/* ==========================================================================
   PDF Master Hub - Premium CSS Design System
   Features: Modern Dark/Light mode, Glassmorphic UI, AdSense optimized layout,
   Responsive Grid, Micro-animations, Drag-and-drop tool components.
   ========================================================================== */

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

:root {
  /* Color Palette - Dark Default */
  --bg-main: #0b0f19;
  --bg-card: #151c2d;
  --bg-card-hover: #1e293b;
  --bg-glass: rgba(21, 28, 45, 0.75);
  --border-color: rgba(255, 255, 255, 0.08);
  --border-focus: #6366f1;
  
  --text-main: #f8fafc;
  --text-muted: #94a3b8;
  --text-dim: #64748b;
  
  --primary: #6366f1;
  --primary-hover: #4f46e5;
  --primary-light: rgba(99, 102, 241, 0.15);
  --secondary: #06b6d4;
  --secondary-hover: #0891b2;
  --accent: #10b981;
  --danger: #ef4444;
  --warning: #f59e0b;
  
  --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.3);
  --shadow-md: 0 8px 24px rgba(0, 0, 0, 0.4);
  --shadow-lg: 0 16px 40px rgba(0, 0, 0, 0.5);
  --shadow-glow: 0 0 25px rgba(99, 102, 241, 0.25);
  
  --radius-sm: 8px;
  --radius-md: 14px;
  --radius-lg: 20px;
  --radius-full: 9999px;

  --transition: all 0.25s cubic-bezier(0.4, 0, 0.2, 1);
}

[data-theme="light"] {
  --bg-main: #f8fafc;
  --bg-card: #ffffff;
  --bg-card-hover: #f1f5f9;
  --bg-glass: rgba(255, 255, 255, 0.85);
  --border-color: #e2e8f0;
  --border-focus: #4f46e5;
  
  --text-main: #0f172a;
  --text-muted: #475569;
  --text-dim: #94a3b8;
  
  --primary: #4f46e5;
  --primary-hover: #4338ca;
  --primary-light: rgba(79, 70, 229, 0.1);
  --shadow-sm: 0 2px 6px rgba(0, 0, 0, 0.05);
  --shadow-md: 0 6px 18px rgba(0, 0, 0, 0.08);
  --shadow-lg: 0 12px 32px rgba(0, 0, 0, 0.12);
  --shadow-glow: 0 0 20px rgba(79, 70, 229, 0.15);
}

/* Reset & Base Styles */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  scroll-behavior: smooth;
  font-family: 'Plus Jakarta Sans', 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
  background-color: var(--bg-main);
  color: var(--text-main);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

body {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  overflow-x: hidden;
}

a {
  color: inherit;
  text-decoration: none;
  transition: var(--transition);
}

button, input, select, textarea {
  font-family: inherit;
  font-size: inherit;
  color: inherit;
}

/* Layout Elements */
.container {
  width: 100%;
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 1.5rem;
}

/* Header & Navbar */
.navbar {
  position: sticky;
  top: 0;
  z-index: 1000;
  background: var(--bg-glass);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border-color);
  padding: 1rem 0;
  transition: var(--transition);
}

.nav-container {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.logo {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  font-size: 1.35rem;
  font-weight: 800;
  color: var(--text-main);
  letter-spacing: -0.02em;
}

.logo i {
  color: var(--primary);
  font-size: 1.6rem;
}

.logo-badge {
  font-size: 0.65rem;
  font-weight: 700;
  text-transform: uppercase;
  background: linear-gradient(135deg, var(--primary), var(--secondary));
  color: #ffffff;
  padding: 0.2rem 0.5rem;
  border-radius: var(--radius-full);
}

.nav-menu {
  display: flex;
  align-items: center;
  gap: 1.5rem;
  list-style: none;
}

.nav-link {
  font-weight: 600;
  font-size: 0.95rem;
  color: var(--text-muted);
  padding: 0.4rem 0.8rem;
  border-radius: var(--radius-sm);
}

.nav-link:hover, .nav-link.active {
  color: var(--text-main);
  background: var(--primary-light);
}

.nav-actions {
  display: flex;
  align-items: center;
  gap: 1rem;
}

.theme-toggle {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  color: var(--text-main);
  width: 40px;
  height: 40px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  transition: var(--transition);
}

.theme-toggle:hover {
  border-color: var(--primary);
  transform: rotate(15deg);
}

