.skip-link {
  position: absolute;
  top: -40px;
  left: 0;
  background: var(--primary);
  color: white;
  padding: 8px 16px;
  z-index: 200;
  font-weight: 600;
  border-radius: 0 0 8px 0;
}

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

:focus-visible {
  outline: 2px solid var(--primary-light);
  outline-offset: 2px;
}

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

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border-width: 0;
}

:root {
  --primary: #2563eb;
  --primary-dark: #1d4ed8;
  --primary-light: #3b82f6;
  --bg: #0f172a;
  --bg-card: #1e293b;
  --bg-card-hover: #334155;
  --text: #f8fafc;
  --text-muted: #94a3b8;
  --border: #334155;
  --success: #22c55e;
  --warning: #f59e0b;
  --error: #ef4444;
  --radius: 12px;
  --shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.3);
}

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

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
  min-height: 100vh;
}

a {
  color: var(--primary-light);
  text-decoration: none;
  transition: color 0.2s;
}

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

.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 20px;
}

header {
  background: var(--bg-card);
  border-bottom: 1px solid var(--border);
  padding: 1rem 0;
  position: sticky;
  top: 0;
  z-index: 100;
}

header .container {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 1rem;
}

.logo {
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--text);
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.logo span {
  color: var(--primary-light);
}

nav {
  display: flex;
  gap: 1.5rem;
  align-items: center;
}

nav a {
  color: var(--text-muted);
  font-weight: 500;
}

nav a:hover,
nav a.active {
  color: var(--text);
}

.hero {
  text-align: center;
  padding: 4rem 0 3rem;
}

.hero h1 {
  font-size: clamp(2rem, 5vw, 3rem);
  margin-bottom: 1rem;
  background: linear-gradient(135deg, var(--primary-light), #8b5cf6);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero p {
  font-size: 1.25rem;
  color: var(--text-muted);
  max-width: 600px;
  margin: 0 auto 2rem;
}

.tools-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 1.5rem;
  padding: 2rem 0 4rem;
}

.tool-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.5rem;
  transition: all 0.2s;
  cursor: pointer;
  display: block;
}

.tool-card:hover {
  background: var(--bg-card-hover);
  border-color: var(--primary);
  transform: translateY(-4px);
  box-shadow: var(--shadow);
}

.tool-card .icon {
  width: 48px;
  height: 48px;
  margin-bottom: 1rem;
  display: flex;
  align-items: center;
  justify-content: center;
  background: rgba(59, 130, 246, 0.1);
  border-radius: 10px;
  color: var(--primary-light);
}

.tool-card .icon svg {
  width: 28px;
  height: 28px;
  fill: none;
  stroke: currentColor;
  stroke-width: 2;
  stroke-linecap: round;
  stroke-linejoin: round;
}

.tool-card h3 {
  font-size: 1.125rem;
  margin-bottom: 0.5rem;
}

.tool-card p {
  color: var(--text-muted);
  font-size: 0.875rem;
}

.tool-page {
  padding: 2rem 0 4rem;
}

.tool-header {
  margin-bottom: 2rem;
}

.tool-header h1 {
  font-size: 1.75rem;
  margin-bottom: 0.5rem;
}

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

.tool-container {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.5rem;
}

.form-group {
  margin-bottom: 1.5rem;
}

.form-group label {
  display: block;
  margin-bottom: 0.5rem;
  font-weight: 500;
  color: var(--text-muted);
}

textarea,
input[type="text"],
input[type="number"],
input[type="password"],
select {
  width: 100%;
  padding: 0.75rem 1rem;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 8px;
  color: var(--text);
  font-family: 'Fira Code', 'Cascadia Code', 'Consolas', monospace;
  font-size: 0.875rem;
  transition: border-color 0.2s;
}

textarea:focus,
input:focus,
select:focus {
  outline: none;
  border-color: var(--primary);
}

textarea {
  min-height: 150px;
  resize: vertical;
}

button {
  padding: 0.75rem 1.5rem;
  background: var(--primary);
  color: white;
  border: none;
  border-radius: 8px;
  font-weight: 600;
  cursor: pointer;
  transition: background 0.2s;
  font-size: 0.875rem;
}

button:hover {
  background: var(--primary-dark);
}

button.secondary {
  background: var(--bg-card-hover);
  border: 1px solid var(--border);
}

button.secondary:hover {
  background: var(--border);
}

.button-group {
  display: flex;
  gap: 0.75rem;
  flex-wrap: wrap;
  margin-bottom: 1.5rem;
}

.output-box {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 1rem;
  font-family: 'Fira Code', 'Cascadia Code', 'Consolas', monospace;
  font-size: 0.875rem;
  word-break: break-all;
  position: relative;
  min-height: 60px;
}

