/* ===========================
   PDF Tools Hub - Main Stylesheet
   A clean, professional blue & white theme
   =========================== */

/* ===========================
   1. CSS RESET & BASE
   =========================== */
*, *::before, *::after {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-family);
  font-size: var(--font-size-base);
  line-height: var(--line-height);
  color: var(--color-gray-800);
  background-color: var(--color-white);
  -webkit-font-smoothing: antialiased;
}

img {
  max-width: 100%;
  height: auto;
  display: block;
}

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

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

ul, ol {
  list-style: none;
}

button {
  cursor: pointer;
  border: none;
  background: none;
  font-family: inherit;
  font-size: inherit;
}

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

/* ===========================
   2. DESIGN TOKENS (Custom Properties)
   =========================== */
:root {
  /* Colors - Blue & White Theme */
  --color-primary: #2563eb;
  --color-primary-dark: #1d4ed8;
  --color-primary-light: #dbeafe;
  --color-primary-lighter: #eff6ff;
  --color-secondary: #1e40af;
  --color-white: #ffffff;
  --color-gray-50: #f9fafb;
  --color-gray-100: #f3f4f6;
  --color-gray-200: #e5e7eb;
  --color-gray-300: #d1d5db;
  --color-gray-400: #9ca3af;
  --color-gray-600: #4b5563;
  --color-gray-700: #374151;
  --color-gray-800: #1f2937;
  --color-gray-900: #111827;
  --color-success: #10b981;
  --color-error: #ef4444;
  --color-warning: #f59e0b;

  /* Typography */
  --font-family: 'Segoe UI', system-ui, -apple-system, sans-serif;
  --font-size-base: 16px;
  --font-size-sm: 14px;
  --font-size-lg: 18px;
  --font-size-xl: 24px;
  --font-size-2xl: 32px;
  --font-size-3xl: 40px;
  --font-size-4xl: 48px;
  --line-height: 1.6;

  /* Spacing */
  --space-xs: 4px;
  --space-sm: 8px;
  --space-md: 16px;
  --space-lg: 24px;
  --space-xl: 32px;
  --space-2xl: 48px;
  --space-3xl: 64px;
  --space-4xl: 80px;

  /* Borders & Shadows */
  --border-radius: 8px;
  --border-radius-lg: 12px;
  --border-radius-xl: 16px;
  --border-radius-full: 9999px;
  --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.08);
  --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.1);
  --shadow-lg: 0 8px 24px rgba(0, 0, 0, 0.12);
  --shadow-xl: 0 12px 32px rgba(0, 0, 0, 0.15);

  /* Layout */
  --container-max: 1200px;
  --container-narrow: 800px;
  --header-height: 70px;
}

/* ===========================
   3. TYPOGRAPHY
   =========================== */
h1, h2, h3, h4, h5, h6 {
  color: var(--color-gray-900);
  line-height: 1.3;
  font-weight: 700;
}

h1 { font-size: var(--font-size-3xl); margin-bottom: var(--space-lg); }
h2 { font-size: var(--font-size-2xl); margin-bottom: var(--space-lg); }
h3 { font-size: var(--font-size-xl); margin-bottom: var(--space-md); }
h4 { font-size: var(--font-size-lg); margin-bottom: var(--space-sm); }

p {
  margin-bottom: var(--space-md);
  color: var(--color-gray-600);
}

/* ===========================
   4. LAYOUT (Container, Grid)
   =========================== */
.container {
  width: 100%;
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 var(--space-lg);
}

.container-narrow {
  max-width: var(--container-narrow);
  margin: 0 auto;
  padding: 0 var(--space-lg);
}

.section {
  padding: var(--space-3xl) 0;
}

.section-gray {
  background-color: var(--color-gray-50);
}

.text-center {
  text-align: center;
}

/* ===========================
   5. HEADER & NAVIGATION
   =========================== */
.site-header {
  position: sticky;
  top: 0;
  z-index: 1000;
  background: var(--color-white);
  border-bottom: 1px solid var(--color-gray-200);
  height: var(--header-height);
  display: flex;
  align-items: center;
  box-shadow: var(--shadow-sm);
}

