:root {
  --primary: #ef4444;
  --primary-dark: #dc2626;
  --bg: #f9fafb;
  --card: #ffffff;
  --text: #111827;
  --text-2: #374151;
  --text-3: #6b7280;
  --border: #e5e7eb;
  --radius: 12px;
  --shadow: 0 1px 3px rgba(0,0,0,.08), 0 1px 2px rgba(0,0,0,.06);
  --nav-h: 60px;
  --sidebar-w: 240px;
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0f172a; --card: #1e293b; --text: #f1f5f9;
    --text-2: #cbd5e1; --text-3: #94a3b8; --border: #334155;
  }
}
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
body { font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif; background: var(--bg); color: var(--text); line-height: 1.5; }
a { color: inherit; text-decoration: none; }

/* NAV */
.topnav { position: fixed; top: 0; left: 0; right: 0; height: var(--nav-h); background: var(--card); border-bottom: 1px solid var(--border); z-index: 100; box-shadow: var(--shadow); }
.nav-inner { display: flex; align-items: center; gap: 1rem; padding: 0 1rem; height: 100%; max-width: 1400px; margin: 0 auto; }
.nav-logo { display: flex; align-items: center; gap: 0.5rem; font-weight: 700; font-size: 1.1rem; flex-shrink: 0; }
.logo-text { color: var(--primary); }
.nav-search { flex: 1; max-width: 400px; display: flex; align-items: center; background: var(--bg); border: 1px solid var(--border); border-radius: 8px; padding: 0 0.75rem; }
.nav-search input { flex: 1; border: none; background: none; padding: 0.5rem 0.5rem 0.5rem 0; font-size: 0.875rem; color: var(--text); outline: none; }
.nav-search button { background: none; border: none; cursor: pointer; color: var(--text-3); padding: 0.25rem; display: flex; }
.nav-actions { display: flex; align-items: center; gap: 0.5rem; margin-left: auto; }

/* HAMBURGER */
.nav-hamburger { display: none; background: none; border: none; cursor: pointer; padding: 0.4rem; border-radius: 6px; color: var(--text); flex-shrink: 0; }
.nav-hamburger:hover { background: var(--bg); }
.nav-hamburger svg { display: block; }

/* MOBILE OVERLAY */
.mobile-overlay { display: none; position: fixed; inset: 0; background: rgba(0,0,0,.45); z-index: 299; opacity: 0; transition: opacity .25s; }
.mobile-overlay.open { display: block; opacity: 1; }

/* MOBILE DRAWER */
.mobile-drawer { position: fixed; top: 0; left: 0; bottom: 0; width: 280px; background: var(--card); z-index: 300; transform: translateX(-100%); transition: transform .28s cubic-bezier(.4,0,.2,1); display: flex; flex-direction: column; overflow-y: auto; }
.mobile-drawer.open { transform: translateX(0); }
.mobile-drawer-head { display: flex; align-items: center; justify-content: space-between; padding: 0 1rem; height: var(--nav-h); border-bottom: 1px solid var(--border); flex-shrink: 0; }
.mobile-drawer-logo { display: flex; align-items: center; gap: 0.5rem; font-weight: 700; font-size: 1.05rem; }
.mobile-drawer-close { background: none; border: none; cursor: pointer; padding: 0.4rem; border-radius: 6px; color: var(--text-3); font-size: 1.2rem; line-height: 1; }
.mobile-drawer-close:hover { background: var(--bg); }
.mobile-drawer-search { padding: 0.875rem 1rem; border-bottom: 1px solid var(--border); flex-shrink: 0; }
.mobile-drawer-search form { display: flex; align-items: center; background: var(--bg); border: 1px solid var(--border); border-radius: 8px; padding: 0 0.75rem; }
.mobile-drawer-search input { flex: 1; border: none; background: none; padding: 0.6rem 0.5rem 0.6rem 0; font-size: 0.875rem; color: var(--text); outline: none; }
.mobile-drawer-search button { background: none; border: none; cursor: pointer; color: var(--text-3); padding: 0.25rem; display: flex; }
.mobile-drawer-cats { flex: 1; padding: 0.75rem; }
.mobile-drawer-cats-title { font-size: 0.7rem; font-weight: 600; color: var(--text-3); text-transform: uppercase; letter-spacing: .08em; padding: 0.5rem 0.75rem 0.75rem; }
.mobile-drawer-item { display: flex; align-items: center; gap: 0.6rem; padding: 0.55rem 0.75rem; border-radius: 8px; font-size: 0.875rem; color: var(--text-2); transition: background .15s; margin-bottom: 2px; }
.mobile-drawer-item:hover { background: var(--bg); }
.mobile-drawer-item.active { background: #fef2f2; color: var(--primary); font-weight: 600; }
.mobile-drawer-lang { padding: 0.875rem 1rem 1rem; border-top: 1px solid var(--border); flex-shrink: 0; }
.mobile-drawer-lang-title { font-size: 0.7rem; font-weight: 600; color: var(--text-3); text-transform: uppercase; letter-spacing: .08em; margin-bottom: 0.5rem; padding: 0 0.25rem; }
.mobile-drawer-lang-grid { display: flex; flex-wrap: wrap; gap: 0.35rem; }
.mobile-drawer-lang-item { padding: 0.3rem 0.6rem; border-radius: 6px; font-size: 0.78rem; border: 1px solid var(--border); color: var(--text-2); background: var(--bg); }
.mobile-drawer-lang-item.active { background: var(--primary); color: #fff; border-color: var(--primary); }

