/* =============================================
   TOOLZO.TOP – Global Stylesheet
   ============================================= */

/* Google Fonts */
@import url('https://fonts.googleapis.com/css2?family=Inter:wght@400;500;600;700;800&display=swap');

/* ---- CSS Variables ---- */
:root {
  --primary: #2563eb;
  --primary-dark: #1d4ed8;
  --primary-light: #eff6ff;
  --secondary: #0ea5e9;
  --accent: #f59e0b;
  --text: #1e293b;
  --text-muted: #64748b;
  --bg: #f8fafc;
  --bg-white: #ffffff;
  --border: #e2e8f0;
  --border-radius: 12px;
  --border-radius-sm: 8px;
  --shadow: 0 2px 8px rgba(0,0,0,0.07);
  --shadow-md: 0 4px 20px rgba(0,0,0,0.10);
  --shadow-lg: 0 8px 40px rgba(0,0,0,0.12);
  --transition: 0.2s ease;
  --max-width: 1200px;
  --header-height: 64px;
}

/* ---- Reset & Base ---- */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; }
body {
  font-family: 'Inter', system-ui, -apple-system, sans-serif;
  font-size: 16px;
  color: var(--text);
  background: var(--bg);
  line-height: 1.6;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}
main { flex: 1; }
a { color: var(--primary); text-decoration: none; }
a:hover { color: var(--primary-dark); }
img { max-width: 100%; height: auto; display: block; }
ul { list-style: none; }
button { cursor: pointer; font-family: inherit; }
input, textarea, select {
  font-family: inherit;
  font-size: 1rem;
}

/* ---- Container ---- */
.container {
  width: 100%;
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 20px;
}

/* =============================================
   HEADER / NAV
   ============================================= */
.site-header {
  background: var(--bg-white);
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  z-index: 1000;
  height: var(--header-height);
  display: flex;
  align-items: center;
  box-shadow: var(--shadow);
}

.site-header .container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
}

.logo {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 1.5rem;
  font-weight: 800;
  color: var(--primary);
  letter-spacing: -0.5px;
}
.logo span.logo-dot { color: var(--accent); }
.logo svg { width: 32px; height: 32px; }

.nav-links {
  display: flex;
  align-items: center;
  gap: 4px;
}
.nav-links a {
  color: var(--text);
  font-weight: 500;
  font-size: 0.9rem;
  padding: 6px 14px;
  border-radius: 8px;
  transition: background var(--transition), color var(--transition);
}
.nav-links a:hover, .nav-links a.active {
  background: var(--primary-light);
  color: var(--primary);
}

.nav-cta {
  background: var(--primary) !important;
  color: #fff !important;
  padding: 8px 18px !important;
  border-radius: 8px !important;
  font-weight: 600 !important;
}
.nav-cta:hover {
  background: var(--primary-dark) !important;
  color: #fff !important;
}

/* Hamburger */
.hamburger {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  padding: 4px;
  cursor: pointer;
  z-index: 1001;
}
.hamburger span {
  display: block;
  width: 24px;
  height: 2px;
  background: var(--text);
  border-radius: 2px;
  transition: transform 0.3s, opacity 0.3s;
}
.hamburger.open span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
.hamburger.open span:nth-child(2) { opacity: 0; }
.hamburger.open span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }

/* =============================================
   BMI CALCULATOR
   ============================================= */
.bmi-gauge {
  position: relative;
  width: 100%;
  max-width: 360px;
  margin: 0 auto;
}
.bmi-scale {
  display: flex;
  height: 20px;
  border-radius: 10px;
  overflow: hidden;
  margin-bottom: 8px;
}
.bmi-segment { flex: 1; }
.bmi-marker-wrap { position: relative; height: 32px; }
.bmi-marker {
  position: absolute;
  width: 16px;
  height: 16px;
  background: #1e293b;
  border-radius: 50%;
  top: 50%;
  transform: translate(-50%, -50%);
  transition: left 0.5s ease;
  box-shadow: 0 2px 8px rgba(0,0,0,.3);
}
.bmi-category-badge {
  display: inline-block;
  padding: 6px 20px;
  border-radius: 20px;
  font-weight: 700;
  font-size: 1.1rem;
  margin-top: 8px;
}