/* Mobile Toggle */
.menu-btn {
  display: none;
  background: none;
  border: none;
  color: var(--text-main);
  font-size: 1.5rem;
  cursor: pointer;
}

/* AdSense Container Slots */
.ads-container {
  width: 100%;
  margin: 2rem 0;
  display: flex;
  justify-content: center;
  align-items: center;
}

.ad-banner {
  width: 100%;
  max-width: 728px;
  min-height: 90px;
  background: var(--bg-card);
  border: 1px dashed var(--border-color);
  border-radius: var(--radius-md);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: 0.75rem;
  color: var(--text-dim);
  font-size: 0.85rem;
}

.ad-banner .ad-label {
  font-size: 0.7rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: 0.25rem;
  opacity: 0.7;
}

/* Tool Hero Section */
.hero-section {
  padding: 3.5rem 0 2rem;
  text-align: center;
}

.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.4rem 1rem;
  background: var(--primary-light);
  color: var(--primary);
  border: 1px solid rgba(99, 102, 241, 0.3);
  border-radius: var(--radius-full);
  font-size: 0.85rem;
  font-weight: 700;
  margin-bottom: 1.25rem;
}

.hero-title {
  font-size: 2.75rem;
  font-weight: 800;
  line-height: 1.2;
  margin-bottom: 1rem;
  letter-spacing: -0.03em;
}

.hero-title span {
  background: linear-gradient(135deg, var(--primary), var(--secondary));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.hero-subtitle {
  font-size: 1.15rem;
  color: var(--text-muted);
  max-width: 700px;
  margin: 0 auto 2.5rem;
}

/* Privacy Guarantee Banner */
.privacy-badge-bar {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 1.5rem;
  flex-wrap: wrap;
  margin-bottom: 2rem;
}

.privacy-item {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 0.9rem;
  color: var(--text-muted);
  font-weight: 500;
}

.privacy-item i {
  color: var(--accent);
}

/* Tool Workspace Card */
.tool-workspace {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 2.5rem;
  box-shadow: var(--shadow-lg);
  margin-bottom: 3rem;
  position: relative;
}

/* Dropzone Upload Area */
.dropzone {
  border: 2px dashed var(--border-color);
  border-radius: var(--radius-md);
  padding: 3.5rem 2rem;
  text-align: center;
  cursor: pointer;
  background: rgba(255, 255, 255, 0.01);
  transition: var(--transition);
  position: relative;
  overflow: hidden;
}

.dropzone:hover, .dropzone.dragover {
  border-color: var(--primary);
  background: var(--primary-light);
  box-shadow: var(--shadow-glow);
}

.dropzone-icon {
  font-size: 3.5rem;
  color: var(--primary);
  margin-bottom: 1rem;
  transition: var(--transition);
}

.dropzone:hover .dropzone-icon {
  transform: translateY(-5px) scale(1.05);
}

.dropzone-title {
  font-size: 1.25rem;
  font-weight: 700;
  margin-bottom: 0.5rem;
}

.dropzone-subtitle {
  font-size: 0.9rem;
  color: var(--text-muted);
  margin-bottom: 1.5rem;
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.6rem;
  padding: 0.85rem 1.75rem;
  font-size: 1rem;
  font-weight: 700;
  border-radius: var(--radius-md);
  border: none;
  cursor: pointer;
  transition: var(--transition);
  text-decoration: none;
}

.btn-primary {
  background: linear-gradient(135deg, var(--primary), var(--primary-hover));
  color: #ffffff;
  box-shadow: 0 4px 14px rgba(99, 102, 241, 0.4);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 20px rgba(99, 102, 241, 0.6);
}

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

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

.btn-danger {
  background: var(--danger);
  color: #ffffff;
}

.btn-danger:hover {
  opacity: 0.9;
}

.btn-lg {
  padding: 1.1rem 2.5rem;
  font-size: 1.1rem;
  border-radius: var(--radius-lg);
}

.btn-sm {
  padding: 0.5rem 1rem;
  font-size: 0.85rem;
  border-radius: var(--radius-sm);
}

/* File List & Previews */
.file-list {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(180px, 1fr));
  gap: 1.25rem;
  margin-top: 2rem;
}

.file-card {
  background: var(--bg-card-hover);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 1rem;
  position: relative;
  display: flex;
  flex-direction: column;
  align-items: center;
  transition: var(--transition);
}

