:root {
      --primary: #FF6B6B;
      --primary-light: #FF8E8E;
      --secondary: #4ECDC4;
      --accent: #FFD166;
      --dark: #2D3047;
      --light: #F7F9FC;
      --gray: #6B7280;
      --success: #06D6A0;
      --border-radius: 16px;
      --shadow: 0 10px 25px rgba(0, 0, 0, 0.08);
      --transition: all 0.3s ease;
    }
    
    body {
      font-family: 'Inter', 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
      color: var(--dark);
      background: linear-gradient(135deg, #FFF5F5 0%, #F0F9FF 100%);
      line-height: 1.6;
      min-height: 100vh;
    }
    
    .main-container {
      max-width: 1000px;
      background: white;
      border-radius: var(--border-radius);
      box-shadow: var(--shadow);
      padding: 2rem;
      margin-top: 2rem;
      margin-bottom: 2rem;
      position: relative;
      overflow: hidden;
    }
    
    .main-container::before {
      content: '';
      position: absolute;
      top: 0;
      left: 0;
      width: 100%;
      height: 5px;
      background: linear-gradient(to right, var(--primary), var(--secondary));
    }
    
    .heading-main {
      font-weight: 800;
      color: var(--dark);
      position: relative;
      display: inline-block;
      margin-bottom: 1.5rem;
    }
    
    .heading-main:after {
      content: '';
      position: absolute;
      bottom: -10px;
      left: 50%;
      transform: translateX(-50%);
      width: 80px;
      height: 4px;
      background: var(--primary);
      border-radius: 2px;
    }
    
    /* Custom File Upload */
    .custom-file-upload {
      background: white;
      border-radius: var(--border-radius);
      padding: 2.5rem;
      text-align: center;
      box-shadow: var(--shadow);
      transition: var(--transition);
      border: 2px dashed #E1E5EE;
      cursor: pointer;
      margin-bottom: 2rem;
      position: relative;
    }
    
    .custom-file-upload:hover {
      transform: translateY(-5px);
      box-shadow: 0 15px 35px rgba(0, 0, 0, 0.1);
      border-color: var(--primary);
    }
    
    .custom-file-upload-color-1 {
      background: linear-gradient(135deg, #ffffff 0%, #fef7f7 100%);
    }
    
    .custom-file-upload img {
      margin-bottom: 1.5rem;
      filter: hue-rotate(320deg);
    }
    
    .custom-file-upload label {
      display: block;
      font-weight: 600;
      color: var(--primary);
      font-size: 1.2rem;
      margin-bottom: 1rem;
      cursor: pointer;
    }
    
    /* Page Input Styling */
    .page-input-container {
      background: white;
      border-radius: var(--border-radius);
      box-shadow: var(--shadow);
      padding: 2rem;
      margin-bottom: 2rem;
      border-left: 4px solid var(--secondary);
    }
    
    .page-input-title {
      font-weight: 600;
      margin-bottom: 1rem;
      color: var(--dark);
      display: flex;
      align-items: center;
    }
    
    .page-input-title i {
      margin-right: 10px;
      color: var(--secondary);
    }
    
    .range-box {
      border-radius: 10px;
      border: 1px solid #E5E7EB;
      padding: 0.75rem 1rem;
      transition: var(--transition);
      background: #F9FAFB;
      width: 100%;
      max-width: 400px;
      font-family: 'Inter', sans-serif;
    }
    
    .range-box:focus {
      border-color: var(--primary);
      box-shadow: 0 0 0 3px rgba(255, 107, 107, 0.1);
      background: white;
    }
    
    .range-box::placeholder {
      color: var(--gray);
    }
    
    .page-input-help {
      margin-top: 0.5rem;
      font-size: 0.9rem;
      color: var(--gray);
    }
    
    /* Common Button */
    .common-btn {
      background: linear-gradient(135deg, var(--primary), var(--primary-light));
      border: none;
      border-radius: 50px;
      padding: 0.9rem 2.5rem;
      font-weight: 600;
      color: white;
      transition: var(--transition);
      box-shadow: 0 5px 15px rgba(255, 107, 107, 0.3);
      position: relative;
      overflow: hidden;
    }
    
