/* ===== CSS RESET & VARIABLES ===== */
:root {
  --primary: #0c4b8a;
  --primary-light: #1a6bb3;
  --secondary: #ff6b6b;
  --accent: #10b981;
  --dark: #1e293b;
  --light: #f8fafc;
  --gray: #64748b;
  --gray-light: #e2e8f0;
  --shadow: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
  --shadow-lg: 0 20px 25px -5px rgba(0, 0, 0, 0.1);
  --radius: 10px;
  --radius-sm: 8px;
  --transition: all 0.3s ease;
  --font-main: 'Inter', 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
  --font-heading: 'Poppins', 'Segoe UI', sans-serif;
}

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

html {
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-main);
  line-height: 1.7;
  color: var(--dark);
  background-color: var(--light);
  overflow-x: hidden;
}

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

/* ===== HEADER STYLES ===== */
header {
  background: linear-gradient(135deg, #0c4b8a 0%, #1a6bb3 100%);
  color: white;
  padding: 15px 0;
  box-shadow: 0 4px 20px rgba(0, 0, 0, 0.15);
  position: sticky;
  top: 0;
  z-index: 1000;
  transition: var(--transition);
}

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

.logo {
  display: flex;
  align-items: center;
  gap: 15px;
  text-decoration: none;
  transition: var(--transition);
}

.logo:hover {
  transform: translateY(-2px);
}

.logo-icon {
  background-color: white;
  color: var(--primary);
  width: 50px;
  height: 50px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 24px;
  font-weight: bold;
  box-shadow: var(--shadow);
  transition: var(--transition);
}

.logo:hover .logo-icon {
  transform: rotate(10deg);
  background-color: var(--accent);
  color: white;
}

.logo-text h1 {
  font-size: 28px;
  font-weight: 700;
  text-shadow: 2px 2px 4px rgba(0, 0, 0, 0.2);
}

/* ===== MAIN CONTENT ===== */
main {
  padding: 30px 0 50px;
  animation: fadeIn 0.8s ease;
}

/* ===== TABS NAVIGATION ===== */
.tabs-container {
  margin-bottom: 30px;
  position: relative;
}

.tabs {
  display: flex;
  flex-wrap: wrap;
  background-color: white;
  border-radius: var(--radius);
  overflow: hidden;
  box-shadow: var(--shadow);
  border: 1px solid var(--gray-light);
}

.tab {
  flex: 1;
  min-width: 120px;
  text-align: center;
  padding: 20px 15px;
  background-color: #f8f9fa;
  border: none;
  border-right: 1px solid var(--gray-light);
  cursor: pointer;
  font-size: 16px;
  font-weight: 600;
  color: var(--gray);
  transition: var(--transition);
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
  position: relative;
  overflow: hidden;
}

.tab:last-child {
  border-right: none;
}

.tab:hover {
  background-color: #e9f2fb;
  color: var(--primary-light);
  transform: translateY(-2px);
}

.tab.active {
  background-color: var(--primary);
  color: white;
  box-shadow: inset 0 -4px 0 var(--accent);
}

.tab.active .tab-icon {
  color: white;
  transform: scale(1.2);
}

.tab-icon {
  font-size: 18px;
  transition: var(--transition);
}

/* ===== SUB TABS ===== */
.sub-tabs-container {
  background-color: white;
  border-radius: var(--radius-sm);
  margin-bottom: 25px;
  box-shadow: var(--shadow);
  overflow: hidden;
  animation: slideDown 0.5s ease;
}

.sub-tabs {
  display: flex;
  border-bottom: 2px solid var(--gray-light);
  overflow-x: auto;
  scrollbar-width: none;
}

.sub-tabs::-webkit-scrollbar {
  display: none;
}

.sub-tab {
  flex: 1;
  min-width: 180px;
  padding: 18px 20px;
  background: none;
  border: none;
  cursor: pointer;
  font-size: 16px;
  font-weight: 600;
  color: var(--gray);
  transition: var(--transition);
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
  text-align: center;
  white-space: nowrap;
  position: relative;
}

