/* =========================
   RESET & ROOT VARIABLES
========================= */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

:root {
  --primary-color: #4299e1;
  --primary-dark: #3182ce;
  --secondary-color: #4a5568;
  --accent-color: #ed8936;
  --light-color: #f7fafc;
  --dark-color: #2d3748;
  --success-color: #48bb78;
  --warning-color: #ecc94b;
  --danger-color: #f56565;
  --gray-light: #e2e8f0;
  --gray: #a0aec0;
  --border-radius: 8px;
  --box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
  --transition: all 0.3s ease;
}

/* =========================
   BASE STYLES
========================= */
body {
  font-family: 'Poppins', sans-serif;
  line-height: 1.6;
  color: var(--dark-color);
  background-color: #f8fafc;
}

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

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

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

/* =========================
   TYPOGRAPHY
========================= */
h1, h2, h3, h4, h5, h6 {
  font-weight: 600;
  line-height: 1.3;
  margin-bottom: 1rem;
}

h1 { font-size: 2.5rem; }
h2 { font-size: 2rem; }
h3 { font-size: 1.5rem; }

p {
  margin-bottom: 1rem;
}

.section-title {
  text-align: center;
  margin-bottom: 1rem;
  position: relative;
}

.section-title::after {
  content: '';
  position: absolute;
  bottom: -10px;
  left: 50%;
  transform: translateX(-50%);
  width: 60px;
  height: 3px;
  background-color: var(--primary-color);
}

.section-subtitle {
  text-align: center;
  max-width: 700px;
  margin: 0 auto 3rem;
  color: var(--secondary-color);
}

/* =========================
   BUTTONS
========================= */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  padding: 12px 24px;
  border-radius: var(--border-radius);
  font-weight: 500;
  cursor: pointer;
  border: none;
  transition: var(--transition);
  font-family: inherit;
}

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

.btn-primary:hover {
  background-color: var(--primary-dark);
  transform: translateY(-2px);
  box-shadow: var(--box-shadow);
}

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

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

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

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

.btn-login {
  padding: 8px 20px;
  background-color: transparent;
  color: var(--primary-color);
  border: 2px solid var(--primary-color);
  border-radius: var(--border-radius);
}

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

/* =========================
   HEADER & NAVBAR
========================= */
header {
  background-color: white;
  box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
  position: sticky;
  top: 0;
  z-index: 1000;
}

.navbar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 1rem 2rem;
  max-width: 1200px;
  margin: 0 auto;
}

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

.logo i {
  margin-right: 10px;
  font-size: 1.8rem;
}

nav {
  display: flex;
  align-items: center;
}

nav a {
  margin-left: 2rem;
  font-weight: 500;
  transition: var(--transition);
  position: relative;
}

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

nav a.active::after {
  content: '';
  position: absolute;
  bottom: -5px;
  left: 0;
  width: 100%;
  height: 2px;
  background-color: var(--primary-color);
}

.menu-toggle {
  display: none;
  flex-direction: column;
  cursor: pointer;
}

.menu-toggle span {
  width: 25px;
  height: 3px;
  background-color: var(--dark-color);
  margin: 3px 0;
}

/* =========================
   FOOTER (FULL WIDTH)
========================= */
footer {
  background-color: var(--dark-color);
  color: white;
  padding: 4rem 0 1rem;
  width: 100%;
}

.footer-content {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 2rem;
  margin-bottom: 3rem;
}

.footer-section h3 {
  margin-bottom: 1.5rem;
  position: relative;
  padding-bottom: 0.5rem;
}

.footer-section h3::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  width: 40px;
  height: 2px;
  background-color: var(--primary-color);
}

.footer-section p,
.footer-section ul li a {
  color: #cbd5e0;
}

.footer-section ul {
  list-style: none;
}

.footer-section ul li {
  margin-bottom: 0.8rem;
}

.footer-section ul li a:hover {
  color: white;
  padding-left: 5px;
}

.social-links {
  display: flex;
  gap: 1rem;
}

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

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

.footer-bottom {
  text-align: center;
  padding-top: 2rem;
  border-top: 1px solid #4a5568;
  color: #cbd5e0;
}

