body {
            font-family: 'Segoe UI', Arial, sans-serif;
            background: #f8f9fa;
            color: #222;
            margin: 0;
            padding: 0;
        }
        header {
            background: #007bff;
            color: #fff;
            position: fixed;
            top: 0;
            left: 0;
            width: 100%;
            height: 40px;
            z-index: 101;
            display: flex;
            align-items: center;
            justify-content: center;
            font-size: 1.1em;
            box-shadow: 0 2px 8px rgba(0,0,0,0.04);
        }
        nav {
            background: #fff;
            position: fixed;
            top: 40px;
            left: 0;
            width: 100%;
            height: 36px;
            z-index: 100;
            box-shadow: 0 2px 4px rgba(0,0,0,0.03);
            display: flex;
            align-items: center;
            justify-content: center;
        }
        nav ul {
            list-style: none;
            margin: 0;
            padding: 0;
            display: flex;
        }
        nav li {
            margin: 0 0.7em;
        }
        nav a {
            color: #007bff;
            text-decoration: none;
            font-weight: 500;
            padding: 0.2em 0.7em;
            border-radius: 4px;
            transition: background 0.2s;
            cursor: pointer;
            font-size: 1em;
        }
        nav a:hover, nav a.active {
            background: #e3f0ff;
        }
        main {
            max-width: 600px;
            margin: 100px auto 60px auto; /* espace pour header/menu et footer */
            background: #fff;
            border-radius: 8px;
            box-shadow: 0 2px 8px rgba(0,0,0,0.04);
            padding: 2em;
            min-height: 300px;
        }
        .section { display: none; }
        .section.active { display: block; }
        ul.features {
            list-style: none;
            margin-top: 1em;
            padding-left: 1.2em;
        }
        ul {
            list-style: none;
            margin-top: 1em;
            padding-left: 1.2em;
        }
        ul.features li {
            margin-bottom: 0.5em;
        }
        form label {
            display: block;
            margin-top: 1em;
            margin-bottom: 0.3em;
        }
        form input {
            padding: 0.4em;
            width: 100%;
            box-sizing: border-box;
            border: 1px solid #bbb;
            border-radius: 4px;
        }
        form button {
            margin-top: 1em;
            background: #007bff;
            color: #fff;
            border: none;
            padding: 0.6em 1.2em;
            border-radius: 4px;
            cursor: pointer;
            font-size: 1em;
        }
        form button:hover {
            background: #0056b3;
        }
        footer {
            background: #007bff;
            color: #fff;
            position: fixed;
            left: 0;
            bottom: 0;
            width: 100%;
            height: 36px;
            z-index: 102;
            text-align: center;
            font-size: 1em;
            display: flex;
            align-items: center;
            justify-content: center;
            box-shadow: 0 -2px 8px rgba(0,0,0,0.04);
        }

    .accordion-btn {
      width: 100%;
      text-align: left;
      padding: 10px 40px 10px 10px; /* espace � droite pour la fl�che */
      font-size: 1.1em;
      background: #eee;
      border: none;
      outline: none;
      cursor: pointer;
      margin-top: 5px;
      position: relative; /* n�cessaire pour positionner la fl�che */
    }
    .arrow {
      position: absolute;
      right: 16px; /* espace du bord droit */
      top: 50%;
      transform: translateY(-50%);
      transition: transform 0.2s;
    }