* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}
main {
    display: flex;
    flex-direction: column;
    align-items: center;
padding-bottom: 100px;
}
main h1 {
    margin: 70px 0;
    font-size: 2.5em;
    color: #333;
}
figure {
    margin: 20px 400px 20px 400px; /* 左右400pxのマージン */
    text-align: center;
    width: calc(100% - 800px); /* 左右400pxずつ引いた幅 */
}
figure img {
    width: 100%;
    height: auto;
    display: block;
}
main h2 {
    margin: 50px 0 20px 0;
    font-size: 2em;
    color: #555;
}
main p {
    margin: 0 100px 30px 100px;
}