/* =============================================

   HERO (Homepage)
   ============================================= */
.hero {
  background: linear-gradient(135deg, #1e40af 0%, #2563eb 50%, #0ea5e9 100%);
  color: #fff;
  padding: 80px 0 60px;
  text-align: center;
  position: relative;
  overflow: hidden;
}
.hero::before {
  content: '';
  position: absolute;
  inset: 0;
  background: url("data:image/svg+xml,%3Csvg width='60' height='60' viewBox='0 0 60 60' xmlns='http://www.w3.org/2000/svg'%3E%3Cg fill='none' fill-rule='evenodd'%3E%3Cg fill='%23ffffff' fill-opacity='0.05'%3E%3Ccircle cx='30' cy='30' r='20'/%3E%3C/g%3E%3C/g%3E%3C/svg%3E") repeat;
  pointer-events: none;
}
.hero h1 {
  font-size: clamp(2rem, 5vw, 3.2rem);
  font-weight: 800;
  line-height: 1.2;
  margin-bottom: 16px;
  position: relative;
}
.hero h1 em { font-style: normal; color: #fde68a; }
.hero p {
  font-size: clamp(1rem, 2vw, 1.2rem);
  opacity: 0.9;
  max-width: 600px;
  margin: 0 auto 32px;
  position: relative;
}
.hero-actions { display: flex; gap: 12px; justify-content: center; flex-wrap: wrap; position: relative; }
.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 12px 28px;
  border-radius: var(--border-radius);
  font-weight: 600;
  font-size: 1rem;
  transition: all var(--transition);
  border: none;
  cursor: pointer;
}
.btn-primary {
  background: #fff;
  color: var(--primary);
  box-shadow: 0 4px 16px rgba(0,0,0,0.15);
}
.btn-primary:hover { transform: translateY(-2px); box-shadow: 0 8px 24px rgba(0,0,0,0.2); color: var(--primary-dark); }
.btn-outline {
  background: rgba(255,255,255,0.15);
  color: #fff;
  border: 2px solid rgba(255,255,255,0.4);
  backdrop-filter: blur(4px);
}
.btn-outline:hover { background: rgba(255,255,255,0.25); color: #fff; }

/* Stats bar */
.hero-stats {
  display: flex;
  gap: 40px;
  justify-content: center;
  flex-wrap: wrap;
  margin-top: 48px;
  padding-top: 32px;
  border-top: 1px solid rgba(255,255,255,0.2);
  position: relative;
}
.hero-stat h3 { font-size: 2rem; font-weight: 800; }
.hero-stat p { font-size: 0.85rem; opacity: 0.8; }

/* =============================================
   SECTION STYLES
   ============================================= */
.section { padding: 64px 0; }
.section-sm { padding: 40px 0; }
.section-header { text-align: center; margin-bottom: 48px; }
.section-header .eyebrow {
  display: inline-block;
  background: var(--primary-light);
  color: var(--primary);
  font-size: 0.8rem;
  font-weight: 700;
  padding: 4px 14px;
  border-radius: 20px;
  margin-bottom: 12px;
  text-transform: uppercase;
  letter-spacing: 0.5px;
}
.section-header h2 {
  font-size: clamp(1.5rem, 3vw, 2.2rem);
  font-weight: 800;
  margin-bottom: 12px;
  line-height: 1.25;
}
.section-header p { color: var(--text-muted); max-width: 560px; margin: 0 auto; }

/* =============================================
   TOOLS GRID
   ============================================= */
.tools-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: 20px;
}

