:root {
  --primary-color: #2563eb;
  --secondary-color: #1e40af;
  --accent-color: #3b82f6;
  --dark-color: #1e293b;
  --light-color: #f8fafc;
  --gray-color: #94a3b8;
  --card-bg: #ffffff;
  --text-color: #1e293b;
  --text-light: #64748b;
  --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.1);
  --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.1);
  --shadow-lg: 0 10px 15px rgba(0, 0, 0, 0.1);
  --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  --border-color: #e2e8f0;
}

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

body {
  font-family: "Poppins", sans-serif;
  line-height: 1.6;
  color: var(--text-color);
  background-color: var(--light-color);
  transition: var(--transition);
}

a {
  text-decoration: none;
  color: inherit;
}

ul {
  list-style: none;
}

.container {
  width: 100%;
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 20px;
}

.btn {
  display: inline-block;
  padding: 12px 24px;
  border-radius: 8px;
  font-weight: 600;
  letter-spacing: 0.5px;
  transition: var(--transition);
  text-align: center;
  cursor: pointer;
}

.btn-primary {
  background-color: var(--primary-color);
  color: white;
  border: 2px solid var(--primary-color);
  box-shadow: 0 4px 6px rgba(37, 99, 235, 0.3);
}

.btn-primary:hover {
  background-color: var(--secondary-color);
  border-color: var(--secondary-color);
  transform: translateY(-3px);
  box-shadow: 0 6px 8px rgba(37, 99, 235, 0.4);
}

.btn-secondary {
  background-color: transparent;
  color: var(--primary-color);
  border: 2px solid var(--primary-color);
  box-shadow: var(--shadow-sm);
}

.btn-secondary:hover {
  background-color: var(--primary-color);
  color: white;
  transform: translateY(-3px);
  box-shadow: var(--shadow-md);
}

.section-title {
  font-size: 2.2rem;
  margin-bottom: 2.5rem;
  text-align: center;
  position: relative;
  color: var(--text-color);
}

.section-title::after {
  content: "";
  display: block;
  width: 80px;
  height: 4px;
  background: linear-gradient(90deg, var(--primary-color), var(--accent-color));
  margin: 15px auto;
  border-radius: 2px;
}

.gradient-text {
  background: linear-gradient(90deg, var(--primary-color), var(--accent-color));
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
  display: inline;
}

/* Header Styles */
.header {
  background-color: var(--card-bg);
  box-shadow: var(--shadow-sm);
  position: fixed;
  width: 100%;
  top: 0;
  left: 0;
  z-index: 1000;
  padding: 15px 0;
  transition: all 0.3s ease;
}

.header.scrolled {
  padding: 10px 0;
  box-shadow: 0 4px 10px rgba(0, 0, 0, 0.1);
  background-color: rgba(255, 255, 255, 0.95);
}

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

.logo {
  display: flex;
  align-items: center;
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--text-color);
}


.logo span {
  position: relative;
}



.navbar {
  transition: var(--transition);
}

.navbar ul {
  display: flex;
}

.navbar ul li {
  margin-left: 30px;
  position: relative;
}

.navbar ul li a {
  font-weight: 500;
  transition: var(--transition);
  position: relative;
  color: var(--text-light);
  padding: 5px 0;
}

.navbar ul li a:hover {
  color: var(--primary-color);
}

.navbar ul li a.active {
  color: var(--primary-color);
  font-weight: 600;
}

.navbar ul li a.active::after {
  content: "";
  position: absolute;
  bottom: -5px;
  left: 0;
  width: 100%;
  height: 2px;
  background: linear-gradient(90deg, var(--primary-color), var(--accent-color));
}

.mobile-menu-btn {
  display: none;
  font-size: 1.5rem;
  cursor: pointer;
  color: var(--text-color);
  transition: var(--transition);
  background: none;
  border: none;
}

