index.html

<!DOCTYPE html>
<html lang="es">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Formulario 1</title>
    <script src="js/funciones.js"></script>
    <link rel="stylesheet" href="css/estilos.css">
    <script src="https://kit.fontawesome.com/b99e675b6e.js"></script>
</head>
<body>

    <header>
        <nav class="navbar">
            <ul>
                <li><a href="index.html" class="menu_link">Ejercicio 1</a></li>
                <li><a href="formulario2.html" class="menu_link">Ejercicio 2</a></li>
                <li><a href="formulario3.html" class="menu_link">Ejercicio 3</a></li>
            </ul>
        </nav>
    </header>

    <main>
        <section class="form">
            <div class="title">
                <h1>Ejercicio 1</h1>
                <i class="far fa-edit"></i>
            </div>
            
            <form action="javascript:void(0)" method="GET" name="formu1" class="formulario1" onsubmit="form1()">
                <h3>Ingrese un número entre 3 y 10:</h3><br>
                <input type="number" name="valor" id="valor" required min="3" max="10" placeholder="Valor numérico"><br>
                <input type="submit" id="submit" value="Aceptar">
            </form>
    
            <div id="salida1">
                <ul id="resultado1"></ul><br>  
                <button onclick="window.location.reload();" class="refresh" >Reiniciar</button>
            </div>
        </section>
    </main>

</body>
</html>