.tool-card {
  background: var(--bg-white);
  border: 1px solid var(--border);
  border-radius: var(--border-radius);
  padding: 28px 24px;
  display: flex;
  flex-direction: column;
  gap: 12px;
  transition: transform var(--transition), box-shadow var(--transition), border-color var(--transition);
  text-decoration: none;
  color: var(--text);
  position: relative;
  overflow: hidden;
}
.tool-card::before {
  content: '';
  position: absolute;
  top: 0; left: 0; right: 0;
  height: 3px;
  background: var(--primary);
  transform: scaleX(0);
  transition: transform var(--transition);
  transform-origin: left;
}
.tool-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-md);
  border-color: var(--primary);
  color: var(--text);
}
.tool-card:hover::before { transform: scaleX(1); }

.tool-icon {
  width: 52px;
  height: 52px;
  border-radius: 14px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.6rem;
  flex-shrink: 0;
}

.tool-card h3 { font-size: 1rem; font-weight: 700; }
.tool-card p { font-size: 0.875rem; color: var(--text-muted); line-height: 1.5; }
.tool-link {
  margin-top: auto;
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--primary);
  display: inline-flex;
  align-items: center;
  gap: 4px;
}
.tool-card:hover .tool-link { gap: 8px; }

/* Category colors */
.cat-text { background: #eff6ff; }
.cat-security { background: #f0fdf4; }
.cat-generator { background: #fff7ed; }
.cat-image { background: #fdf4ff; }
.cat-developer { background: #f0f9ff; }
.cat-health { background: #fef2f2; }

/* =============================================
   TOOL PAGE LAYOUT
   ============================================= */
.tool-page-header {
  background: linear-gradient(135deg, #1e40af 0%, #2563eb 100%);
  color: #fff;
  padding: 48px 0 40px;
  text-align: center;
}
.tool-page-header .eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  background: rgba(255,255,255,0.15);
  color: #fff;
  border-radius: 20px;
  padding: 4px 14px;
  font-size: 0.8rem;
  font-weight: 600;
  margin-bottom: 12px;
}
.tool-page-header h1 { font-size: clamp(1.6rem, 4vw, 2.4rem); font-weight: 800; margin-bottom: 10px; }
.tool-page-header p { opacity: 0.88; max-width: 540px; margin: 0 auto; }

.tool-layout {
  display: grid;
  grid-template-columns: 1fr 300px;
  gap: 32px;
  padding: 40px 0 60px;
  align-items: start;
}
@media (max-width: 900px) {
  .tool-layout { grid-template-columns: 1fr; }
}

.tool-content-panel {
  background: var(--bg-white);
  border: 1px solid var(--border);
  border-radius: var(--border-radius);
  padding: 32px;
  box-shadow: var(--shadow);
}
.tool-sidebar { display: flex; flex-direction: column; gap: 20px; }

/* Tool UI elements */
.tool-label {
  display: block;
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--text);
  margin-bottom: 6px;
}
.tool-textarea {
  width: 100%;
  padding: 14px;
  border: 1.5px solid var(--border);
  border-radius: var(--border-radius-sm);
  resize: vertical;
  font-size: 0.95rem;
  line-height: 1.6;
  color: var(--text);
  background: var(--bg);
  transition: border-color var(--transition);
  min-height: 180px;
}
.tool-textarea:focus { outline: none; border-color: var(--primary); background: #fff; }
.tool-input {
  width: 100%;
  padding: 12px 14px;
  border: 1.5px solid var(--border);
  border-radius: var(--border-radius-sm);
  font-size: 0.95rem;
  color: var(--text);
  background: var(--bg);
  transition: border-color var(--transition);
}
.tool-input:focus { outline: none; border-color: var(--primary); background: #fff; }
.tool-select {
  width: 100%;
  padding: 12px 14px;
  border: 1.5px solid var(--border);
  border-radius: var(--border-radius-sm);
  font-size: 0.95rem;
  color: var(--text);
  background: var(--bg);
  cursor: pointer;
}
.tool-select:focus { outline: none; border-color: var(--primary); }

