*{
    padding: 0;
    margin: 0;
    box-sizing: border-box;
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, 'Open Sans', 'Helvetica Neue', sans-serif;
}
.container{
    width: 100%;
    height: 100vh;
    background: #f6f9fc;
}
.title{
    width: 100%;
    height: 10vh;
    display: flex;
    align-items: center;
    justify-content: center;
    text-align: center;
}
.title h1{
    font-size: 25px;
    color: #555;
}
.contents{
    width: 100%;
    height: 90vh;
    display: flex;
    align-items: center;
    flex-direction: column;
    justify-content: center;
}
.images{
    width: 400px;
}
.image{
    padding: 1em;
    background: #fff;
    display: flex;
    align-items: center;
    justify-content: center;
    box-shadow: 0 2px 4px rgb(50 50 93 / 10%);
}
.big-image{
    width: 400px;
    height: 200px;
    background: #fff;
    box-shadow: 0 2px 4px rgb(50 50 93 / 10%);
    background: url(./images/1.jpg) no-repeat;
    background-size: cover;
    background-position: center;
}
.small-image{
    width: 400px;
    padding: 1em;
    background: #fff;
    margin: 1em 0;
    box-shadow: 0 2px 4px rgb(50 50 93 / 10%);
    display: flex;
    align-items: center;
    justify-content: center;
}
.one{
    width: 100px;
    height: 70px;
    background: url(./images/1.jpg) no-repeat;
    background-size: cover;
    background-position: center;
    border-right: 0.1em solid #fff;
}
.two{
    width: 100px;
    height: 70px;
    background: url(./images/2.jpg) no-repeat;
    background-size: cover;
    background-position: center;
    border-right: 0.1em solid #fff;
}
.three{
    width: 100px;
    height: 70px;
    background: url(./images/3.jpg) no-repeat;
    background-size: cover;
    background-position: center;
    border-right: 0.1em solid #fff;
}
.four{
    width: 100px;
    height: 70px;
    background: url(./images/4.jpg) no-repeat;
    background-size: cover;
    background-position: center;
}
.small-image-switch:hover, .small-image-switch:hover, .small-image-switch:hover, .small-image-switch:hover{
    border: 0.2em solid rgb(62 125 229);
    cursor: pointer;
}
.first{
    background: url(./images/1.jpg);
    background-size: cover;
    background-position: center;
}
.second{
    background: url(./images/2.jpg);
    background-size: cover;
    background-position: center;
}
.third{
    background: url(./images/3.jpg);
    background-size: cover;
    background-position: center;
}
.fourth{
    background: url(./images/4.jpg);
    background-size: cover;
    background-position: center;
}
/* when your width of your phone is less than or equal to 600px */
@media (max-width: 600px) {
    .contents{
        padding: 0 1em;
    }
    .images{
        width: 100%;
    }
    .small-image{
        width: 100%;
    }
    .big-image{
        width: 100%;
    }
    .small-image-switch{
        width: 25%;
    }
}