* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

a {
    text-decoration: none;
    padding: 5px;
}

.boton {
    width: 25%;
    height: 20%;
    border: 2px black solid;
    background-color: darkred;
    cursor: pointer;
    color: white;
    text-align: center;
}

header {
    background-color: black;
    color: white;
    width: 100%;
    height: 30%;
    margin-bottom: 5px;
}

header h1 {
    font-size: 45px;
    font-weight: 900;
    text-align: center;
}

.rotacion-tronco {
    padding: 5px;
    width: 50%;
    display: flex;
    flex-direction: column;
    justify-content: space-between;
    align-items: center;
    border: solid black 2px;
    margin: 1rem;
}

li {
    margin: 1rem;
}

img {
    width: 500px;
    height: 250px;
}

.escalones {
    padding: 5px;
    width: 50%;
    display: flex;
    flex-direction: column;
    justify-content: space-between;
    align-items: center;
    border: solid black 2px;
    margin: 1rem;
}

.ejercicios-1y2 {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.retraccion-y-protraccion {
    padding: 5px;
    width: 50%;
    display: flex;
    flex-direction: column;
    justify-content: space-between;
    align-items: center;
    border: solid black 2px;
    margin: 1rem;
}

.educacion-marcha {
    padding: 5px;
    width: 50%;
    display: flex;
    flex-direction: column;
    justify-content: space-between;
    align-items: center;
    border: solid black 2px;
    margin: 1rem;
}

.ejercicios-3y4 {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

/*!------MQ---------*/
@media screen and (max-width: 1095px) {
    .ejercicios-1y2 {
        display: flex;
        flex-direction: column;
        justify-content: space-between;
        align-items: center;
    }
    .ejercicios-3y4 {
        display: flex;
        flex-direction: column;
        justify-content: space-between;
        align-items: center;
    }
    img {
        width: 80%;
        height: 40%;
    }
}

@media screen and (max-width: 950px) {
    h2 {
        font-size: 20px;
    }
}

@media screen and (max-width: 880px) {
    .educacion-marcha {
        width: 80%;
    }
    .retraccion-y-protraccion {
        width: 80%;
    }
    .escalones {
        width: 80%;
    }
    .rotacion-tronco {
        width: 80%;
    }
}


@media screen and (max-width: 810px) {
    h2 {
        text-align: center;
    }
}

@media screen and (max-width: 710px) {
    .educacion-marcha {
        width: 80%;
    }
    .retraccion-y-protraccion {
        width: 80%;
    }
    .escalones {
        width: 80%;
    }
    .rotacion-tronco {
        width: 80%;
    }
}

@media screen and (max-width: 560px) {
    .boton {
        font-size: 13px;
    }
        .boton {
        font-size: 13px;
    }
    .educacion-marcha {
        font-size: 13px;
    }
    .retraccion-y-protraccion {
        font-size: 13px;
    }
    .escalones {
        font-size: 13px;
    }
    .rotacion-tronco {
        font-size: 13px;
    }
}

@media screen and (max-width: 400px) {
    h1 {
        font-size: 30px;
    }
}