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

:root {
  --color-primary: #6366F1;
  --color-primary-hover: #818CF8;
  --color-bg: #0F1117;
  --color-surface: #1A1D2E;
  --color-surface-hover: #232740;
  --color-text: #E2E8F0;
  --color-text-secondary: #94A3B8;
  --color-border: #2D3348;
  --color-success: #10B981;
  --color-error: #EF4444;
  --color-warning: #F59E0B;
  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 16px;
  --shadow-card: 0 4px 6px -1px rgba(0, 0, 0, 0.3);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.4);
  --font-mono: 'SF Mono', 'Fira Code', 'Cascadia Code', monospace;
  --font-sans: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --container-max: 1200px;
  --header-height: 64px;
}

[data-theme="light"] {
  --color-bg: #F8FAFC;
  --color-surface: #FFFFFF;
  --color-surface-hover: #F1F5F9;
  --color-text: #0F172A;
  --color-text-secondary: #475569;
  --color-border: #E2E8F0;
  --shadow-card: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
}

html {
  font-size: 16px;
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-sans);
  background-color: var(--color-bg);
  color: var(--color-text);
  line-height: 1.6;
  min-height: 100vh;
  -webkit-font-smoothing: antialiased;
}

.container {
  width: 100%;
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 1rem;
}

@media (min-width: 768px) {
  .container {
    padding: 0 2rem;
  }
}

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

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

/* Header */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: var(--color-surface);
  border-bottom: 1px solid var(--color-border);
  height: var(--header-height);
  backdrop-filter: blur(8px);
}

.header-inner {
  display: flex;
  align-items: center;
  height: 100%;
  gap: 2rem;
}

.logo {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  color: var(--color-text);
  font-weight: 700;
  font-size: 1.25rem;
  text-decoration: none;
}

.logo-icon {
  font-size: 1.5rem;
}

.main-nav {
  display: none;
  align-items: center;
  gap: 1.5rem;
}

.main-nav a {
  color: var(--color-text-secondary);
  font-size: 0.9rem;
  font-weight: 500;
  transition: color 0.2s;
}

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

@media (min-width: 768px) {
  .main-nav {
    display: flex;
  }
}

.header-actions {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  margin-left: auto;
}

.theme-toggle {
  background: none;
  border: none;
  color: var(--color-text-secondary);
  font-size: 1.25rem;
  cursor: pointer;
  padding: 0.5rem;
  border-radius: var(--radius-sm);
  transition: background 0.2s;
}

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

[data-theme="dark"] .theme-icon-light { display: none; }
[data-theme="light"] .theme-icon-dark { display: none; }

.mobile-menu-btn {
  display: flex;
  flex-direction: column;
  gap: 4px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 0.5rem;
}

.mobile-menu-btn span {
  display: block;
  width: 20px;
  height: 2px;
  background: var(--color-text-secondary);
  border-radius: 1px;
  transition: transform 0.2s;
}

@media (min-width: 768px) {
  .mobile-menu-btn {
    display: none;
  }
}

/* Mobile nav overlay */
.main-nav.open {
  display: flex;
  flex-direction: column;
  position: fixed;
  top: var(--header-height);
  left: 0;
  right: 0;
  bottom: 0;
  background: var(--color-surface);
  padding: 2rem;
  gap: 1.5rem;
  z-index: 99;
}

.main-nav.open a {
  font-size: 1.1rem;
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  padding: 0.75rem 1.5rem;
  border-radius: var(--radius-sm);
  font-size: 0.95rem;
  font-weight: 600;
  border: none;
  cursor: pointer;
  transition: background 0.2s, transform 0.1s;
}

.btn:active {
  transform: scale(0.98);
}

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

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

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

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

.btn-sm {
  padding: 0.4rem 0.75rem;
  font-size: 0.8rem;
}

/* Form elements */
label {
  display: block;
  font-size: 0.9rem;
  font-weight: 500;
  color: var(--color-text-secondary);
  margin-bottom: 0.4rem;
}

textarea,
input[type="text"],
input[type="number"],
input[type="search"],
select {
  width: 100%;
  padding: 0.75rem 1rem;
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  color: var(--color-text);
  font-size: 0.95rem;
  font-family: inherit;
  transition: border-color 0.2s;
}

textarea {
  font-family: var(--font-mono);
  resize: vertical;
}

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

select {
  appearance: none;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 12 12'%3E%3Cpath fill='%2394A3B8' d='M6 8L1 3h10z'/%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right 0.75rem center;
  padding-right: 2.5rem;
}

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

.checkbox-group input[type="checkbox"] {
  width: 1.1rem;
  height: 1.1rem;
  accent-color: var(--color-primary);
}

.checkbox-group label {
  margin-bottom: 0;
}

/* Breadcrumb */
.breadcrumb {
  padding: 1rem 0;
  font-size: 0.85rem;
  color: var(--color-text-secondary);
}

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

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

.breadcrumb span {
  margin: 0 0.5rem;
}

/* Footer */
.site-footer {
  margin-top: 4rem;
  border-top: 1px solid var(--color-border);
  padding: 3rem 0 2rem;
  background: var(--color-surface);
}

.footer-inner {
  display: grid;
  gap: 2rem;
}

@media (min-width: 768px) {
  .footer-inner {
    grid-template-columns: 1fr 2fr;
  }
}

.footer-brand .logo-icon {
  font-size: 1.25rem;
}

.footer-brand .logo-text {
  font-weight: 700;
  font-size: 1.1rem;
}

.footer-tagline {
  color: var(--color-text-secondary);
  font-size: 0.9rem;
  margin-top: 0.5rem;
}

.footer-links {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
  gap: 2rem;
}

.footer-col h4 {
  font-size: 0.85rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--color-text-secondary);
  margin-bottom: 0.75rem;
}

.footer-col a {
  display: block;
  color: var(--color-text);
  font-size: 0.9rem;
  padding: 0.3rem 0;
}

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

.footer-bottom {
  grid-column: 1 / -1;
  padding-top: 2rem;
  border-top: 1px solid var(--color-border);
  text-align: center;
  color: var(--color-text-secondary);
  font-size: 0.85rem;
}

/* Ad slots */
.ad-slot {
  min-height: 90px;
  display: flex;
  align-items: center;
  justify-content: center;
  margin: 1.5rem 0;
  border-radius: var(--radius-sm);
}

/* Copy button */
.copy-btn {
  position: absolute;
  top: 0.5rem;
  right: 0.5rem;
  background: var(--color-surface-hover);
  border: 1px solid var(--color-border);
  color: var(--color-text-secondary);
  padding: 0.35rem 0.6rem;
  border-radius: var(--radius-sm);
  font-size: 0.75rem;
  cursor: pointer;
  transition: background 0.2s, color 0.2s;
}

.copy-btn:hover {
  background: var(--color-primary);
  color: #fff;
  border-color: var(--color-primary);
}

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

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