.output-box .copy-btn {
  position: absolute;
  top: 0.5rem;
  right: 0.5rem;
  padding: 0.4rem 0.75rem;
  font-size: 0.75rem;
}

.ad-container {
  background: var(--bg-card);
  border: 1px dashed var(--border);
  border-radius: var(--radius);
  padding: 1rem;
  margin: 2rem 0;
  text-align: center;
  min-height: 100px;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--text-muted);
  font-size: 0.875rem;
}

.ad-sidebar {
  position: sticky;
  top: 100px;
}

footer {
  background: var(--bg-card);
  border-top: 1px solid var(--border);
  padding: 2rem 0;
  margin-top: 4rem;
}

footer .container {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 1rem;
}

footer p {
  color: var(--text-muted);
  font-size: 0.875rem;
}

.breadcrumb {
  display: flex;
  gap: 0.5rem;
  align-items: center;
  margin-bottom: 1.5rem;
  font-size: 0.875rem;
  color: var(--text-muted);
}

.breadcrumb a {
  color: var(--text-muted);
}

.breadcrumb a:hover {
  color: var(--text);
}

.options-row {
  display: flex;
  gap: 1rem;
  align-items: flex-end;
  flex-wrap: wrap;
  margin-bottom: 1.5rem;
}

.options-row .form-group {
  margin-bottom: 0;
  flex: 1;
  min-width: 150px;
}

.checkbox-group {
  display: flex;
  gap: 1rem;
  flex-wrap: wrap;
  margin-bottom: 1rem;
}

.checkbox-group label {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  cursor: pointer;
}

input[type="checkbox"] {
  width: 18px;
  height: 18px;
  accent-color: var(--primary);
}

.color-preview {
  width: 100%;
  height: 80px;
  border-radius: 8px;
  border: 1px solid var(--border);
  margin-top: 0.5rem;
}

.result-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 1rem;
  margin-top: 1rem;
}

.result-item {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 1rem;
}

.result-item label {
  display: block;
  color: var(--text-muted);
  font-size: 0.75rem;
  margin-bottom: 0.25rem;
}

.result-item span {
  font-family: monospace;
  font-size: 0.875rem;
}

.search-box {
  position: relative;
  margin-bottom: 2rem;
}

.search-box input {
  padding-left: 2.5rem;
}

.search-box::before {
  content: "";
  position: absolute;
  left: 0.75rem;
  top: 50%;
  transform: translateY(-50%);
  width: 18px;
  height: 18px;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24' fill='none' stroke='%2394a3b8' stroke-width='2' stroke-linecap='round' stroke-linejoin='round'%3E%3Ccircle cx='11' cy='11' r='8'/%3E%3Cpath d='m21 21-4.35-4.35'/%3E%3C/svg%3E");
  background-size: contain;
  background-repeat: no-repeat;
}

.stats {
  display: flex;
  gap: 1.5rem;
  flex-wrap: wrap;
  margin-top: 1rem;
}

.stat-item {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 0.75rem 1.25rem;
}

.stat-item .value {
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--primary-light);
}

.stat-item .label {
  font-size: 0.75rem;
  color: var(--text-muted);
}

@media (max-width: 768px) {
  .hero {
    padding: 2rem 0 1.5rem;
  }

  .tools-grid {
    grid-template-columns: 1fr;
    padding: 1rem 0 3rem;
  }

  header .container {
    flex-direction: column;
    text-align: center;
  }

  nav {
    justify-content: center;
  }

  footer .container {
    flex-direction: column;
    text-align: center;
  }

  .options-row {
    flex-direction: column;
  }

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

  #ia-tips h3 {
    font-size: 1rem;
  }
}

.back-to-top {
  position: fixed;
  bottom: 2rem;
  right: 2rem;
  width: 48px;
  height: 48px;
  background: var(--primary);
  color: white;
  border: none;
  border-radius: 50%;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  opacity: 0;
  visibility: hidden;
  transition: all 0.3s;
  z-index: 99;
  box-shadow: var(--shadow);
}

.back-to-top.visible {
  opacity: 1;
  visibility: visible;
}

.back-to-top:hover {
  background: var(--primary-dark);
  transform: translateY(-2px);
}

.back-to-top svg {
  width: 24px;
  height: 24px;
  fill: none;
  stroke: currentColor;
  stroke-width: 2;
  stroke-linecap: round;
  stroke-linejoin: round;
}

.related-tools {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.5rem;
  margin-top: 2rem;
}

.related-tools h3 {
  margin-bottom: 1rem;
  font-size: 1rem;
}

.related-tools-grid {
  display: flex;
  gap: 0.5rem;
  flex-wrap: wrap;
}

.related-tools a {
  padding: 0.4rem 0.75rem;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 6px;
  color: var(--text);
  font-size: 0.8rem;
  transition: all 0.2s;
}

.related-tools a:hover {
  border-color: var(--primary);
  background: var(--bg-card-hover);
}