }
  .related-tools { grid-template-columns: 1fr; }
}

/* === FEEDBACK WIDGET === */
.feedback-widget {
  max-width: 600px;
  margin-bottom: 32px;
  padding: 20px 24px;
  background: var(--color-smoke);
  border: 1px solid var(--color-mist);
  border-radius: var(--radius-card);
  display: flex;
  align-items: center;
  gap: 16px;
  flex-wrap: wrap;
}

.feedback-question {
  font-weight: 600;
  font-size: 0.9rem;
}

.feedback-buttons {
  display: flex;
  gap: 8px;
}

.feedback-btn {
  padding: 6px 16px;
  border: 1px solid var(--color-mist);
  border-radius: var(--radius-pill);
  background: var(--color-canvas);
  cursor: pointer;
  font-size: 0.85rem;
  font-family: inherit;
  transition: border-color 0.15s, background 0.15s;
}

.feedback-btn:hover {
  border-color: var(--color-red);
  background: var(--color-red-light);
}

.feedback-thanks {
  font-size: 0.9rem;
  color: var(--color-success);
  font-weight: 500;
}

/* === 404 PAGE === */
.error-page {
  text-align: center;
  padding: 80px 20px;
  max-width: 600px;
  margin: 0 auto;
}

.error-page .error-code {
  font-size: 5rem;
  font-weight: 800;
  color: var(--color-red);
  line-height: 1;
  margin-bottom: 8px;
}

.error-page h1 {
  font-size: 1.6rem;
  margin-bottom: 12px;
}

.error-page p {
  color: var(--color-graphite);
  margin-bottom: 24px;
}

.error-page .tool-grid {
  margin: 24px 0;
  text-align: left;
}

/* === AD CONTAINER === */
.ad-container {
  min-height: 90px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--color-smoke);
  border: 1px solid var(--color-mist);
  border-radius: var(--radius-card);
  color: var(--color-mist);
  font-size: 0.75rem;
  margin-bottom: 24px;
}

.ad-container-sidebar {
  min-height: 250px;
  margin: 16px 12px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--color-smoke);
  border: 1px solid var(--color-mist);
  border-radius: var(--radius-card);
  color: var(--color-mist);
  font-size: 0.75rem;
}

/* === UTILITY === */
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0,0,0,0);
  border: 0;
}

.mt-20 { margin-top: 20px; }
.mb-20 { margin-bottom: 20px; }
.text-center { text-align: center; }
.text-graphite { color: var(--color-graphite); }