/* ===== Глобальные стили ===== */
:root {
  --primary-color: #3498db;
  --primary-dark: #2980b9;
  --secondary-color: #2ecc71;
  --secondary-dark: #27ae60;
  --danger-color: #e74c3c;
  --danger-dark: #c0392b;
  --warning-color: #f39c12;
  --warning-dark: #e67e22;
  --dark-color: #2c3e50;
  --light-color: #ecf0f1;
  --gray-color: #95a5a6;
  --light-gray: #f5f7fa;
  --text-color: #333;
  --text-light: #7f8c8d;
  --white: #ffffff;
  --shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
  --shadow-hover: 0 8px 15px rgba(0, 0, 0, 0.1);
  --transition: all 0.3s ease;
}

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

html {
  scroll-behavior: smooth;
}

body {
  font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
  color: var(--text-color);
  background-color: var(--light-gray);
  line-height: 1.6;
}

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

ul {
  list-style: none;
}

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

/* ===== Кнопки ===== */
.btn {
  display: inline-block;
  padding: 10px 20px;
  border-radius: 4px;
  font-weight: 500;
  text-align: center;
  cursor: pointer;
  transition: var(--transition);
  border: none;
}

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

.btn-primary:hover {
  background-color: var(--primary-dark);
  box-shadow: var(--shadow-hover);
}

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

.btn-danger:hover {
  background-color: var(--danger-dark);
  box-shadow: var(--shadow-hover);
}

.btn-accent {
  background-color: var(--secondary-color);
  color: var(--white);
}

.btn-accent:hover {
  background-color: var(--secondary-dark);
  box-shadow: var(--shadow-hover);
}

.btn-large {
  padding: 12px 30px;
  font-size: 1.1em;
}

.btn-outline {
  border: 1px solid var(--primary-color);
  color: var(--primary-color);
  background: transparent;
}

.btn-outline:hover {
  background-color: var(--primary-color);
  color: var(--white);
}

/* ===== Шапка ===== */
.main-header {
  background-color: var(--white);
  box-shadow: var(--shadow);
  position: sticky;
  top: 0;
  z-index: 100;
  padding: 15px 0;
}

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

.logo {
  display: flex;
  align-items: center;
  gap: 10px;
}

.logo i {
  font-size: 1.8em;
  color: var(--primary-color);
}

.logo h1 {
  font-size: 1.5em;
  font-weight: 700;
}

.main-nav ul {
  display: flex;
  gap: 20px;
}

.main-nav a {
  padding: 8px 12px;
  border-radius: 4px;
  transition: var(--transition);
  font-weight: 500;
}

.main-nav a:hover, 
.main-nav .active a {
  color: var(--primary-color);
  background-color: rgba(52, 152, 219, 0.1);
}

.auth-panel {
  display: flex;
  align-items: center;
  gap: 10px;
}

.login-form {
  display: flex;
  gap: 10px;
  align-items: center;
}

.login-form input {
  padding: 8px 12px;
  border: 1px solid #ddd;
  border-radius: 4px;
  min-width: 150px;
}

.user-info {
  display: flex;
  align-items: center;
  gap: 15px;
}

.user-greeting {
  display: flex;
  flex-direction: column;
  align-items: flex-end;
}

.user-role {
  padding: 2px 8px;
  border-radius: 4px;
  font-size: 0.8em;
  font-weight: bold;
}

.role-admin {
  background-color: var(--danger-color);
  color: var(--white);
}

.role-teacher {
  background-color: var(--primary-color);
  color: var(--white);
}

.role-student {
  background-color: var(--secondary-color);
  color: var(--white);
}

/* ===== Герой секция ===== */
.hero {
  background: linear-gradient(135deg, var(--primary-color), var(--primary-dark));
  color: var(--white);
  padding: 60px 0;
}

.hero .container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 40px;
}

.hero-content {
  flex: 1;
  max-width: 600px;
}

.hero-content h2 {
  font-size: 2.5em;
  margin-bottom: 20px;
  line-height: 1.2;
}

.hero-content p {
  font-size: 1.2em;
  margin-bottom: 30px;
  opacity: 0.9;
}

.hero-image {
  flex: 1;
  display: flex;
  justify-content: center;
}

.hero-image img {
  max-width: 100%;
  height: auto;
  border-radius: 8px;
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.2);
}

/* ===== Основное содержимое ===== */
.main-content {
  padding: 60px 0;
}

.section-title {
  font-size: 1.8em;
  margin-bottom: 30px;
  color: var(--dark-color);
  display: flex;
  align-items: center;
  gap: 10px;
}

