height: auto;で設定した範囲が、中途半端なところで途切れます。

<section class="section-article">
    <div class="article">
        <div class="article-container">
            <div class="article-wrapper">
                <div>
                    <h2 class="article-title">TOEFL対策に特化した<br class="paragraph-eleventh">Engress３つの強み</h2>
                </div>
                <div class="article-content">
                    <div class="article-inner-second article-inner">
                        <div class="article-area-fourth  article-area-fourth-second">
                            <div class="article-section">
                                <p class="article-item">特徴1</p></div>
                                <div class="article-item-second">
                                    <p class="article-area-txt">TOEFLに最適化された<br>無駄のないカリキュラム</p>
                                </div>
                                <div class="article-item-third">
                                <p class="article-area-fifth">
                                TOEFLではビジネス英語には登場しない数多くの学術<br class="paragraph-fourth">的内容が出題さ<br class="paragraph-fifth">れます。そのため、ベースとなる知識<br class="paragraph-sixth">も必要になります。Engressでは過去1000題を<br class="paragraph-seventh">分析し、最適なカリキュラムを組んでいます。
                                </p>
                            </div>
                        </div>
                        <div class="article-group">
                            <img src="<?php echo get_template_directory_uri(); ?>/images/main_img_01.png" class="main-logo" alt="Engress" /> 
                        </div>
                    </div>
                    <div class="article-inner-fourth article-inner">
                        <div class="article-group">
                            <img src="<?php echo get_template_directory_uri(); ?>/images/main_img_02.png" class="main-logo" alt="Engress" />
                        </div>
                        <div class="article-area-fourth  article-area-sixth">
                            <div class="article-section">
                                <p class="article-item">特徴2</p>
                            </div>
                            <div class="article-item-second">
                                    <p class="article-area-txt">日本人指導歴10年以上の<br>経験豊富な講師陣</p>
                            </div>
                            <div class="article-item-third">
                            <p class="article-area-fifth">
                                Engressの講師陣は、もともと日本人向けにTOEFL<br class="paragraph-fourth">を教えていた人が大多数です。また全メンバーが<br class="paragraph-sixth">TOSOL(英語教授法)を取得しており、知識と経験を<br class="paragraph-seventh">兼ね備えている教育のプロフェッショナルです。<br>
                            </p> 
                        </div> 
                    </div>
                    </div>
                    <div class="article-inner-second article-inner">
                        <div class="article-area-fourth article-area-fourth-second">
                            <div class="article-section">
                                <p class="article-item">特徴3</p>
                            </div>
                                <div class="article-item-second">
                                    <p class="article-area-txt">平均３ヶ月でTOEFLiBT２０点<br class="paragraph-eighth">アップ</p>
                                </div>
                                <div class="article-item-third">
                                <p class="article-area-fifth">
                                Engressは高校生からサラリーマンまで様々な年齢層<br class="paragraph-fourth">の方々が通われていますが、完全オーダーメイドの<br class="paragraph-sixth">カリキュラムで柔軟に対応しているため、平均3ヶ月で<br class="paragraph-seventh">TOEFLスコアを20点アップさせています。
                                </p>
                            </div>
                        </div>
                        <div class="article-group ">
                            <img src="<?php echo get_template_directory_uri(); ?>/images/main_img_03.png" class="main-logo" alt="Engress" /> 
                        </div>
                    </div>
            </div>
        </div>
    </div>
    <div class="article-caption">
        <div class="article-caption-container"> 
                <div class="article-caption-title">
                    <h3 class="article-caption-nav">Engressの料金プランはこちら</h3>
                </div>
                <div class="article-caption-inner">
                    <a class="article-caption-area" href="#" style="text-decoration: none;">
                        <p>料金を見てみる</p>
                    </a>
                </div>
            </div>
        </div>
</section>
<section class="section-list-wrapper">
<div class="list-wrapper">
        <div class="list-outer">
            <h2 class="list-title">TOEPL成功事例</h2>
        </div>
        <div class="list-outer-second">
        <div class="list-content">
                <div class="list-inner">
                    <div class="list-area">
                        <div class="list-area-title">
                            <p class="area-txt">TOEFLiBT１００点を突破してコロンビア大学大学院に進学できました!</p>
                        </div>
                        <div class="list-img">
                            <div class="person-img">
                            <?php if (get_field('participant-photo', 2)) : ?>
                        <img class="test-image" src="<?php the_field('participant-photo', 2); ?>" />
                    <?php endif; ?>
                            </div>
                        </div>
                        <div class="list-area-txt">
                                    <div class="txt-item">
                                    <div class="txt-item-area-fourth"><?php the_field('participant1', '2'); ?></div>
                                    </div>
                    </div>
                </div>
            </div>
<sectin/>

section.section-article {
    height: auto;
}


.article {
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    width: 100%;
}
.article .article-container {
    max-width: 880px;
    height: auto;
    margin: 0 auto;
}

