section {
    background-image: url(../img/flag_left.png), url(../img/flag_right.png);
    background-position: left top, right top;
    background-repeat: no-repeat, no-repeat;
}

@media screen and (min-width: 1025px) {
    #top_image {
        background-image: url('../img/respiratory_organs_bg.jpg');
        background-repeat: no-repeat;
        background-size: cover;
        background-position: center center;
        padding: 0;
        margin: 0;
        height: 500px;
        width: 100%;
        max-width: 2000px;
        overflow: hidden;
    }

    ul {
        display: flex;
        flex-wrap: wrap;
    }

    li {
        width: 50%;
    }
}

@media screen and (max-width: 1024px) {
    #top_image {
        background-image: url('../img/respiratory_organs_bg.jpg');
        background-repeat: no-repeat;
        background-size: cover;
        background-position: center center;
        padding: 0;
        margin: 0;
        height: 55vw;
        width: 100%;
        overflow: hidden;
    }

    .senyou {
        color: #e66959;
        font-size: 1.5rem;
        font-weight: 800;
        margin: 0 0.5rem;
    }

    ul {
        display: flex;
        flex-wrap: wrap;
    }

    li {
        width: 50%;
    }
}

@media screen and (max-width: 767px) {
    #top_image {
        background-image: url('../img/respiratory_organs_bg.jpg');
        background-repeat: no-repeat;
        background-size: cover;
        background-position: center center;
        padding: 0;
        margin-top: 60px;
        height: 55vw;
        width: 100%;
        overflow: hidden;
    }
}