.sub-tab:hover {
  background-color: #f0f7ff;
  color: var(--primary-light);
}

.sub-tab.active {
  background-color: #e9f2fb;
  color: var(--primary);
  border-bottom: 3px solid var(--primary);
}

.sub-tab.active::after {
  content: '';
  position: absolute;
  bottom: -2px;
  left: 50%;
  transform: translateX(-50%);
  width: 0;
  height: 0;
  border-left: 8px solid transparent;
  border-right: 8px solid transparent;
  border-bottom: 8px solid var(--primary);
}

/* ===== TAB CONTENT ===== */
.tab-content {
  display: none;
  animation: fadeIn 0.5s ease;
}

.tab-content.active {
  display: block;
}

.content-card {
  background-color: white;
  border-radius: var(--radius);
  padding: 35px;
  box-shadow: var(--shadow);
  margin-top: 20px;
  border: 1px solid var(--gray-light);
  transition: var(--transition);
}

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

.content-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 30px;
  padding-bottom: 20px;
  border-bottom: 3px solid #f0f0f0;
}

.content-header h2 {
  color: var(--primary);
  font-size: 32px;
  font-weight: 700;
  display: flex;
  align-items: center;
  gap: 15px;
}

.update-badge {
  background: linear-gradient(135deg, var(--secondary), #ff8e8e);
  color: white;
  padding: 8px 20px;
  border-radius: 25px;
  font-size: 14px;
  font-weight: 600;
  letter-spacing: 0.5px;
  box-shadow: 0 4px 6px rgba(255, 107, 107, 0.2);
  animation: pulse 2s infinite;
}

/* ===== SUB TAB CONTENT ===== */
.sub-tab-content {
  display: none;
  animation: fadeIn 0.5s ease;
}

.sub-tab-content.active {
  display: block;
}

/* ===== SCHEME CONTENT ===== */
.scheme-content {
  margin-top: 30px;
}

.exam-card {
  background: #f8fafc;
  border-radius: var(--radius-sm);
  padding: 30px;
  margin-bottom: 25px;
  border-left: 5px solid var(--primary);
  transition: var(--transition);
}

.exam-card:hover {
  transform: translateX(10px);
  box-shadow: var(--shadow);
}

.exam-card h3 {
  color: var(--primary);
  font-size: 24px;
  margin-bottom: 15px;
  display: flex;
  align-items: center;
  gap: 12px;
}

.exam-details {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 25px;
  margin-top: 20px;
}

.detail-item {
  background: white;
  padding: 25px;
  border-radius: var(--radius-sm);
  border: 1px solid var(--gray-light);
}

.detail-item h4 {
  color: var(--primary-light);
  margin-bottom: 15px;
  padding-bottom: 10px;
  border-bottom: 2px solid #e9f2fb;
}

.detail-item ul {
  list-style-type: none;
}

.detail-item li {
  margin-bottom: 10px;
  padding-left: 20px;
  position: relative;
  color: var(--gray);
}

.detail-item li:before {
  content: "→";
  color: var(--primary);
  font-weight: bold;
  position: absolute;
  left: 0;
}

/* ===== CATEGORY GRID ===== */
.category-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(500px, 1fr));
  gap: 30px;
}

.category-section {
  background-color: #f8fafc;
  border-radius: var(--radius);
  padding: 30px;
  border-left: 5px solid var(--primary-light);
  transition: var(--transition);
  animation: slideUp 0.5s ease;
}

.category-section:hover {
  transform: translateY(-5px);
  box-shadow: var(--shadow);
}

.category-header {
  display: flex;
  align-items: center;
  gap: 20px;
  margin-bottom: 25px;
  padding-bottom: 20px;
  border-bottom: 2px solid var(--gray-light);
}

