* {
    box-sizing: border-box;
}

body {
    margin: 0;
    padding: 0;
    background: #f4f5f6;
    color: #333333;
    font-family:
        -apple-system,
        BlinkMacSystemFont,
        "Segoe UI",
        "Yu Gothic",
        "YuGothic",
        "Meiryo",
        sans-serif;
    line-height: 1.7;
}

a {
    color: #185f91;
    text-decoration: none;
}

a:hover {
    text-decoration: underline;
}

/* ページ全体 */

.page {
    max-width: 1100px;
    margin: 0 auto;
    background: #ffffff;
    min-height: 100vh;
    box-shadow: 0 0 12px rgba(0, 0, 0, 0.10);
}

/* ヘッダー */

.header img {
    display: block;
    width: 100%;
    height: auto;
}

/* ナビゲーション */

.navigation {
    display: flex;
    justify-content: center;
    flex-wrap: wrap;
    background: #294b63;
    border-top: 1px solid #ffffff;
    border-bottom: 1px solid #183345;
}

.navigation a {
    padding: 11px 22px;
    color: #ffffff;
    border-right: 1px solid #557184;
    font-size: 15px;
}

.navigation a:first-child {
    border-left: 1px solid #557184;
}

.navigation a:hover {
    background: #376985;
    text-decoration: none;
}

/* メイン */

.main {
    padding: 32px 42px 45px 42px;
}

/* 製品タイトル */

.product-header {
    margin-bottom: 32px;
    padding-bottom: 16px;
    border-bottom: 2px solid #294b63;
}

.product-header h1 {
    margin: 0 0 7px 0;
    color: #24485f;
    font-size: 28px;
    font-weight: 500;
}

.product-header p {
    margin: 0;
    color: #666666;
    font-size: 15px;
}

/* 特長 */

.features-title {
    margin: 0 0 24px 0;
    color: #294b63;
    font-size: 23px;
    font-weight: 500;
}

.feature {
    margin-bottom: 42px;
}

.feature h2 {
    margin: 0 0 7px 0;
    padding: 7px 12px;
    background: #e8edf0;
    border-left: 5px solid #294b63;
    color: #294b63;
    font-size: 19px;
    font-weight: 600;
}

.feature-description {
    margin: 10px 6px 18px 6px;
    color: #555555;
}

/* 画像 */

.image-row {
    display: flex;
    flex-wrap: wrap;
    gap: 22px;
    align-items: flex-start;
}

.image-item3 {
    flex: 0 1 280px;
    text-align: center;
}

.image-item3 img {
    display: block;
    width: 100%;
    height: auto;
    border: 1px solid #cbd2d7;
    background: #fafafa;
}

.image-item2 {
    flex: 0 1 420px;
    text-align: center;
}

.image-item2 img {
    display: block;
    width: 100%;
    height: auto;
    border: 1px solid #cbd2d7;
    background: #fafafa;
}

.image-item1 {
    flex: 0 1 840px;
    text-align: center;
}

.image-item1 img {
    display: block;
    width: 100%;
    height: auto;
    border: 1px solid #cbd2d7;
    background: #fafafa;
}

.image-caption {
    margin-top: 7px;
    color: #555555;
    font-size: 14px;
}

/* その他の機能 */

.other-function {
    margin: 0 6px 20px 6px;
}

.other-function h3 {
    margin: 0 0 3px 0;
    color: #333333;
    font-size: 17px;
}

.other-function p {
    margin: 0 0 0 1.2em;
    color: #555555;
}

/* フッター */

.footer-navigation {
    display: flex;
    justify-content: center;
    flex-wrap: wrap;
    padding: 13px 10px;
    background: #eef1f3;
    border-top: 1px solid #d3d8dc;
    font-size: 14px;
}

.footer-navigation a {
    padding: 0 12px;
    border-right: 1px solid #aaaaaa;
}

.footer-navigation a:last-child {
    border-right: none;
}

.copyright {
    padding: 14px;
    background: #294b63;
    color: #ffffff;
    text-align: center;
    font-size: 13px;
}

/* スマートフォン */

@media (max-width: 700px) {

    .main {
        padding: 20px 15px 30px 15px;
    }

    .navigation {
        justify-content: flex-start;
    }

    .navigation a {
        padding: 9px 11px;
        font-size: 13px;
    }

    .product-header h1 {
        font-size: 23px;
    }

    .features-title {
        font-size: 21px;
    }

    .feature h2 {
        font-size: 17px;
    }

    .image-row {
        display: block;
    }

    .image-item1 {
        max-width: 500px;
        margin: 0 auto 22px auto;
    }

    .image-item2 {
        max-width: 500px;
        margin: 0 auto 22px auto;
    }

    .image-item3 {
        max-width: 500px;
        margin: 0 auto 22px auto;
    }
}