:root {
    --color-lightest: #e5e4e2;
    --color-light: #d9d9d9;
    --color-medium: #c0c0c0;
    --color-dark: #4a4a4a;
    --color-darkest: #2e2e2e;
  
    --color-accent-lightest: #ddeaf6;
    --color-accent-light: #a8bccb;
    --color-accent: #345678;
    --color-accent-dark: #4e6172;
    --color-highlight: #aedff7;
  
    --primary-color: #345678;
    --secondary-color: #4e6172;
    --background-color: #ddeaf6;
  }
  
  body {
    background-color: var(--background-color);
    font-family: Arial, sans-serif;
    color: var(--color-darkest);
    margin: 0;
    padding: 0;
  }
  
  .header {
    background-color: var(--primary-color);
    padding: 15px;
    text-align: center;
  }
  
  .header img {
    max-width: 140px;
    height: auto;
  }
  
  .nav-tabs .nav-link.active {
    background-color: var(--secondary-color);
    color: white;
  }
  
  .nav-tabs .nav-link {
    color: var(--primary-color);
  }
  
  .container {
    max-width: 700px;
    margin: 30px auto;
    padding: 20px;
    background: white;
    border-radius: 8px;
    box-shadow: 0 0 10px rgba(0, 0, 0, 0.05);
  }
  
  .task-card {
    background: var(--color-lightest);
    padding: 15px;
    margin-bottom: 10px;
    border-radius: 5px;
    box-shadow: 2px 2px 5px rgba(0, 0, 0, 0.05);
  }
  
  .done {
    background-color: var(--color-light);
    text-decoration: line-through;
    color: var(--color-dark);
  }
  
  .comment {
    font-size: 0.85em;
    color: var(--color-dark);
  }
  
  .btn-primary {
    background-color: var(--primary-color);
    border-color: var(--primary-color);
  }
  
  .btn-success {
    background-color: var(--color-highlight);
    border-color: var(--color-highlight);
    color: var(--color-darkest);
  }
  
  #progressBar {
    width: 100%;
    height: 20px;
    background-color: #e9ecef;
    border-radius: 10px;
    overflow: hidden;
    margin-bottom: 15px;
  }
  
  #progressBar .bar {
    height: 100%;
    background-color: var(--primary-color);
    width: 0%;
    transition: width 0.3s;
  }
  
  #timerDisplay {
    font-weight: bold;
    margin-bottom: 10px;
  }
  
  /* ===== DESKTOP STYLES ===== */
  @media (min-width: 768px) {
    .container {
      max-width: 900px;
      margin: 40px auto;
      padding: 30px;
    }
  
    .header img {
      max-width: 200px;
    }
  
    .task-card {
      font-size: 1.1rem;
      padding: 20px;
    }
  
    #reader {
      max-width: 500px;
      margin: 0 auto;
    }
  
    .nav-tabs .nav-link {
      font-size: 1.1rem;
      padding: 12px 20px;
    }
  
    .btn {
      font-size: 1rem;
      padding: 10px 20px;
    }
  
    .btn-primary {
      font-size: 1rem;
    }
  
    .btn-success {
      font-size: 1rem;
    }
  
    #timerDisplay {
      font-size: 1rem;
    }
  
    h4, h5 {
      font-size: 1.4rem;
    }
  }