.category-header h3 {
  color: var(--primary);
  font-size: 24px;
  margin: 0;
  display: flex;
  align-items: center;
  gap: 12px;
}

.category-icon {
  background: linear-gradient(135deg, var(--primary), var(--primary-light));
  color: white;
  width: 50px;
  height: 50px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 20px;
  box-shadow: 0 4px 6px rgba(12, 75, 138, 0.2);
}

.category-content {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
  gap: 25px;
}

.category-card {
  background-color: white;
  border-radius: var(--radius-sm);
  padding: 25px;
  border: 1px solid var(--gray-light);
  transition: var(--transition);
}

.category-card:hover {
  transform: translateY(-5px);
  box-shadow: var(--shadow);
  border-color: var(--primary-light);
}

.category-card h4 {
  color: var(--primary-light);
  margin-bottom: 20px;
  font-size: 18px;
  display: flex;
  align-items: center;
  gap: 10px;
}

.category-card ul {
  list-style-type: none;
}

.category-card li {
  margin-bottom: 12px;
  padding-left: 25px;
  position: relative;
  color: var(--gray);
  line-height: 1.6;
}

.category-card li:before {
  content: "✓";
  color: var(--accent);
  font-weight: bold;
  position: absolute;
  left: 0;
}

/* ===== PAPER CONTENT ===== */
.paper-content {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(350px, 1fr));
  gap: 30px;
}

.topic-card {
  background: linear-gradient(145deg, #ffffff, #f0f7ff);
  border-radius: var(--radius);
  padding: 30px;
  border-left: 5px solid var(--primary-light);
  transition: var(--transition);
  animation: fadeInUp 0.6s ease;
}

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

.topic-card h3 {
  color: var(--primary);
  margin-bottom: 20px;
  font-size: 22px;
  display: flex;
  align-items: center;
  gap: 12px;
}

.topic-list {
  list-style-type: none;
  margin-top: 20px;
}

.topic-list li {
  margin-bottom: 15px;
  padding: 15px 20px;
  background-color: white;
  border-radius: var(--radius-sm);
  border-left: 3px solid var(--primary-light);
  transition: var(--transition);
  cursor: pointer;
}

.topic-list li:hover {
  background-color: #e9f2fb;
  transform: translateX(10px);
  box-shadow: 0 4px 6px rgba(0, 0, 0, 0.05);
}

/* ===== NOTES CONTAINER ===== */
.notes-container {
  display: grid;
  grid-template-columns: 2fr 1fr;
  gap: 30px;
}

.main-notes, .sidebar {
  background-color: #f8fafc;
  border-radius: var(--radius);
  padding: 30px;
  border: 1px solid var(--gray-light);
}

.notes-section {
  margin-bottom: 40px;
}

.notes-section:last-child {
  margin-bottom: 0;
}

.notes-section h3 {
  color: var(--primary);
  font-size: 22px;
  margin-bottom: 20px;
  padding-bottom: 15px;
  border-bottom: 2px solid var(--gray-light);
  display: flex;
  align-items: center;
  gap: 12px;
}

.notes-list {
  list-style-type: none;
}

.notes-list li {
  margin-bottom: 15px;
  padding-left: 30px;
  position: relative;
  transition: var(--transition);
}

.notes-list li:before {
  content: "📌";
  position: absolute;
  left: 0;
  top: 0;
}

.notes-list a {
  color: var(--dark);
  text-decoration: none;
  transition: var(--transition);
  display: block;
  padding: 8px 0;
}

.notes-list a:hover {
  color: var(--primary);
  padding-left: 10px;
}

.topic-summary {
  background-color: white;
  border: 1px solid var(--gray-light);
  border-radius: var(--radius-sm);
  padding: 25px;
  margin-bottom: 25px;
  transition: var(--transition);
}

.topic-summary:hover {
  border-color: var(--primary-light);
  box-shadow: 0 5px 15px rgba(0, 0, 0, 0.05);
}