.tool-actions {
  display: flex;
  gap: 10px;
  flex-wrap: wrap;
  margin: 16px 0;
}
.btn-tool {
  padding: 10px 22px;
  border-radius: var(--border-radius-sm);
  font-weight: 600;
  font-size: 0.9rem;
  border: none;
  transition: all var(--transition);
}
.btn-tool-primary {
  background: var(--primary);
  color: #fff;
}
.btn-tool-primary:hover { background: var(--primary-dark); transform: translateY(-1px); }
.btn-tool-secondary {
  background: var(--bg);
  color: var(--text);
  border: 1.5px solid var(--border);
}
.btn-tool-secondary:hover { background: var(--border); }
.btn-tool-success {
  background: #10b981;
  color: #fff;
}
.btn-tool-success:hover { background: #059669; }
.btn-tool-danger {
  background: #ef4444;
  color: #fff;
}
.btn-tool-danger:hover { background: #dc2626; }

/* Stats/output boxes */
.stats-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(130px, 1fr));
  gap: 12px;
  margin: 16px 0;
}
.stat-box {
  background: var(--primary-light);
  border-radius: var(--border-radius-sm);
  padding: 14px 16px;
  text-align: center;
}
.stat-box .num { font-size: 1.6rem; font-weight: 800; color: var(--primary); line-height: 1; }
.stat-box .label { font-size: 0.75rem; color: var(--text-muted); margin-top: 4px; }

.output-box {
  background: #1e293b;
  color: #e2e8f0;
  border-radius: var(--border-radius-sm);
  padding: 16px;
  font-family: 'Courier New', monospace;
  font-size: 0.9rem;
  line-height: 1.6;
  overflow-x: auto;
  white-space: pre-wrap;
  word-break: break-word;
  min-height: 100px;
}

.result-output {
  background: var(--bg);
  border: 1.5px solid var(--border);
  border-radius: var(--border-radius-sm);
  padding: 16px;
  font-size: 0.95rem;
  min-height: 60px;
  word-break: break-all;
}

/* Checkbox group */
.checkbox-group {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
}
.checkbox-item {
  display: flex;
  align-items: center;
  gap: 6px;
  font-size: 0.9rem;
  cursor: pointer;
}
.checkbox-item input { width: 16px; height: 16px; cursor: pointer; accent-color: var(--primary); }

/* Range slider */
.range-wrap {
  display: flex;
  align-items: center;
  gap: 12px;
}
.tool-range {
  flex: 1;
  accent-color: var(--primary);
  cursor: pointer;
}
.range-val {
  font-weight: 700;
  font-size: 1.1rem;
  color: var(--primary);
  min-width: 36px;
  text-align: center;
}

/* Toast notification */
.toast {
  position: fixed;
  bottom: 24px;
  right: 24px;
  background: #1e293b;
  color: #fff;
  padding: 12px 22px;
  border-radius: 10px;
  font-size: 0.9rem;
  font-weight: 500;
  box-shadow: var(--shadow-lg);
  z-index: 9999;
  opacity: 0;
  transform: translateY(12px);
  transition: all 0.3s;
  pointer-events: none;
}
.toast.show { opacity: 1; transform: translateY(0); }
.toast.toast-success { background: #10b981; }
.toast.toast-error { background: #ef4444; }

/* How-to info box on sidebar */
.info-card {
  background: var(--bg-white);
  border: 1px solid var(--border);
  border-radius: var(--border-radius);
  padding: 20px;
  box-shadow: var(--shadow);
}
.info-card h4 {
  font-size: 0.95rem;
  font-weight: 700;
  margin-bottom: 12px;
  display: flex;
  align-items: center;
  gap: 6px;
}
.info-card ol, .info-card ul { padding-left: 18px; list-style: decimal; }
.info-card li { font-size: 0.85rem; color: var(--text-muted); margin-bottom: 6px; line-height: 1.5; }

/* =============================================
   FEATURES SECTION
   ============================================= */
.features-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
  gap: 24px;
}
.feature-card {
  background: var(--bg-white);
  border: 1px solid var(--border);
  border-radius: var(--border-radius);
  padding: 24px;
  text-align: center;
  box-shadow: var(--shadow);
  transition: transform var(--transition);
}
.feature-card:hover { transform: translateY(-3px); }
.feature-icon {
  font-size: 2.2rem;
  margin-bottom: 12px;
}
.feature-card h3 { font-size: 1rem; font-weight: 700; margin-bottom: 8px; }
.feature-card p { font-size: 0.85rem; color: var(--text-muted); line-height: 1.5; }

