:root {
        --primary-color: #007aff;
        --bg-color: #ffffff;
        --text-color: #333333;
        --secondary-bg: #f2f2f7;
        --border-color: #e5e5ea;
        --header-height: 60px;
        --footer-height: 70px;
        --content-padding: 20px;
      }
body::-webkit-scrollbar {
    display: none;
}
      .dark-mode {
        --primary-color: #0a84ff;
        --bg-color: #1c1c1e;
        --text-color: #e5e5ea;
        --secondary-bg: #2c2c2e;
        --border-color: #38383a;
      }

      * {
        margin: 0;
        padding: 0;
        box-sizing: border-box;
        transition: background-color 0.3s, color 0.3s;
      }

      body {
             font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;
        background-color: var(--bg-color);
        color: var(--text-color);
        line-height: 1.6;
        display: flex;
        flex-direction: column;
        min-height: 100vh;
      }

      .container {
        max-width: 800px;
        margin: 0 auto;
        width: 100%;
        padding: 0 var(--content-padding);
      }

      header {
        height: var(--header-height);
        background-color: var(--bg-color);
        border-bottom: 1px solid var(--border-color);
        /* position: sticky; */
        top: 0;
        z-index: 100;
        display: flex;
        align-items: center;
      }

      .header-content {
        display: flex;
        justify-content: space-between;
        align-items: center;
        width: 100%;
      }

      .left-header,
      .right-header {
        display: flex;
        align-items: center;
        gap: 15px;
      }

      .logo {
        font-weight: 700;
        font-size: 22px;
        color: var(--primary-color);
        text-decoration: none;
      }

      .btn {
        background: none;
        border: none;
        color: var(--text-color);
        font-size: 18px;
        cursor: pointer;
        padding: 8px;
        border-radius: 8px;
        display: flex;
        align-items: center;
        justify-content: center;
        text-decoration: none;
      }

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

      .theme-toggle {
        width: 40px;
        height: 24px;
        background-color: var(--secondary-bg);
        border-radius: 12px;
        position: relative;
        cursor: pointer;
      }

      .theme-toggle::after {
        content: "";
        position: absolute;
        width: 20px;
        height: 20px;
        background-color: var(--primary-color);
        border-radius: 50%;
        top: 2px;
        left: 2px;
        transition: transform 0.3s;
      }

      .dark-mode .theme-toggle::after {
        transform: translateX(16px);
      }

      main {
        flex: 1;
        padding: 30px 0;
      }

      .chapter-title {
        font-size: 24px;
        margin-bottom: 20px;
        font-weight: 600;
      }

      .content {
        font-size: 18px;
        text-align: justify;
      }

      .content p {
        margin-bottom: 20px;
      }

      .font-controls {
        display: flex;
        gap: 10px;
        margin-top: 30px;
        justify-content: center;
      }

      .font-btn {
        padding: 8px 16px;
        background-color: var(--secondary-bg);
        border: none;
        border-radius: 8px;
        color: var(--text-color);
        cursor: pointer;
      }

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

      footer {
        min-height: var(--footer-height);
        background-color: var(--bg-color);
        border-top: 1px solid var(--border-color);
        display: flex;
        align-items: center;
        padding-bottom: 140px;
      }

      .footer-content {
        display: flex;
        justify-content: space-between;
        align-items: center;
        width: 100%;
      }

      .nav-btn {
        padding: 12px 20px;
        background-color: var(--primary-color);
        color: white;
        border: none;
        border-radius: 10px;
        cursor: pointer;
        display: flex;
        align-items: center;
        gap: 8px;
        font-weight: 500;
        text-decoration: none;
      }

      .nav-btn:disabled {
        background-color: var(--secondary-bg);
        color: var(--text-color);
        opacity: 0.7;
        cursor: not-allowed;
      }

      .chapter-nav {
        display: flex;
        gap: 15px;
      }

      .sidebar {
        position: fixed;
        top: 0;
        left: -300px;
        width: 300px;
        height: 100%;
        background-color: var(--bg-color);
        border-right: 1px solid var(--border-color);
        z-index: 200;
        overflow-y: auto;
        padding: 20px;
        transition: left 0.3s ease;
      }

      .sidebar.open {
        left: 0;
      }

      .sidebar-overlay {
        position: fixed;
        top: 0;
        left: 0;
        width: 100%;
        height: 100%;
        background-color: rgba(0, 0, 0, 0.5);
        z-index: 199;
        display: none;
      }

      .sidebar-overlay.open {
        display: block;
      }

      .sidebar-header {
        display: flex;
        justify-content: space-between;
        align-items: center;
        margin-bottom: 20px;
        padding-bottom: 10px;
        border-bottom: 1px solid var(--border-color);
      }

      .sidebar-title {
        font-size: 20px;
        font-weight: 600;
      }

      .chapter-list {
        list-style: none;
      }

      .chapter-item {
        padding: 12px 0;
        cursor: pointer;
        border-bottom: 1px solid var(--border-color);
      }

      .chapter-item a {
        color: var(--text-color);
        text-decoration: none;
        display: block;
      }

      .chapter-item.active {
        color: var(--primary-color);
        font-weight: 600;
      }

      .font-small {
        font-size: 16px;
      }

      .font-medium {
        font-size: 18px;
      }

      .font-large {
        font-size: 20px;
      }
.footer-content{
      margin: 10px 0;
}
      @media (max-width: 768px) {
        :root {
          --content-padding: 15px;
        }

        .chapter-title {
          font-size: 22px;
        }

        .content {
          font-size: 16px;
        }

        .nav-btn {
          padding: 10px 15px;
          font-size: 14px;
        }

        .sidebar {
          width: 85%;
          left: -85%;
        }
      }