/* botones prev y next */
.cont-controls {
    display: flex;
    justify-content: space-between;
    /* - */
    position: absolute;
    top: 45%;
    z-index: 4;
    width: 100%;
    padding: 1rem;
}

.btn {
    padding: 5px 10px;
    /* - */
    color: black;
    font-size: 3rem;
    font-weight: bold;
    /* - */
    border: 1px solid transparent;
    border-radius: 50%;
    background: #fff;
}

#btn-prev {
    opacity: 20%;
}

#btn-next {
    opacity: 100%;
}

/* slider ------------- */
.cont-slider {
    position: relative;
    overflow: hidden;
    width: 100%;
    margin: auto;
    background: linear-gradient(to bottom right, rgb(115, 174, 231), rgb(0, 0, 0));
}

.slider {
    display: flex;
    margin-left: 0;
}

.slider__frame {
    flex: 1;
    display: flex;
    justify-content: center;
    align-items: center;
}

.slider__frame--img {
    padding: 20px;
    max-width: 100%;
    max-height: 100%;
}