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

.logo {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  font-size: var(--font-size-lg);
  font-weight: 700;
  color: var(--color-primary);
  text-decoration: none;
}

.logo:hover {
  color: var(--color-primary-dark);
}

.logo img {
  width: 36px;
  height: 36px;
}

.main-nav ul {
  display: flex;
  align-items: center;
  gap: var(--space-xl);
}

.main-nav a {
  color: var(--color-gray-700);
  font-weight: 500;
  padding: var(--space-sm) 0;
  transition: color 0.2s ease;
}

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

.mobile-menu-btn {
  display: none;
  flex-direction: column;
  gap: 5px;
  padding: var(--space-sm);
  width: 44px;
  height: 44px;
  align-items: center;
  justify-content: center;
}

.hamburger-line {
  display: block;
  width: 24px;
  height: 2px;
  background: var(--color-gray-800);
  border-radius: 2px;
  transition: transform 0.3s ease, opacity 0.3s ease;
}

/* Mobile menu open state */
.mobile-menu-btn.active .hamburger-line:nth-child(1) {
  transform: translateY(7px) rotate(45deg);
}
.mobile-menu-btn.active .hamburger-line:nth-child(2) {
  opacity: 0;
}
.mobile-menu-btn.active .hamburger-line:nth-child(3) {
  transform: translateY(-7px) rotate(-45deg);
}

/* ===========================
   6. FOOTER
   =========================== */
.site-footer {
  background: var(--color-gray-900);
  color: var(--color-gray-300);
  padding: var(--space-3xl) 0 var(--space-lg);
}

.footer-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: var(--space-2xl);
  margin-bottom: var(--space-2xl);
}

.footer-section h3 {
  color: var(--color-white);
  font-size: var(--font-size-lg);
  margin-bottom: var(--space-md);
}

.footer-section p {
  color: var(--color-gray-400);
}

.footer-section ul li {
  margin-bottom: var(--space-sm);
}

.footer-section ul a {
  color: var(--color-gray-400);
  transition: color 0.2s ease;
}

.footer-section ul a:hover {
  color: var(--color-white);
}

.footer-bottom {
  border-top: 1px solid var(--color-gray-700);
  padding-top: var(--space-lg);
  text-align: center;
}

.footer-bottom p {
  color: var(--color-gray-400);
  font-size: var(--font-size-sm);
}

/* ===========================
   7. HOMEPAGE SECTIONS
   =========================== */

/* Hero Section */
.hero {
  background: linear-gradient(135deg, var(--color-primary-lighter) 0%, var(--color-primary-light) 100%);
  padding: var(--space-4xl) 0;
  text-align: center;
}

.hero h1 {
  font-size: var(--font-size-4xl);
  color: var(--color-gray-900);
  margin-bottom: var(--space-md);
}

.hero p {
  font-size: var(--font-size-lg);
  max-width: 600px;
  margin: 0 auto var(--space-xl);
  color: var(--color-gray-600);
}

/* Tools Grid */
.tools-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
  gap: var(--space-lg);
}

.tools-grid--small {
  grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
}

.tool-card {
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  padding: var(--space-xl);
  background: var(--color-white);
  border: 1px solid var(--color-gray-200);
  border-radius: var(--border-radius-lg);
  box-shadow: var(--shadow-sm);
  transition: transform 0.2s ease, box-shadow 0.2s ease;
  text-decoration: none;
  color: inherit;
}

.tool-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
  color: inherit;
}

.tool-card img {
  width: 48px;
  height: 48px;
  margin-bottom: var(--space-md);
}

.tool-card h3 {
  font-size: var(--font-size-lg);
  margin-bottom: var(--space-sm);
  color: var(--color-gray-900);
}