.topic-summary h4 {
  color: var(--primary);
  margin-bottom: 15px;
  display: flex;
  align-items: center;
  gap: 12px;
}

.topic-summary p {
  color: var(--gray);
  line-height: 1.8;
}

.important-points {
  background: linear-gradient(135deg, #e9f2fb, #d4e4fa);
  border-left: 6px solid var(--primary);
  padding: 25px;
  margin: 30px 0;
  border-radius: 0 var(--radius) var(--radius) 0;
}

.important-points h4 {
  color: var(--primary);
  margin-bottom: 15px;
  display: flex;
  align-items: center;
  gap: 12px;
}

/* ===== FOOTER ===== */
footer {
  background: linear-gradient(135deg, #0c2d4d, #1a4a7a);
  color: white;
  padding: 40px 0;
  margin-top: 50px;
}

.copyright {
  text-align: center;
  font-size: 14px;
  color: #cbd5e1;
}

/* ===== ANIMATIONS ===== */
@keyframes fadeIn {
  from {
    opacity: 0;
    transform: translateY(20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes fadeInUp {
  from {
    opacity: 0;
    transform: translateY(30px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes slideDown {
  from {
    opacity: 0;
    transform: translateY(-20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes slideUp {
  from {
    opacity: 0;
    transform: translateY(30px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes pulse {
  0%, 100% {
    transform: scale(1);
  }
  50% {
    transform: scale(1.05);
  }
}

/* ===== RESPONSIVE DESIGN ===== */
@media (max-width: 1200px) {
  .category-grid {
    grid-template-columns: 1fr;
  }
  
  .exam-details {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 992px) {
  .notes-container {
    grid-template-columns: 1fr;
  }
  
  .paper-content {
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  }
  
  .tabs {
    border-radius: 8px;
  }
  
  .tab {
    flex-basis: calc(33.333% - 10px);
    margin: 5px;
    border-radius: 8px;
    border: none;
  }
}

@media (max-width: 768px) {
  .content-header {
    flex-direction: column;
    align-items: flex-start;
    gap: 15px;
  }
  
  .content-header h2 {
    font-size: 24px;
  }
  
  .content-card {
    padding: 25px;
  }
  
  .sub-tab {
    min-width: 150px;
    padding: 15px 10px;
    font-size: 14px;
  }
  
  .category-content {
    grid-template-columns: 1fr;
  }
  
  .paper-content {
    grid-template-columns: 1fr;
  }
  
  .header-content {
    justify-content: center;
  }
  
  .logo-text h1 {
    font-size: 22px;
  }
}

@media (max-width: 576px) {
  .tab {
    flex-basis: calc(50% - 10px);
  }
  
  .sub-tab {
    min-width: 120px;
    padding: 12px 8px;
    font-size: 13px;
    flex-direction: column;
    gap: 5px;
  }
  
  .category-header h3 {
    font-size: 20px;
  }
  
  .exam-card h3 {
    font-size: 20px;
  }
  
  .content-header h2 {
    font-size: 20px;
  }
}

/* ===== UTILITY CLASSES ===== */
.highlight {
  background: linear-gradient(120deg, rgba(255, 107, 107, 0.2) 0%, rgba(255, 107, 107, 0) 100%);
  padding: 2px 6px;
  border-radius: 4px;
}

.loading {
  position: relative;
  overflow: hidden;
}

.loading::after {
  content: '';
  position: absolute;
  top: 0;
  left: -100%;
  width: 100%;
  height: 100%;
  background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.4), transparent);
  animation: loading 1.5s infinite;
}

@keyframes loading {
  to {
    left: 100%;
  }
}

/* ===== PRINT & DOWNLOAD TOOLBAR ===== */
.print-toolbar {
  position: fixed;
  bottom: 30px;
  right: 30px;
  display: flex;
  gap: 10px;
  z-index: 999;
}

