body {
    /* Fuentes seleccionadas */
    font-family: Verdana, Geneva, Tahoma, sans-serif;
    background-color: aliceblue;
    margin: 0;
    background-image: 
        repeating-linear-gradient(
        -45deg,
        #fff,
        #fff 20px,
        aliceblue 20px,
        aliceblue 40px
        );
        height: 100vh;
}
.topnav {
    background-color: #333;
    overflow: hidden;
    height: 50px;
}
.topnav div{
    float: left;
    vertical-align: middle;
    margin: 8px;
}
.topnav a {
    float: left;
    color: #f2f2f2;
    text-align: center;
    padding: 14px 16px;
    padding-left: 12px;
    padding-right: 16px;
    text-decoration: none;
    font-size: 17px;
    display: flex;
}
.topnav a:hover {
    background-color: #ddd;
    color: black;
}
.topnav a.active {
    background-color: #00aeff;
    color: white;
}
.topnav a svg {
    margin-right: 8px;
}
.contenedor {
    margin: 10em;
    background-color: white;
    padding: 1em;
}

@media (max-width: 1000px) {
    .contenedor {
        margin: 1em;;
    }
    .topnav {
        height: auto;
    }
  }
  

/* FORMULARIOS */

input[type=text], input[type=email], select, textarea {
    width: 100%;
    padding: 12px;
    border: 1px solid #ccc;
    border-radius: 4px;
    box-sizing: border-box;
    margin-top: 6px;
    margin-bottom: 6px;
    resize: vertical
}

input[type=submit] {
    background-color: #04AA6D;
    color: white;
    padding: 12px 20px;
    border: none;
    border-radius: 4px;
    cursor: pointer;
    }

input[type=submit]:hover {
    background-color: #45a049;
    }
    
.container {
    border-radius: 5px;
    background-color: #f2f2f2;
    padding: 20px;
    }

/* LISTA */

.formulario {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.formulario__introducir {
    flex-basis: 75%;
    border: 0;
    padding: 5px;
}

.formulario__enviar {
    flex-basis: 50%;
    border: 0;
    background-color: gray;
    color: white;
    padding: 5px;
}

.tareas {
    padding: 0;
}

.tarea {
    cursor: pointer;
    display: flex;
    justify-content: space-between;
    padding: 5px;
    margin-bottom: 5px;
}

.tarea:last-of-type {
    margin-bottom: 0;
}

.tarea__nombre {
    flex-basis: 75%;
}

.tarea--completada {
    text-decoration: line-through;
    opacity: .6;
    background-color: lightgreen;
}

@media screen and (max-width: 600px) {
    .formulario {
        flex-wrap: wrap;
    }

    .formulario > * {
        flex-basis: 100%;
    }
}