/* =============================================
   PAGE HERO (inner pages)
   ============================================= */
.page-hero {
  background: linear-gradient(135deg, #1e40af 0%, #2563eb 100%);
  color: #fff;
  padding: 56px 0;
  text-align: center;
}
.page-hero h1 { font-size: clamp(1.8rem, 4vw, 2.6rem); font-weight: 800; margin-bottom: 10px; }
.page-hero p { opacity: 0.88; max-width: 540px; margin: 0 auto; }

/* Breadcrumb */
.breadcrumb {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 0.85rem;
  color: var(--text-muted);
  margin-bottom: 24px;
}
.breadcrumb a { color: var(--primary); }
.breadcrumb span { color: var(--border); }

/* =============================================
   CARDS & PROSE
   ============================================= */
.card {
  background: var(--bg-white);
  border: 1px solid var(--border);
  border-radius: var(--border-radius);
  padding: 32px;
  box-shadow: var(--shadow);
}
.prose h2 { font-size: 1.4rem; font-weight: 700; margin: 32px 0 12px; }
.prose h3 { font-size: 1.1rem; font-weight: 700; margin: 24px 0 10px; }
.prose p { color: var(--text-muted); margin-bottom: 14px; line-height: 1.7; }
.prose ul { list-style: disc; padding-left: 20px; }
.prose ul li { color: var(--text-muted); margin-bottom: 8px; line-height: 1.6; font-size: 0.95rem; }
.prose a { color: var(--primary); text-decoration: underline; }

/* =============================================
   CONTACT FORM
   ============================================= */
.contact-form { display: flex; flex-direction: column; gap: 16px; }
.form-row { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; }
@media (max-width: 600px) { .form-row { grid-template-columns: 1fr; } }
.form-group { display: flex; flex-direction: column; gap: 6px; }
.form-group label { font-size: 0.85rem; font-weight: 600; }
.form-group input, .form-group textarea, .form-group select {
  padding: 11px 14px;
  border: 1.5px solid var(--border);
  border-radius: var(--border-radius-sm);
  font-size: 0.95rem;
  color: var(--text);
  background: var(--bg);
  transition: border-color var(--transition);
}
.form-group input:focus, .form-group textarea:focus {
  outline: none;
  border-color: var(--primary);
  background: #fff;
}
.form-group textarea { min-height: 140px; resize: vertical; }
.btn-submit {
  background: var(--primary);
  color: #fff;
  border: none;
  padding: 13px 32px;
  border-radius: var(--border-radius-sm);
  font-weight: 600;
  font-size: 1rem;
  cursor: pointer;
  transition: background var(--transition), transform var(--transition);
  align-self: flex-start;
}
.btn-submit:hover { background: var(--primary-dark); transform: translateY(-1px); }

/* =============================================
   FOOTER
   ============================================= */
.site-footer {
  background: #0f172a;
  color: #94a3b8;
  padding: 56px 0 0;
  margin-top: auto;
}
.footer-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: 40px;
  margin-bottom: 48px;
}
@media (max-width: 768px) {
  .footer-grid { grid-template-columns: 1fr 1fr; }
}
@media (max-width: 480px) {
  .footer-grid { grid-template-columns: 1fr; }
}
.footer-brand .logo { font-size: 1.4rem; color: #fff; margin-bottom: 12px; }
.footer-brand p { font-size: 0.875rem; line-height: 1.7; }
.footer-col h4 { color: #fff; font-size: 0.9rem; font-weight: 700; margin-bottom: 14px; }
.footer-col ul li { margin-bottom: 8px; }
.footer-col ul li a { color: #94a3b8; font-size: 0.875rem; transition: color var(--transition); }
.footer-col ul li a:hover { color: #fff; }
.footer-bottom {
  border-top: 1px solid #1e293b;
  padding: 20px 0;
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 10px;
}
.footer-bottom p { font-size: 0.8rem; }
.footer-bottom-links { display: flex; gap: 16px; }
.footer-bottom-links a { color: #94a3b8; font-size: 0.8rem; transition: color var(--transition); }
.footer-bottom-links a:hover { color: #fff; }