.print-toolbar button {
  width: 50px;
  height: 50px;
  border-radius: 50%;
  border: none;
  background: var(--primary);
  color: white;
  font-size: 18px;
  cursor: pointer;
  transition: var(--transition);
  box-shadow: var(--shadow);
  display: flex;
  align-items: center;
  justify-content: center;
}

.print-toolbar button:hover {
  transform: translateY(-3px) scale(1.1);
  background: var(--primary-light);
}

/* ===== SEARCH BOX ===== */
.search-container {
  position: relative;
}

.search-input {
  padding: 12px 45px 12px 20px;
  border: 2px solid var(--primary);
  border-radius: 30px;
  width: 300px;
  font-size: 16px;
  background: white;
  box-shadow: var(--shadow);
  transition: var(--transition);
}

.search-input:focus {
  outline: none;
  width: 350px;
  box-shadow: 0 10px 25px rgba(0, 0, 0, 0.1);
}

.search-btn {
  position: absolute;
  right: 5px;
  top: 50%;
  transform: translateY(-50%);
  background: var(--primary);
  color: white;
  border: none;
  border-radius: 50%;
  width: 40px;
  height: 40px;
  cursor: pointer;
  transition: var(--transition);
}

.search-btn:hover {
  background: var(--primary-light);
  transform: translateY(-50%) scale(1.1);
}

.search-results {
  position: absolute;
  top: 100%;
  left: 0;
  right: 0;
  background: white;
  border-radius: 10px;
  box-shadow: var(--shadow-lg);
  max-height: 400px;
  overflow-y: auto;
  display: none;
  z-index: 1000;
}

.search-result-item {
  padding: 15px 20px;
  border-bottom: 1px solid var(--gray-light);
  cursor: pointer;
  transition: var(--transition);
}

.search-result-item:hover {
  background: #f0f7ff;
}

.search-result-item.active {
  background: #e9f2fb;
  border-left: 4px solid var(--primary);
}

/* ===== BOOKMARK BUTTON ===== */
.bookmark-btn {
  position: absolute;
  top: 15px;
  right: 15px;
  background: none;
  border: none;
  color: var(--gray);
  font-size: 18px;
  cursor: pointer;
  transition: var(--transition);
  z-index: 1;
}

.bookmark-btn:hover {
  color: var(--accent);
  transform: scale(1.2);
}

/* ===== PROGRESS BAR ===== */
.progress-bar {
  position: fixed;
  top: 0;
  left: 0;
  height: 3px;
  background: linear-gradient(90deg, var(--accent), var(--primary));
  z-index: 1001;
  transition: width 0.3s ease;
}

/* ===== NOTIFICATION ===== */
.notification {
  position: fixed;
  bottom: 100px;
  right: 30px;
  background: var(--primary);
  color: white;
  padding: 15px 25px;
  border-radius: 10px;
  box-shadow: var(--shadow-lg);
  z-index: 1000;
  animation: slideUp 0.3s ease;
}

/* ===== DARK MODE ===== */
.dark-mode {
  background-color: #0f172a;
  color: #e2e8f0;
}

.dark-mode .content-card,
.dark-mode .exam-card,
.dark-mode .detail-item,
.dark-mode .category-card,
.dark-mode .topic-card,
.dark-mode .main-notes,
.dark-mode .sidebar,
.dark-mode .topic-summary {
  background-color: #1e293b;
  border-color: #334155;
  color: #cbd5e1;
}

.dark-mode .category-section,
.dark-mode .important-points {
  background-color: #1e293b;
}

.dark-mode .tabs,
.dark-mode .sub-tabs-container {
  background-color: #1e293b;
  border-color: #334155;
}

.dark-mode .tab {
  background-color: #334155;
  color: #cbd5e1;
}

.dark-mode .tab:hover {
  background-color: #475569;
}

.dark-mode .notes-list a,
.dark-mode .detail-item li,
.dark-mode .topic-summary p {
  color: #cbd5e1;
}