.tool-card p {
  font-size: var(--font-size-sm);
  color: var(--color-gray-600);
  margin-bottom: 0;
}

/* Why Choose Us */
.features-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
  gap: var(--space-xl);
}

.feature-item {
  text-align: center;
  padding: var(--space-xl);
}

.feature-icon {
  width: 64px;
  height: 64px;
  background: var(--color-primary-light);
  border-radius: var(--border-radius-full);
  display: flex;
  align-items: center;
  justify-content: center;
  margin: 0 auto var(--space-md);
}

.feature-icon svg {
  width: 32px;
  height: 32px;
  color: var(--color-primary);
}

/* How It Works */
.steps-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
  gap: var(--space-xl);
  counter-reset: step;
}

.step-item {
  text-align: center;
  padding: var(--space-xl);
  position: relative;
}

.step-number {
  width: 48px;
  height: 48px;
  background: var(--color-primary);
  color: var(--color-white);
  border-radius: var(--border-radius-full);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: var(--font-size-xl);
  font-weight: 700;
  margin: 0 auto var(--space-md);
}

/* ===========================
   8. TOOL PAGE SECTIONS
   =========================== */

/* Tool Section */
.tool-section {
  padding: var(--space-2xl) 0;
}

.tool-description {
  font-size: var(--font-size-lg);
  max-width: 700px;
  margin-bottom: var(--space-xl);
}

/* Tool Workspace */
.tool-workspace {
  background: var(--color-white);
  border: 2px solid var(--color-gray-200);
  border-radius: var(--border-radius-xl);
  padding: var(--space-2xl);
  box-shadow: var(--shadow-md);
  margin-bottom: var(--space-xl);
}

/* Upload Area */
.upload-area {
  border: 2px dashed var(--color-primary);
  border-radius: var(--border-radius-lg);
  padding: var(--space-3xl) var(--space-xl);
  text-align: center;
  cursor: pointer;
  transition: background 0.2s ease, border-color 0.2s ease;
  background: var(--color-primary-lighter);
}

.upload-area:hover,
.upload-area.drag-over {
  background: var(--color-primary-light);
  border-color: var(--color-primary-dark);
}

.upload-icon {
  margin-bottom: var(--space-md);
}

.upload-icon svg {
  width: 48px;
  height: 48px;
  color: var(--color-primary);
}

.upload-area p {
  color: var(--color-gray-600);
  margin-bottom: var(--space-sm);
}

.upload-hint {
  font-size: var(--font-size-sm);
  color: var(--color-gray-400);
}

/* Action Area */
.action-area {
  padding: var(--space-xl) 0;
}

.action-area label {
  display: block;
  font-weight: 600;
  margin-bottom: var(--space-sm);
  color: var(--color-gray-800);
}

/* Output Area */
.output-area {
  text-align: center;
  padding: var(--space-xl);
  background: var(--color-gray-50);
  border-radius: var(--border-radius-lg);
}

.success-msg {
  color: var(--color-success);
  font-weight: 600;
  font-size: var(--font-size-lg);
  margin-bottom: var(--space-md);
}

/* File List */
.file-list {
  margin: var(--space-md) 0;
}

.file-item {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: var(--space-sm) var(--space-md);
  background: var(--color-gray-50);
  border-radius: var(--border-radius);
  margin-bottom: var(--space-sm);
}

.file-item span {
  font-size: var(--font-size-sm);
  color: var(--color-gray-700);
}

.file-item button {
  color: var(--color-error);
  font-size: var(--font-size-sm);
  font-weight: 500;
}

/* How To Use */
.how-to-use {
  padding: var(--space-2xl) 0;
}

.steps-list {
  max-width: 700px;
  counter-reset: steps;
}

.steps-list li {
  position: relative;
  padding: var(--space-md) 0 var(--space-md) var(--space-3xl);
  border-left: 2px solid var(--color-primary-light);
  margin-left: var(--space-md);
}