.file-card:hover {
  border-color: var(--primary);
  transform: translateY(-3px);
}

.file-preview {
  width: 100%;
  height: 140px;
  background: #000;
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 0.75rem;
  overflow: hidden;
  position: relative;
}

.file-preview canvas, .file-preview img {
  max-width: 100%;
  max-height: 100%;
  object-fit: contain;
}

.file-name {
  font-size: 0.85rem;
  font-weight: 600;
  text-align: center;
  width: 100%;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
  margin-bottom: 0.25rem;
}

.file-size {
  font-size: 0.75rem;
  color: var(--text-dim);
}

.file-remove-btn {
  position: absolute;
  top: 0.5rem;
  right: 0.5rem;
  width: 26px;
  height: 26px;
  background: var(--danger);
  color: #fff;
  border: none;
  border-radius: 50%;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.75rem;
  opacity: 0.8;
  transition: var(--transition);
}

.file-remove-btn:hover {
  opacity: 1;
  transform: scale(1.1);
}

/* Action Controls Panel */
.tool-controls {
  margin-top: 2rem;
  padding-top: 1.5rem;
  border-top: 1px solid var(--border-color);
  display: flex;
  flex-wrap: wrap;
  gap: 1.25rem;
  align-items: center;
  justify-content: space-between;
}

.control-group {
  display: flex;
  flex-direction: column;
  gap: 0.4rem;
}

.control-group label {
  font-size: 0.85rem;
  font-weight: 700;
  color: var(--text-muted);
}

.form-control {
  background: var(--bg-main);
  border: 1px solid var(--border-color);
  color: var(--text-main);
  padding: 0.65rem 1rem;
  border-radius: var(--radius-sm);
  outline: none;
  transition: var(--transition);
}

.form-control:focus {
  border-color: var(--border-focus);
  box-shadow: 0 0 0 3px var(--primary-light);
}

/* Progress Bar & Status */
.progress-container {
  width: 100%;
  margin-top: 1.5rem;
  display: none;
}

.progress-bar {
  width: 100%;
  height: 8px;
  background: var(--bg-main);
  border-radius: var(--radius-full);
  overflow: hidden;
}

.progress-fill {
  height: 100%;
  width: 0%;
  background: linear-gradient(90deg, var(--primary), var(--secondary));
  transition: width 0.3s ease;
}

.progress-text {
  font-size: 0.85rem;
  color: var(--text-muted);
  text-align: center;
  margin-top: 0.5rem;
  font-weight: 600;
}

/* Tool Grid Hub (Index Page) */
.tool-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 1.75rem;
  margin: 3rem 0;
}

.tool-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 2rem 1.5rem;
  transition: var(--transition);
  display: flex;
  flex-direction: column;
  position: relative;
}

.tool-card:hover {
  transform: translateY(-6px);
  border-color: var(--primary);
  box-shadow: var(--shadow-glow);
}

.tool-icon {
  width: 54px;
  height: 54px;
  background: var(--primary-light);
  color: var(--primary);
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.6rem;
  margin-bottom: 1.25rem;
  transition: var(--transition);
}

.tool-card:hover .tool-icon {
  background: var(--primary);
  color: #ffffff;
  transform: scale(1.05);
}

.tool-title {
  font-size: 1.2rem;
  font-weight: 700;
  margin-bottom: 0.5rem;
}

.tool-desc {
  font-size: 0.9rem;
  color: var(--text-muted);
  margin-bottom: 1.5rem;
  flex-grow: 1;
}

.tool-link {
  font-size: 0.9rem;
  font-weight: 700;
  color: var(--primary);
  display: flex;
  align-items: center;
  gap: 0.4rem;
}

.tool-card:hover .tool-link i {
  transform: translateX(4px);
}

/* Rich SEO Article Content Section */
.seo-article {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 3rem;
  margin-bottom: 4rem;
  line-height: 1.8;
}

.seo-article h2 {
  font-size: 1.85rem;
  font-weight: 800;
  margin: 2rem 0 1rem;
  color: var(--text-main);
  letter-spacing: -0.02em;
}

.seo-article h2:first-child {
  margin-top: 0;
}

.seo-article h3 {
  font-size: 1.35rem;
  font-weight: 700;
  margin: 1.5rem 0 0.75rem;
  color: var(--text-main);
}