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

.mobile-menu-btn i.fa-times {
  display: none;
}

.mobile-menu-btn.active i.fa-bars {
  display: none;
}

.mobile-menu-btn.active i.fa-times {
  display: block;
}

/* Hero Section */
.book-hero {
  text-align: center;
  padding: 8rem 0 6rem;
  margin-top: 80px;
  margin-bottom: 3rem;
  position: relative;
  overflow: hidden;
  background-color: #f8fafc;
  border-bottom: 1px solid rgba(0, 0, 0, 0.05);
}

.book-hero.scrani::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: url('https://t3.ftcdn.net/jpg/08/15/90/80/360_F_815908053_Mfy2DJfv1iFSdL6ET9pRD5R5VzOOEu5k.jpg') center/cover;
  opacity: 0.15;
  z-index: 1;
}

.book-hero .container {
  position: relative;
  z-index: 2;
}

.book-hero h1 {
  font-size: 3rem;
  margin-bottom: 1.5rem;
  animation: fadeInUp 0.8s ease;
  background: linear-gradient(90deg, var(--primary-color), var(--accent-color));
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}

/* Book Info Section */
.book-info {
  padding: 80px 0;
  background-color: var(--light-color);
}

.book-description {
  max-width: 1000px;
  margin: 0 auto 20px;
  text-align: justify;
  font-size: 1.1rem;
  color: var(--text-light);
}

/* Versions Section */
.book-versions {
  padding: 60px 0;
  background-color: var(--card-bg);
}

.version-cards {
  display: flex;
  justify-content: center;
  gap: 30px;
  flex-wrap: wrap;
  margin-top: 40px;
}

.version-card {
  background-color: var(--card-bg);
  border-radius: 12px;
  padding: 40px 30px;
  width: 350px;
  box-shadow: var(--shadow-md);
  transition: var(--transition);
  border: 1px solid var(--border-color);
  text-align: center;
}

.version-card:hover {
  transform: translateY(-10px);
  box-shadow: var(--shadow-lg);
}

.version-icon {
  font-size: 2.5rem;
  color: var(--primary-color);
  margin-bottom: 20px;
}

.version-title {
  font-size: 1.5rem;
  margin-bottom: 15px;
  color: var(--text-color);
}

.version-authors {
  color: var(--gray-color);
  margin-bottom: 25px;
  font-size: 0.95rem;
}

.version-buttons {
  display: flex;
  justify-content: center;
  gap: 15px;
  margin-top: 20px;
}

/* Publisher Section */
.book-publisher {
  padding: 80px 0 100px;
  background-color: var(--light-color);
  text-align: center;
}

.publisher-card {
  background-color: var(--card-bg);
  border-radius: 12px;
  padding: 40px;
  max-width: 600px;
  margin: 0 auto;
  box-shadow: var(--shadow-md);
  transition: var(--transition);
  border: 1px solid var(--border-color);
}

.publisher-card:hover {
  transform: translateY(-5px);
  box-shadow: var(--shadow-lg);
}

.publisher-img {
  width: 200px;
  height: 200px;
  object-fit: contain;
  margin: 0 auto;
}

.publisher-name {
  font-size: 1.3rem;
  font-weight: 600;
  margin: 20px 0 15px;
  color: var(--text-color);
}

.publisher-year {
  display: inline-block;
  background-color: rgba(59, 130, 246, 0.1);
  color: var(--primary-color);
  padding: 8px 20px;
  border-radius: 20px;
  font-weight: 600;
  margin-top: 15px;
}

/* Dark Mode Toggle */
.dark-mode-toggle {
  position: fixed;
  bottom: 2rem;
  right: 2rem;
  z-index: 999;
  width: 50px;
  height: 50px;
  border-radius: 50%;
  background: var(--primary-color);
  color: white;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  box-shadow: var(--shadow-md);
  transition: var(--transition);
  border: none;
  outline: none;
}

.dark-mode-toggle:hover {
  transform: scale(1.1) rotate(30deg);
  box-shadow: var(--shadow-lg);
}