    .common-btn:hover {
      transform: translateY(-3px);
      box-shadow: 0 8px 20px rgba(255, 107, 107, 0.4);
      color: white;
    }
    
    .common-btn:active {
      transform: translateY(1px);
    }
    
    .common-btn:after {
      content: '';
      position: absolute;
      top: 0;
      left: -100%;
      width: 100%;
      height: 100%;
      background: rgba(255, 255, 255, 0.1);
      transform: translateX(-100%);
      transition: transform 0.4s ease;
    }
    
    .common-btn:hover:after {
      transform: translateX(100%);
    }
    
    /* File List */
    #pdf-list {
      margin-top: 1.5rem;
    }
    
    .list-group-item {
      border-radius: 10px;
      margin-bottom: 0.5rem;
      border: 1px solid #E5E7EB;
      display: flex;
      align-items: center;
      padding: 0.75rem 1rem;
      background: white;
      transition: var(--transition);
    }
    
    .list-group-item:hover {
      border-color: var(--primary);
      box-shadow: 0 0 10px rgba(255, 107, 107, 0.1);
      transform: translateX(5px);
    }
    
    .list-group-item i {
      color: var(--primary);
      margin-right: 10px;
    }
    
    /* Preview Section */
    .preview-section {
      background: white;
      border-radius: var(--border-radius);
      box-shadow: var(--shadow);
      padding: 1.5rem;
      margin-top: 2rem;
      border-left: 4px solid var(--accent);
      display: none;
    }
    
    .preview-section.active {
      display: block;
      animation: fadeIn 0.5s ease;
    }
    
    .preview-title {
      font-weight: 600;
      margin-bottom: 1rem;
      color: var(--dark);
      display: flex;
      align-items: center;
    }
    
    .preview-title i {
      margin-right: 8px;
      color: var(--accent);
    }
    
    .preview-box {
      border: 1px solid #E5E7EB;
      border-radius: 8px;
      height: 200px;
      display: flex;
      align-items: center;
      justify-content: center;
      background-color: #F9FAFB;
      position: relative;
      overflow: hidden;
    }
    
    .page-preview {
      display: flex;
      flex-wrap: wrap;
      gap: 10px;
      padding: 10px;
      justify-content: center;
    }
    
    .page-item {
      width: 50px;
      height: 70px;
      background: white;
      border: 2px solid #E5E7EB;
      border-radius: 5px;
      display: flex;
      align-items: center;
      justify-content: center;
      font-weight: 600;
      color: var(--dark);
      transition: var(--transition);
      position: relative;
    }
    
    .page-item.to-delete {
      background: #FFF5F5;
      border-color: var(--primary);
      color: var(--primary);
    }
    
    .page-item.to-delete::after {
      content: '×';
      position: absolute;
      top: -8px;
      right: -8px;
      width: 20px;
      height: 20px;
      background: var(--primary);
      color: white;
      border-radius: 50%;
      display: flex;
      align-items: center;
      justify-content: center;
      font-size: 14px;
      font-weight: bold;
    }
    
    /* Animation */
    @keyframes fadeIn {
      from { opacity: 0; transform: translateY(20px); }
      to { opacity: 1; transform: translateY(0); }
    }
    
    .fade-in {
      animation: fadeIn 0.6s ease forwards;
    }
    
    /* Responsive */
    @media (max-width: 768px) {
      .main-container {
        padding: 1.5rem;
      }
      
      .custom-file-upload {
        padding: 1.5rem;
      }
      
      .page-input-container {
        padding: 1.5rem;
      }
    }
    /* Reset Button */
    .reset-btn {
      background: linear-gradient(135deg, var(--gray), #9CA3AF);
      border: none;
      border-radius: 50px;
      padding: 0.9rem 2.5rem;
      font-weight: 600;
      color: white;
      transition: var(--transition);
      box-shadow: 0 5px 15px rgba(107, 114, 128, 0.3);
      position: relative;
      overflow: hidden;
      margin-left: 1rem;
    }
    
    .reset-btn:hover {
      transform: translateY(-3px);
      box-shadow: 0 8px 20px rgba(107, 114, 128, 0.4);
      color: white;
    }
    
    .reset-btn:active {
      transform: translateY(1px);
    }