.seo-article p {
  color: var(--text-muted);
  margin-bottom: 1.25rem;
  font-size: 1.02rem;
}

.seo-article ul, .seo-article ol {
  margin: 1rem 0 1.5rem 1.5rem;
  color: var(--text-muted);
}

.seo-article li {
  margin-bottom: 0.5rem;
}

/* Steps Grid */
.steps-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 1.5rem;
  margin: 2rem 0;
}

.step-card {
  background: var(--bg-main);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 1.5rem;
  position: relative;
}

.step-num {
  font-size: 2rem;
  font-weight: 800;
  color: var(--primary);
  margin-bottom: 0.5rem;
  opacity: 0.8;
}

.step-title {
  font-weight: 700;
  margin-bottom: 0.5rem;

}

.step-desc {
  font-size: 0.88rem;
  color: var(--text-muted);
}

/* FAQ Accordion */
.faq-container {
  margin-top: 2rem;
}

.faq-item {
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  margin-bottom: 1rem;
  background: var(--bg-main);
  overflow: hidden;
}

.faq-question {
  padding: 1.25rem 1.5rem;
  font-weight: 700;
  cursor: pointer;
  display: flex;
  justify-content: space-between;
  align-items: center;
  user-select: none;
  font-size: 1.05rem;
}

.faq-answer {
  padding: 0 1.5rem 1.25rem;
  color: var(--text-muted);
  font-size: 0.95rem;
  display: none;
}

.faq-item.active .faq-answer {
  display: block;
}

.faq-item.active .faq-icon {
  transform: rotate(180deg);
}

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

.footer-grid {
  display: grid;
  grid-template-columns: 2fr repeat(3, 1fr);
  gap: 3rem;
  margin-bottom: 3rem;
}

.footer-brand p {
  color: var(--text-muted);
  font-size: 0.9rem;
  margin-top: 1rem;
  max-width: 320px;
}

.footer-heading {
  font-size: 1rem;
  font-weight: 700;
  margin-bottom: 1.25rem;
  color: var(--text-main);
}

.footer-links {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

.footer-links a {
  color: var(--text-muted);
  font-size: 0.9rem;
}

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

.footer-bottom {
  border-top: 1px solid var(--border-color);
  padding-top: 2rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 0.85rem;
  color: var(--text-dim);
}

/* Toast Notifications */
.toast-container {
  position: fixed;
  bottom: 2rem;
  right: 2rem;
  z-index: 9999;
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

.toast {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-left: 4px solid var(--primary);
  padding: 1rem 1.25rem;
  border-radius: var(--radius-sm);
  box-shadow: var(--shadow-md);
  color: var(--text-main);
  font-size: 0.9rem;
  font-weight: 600;
  display: flex;
  align-items: center;
  gap: 0.75rem;
  animation: slideIn 0.3s ease;
}

.toast.success { border-left-color: var(--accent); }
.toast.error { border-left-color: var(--danger); }
.toast.warning { border-left-color: var(--warning); }

@keyframes slideIn {
  from { transform: translateX(100%); opacity: 0; }
  to { transform: translateX(0); opacity: 1; }
}

/* Canvas & Drawing Overlay Styling (Signer tool) */
.canvas-wrapper {
  position: relative;
  display: inline-block;
  box-shadow: var(--shadow-md);
  background: #ffffff;
  border-radius: var(--radius-sm);
  overflow: hidden;
  margin: 1rem auto;
}

/* Responsive Media Queries */
@media (max-width: 992px) {
  .footer-grid {
    grid-template-columns: 1fr 1fr;
  }
  .hero-title {
    font-size: 2.25rem;
  }
}

@media (max-width: 768px) {
  .nav-menu {
    position: fixed;
    top: 70px;
    left: -100%;
    width: 100%;
    height: calc(100vh - 70px);
    background: var(--bg-main);
    flex-direction: column;
    padding: 2rem;
    transition: 0.3s ease;
  }
  .nav-menu.active {
    left: 0;
  }
  .menu-btn {
    display: block;
  }
  .tool-workspace {
    padding: 1.5rem;
  }
  .seo-article {
    padding: 1.75rem;
  }
  .footer-grid {
    grid-template-columns: 1fr;
  }
  .footer-bottom {
    flex-direction: column;
    gap: 1rem;
    text-align: center;
  }
}