.section-title i {
  color: var(--primary-color);
}

/* ===== Материалы ===== */
.materials-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 25px;
  margin-bottom: 50px;
}

.material-card {
  background-color: var(--white);
  border-radius: 8px;
  overflow: hidden;
  box-shadow: var(--shadow);
  transition: var(--transition);
}

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

.material-header {
  padding: 15px;
  border-bottom: 1px solid #eee;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.material-name {
  font-weight: 600;
  font-size: 1.1em;
  display: flex;
  align-items: center;
  gap: 8px;
}

.file-type {
  font-size: 0.8em;
  padding: 2px 8px;
  border-radius: 4px;
  background-color: #eee;
  color: #555;
}

.material-body {
  padding: 15px;
}

.material-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  font-size: 0.9em;
  color: var(--text-light);
  margin-bottom: 10px;
}

.material-meta span {
  display: flex;
  align-items: center;
  gap: 5px;
}

.material-description {
  margin-bottom: 15px;
  color: var(--text-color);
}

.material-footer {
  padding: 15px;
  border-top: 1px solid #eee;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.material-actions {
  display: flex;
  gap: 10px;
}

.loading-spinner {
  grid-column: 1 / -1;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: 40px;
}

.spinner {
  width: 50px;
  height: 50px;
  border: 5px solid rgba(52, 152, 219, 0.2);
  border-radius: 50%;
  border-top-color: var(--primary-color);
  animation: spin 1s ease-in-out infinite;
  margin-bottom: 15px;
}

@keyframes spin {
  to { transform: rotate(360deg); }
}

/* ===== Категории ===== */
.categories-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
  gap: 25px;
  margin-bottom: 50px;
}

.category-card {
  background-color: var(--white);
  border-radius: 8px;
  padding: 25px;
  text-align: center;
  box-shadow: var(--shadow);
  transition: var(--transition);
}

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

.category-icon {
  width: 70px;
  height: 70px;
  margin: 0 auto 20px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.8em;
  color: var(--white);
}

.category-card h3 {
  margin-bottom: 10px;
  color: var(--dark-color);
}

.category-card p {
  color: var(--text-light);
  margin-bottom: 20px;
  font-size: 0.95em;
}

.lectures .category-icon {
  background-color: var(--primary-color);
}

.practice .category-icon {
  background-color: var(--secondary-color);
}

.exams .category-icon {
  background-color: var(--danger-color);
}

.other .category-icon {
  background-color: var(--warning-color);
}

/* ===== Преимущества ===== */
.advantages-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
  gap: 25px;
}

.advantage-card {
  background-color: var(--white);
  border-radius: 8px;
  padding: 25px;
  text-align: center;
  box-shadow: var(--shadow);
  transition: var(--transition);
}

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

.advantage-icon {
  width: 70px;
  height: 70px;
  margin: 0 auto 20px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.8em;
  color: var(--white);
  background-color: var(--primary-color);
}

.advantage-card h3 {
  margin-bottom: 10px;
  color: var(--dark-color);
}

.advantage-card p {
  color: var(--text-light);
  font-size: 0.95em;
}

/* ===== Подвал ===== */
.main-footer {
  background-color: var(--dark-color);
  color: var(--white);
  padding: 60px 0 0;
}

.footer-content {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 40px;
  margin-bottom: 40px;
}

.footer-about .logo {
  margin-bottom: 20px;
}

.footer-about .logo i {
  color: var(--white);
}

.footer-about .logo h3 {
  color: var(--white);
}

.footer-about p {
  margin-bottom: 20px;
  opacity: 0.8;
}

.social-links {
  display: flex;
  gap: 15px;
}

.social-links a {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
  border-radius: 50%;
  background-color: rgba(255, 255, 255, 0.1);
  transition: var(--transition);
}

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

.footer-links h4 {
  font-size: 1.2em;
  margin-bottom: 20px;
  color: var(--white);
}

.footer-links ul li {
  margin-bottom: 10px;
}

.footer-links a {
  opacity: 0.8;
  transition: var(--transition);
}

.footer-links a:hover {
  opacity: 1;
  color: var(--primary-color);
}

.footer-contacts h4 {
  font-size: 1.2em;
  margin-bottom: 20px;
  color: var(--white);
}

.footer-contacts p {
  display: flex;
  align-items: center;
  gap: 10px;
  margin-bottom: 15px;
  opacity: 0.8;
}