.dark-mode-toggle i {
  transition: var(--transition);
}

.dark-mode-toggle:hover i {
  transform: scale(1.2);
}

/* Dark Mode Styles */
body.dark-mode {
  --primary-color: #60a5fa;
  --secondary-color: #3b82f6;
  --accent-color: #818cf8;
  --dark-color: #f8fafc;
  --light-color: #0f172a;
  --gray-color: #64748b;
  --card-bg: #1e293b;
  --text-color: #e2e8f0;
  --text-light: #94a3b8;
  --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.3);
  --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.3);
  --shadow-lg: 0 10px 15px rgba(0, 0, 0, 0.3);
  --border-color: #334155;
  background-color: #0f172a;
}

body.dark-mode .header {
  background-color: #1e293b;
  box-shadow: 0 2px 15px rgba(0, 0, 0, 0.4);
  border-bottom: 1px solid #334155;
}

body.dark-mode .book-hero {
  background-color: #1e293b;
  border-bottom: 1px solid #334155;
}

body.dark-mode .header.scrolled {
  background-color: rgba(30, 41, 59, 0.95);
  box-shadow: 0 4px 10px rgba(0, 0, 0, 0.3);
}

body.dark-mode .navbar ul li a {
  color: var(--text-light);
}

body.dark-mode .navbar ul li a:hover,
body.dark-mode .navbar ul li a.active {
  color: var(--accent-color);
}

body.dark-mode .version-card,
body.dark-mode .publisher-card {
  background-color: var(--card-bg);
  border-color: var(--border-color);
}

body.dark-mode .section-title,
body.dark-mode .version-title,
body.dark-mode .publisher-name {
  color: white;
}

body.dark-mode .version-authors,
body.dark-mode .book-description {
  color: var(--gray-color);
}

body.dark-mode .book-info,
body.dark-mode .book-publisher  {
  background-color: #0f172a;
}

body.dark-mode .book-versions{
  background-color: #1e293b;
}

body.dark-mode .publisher-year {
  background-color: rgba(96, 165, 250, 0.1);
  color: #60a5fa;
}

/* Mobile Menu Styles */
@media (max-width: 768px) {
  .navbar {
    position: fixed;
    top: 70px;
    left: -100%;
    width: 100%;
    height: calc(100vh - 70px);
    background-color: var(--card-bg);
    transition: all 0.5s ease;
    padding-top: 30px;
    overflow-y: auto;
  }

  .navbar.active {
    left: 0;
  }

  .navbar ul {
    flex-direction: column;
    padding: 0 20px;
  }

  .navbar ul li {
    margin: 0;
    padding: 15px 0;
    border-bottom: 1px solid var(--border-color);
  }

  .navbar ul li:last-child {
    border-bottom: none;
  }

  .navbar ul li a {
    display: block;
    font-size: 1.1rem;
    padding: 10px 0;
  }

  .navbar ul li a.active::after {
    display: none;
  }

  .mobile-menu-btn {
    display: block;
  }

  .book-hero h1 {
    font-size: 2.5rem;
  }

  .version-cards {
    flex-direction: column;
    align-items: center;
  }

  .version-card {
    width: 100%;
    max-width: 400px;
  }

  .version-buttons {
    flex-direction: column;
  }

  .btn {
    width: 100%;
  }

  .publisher-card {
    padding: 30px 20px;
  }
}

/* Animations */
@keyframes fadeInUp {
  from {
    opacity: 0;
    transform: translateY(20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

/* Responsive Styles */
@media (max-width: 992px) {
  .container {
    padding: 0 25px;
  }

  .book-hero h1 {
    font-size: 2.5rem;
  }
}

@media (max-width: 576px) {
  .container {
    padding: 0 20px;
  }

  .book-hero h1 {
    font-size: 2rem;
  }

  .section-title {
    font-size: 1.8rem;
  }

  .dark-mode-toggle {
    width: 45px;
    height: 45px;
    bottom: 1.5rem;
    right: 1.5rem;
  }
}