.steps-list li::before {
  counter-increment: steps;
  content: counter(steps);
  position: absolute;
  left: -16px;
  top: var(--space-md);
  width: 30px;
  height: 30px;
  background: var(--color-primary);
  color: var(--color-white);
  border-radius: var(--border-radius-full);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: var(--font-size-sm);
  font-weight: 700;
}

.steps-list li:last-child {
  border-left-color: transparent;
}

/* Related Tools */
.related-tools {
  padding: var(--space-2xl) 0;
}

/* ===========================
   9. FAQ SECTION
   =========================== */
.faq-section {
  padding: var(--space-2xl) 0;
}

.faq-item {
  border: 1px solid var(--color-gray-200);
  border-radius: var(--border-radius);
  margin-bottom: var(--space-md);
  overflow: hidden;
}

.faq-question {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: var(--space-lg);
  cursor: pointer;
  background: var(--color-white);
  transition: background 0.2s ease;
  width: 100%;
  text-align: left;
  font-weight: 600;
  font-size: var(--font-size-base);
  color: var(--color-gray-800);
}

.faq-question:hover {
  background: var(--color-gray-50);
}

.faq-question::after {
  content: '+';
  font-size: var(--font-size-xl);
  color: var(--color-primary);
  font-weight: 300;
  transition: transform 0.3s ease;
}

.faq-item.active .faq-question::after {
  transform: rotate(45deg);
}

.faq-answer {
  padding: 0 var(--space-lg) var(--space-lg);
  display: none;
}

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

.faq-answer p {
  color: var(--color-gray-600);
  margin-bottom: 0;
}

/* ===========================
   10. INFORMATIONAL PAGES
   =========================== */
.page-content {
  padding: var(--space-3xl) 0;
}

.page-content h1 {
  margin-bottom: var(--space-xl);
}

.page-content h2 {
  margin-top: var(--space-xl);
  font-size: var(--font-size-xl);
}

.page-content p {
  margin-bottom: var(--space-md);
  line-height: 1.8;
}

.page-content ul {
  list-style: disc;
  padding-left: var(--space-xl);
  margin-bottom: var(--space-md);
}

.page-content ul li {
  margin-bottom: var(--space-sm);
  color: var(--color-gray-600);
}

/* Contact Form */
.contact-form {
  max-width: 600px;
}

.form-group {
  margin-bottom: var(--space-lg);
}

.form-group label {
  display: block;
  font-weight: 600;
  margin-bottom: var(--space-sm);
  color: var(--color-gray-800);
}

.form-group input,
.form-group textarea,
.form-group select {
  width: 100%;
  padding: var(--space-md);
  border: 1px solid var(--color-gray-300);
  border-radius: var(--border-radius);
  font-size: var(--font-size-base);
  transition: border-color 0.2s ease, box-shadow 0.2s ease;
}

.form-group input:focus,
.form-group textarea:focus,
.form-group select:focus {
  outline: none;
  border-color: var(--color-primary);
  box-shadow: 0 0 0 3px var(--color-primary-light);
}

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

.form-error {
  color: var(--color-error);
  font-size: var(--font-size-sm);
  margin-top: var(--space-xs);
  display: none;
}

/* ===========================
   11. COMPONENTS
   =========================== */

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: var(--space-md) var(--space-xl);
  font-size: var(--font-size-base);
  font-weight: 600;
  border-radius: var(--border-radius);
  transition: all 0.2s ease;
  text-decoration: none;
  cursor: pointer;
  border: none;
  min-height: 44px;
}

.btn-primary {
  background: var(--color-primary);
  color: var(--color-white);
  box-shadow: var(--shadow-sm);
}

.btn-primary:hover {
  background: var(--color-primary-dark);
  box-shadow: var(--shadow-md);
  color: var(--color-white);
  transform: translateY(-1px);
}