/* =============================================
   TOOLS LISTING PAGE
   ============================================= */
.category-filter {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: 32px;
}
.filter-btn {
  padding: 7px 18px;
  border-radius: 20px;
  border: 1.5px solid var(--border);
  background: var(--bg-white);
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--text-muted);
  cursor: pointer;
  transition: all var(--transition);
}
.filter-btn:hover { border-color: var(--primary); color: var(--primary); }
.filter-btn.active {
  background: var(--primary);
  border-color: var(--primary);
  color: #fff;
}
.search-bar {
  display: flex;
  gap: 10px;
  margin-bottom: 28px;
}
.search-bar input {
  flex: 1;
  padding: 12px 16px;
  border: 1.5px solid var(--border);
  border-radius: var(--border-radius-sm);
  font-size: 0.95rem;
  color: var(--text);
  background: var(--bg-white);
  transition: border-color var(--transition);
}
.search-bar input:focus { outline: none; border-color: var(--primary); }

/* =============================================
   RESPONSIVE / MOBILE
   ============================================= */
@media (max-width: 768px) {
  .nav-links {
    display: none;
    position: fixed;
    top: var(--header-height);
    left: 0; right: 0;
    background: var(--bg-white);
    flex-direction: column;
    align-items: stretch;
    padding: 16px;
    border-bottom: 1px solid var(--border);
    box-shadow: var(--shadow-md);
    gap: 4px;
  }
  .nav-links.open { display: flex; }
  .nav-links a { padding: 12px 16px; border-radius: 8px; }
  .hamburger { display: flex; }
  .hero { padding: 60px 0 48px; }
  .hero-stats { gap: 24px; }
  .section { padding: 48px 0; }
}

/* =============================================
   UTILITIES
   ============================================= */
.text-center { text-align: center; }
.text-muted { color: var(--text-muted); }
.mt-4 { margin-top: 16px; }
.mt-8 { margin-top: 32px; }
.mb-4 { margin-bottom: 16px; }
.mb-8 { margin-bottom: 32px; }
.gap-8 { gap: 32px; }
.flex { display: flex; }
.flex-center { display: flex; align-items: center; justify-content: center; }
.grid-2 { display: grid; grid-template-columns: 1fr 1fr; gap: 24px; }
@media (max-width: 640px) { .grid-2 { grid-template-columns: 1fr; } }

/* Progress bar for image compressor */
.progress-bar-wrap {
  background: var(--border);
  border-radius: 99px;
  height: 8px;
  overflow: hidden;
  margin: 8px 0;
}
.progress-bar-fill {
  height: 100%;
  background: var(--primary);
  border-radius: 99px;
  transition: width 0.4s;
  width: 0%;
}
/* QR canvas wrapper */
.qr-canvas-wrap {
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 24px;
  background: var(--bg);
  border: 1.5px dashed var(--border);
  border-radius: var(--border-radius-sm);
  min-height: 200px;
}

/* =============================================
   SCROLL TO TOP BUTTON
   ============================================= */
#scrollTopBtn {
  position: fixed;
  bottom: 28px;
  right: 28px;
  width: 44px;
  height: 44px;
  border-radius: 50%;
  background: var(--primary);
  color: #fff;
  font-size: 1.2rem;
  font-weight: 700;
  border: none;
  cursor: pointer;
  box-shadow: 0 4px 16px rgba(37,99,235,0.35);
  opacity: 0;
  transform: translateY(16px);
  transition: opacity 0.3s, transform 0.3s;
  pointer-events: none;
  z-index: 9998;
  line-height: 1;
}
#scrollTopBtn.visible {
  opacity: 1;
  transform: translateY(0);
  pointer-events: auto;
}
#scrollTopBtn:hover {
  background: var(--primary-dark);
  transform: translateY(-2px);
}