/* LANGUAGE SWITCHER */
.lang-switcher { position: relative; }
.lang-btn { background: var(--bg); border: 1px solid var(--border); border-radius: 8px; padding: 0.4rem 0.75rem; font-size: 0.8rem; cursor: pointer; color: var(--text-2); }
.lang-menu { display: none; position: absolute; right: 0; top: calc(100% + 4px); background: var(--card); border: 1px solid var(--border); border-radius: 10px; box-shadow: 0 8px 24px rgba(0,0,0,.12); min-width: 160px; max-height: 320px; overflow-y: auto; z-index: 200; }
.lang-menu.open { display: block; }
.lang-item { display: block; padding: 0.5rem 1rem; font-size: 0.85rem; color: var(--text-2); }
.lang-item:hover, .lang-item.active { background: #fef2f2; color: var(--primary); }

/* LAYOUT */
.layout { display: flex; margin-top: var(--nav-h); min-height: calc(100vh - var(--nav-h)); }
.sidebar { width: var(--sidebar-w); flex-shrink: 0; padding: 1rem 0.75rem; position: sticky; top: var(--nav-h); height: calc(100vh - var(--nav-h)); overflow-y: auto; border-right: 1px solid var(--border); background: var(--card); }
.sidebar-title { font-size: 0.7rem; font-weight: 600; color: var(--text-3); text-transform: uppercase; letter-spacing: .08em; padding: 0.5rem 0.75rem 0.75rem; }
.sidebar-item { display: flex; align-items: center; gap: 0.6rem; padding: 0.5rem 0.75rem; border-radius: 8px; font-size: 0.85rem; color: var(--text-2); transition: background .15s; margin-bottom: 2px; }
.sidebar-item:hover { background: var(--bg); }
.sidebar-item.active { background: #fef2f2; color: var(--primary); font-weight: 600; }
.main-content { flex: 1; padding: 2rem 1.5rem; max-width: 960px; }

/* HERO */
.hero { margin-bottom: 2rem; }
.hero h1 { font-size: 2rem; font-weight: 700; line-height: 1.2; }
.hero-sub { color: var(--text-3); margin-top: 0.5rem; font-size: 1rem; }
.section-title { font-size: 1.1rem; font-weight: 700; margin-bottom: 1rem; color: var(--text); }