.btn-secondary {
  background: var(--color-white);
  color: var(--color-primary);
  border: 2px solid var(--color-primary);
}

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

.btn-large {
  padding: var(--space-lg) var(--space-2xl);
  font-size: var(--font-size-lg);
  border-radius: var(--border-radius-lg);
}

.upload-btn {
  color: var(--color-primary);
  font-weight: 600;
  text-decoration: underline;
  cursor: pointer;
}

/* Ad Placeholder */
.ad-placeholder {
  width: 100%;
  max-width: 728px;
  min-height: 90px;
  margin: var(--space-2xl) auto;
  background: var(--color-gray-50);
  border: 1px dashed var(--color-gray-300);
  border-radius: var(--border-radius);
  display: flex;
  align-items: center;
  justify-content: center;
}

.ad-label {
  color: var(--color-gray-400);
  font-size: var(--font-size-sm);
  margin-bottom: 0;
}

/* Error/Success Messages */
.message {
  padding: var(--space-md);
  border-radius: var(--border-radius);
  margin-bottom: var(--space-md);
  font-size: var(--font-size-sm);
}

.message-error {
  background: #fef2f2;
  color: var(--color-error);
  border: 1px solid #fecaca;
}

.message-success {
  background: #ecfdf5;
  color: var(--color-success);
  border: 1px solid #a7f3d0;
}

/* Section Header */
.section-header {
  text-align: center;
  margin-bottom: var(--space-2xl);
}

.section-header p {
  max-width: 600px;
  margin: 0 auto;
}

/* ===========================
   12. UTILITY CLASSES
   =========================== */
.hidden { display: none !important; }
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  border: 0;
}

/* ===========================
   13. RESPONSIVE OVERRIDES
   =========================== */

/* Tablet: 768px and below */
@media (max-width: 767px) {
  .mobile-menu-btn {
    display: flex;
  }

  .main-nav {
    position: fixed;
    top: var(--header-height);
    left: 0;
    right: 0;
    background: var(--color-white);
    border-bottom: 1px solid var(--color-gray-200);
    box-shadow: var(--shadow-lg);
    padding: var(--space-lg);
    transform: translateY(-100%);
    opacity: 0;
    visibility: hidden;
    transition: all 0.3s ease;
    z-index: 999;
  }

  .main-nav.active {
    transform: translateY(0);
    opacity: 1;
    visibility: visible;
  }

  .main-nav ul {
    flex-direction: column;
    gap: var(--space-md);
  }

  .main-nav a {
    display: block;
    padding: var(--space-md);
    font-size: var(--font-size-lg);
  }

  /* Hero */
  .hero {
    padding: var(--space-2xl) 0;
  }

  .hero h1 {
    font-size: var(--font-size-2xl);
  }

  /* Grids */
  .tools-grid {
    grid-template-columns: 1fr;
  }

  .tools-grid--small {
    grid-template-columns: 1fr;
  }

  .footer-grid {
    grid-template-columns: 1fr;
    gap: var(--space-xl);
  }

  .features-grid,
  .steps-grid {
    grid-template-columns: 1fr;
  }

  /* Ad Placeholder */
  .ad-placeholder {
    max-width: 320px;
    min-height: 50px;
  }

  /* Typography */
  h1 { font-size: var(--font-size-2xl); }
  h2 { font-size: var(--font-size-xl); }

  /* Tool Workspace */
  .tool-workspace {
    padding: var(--space-lg);
  }

  .upload-area {
    padding: var(--space-xl) var(--space-md);
  }
}

/* Small tablet */
@media (min-width: 768px) and (max-width: 1023px) {
  .tools-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .footer-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

/* Desktop: 1024px+ */
@media (min-width: 1024px) {
  .tools-grid {
    grid-template-columns: repeat(3, 1fr);
  }
}

/* Large desktop: 1440px+ */
@media (min-width: 1440px) {
  .tools-grid {
    grid-template-columns: repeat(4, 1fr);
  }
}