.article .article-container .article-wrapper {
    max-width: 745px;
    padding: 59px 0px 70px 0px;
    margin: 0 auto;
}

h2.article-title {
    font-size: 30px;
}
.article .article-container .article-wrapper div .article-inner-second {
    display: flex;
    flex-direction: column-reverse;
    padding-bottom: 60px;
    height: auto;
    max-width: 700px;
    margin: 0 auto;
}

.article-area-fourth {
    margin: 0px 123px;
}

.article-section {
    padding-top: 30px;
}

p.article-item {
    height: 30px;
    width: 90px;
    background-color: #F5A623;
    text-align: center;
    color: #fff;
    font-size: 12px;
    line-height: 30px;
}

p.article-area-txt {
    font-size: 21px;
    color: #1B224C;
    font-weight: bold;
    line-height: 1.3;
    padding-top: 16px;
    padding-bottom: 7px;
    height: 66px;
}
.article-item-third {
    width: auto;
}

p.article-area-fifth {
    color: #1B224C;
    font-size: 16px;
    line-height: 1.187;
    height: auto;
}

.paragraph-fourth {
    display: none;
}

.paragraph-fifth {
    display: none;
}
.paragraph-sixth {
    display: none;
}
.paragraph-seventh {
    display: none;
}
.article-group {
    max-width: 460px;
    margin: 0px 123px;
}

img.main-logo {
    width: 100%;
    margin: 0 auto;
}
.article .article-container .article-wrapper div .article-inner-fourth {
    display: flex;
    flex-direction: column;
    padding-bottom: 60px;
    height: auto;
    max-width: 700px;
    margin: 0 auto;
}

.article-group {
    max-width: 460px;
    margin: 0px 123px;
}

img.main-logo {
    width: 100%;
    margin: 0 auto;
}
.article-section {
    padding-top: 30px;
}



.article-item-third {
    width: auto;
}
p.article-area-fifth {
    color: #1B224C;
    font-size: 16px;
    line-height: 1.187;
    height: auto;
}

.article .article-container .article-wrapper div .article-inner-second {
    display: flex;
    flex-direction: column-reverse;
    padding-bottom: 60px;
    height: auto;
    max-width: 700px;
    margin: 0 auto;
}

.article-area-fourth {
    margin: 0px 123px;
}

p.article-item {
    height: 30px;
    width: 90px;
    background-color: #F5A623;
    text-align: center;
    color: #fff;
    font-size: 12px;
    line-height: 30px;
}

p.article-area-txt {
    font-size: 21px;
    color: #1B224C;
    font-weight: bold;
    line-height: 1.3;
    padding-top: 16px;
    padding-bottom: 7px;
    height: 66px;
}


.article-item-third {
    width: auto;
}

p.article-area-fifth {
    color: #1B224C;
    font-size: 16px;
    line-height: 1.187;
    height: auto;
}

body section .article-caption {
    max-width: 712px;
    height: 217px;
}
.article-caption .article-caption-container {
    padding-top: 61px;
    text-align: center;
}
article, aside, details, figcaption, figure, footer, header, hgroup, menu, nav, section {
    display: block;
}
body .list-wrapper {
    height: 592px;
    background-color: #1B224C;
    border: 1px solid #707070;
}
.list-wrapper .list-outer {
    padding-top: 70px;
    margin-bottom: 110px;
}
body .list-wrapper .list-outer .list-title {
    font-size: 30px;
}
.list-wrapper .list-outer {
    text-align: center;
    height: 34px;
    line-height: 1.388;
}
.list-wrapper .list-outer-second {
    display: flex;
    justify-content: space-between;
    background-color: #1B224C;
    margin: 0 auto;
    height: 317px;
    max-width: 901px;
}
body .list-wrapper .list-outer-second {
    width: 668px;
}