/* CALC GRID */
.calc-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(280px, 1fr)); gap: 0.75rem; margin-bottom: 1rem; }
.calc-grid-sm { grid-template-columns: repeat(auto-fill, minmax(200px, 1fr)); }
.calc-card { display: flex; align-items: flex-start; gap: 0.75rem; padding: 0.875rem 1rem; background: var(--card); border: 1px solid var(--border); border-radius: var(--radius); transition: transform .15s, box-shadow .15s; }
.calc-card:hover { transform: translateY(-1px); box-shadow: 0 4px 12px rgba(0,0,0,.1); border-color: var(--primary); }
.calc-icon { font-size: 1.5rem; flex-shrink: 0; }
.calc-name { font-size: 0.875rem; font-weight: 600; color: var(--text); line-height: 1.3; }
.calc-desc { font-size: 0.75rem; color: var(--text-3); margin-top: 0.2rem; line-height: 1.4; display: -webkit-box; -webkit-line-clamp: 2; -webkit-box-orient: vertical; overflow: hidden; }

/* CALC PAGE */
.breadcrumb { font-size: 0.8rem; color: var(--text-3); margin-bottom: 1.5rem; }
.breadcrumb a { color: var(--text-3); }
.breadcrumb a:hover { color: var(--primary); }
.calc-page-card { background: var(--card); border: 1px solid var(--border); border-radius: var(--radius); padding: 1.5rem; margin-bottom: 1.5rem; }
.calc-page-header { display: flex; align-items: flex-start; gap: 1rem; margin-bottom: 1.5rem; padding-bottom: 1.5rem; border-bottom: 1px solid var(--border); }
.calc-page-icon { font-size: 2.5rem; }
.calc-page-title { font-size: 1.5rem; font-weight: 700; }
.calc-page-desc { color: var(--text-3); font-size: 0.875rem; margin-top: 0.25rem; }

/* CALCULATOR WIDGET */
.calc-widget { padding: 0.5rem 0; }
.calc-interactive { }
.calc-field { margin-bottom: 1rem; }
.calc-field label { display: block; font-size: 0.8rem; font-weight: 600; color: var(--text-2); margin-bottom: 0.4rem; }
.calc-field input, .calc-field select { width: 100%; padding: 0.6rem 0.75rem; border: 1px solid var(--border); border-radius: 8px; font-size: 0.9rem; background: var(--bg); color: var(--text); outline: none; transition: border-color .15s, box-shadow .15s; }
.calc-field input:focus, .calc-field select:focus { border-color: var(--primary); box-shadow: 0 0 0 3px rgba(239,68,68,.12); }
.calc-row { display: grid; grid-template-columns: 1fr 1fr; gap: 1rem; }
.calc-row-3 { display: grid; grid-template-columns: 1fr 1fr 1fr; gap: 1rem; }
.unit-toggle { display: flex; gap: 0.5rem; margin-bottom: 1rem; }
.unit-btn { padding: 0.4rem 1rem; border: 1px solid var(--border); border-radius: 8px; background: var(--bg); color: var(--text-2); cursor: pointer; font-size: 0.85rem; transition: background .15s, color .15s; }
.unit-btn.active { background: var(--primary); color: white; border-color: var(--primary); }
.btn-primary { display: inline-block; padding: 0.65rem 1.5rem; background: var(--primary); color: white; border: none; border-radius: 8px; font-size: 0.9rem; font-weight: 600; cursor: pointer; transition: background .15s; margin-top: 0.5rem; }
.btn-primary:hover { background: var(--primary-dark); }
.calc-result { background: var(--bg); border-radius: 10px; padding: 1.25rem; margin-top: 1rem; border: 1px solid var(--border); }
.result-value { font-size: 2.5rem; font-weight: 700; line-height: 1; }
.result-label { font-size: 1rem; font-weight: 600; margin-top: 0.25rem; }
.result-row { display: flex; justify-content: space-between; padding: 0.5rem 0; border-bottom: 1px solid var(--border); font-size: 0.875rem; }
.result-row:last-child { border-bottom: none; }
.result-row .label { color: var(--text-3); }
.result-row .value { font-weight: 600; color: var(--text); }
.calc-coming-soon { text-align: center; padding: 3rem 1rem; color: var(--text-3); }
.calc-content { line-height: 1.7; }
.calc-content h2 { font-size: 1.1rem; font-weight: 700; margin: 1.5rem 0 0.75rem; }
.calc-content h3 { font-size: 1rem; font-weight: 600; margin: 1.25rem 0 0.5rem; }
.calc-content p { margin-bottom: 0.75rem; color: var(--text-2); }
.calc-content ul, .calc-content ol { padding-left: 1.5rem; margin-bottom: 0.75rem; color: var(--text-2); }
.calc-content li { margin-bottom: 0.25rem; }