.footer-bottom {
  padding: 20px 0;
  border-top: 1px solid rgba(255, 255, 255, 0.1);
  text-align: center;
  opacity: 0.7;
  font-size: 0.9em;
}

/* ===== Страница "О владельце" ===== */
.about-container {
  max-width: 800px;
  margin: 40px auto;
  padding: 30px;
  background-color: var(--white);
  border-radius: 8px;
  box-shadow: var(--shadow);
}

.about-header {
  text-align: center;
  margin-bottom: 30px;
}

.about-header h1 {
  color: var(--dark-color);
  margin-bottom: 10px;
}

.about-header p {
  color: var(--text-light);
  font-size: 1.1em;
}

.owner-info {
  display: flex;
  flex-direction: column;
  align-items: center;
  margin-bottom: 30px;
}

.owner-photo {
  width: 150px;
  height: 150px;
  border-radius: 50%;
  object-fit: cover;
  border: 5px solid var(--primary-color);
  margin-bottom: 20px;
}

.owner-name {
  font-size: 1.5em;
  font-weight: bold;
  color: var(--dark-color);
  margin-bottom: 5px;
}

.owner-position {
  color: var(--primary-color);
  font-weight: 500;
  margin-bottom: 15px;
}

.owner-description {
  text-align: center;
  color: var(--text-color);
  line-height: 1.6;
  margin-bottom: 30px;
}

.owner-contacts {
  width: 100%;
  background-color: var(--light-gray);
  padding: 20px;
  border-radius: 8px;
}

.contact-item {
  display: flex;
  align-items: center;
  margin-bottom: 15px;
}

.contact-icon {
  width: 40px;
  height: 40px;
  background-color: var(--primary-color);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  margin-right: 15px;
  color: var(--white);
}

.contact-text {
  color: var(--text-color);
}

.contact-text a {
  color: var(--primary-color);
  text-decoration: none;
}

.contact-text a:hover {
  text-decoration: underline;
}

.back-to-main {
  display: inline-block;
  margin-top: 30px;
  padding: 10px 20px;
  background-color: var(--primary-color);
  color: var(--white);
  text-decoration: none;
  border-radius: 4px;
  transition: var(--transition);
}

.back-to-main:hover {
  background-color: var(--primary-dark);
}

/* ===== Страница "Выбор раздела" ===== */
.categories-container {
  max-width: 1000px;
  margin: 40px auto;
  padding: 30px;
  background-color: var(--white);
  border-radius: 8px;
  box-shadow: var(--shadow);
}

.categories-header {
  text-align: center;
  margin-bottom: 40px;
}

.categories-header h1 {
  color: var(--dark-color);
  margin-bottom: 10px;
}

.categories-header p {
  color: var(--text-light);
  font-size: 1.1em;
}

.categories-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 30px;
}

.category-card {
  background-color: var(--light-gray);
  border-radius: 8px;
  overflow: hidden;
  transition: transform 0.3s, box-shadow 0.3s;
  text-decoration: none;
  color: inherit;
}

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

.category-image {
  height: 180px;
  background-size: cover;
  background-position: center;
}

.category-content {
  padding: 20px;
}

.category-title {
  font-size: 1.3em;
  font-weight: bold;
  color: var(--dark-color);
  margin-bottom: 10px;
}

.category-description {
  color: var(--text-light);
  line-height: 1.5;
  margin-bottom: 15px;
}

.category-button {
  display: inline-block;
  padding: 8px 20px;
  background-color: var(--primary-color);
  color: var(--white);
  border-radius: 4px;
  text-align: center;
  transition: var(--transition);
}

.category-card:hover .category-button {
  background-color: var(--primary-dark);
}

.lectures {
  border-top: 4px solid var(--primary-color);
}

.practice {
  border-top: 4px solid var(--secondary-color);
}

.exams {
  border-top: 4px solid var(--danger-color);
}

.other {
  border-top: 4px solid var(--warning-color);
}

/* ===== Адаптивность ===== */
@media (max-width: 992px) {
  .hero .container {
    flex-direction: column;
    text-align: center;
  }
  
  .hero-content {
    max-width: 100%;
  }
  
  .main-nav {
    order: 3;
    width: 100%;
    margin-top: 20px;
  }
  
  .main-nav ul {
    justify-content: center;
  }
}

@media (max-width: 768px) {
  .hero-content h2 {
    font-size: 2em;
  }
  
  .hero-content p {
    font-size: 1em;
  }
  
  .section-title {
    font-size: 1.5em;
  }
  
  .footer-content {
    grid-template-columns: 1fr;
  }
  
  .about-container,
  .categories-container {
    padding: 20px;
    margin: 20px;
  }
  