/* =========================
   RESPONSIVE
========================= */
@media (max-width: 768px) {
  .menu-toggle { display: flex; }

  nav {
    position: fixed;
    top: 70px;
    left: -100%;
    width: 100%;
    height: calc(100vh - 70px);
    background: white;
    flex-direction: column;
    padding-top: 2rem;
  }

  nav.active { left: 0; }

  nav a {
    margin: 1rem 0;
    font-size: 1.2rem;
  }
}

@media (max-width: 576px) {
  .footer-content {
    grid-template-columns: 1fr;
  }

  h1 { font-size: 2rem; }
  h2 { font-size: 1.7rem; }
}
.notes-tools {
      display: flex;
      gap: 1rem;
      margin: 1.5rem 0;
      flex-wrap: wrap;
      }
/* Additional styles specific to notes page */
    .notes-container {
      max-width: 1000px;
      margin: 2rem auto;
      padding: 0 20px;
    }
    
    .notes-header {
      display: flex;
      justify-content: space-between;
      align-items: center;
      margin-bottom: 2rem;
      flex-wrap: wrap;
      gap: 1rem;
    }
    
    .chapter-info {
      background: white;
      padding: 1.5rem;
      border-radius: var(--border-radius);
      box-shadow: var(--box-shadow);
      margin-bottom: 2rem;
    }
    
    .chapter-title {
      color: var(--primary-color);
      margin-bottom: 0.5rem;
    }
    
    .chapter-progress {
      display: flex;
      align-items: center;
      gap: 1rem;
      margin-top: 1rem;
    }
    
    .progress-bar {
      flex-grow: 1;
      height: 8px;
      background-color: var(--gray-light);
      border-radius: 4px;
      overflow: hidden;
    }
    
    .progress-fill {
      height: 100%;
      background-color: var(--primary-color);
      width: 100%; /* Adjust based on actual progress */
    }
    
    .notes-content {
      background: white;
      padding: 2rem;
      border-radius: var(--border-radius);
      box-shadow: var(--box-shadow);
      margin-bottom: 2rem;
      min-height: 400px;
    }
    
    .notes-actions {
      display: flex;
      justify-content: space-between;
      align-items: center;
      margin-top: 2rem;
      flex-wrap: wrap;
      gap: 1rem;
    }
    
    .nav-buttons {
      display: flex;
      gap: 1rem;
    }
    
    .btn-disabled {
      background-color: var(--gray-light);
      color: var(--gray);
      cursor: not-allowed;
    }
    
    .btn-disabled:hover {
      transform: none;
      box-shadow: none;
    }
    
    .notes-tools {
      display: flex;
      gap: 1rem;
      margin: 1.5rem 0;
      flex-wrap: wrap;
    }
    
    .tool-btn {
      background: white;
      border: 1px solid var(--gray-light);
      padding: 0.5rem 1rem;
      border-radius: var(--border-radius);
      cursor: pointer;
      display: flex;
      align-items: center;
      gap: 0.5rem;
      transition: var(--transition);
    }
    
    #share-page {
  background-color: #007bff; /* Professional Blue */
  color: white;
}

#share-page:hover {
  background-color: #0056b3;
}

    .tool-btn:hover {
      background: var(--light-color);
      border-color: var(--primary-color);
    }
    
    .highlight-yellow {
      background-color: #fff9c4;
    }
    
    .highlight-pink {
      background-color: #f8bbd0;
    }
    
    .highlight-blue {
      background-color: #bbdefb;
    }
    
    .note-text {
      line-height: 1.8;
      font-size: 1.1rem;
    }
    
    .note-text h3 {
      color: var(--primary-color);
      margin-top: 1.5rem;
      margin-bottom: 0.5rem;
    }
    
    .note-text ul, .note-text ol {
      margin-left: 1.5rem;
      margin-bottom: 1rem;
    }
    
    .note-text li {
      margin-bottom: 0.5rem;
    }
    
    .formula-box {
      background: var(--light-color);
      padding: 1rem;
      border-left: 4px solid var(--primary-color);
      margin: 1.5rem 0;
      font-family: 'Courier New', monospace;
      font-size: 1.2rem;
    }
    
    .important-point {
      background: #fff3e0;
      padding: 1rem;
      border-radius: var(--border-radius);
      margin: 1rem 0;
      border-left: 4px solid var(--accent-color);
    }
    
    @media (max-width: 768px) {
      .notes-header {
        flex-direction: column;
        align-items: flex-start;
      }
      
      .notes-actions {
        flex-direction: column;
        align-items: stretch;
      }
      
      .nav-buttons {
        width: 100%;
        justify-content: space-between;
      }
      
      .nav-buttons .btn {
        flex: 1;
        text-align: center;
      }
    }