/* FAQ */
.faq-section { margin-bottom: 1.5rem; }
.faq-section h2 { font-size: 1.1rem; font-weight: 700; margin-bottom: 1rem; }
.faq-item { border: 1px solid var(--border); border-radius: 8px; margin-bottom: 0.5rem; overflow: hidden; }
.faq-item summary { padding: 0.875rem 1rem; cursor: pointer; font-weight: 500; font-size: 0.9rem; list-style: none; display: flex; justify-content: space-between; align-items: center; }
.faq-item summary::-webkit-details-marker { display: none; }
.faq-item summary::after { content: '+'; font-size: 1.1rem; color: var(--text-3); }
.faq-item[open] summary::after { content: '−'; }
.faq-item summary:hover { background: var(--bg); }
.faq-item p { padding: 0 1rem 0.875rem; color: var(--text-2); font-size: 0.875rem; line-height: 1.6; }

/* RELATED */
.related-section { margin-bottom: 1.5rem; }
.related-section h2 { font-size: 1.1rem; font-weight: 700; margin-bottom: 1rem; }

/* FOOTER */
.site-footer { background: var(--card); border-top: 1px solid var(--border); padding: 1.5rem; text-align: center; color: var(--text-3); font-size: 0.8rem; margin-top: 2rem; }
.footer-inner { display: flex; flex-direction: column; align-items: center; gap: 0.5rem; }
.footer-logo { display: flex; align-items: center; gap: 0.5rem; font-weight: 700; color: var(--primary); }

/* ADMIN */
.admin-layout { display: flex; margin-top: var(--nav-h); min-height: calc(100vh - var(--nav-h)); }
.admin-sidebar { width: 220px; flex-shrink: 0; background: #1e293b; color: #e2e8f0; padding: 1rem 0; }
.admin-sidebar-logo { padding: 1rem 1.25rem 1.5rem; font-weight: 700; font-size: 0.9rem; color: var(--primary); display: flex; align-items: center; gap: 0.5rem; }
.admin-nav-item { display: flex; align-items: center; gap: 0.75rem; padding: 0.65rem 1.25rem; color: #94a3b8; font-size: 0.85rem; transition: background .15s, color .15s; }
.admin-nav-item:hover, .admin-nav-item.active { background: rgba(239,68,68,.15); color: var(--primary); }
.admin-main { flex: 1; padding: 2rem; background: var(--bg); overflow-x: auto; }
.admin-header { margin-bottom: 2rem; }
.admin-header h1 { font-size: 1.5rem; font-weight: 700; }
.admin-card { background: var(--card); border: 1px solid var(--border); border-radius: var(--radius); padding: 1.5rem; margin-bottom: 1.5rem; }
.admin-table { width: 100%; border-collapse: collapse; font-size: 0.85rem; }
.admin-table th { text-align: left; padding: 0.75rem 1rem; background: var(--bg); border-bottom: 2px solid var(--border); font-weight: 600; color: var(--text-3); font-size: 0.75rem; text-transform: uppercase; }
.admin-table td { padding: 0.75rem 1rem; border-bottom: 1px solid var(--border); color: var(--text-2); }
.admin-table tr:hover td { background: var(--bg); }
.badge { display: inline-block; padding: 0.2rem 0.6rem; border-radius: 20px; font-size: 0.7rem; font-weight: 600; }
.badge-popular { background: #fef2f2; color: var(--primary); }
.badge-cat { background: var(--bg); color: var(--text-3); border: 1px solid var(--border); }
.form-group { margin-bottom: 1rem; }
.form-group label { display: block; font-size: 0.8rem; font-weight: 600; color: var(--text-2); margin-bottom: 0.4rem; }
.form-group input, .form-group textarea, .form-group select { width: 100%; padding: 0.6rem 0.75rem; border: 1px solid var(--border); border-radius: 8px; font-size: 0.875rem; background: var(--bg); color: var(--text); outline: none; transition: border-color .15s; }
.form-group input:focus, .form-group textarea:focus, .form-group select:focus { border-color: var(--primary); box-shadow: 0 0 0 3px rgba(239,68,68,.12); }
.form-group textarea { min-height: 120px; resize: vertical; font-family: inherit; }
.btn-sm { padding: 0.3rem 0.75rem; font-size: 0.8rem; }
.btn-secondary { display: inline-block; background: var(--bg); color: var(--text-2); border: 1px solid var(--border); border-radius: 8px; padding: 0.6rem 1rem; cursor: pointer; font-size: 0.875rem; transition: background .15s; }
.btn-secondary:hover { background: var(--border); }