  .owner-info {
    text-align: center;
  }
  
  .categories-grid {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 576px) {
  .login-form {
    flex-direction: column;
    width: 100%;
  }
  
  .login-form input {
    width: 100%;
  }
  
  .user-info {
    flex-direction: column;
    align-items: flex-end;
  }
  
  .user-greeting {
    align-items: flex-start;
  }
  
  .material-item {
    flex-direction: column;
    align-items: flex-start;
    gap: 10px;
  }
  
  .material-actions {
    align-self: flex-end;
  }
}
/* ===== Специфичные стили для страницы разделов ===== */
.hero-categories {
  background: linear-gradient(135deg, var(--secondary-color), var(--secondary-dark));
}

.categories-detailed {
  display: grid;
  grid-template-columns: 1fr;
  gap: 20px;
  margin-bottom: 50px;
}

.category-detailed-card {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 20px;
  border-radius: 8px;
  background-color: var(--white);
  box-shadow: var(--shadow);
  transition: var(--transition);
}

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

.category-info {
  display: flex;
  align-items: center;
  gap: 20px;
}

.category-icon {
  width: 60px;
  height: 60px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.5em;
  color: var(--white);
}

.lectures .category-icon {
  background-color: var(--primary-color);
}

.practice .category-icon {
  background-color: var(--secondary-color);
}

.exams .category-icon {
  background-color: var(--danger-color);
}

.other .category-icon {
  background-color: var(--warning-color);
}

/* ===== Специфичные стили для страницы "О нас" ===== */
.hero-about {
  background: linear-gradient(135deg, var(--danger-color), var(--danger-dark));
}

.about-content {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 40px;
  margin-bottom: 50px;
}

.about-text {
  font-size: 1.1em;
  line-height: 1.7;
}

.about-text p {
  margin-bottom: 20px;
}

.about-stats {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
  gap: 20px;
}

.stat-card {
  background-color: var(--white);
  border-radius: 8px;
  padding: 20px;
  text-align: center;
  box-shadow: var(--shadow);
}

.stat-number {
  font-size: 2em;
  font-weight: bold;
  color: var(--primary-color);
  margin-bottom: 5px;
}

.stat-label {
  color: var(--text-light);
  font-size: 0.9em;
}

.team-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 30px;
  margin-bottom: 50px;
}

.team-member {
  background-color: var(--white);
  border-radius: 8px;
  padding: 25px;
  text-align: center;
  box-shadow: var(--shadow);
  transition: var(--transition);
}

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

.member-photo {
  width: 150px;
  height: 150px;
  margin: 0 auto 20px;
  border-radius: 50%;
  overflow: hidden;
  border: 5px solid var(--light-gray);
}

.member-photo img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.member-position {
  color: var(--primary-color);
  font-weight: 500;
  margin-bottom: 15px;
}

.member-bio {
  color: var(--text-light);
  font-size: 0.95em;
}

.principles-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 30px;
}

.principle-card {
  background-color: var(--white);
  border-radius: 8px;
  padding: 25px;
  text-align: center;
  box-shadow: var(--shadow);
  transition: var(--transition);
}

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

.principle-icon {
  width: 70px;
  height: 70px;
  margin: 0 auto 20px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.8em;
  color: var(--white);
  background-color: var(--primary-color);
}

.principle-card h3 {
  margin-bottom: 15px;
  color: var(--dark-color);
}

/* ===== Адаптивность для новых страниц ===== */
@media (max-width: 768px) {
  .about-content {
    grid-template-columns: 1fr;
  }
  
  .category-detailed-card {
    flex-direction: column;
    align-items: flex-start;
    gap: 20px;
  }
  
  .category-info {
    width: 100%;
  }
}
/* Стили для блока приглашения */
.invitation-block {
    background-color: #f8f9fa;
    border-radius: 8px;
    padding: 30px;
    margin: 30px 0;
    text-align: center;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
}

.invitation-text {
    max-width: 800px;
    margin: 0 auto;
}

.invitation-text p {
    font-size: 1.2rem;
    line-height: 1.6;
    margin-bottom: 20px;
    color: #333;
}

.invitation-text .btn {
    margin-top: 15px;
    font-size: 1rem;
    padding: 12px 25px;
}
.survey-buttons {
    display: flex;
    gap: 10px;
    margin-top: 20px;
    flex-wrap: wrap;
}

.survey-buttons .btn {
    flex: 1;
    min-width: 120px;
}