/* LOGIN */
.login-page { min-height: 100vh; display: flex; align-items: center; justify-content: center; background: #0f172a; }
.login-card { background: #1e293b; border: 1px solid #334155; border-radius: 16px; padding: 2.5rem; width: 360px; }
.login-logo { text-align: center; margin-bottom: 2rem; }
.login-logo svg { margin-bottom: 0.75rem; }
.login-logo h1 { color: var(--primary); font-size: 1.5rem; font-weight: 700; }
.login-logo p { color: #64748b; font-size: 0.85rem; margin-top: 0.25rem; }
.login-field { margin-bottom: 1rem; }
.login-field label { display: block; font-size: 0.8rem; font-weight: 600; color: #94a3b8; margin-bottom: 0.4rem; }
.login-field input { width: 100%; padding: 0.65rem 0.875rem; background: #0f172a; border: 1px solid #334155; border-radius: 8px; color: #f1f5f9; font-size: 0.9rem; outline: none; transition: border-color .15s; }
.login-field input:focus { border-color: var(--primary); }
.btn-login { width: 100%; padding: 0.75rem; background: var(--primary); color: white; border: none; border-radius: 8px; font-size: 0.9rem; font-weight: 600; cursor: pointer; margin-top: 0.5rem; transition: background .15s; }
.btn-login:hover { background: var(--primary-dark); }
.error-msg { background: rgba(239,68,68,.15); color: var(--primary); border: 1px solid rgba(239,68,68,.3); border-radius: 8px; padding: 0.65rem 0.875rem; font-size: 0.85rem; margin-bottom: 1rem; }

/* ERROR 404 */
.error-404 { text-align: center; padding: 4rem 1rem; }
.error-404 h1 { font-size: 5rem; font-weight: 700; color: var(--primary); }
.error-404 p { color: var(--text-3); margin: 1rem 0 2rem; }

/* RESPONSIVE */
@media (max-width: 768px) {
  /* Sidebar gizle — kategoriler mobil drawer'da */
  .sidebar { display: none; }
  .main-content { padding: 1rem; max-width: 100%; }
  .calc-grid { grid-template-columns: 1fr 1fr; gap: 0.5rem; }
  .calc-grid-sm { grid-template-columns: 1fr 1fr; }
  .hero h1 { font-size: 1.5rem; }
  /* Nav: arama gizle, hamburger göster */
  .nav-search { display: none; }
  .nav-hamburger { display: flex; }
  .admin-sidebar { display: none; }
  .calc-row { grid-template-columns: 1fr; }
  .calc-row-3 { grid-template-columns: 1fr; }
}

@media (max-width: 480px) {
  .calc-grid { grid-template-columns: 1fr; }
  .calc-grid-sm { grid-template-columns: 1fr; }
  .login-card { width: 100%; margin: 1rem; }
  .calc-page-header { flex-direction: column; gap: 0.5rem; }
  .calc-page-icon { font-size: 2rem; }
  .hero h1 { font-size: 1.3rem; }
  .logo-text { display: none; }
}

/* ===== FOUC Fix: Loading placeholder ===== */
.calc-loading-placeholder {
  min-height: 220px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--bg);
  border-radius: var(--radius);
}
.calc-spinner {
  width: 36px; height: 36px;
  border: 3px solid var(--border);
  border-top-color: var(--primary);
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
}
@keyframes spin { to { transform: rotate(360deg); } }
@keyframes shimmer { 0%{background-position:200% 0} 100%{background-position:-200% 0} }