body { font-family: Arial, sans-serif; line-height: 1.6; margin: 20px; padding: 0; }
.container {
    max-width: 800px;
    margin: auto;
    padding: 20px;
    /*border: 1px solid #ddd;
    border-radius: 8px;
    box-shadow: 0 0 10px rgba(0,0,0,0.1);*/
}
.book-title { 
    color: #333;
    padding-bottom: 10px;
    font-size: 2.2rem;
    margin-top: 10px;
    margin-bottom: 60px;
    }
.book-title .subtitle {
    font-size: 1.5rem;
    display: inline-block;
    font-style: italic;
}
.author-info {
    color: #888;
}
.book-author {
    /*font-style: italic;*/
    /*<!-- border-bottom: 2px solid #1d2088; -->*/
    /*padding-bottom: 60px;*/
    padding-bottom: 10px;
    font-size: 1.5rem;
    font-weight: bold;
}
.degrees, .aff {
    font-size: 0.9rem;
}

.cover-title {
    display: flex;
    border-bottom: 2px solid #1d2088;
    padding-bottom: 20px;
}
.img-container {
    text-align: center;
     margin-right: 20px;
}
/*.cover-img {
    background: aliceblue;
    width: 85%;
    padding: 110px 5px;
    margin: 35px 0 0 0;
}*/

.cover-img img {
    height: 400px;
}

.chapter {
  margin-top: 60px;
  margin-bottom: 100px;
}
.container>.chapter:not(:first-child) {
    border-top: 2px solid #1d2088;
    padding-top: 60px;
}

.chapter-title {
    background-color: #6fb3fd;
    color: #fff;
    font-weight: bold;
    padding: 40px 0 120px 20px;
    margin: 0px 0 40px 0;
    font-size: 1.5rem;
    }
.section-body { margin-top: 15px; }
.section-body .chapter-title {
    color: #1d2088;
    background-color: unset;
    padding: 80px 0 20px 0;
    margin: 60px 0 0 0;
    border-top: 2px solid #1d2088;
    font-size: 1.18rem;

}
.section-body .chapter:first-child .chapter-title {
    border-top: unset;
    padding: 20px 0;
    margin: 40px 0 0 0;
}
p { margin-bottom: 10px; }
p.based-on {
    margin: 0;
}
a { color: #007bff; text-decoration: none; }
a:hover { text-decoration: underline; }
.section {margin-bottom: 40px}

.title { color: #555252; font-weight: bold; font-size: 16px}
.section .title { color: #979797;}


/* 참조 링크 스타일 */
.citation { font-size: 0.8em; vertical-align: super; }
.ref-list {
    <!-- margin-bottom: 100px; -->
}

.ref-list h4 { margin-bottom: 10px; border-bottom: 1px solid #ccc; padding-bottom: 5px; }
.ref-item { margin-bottom: 10px; font-size: 0.9em; }
.ref-item a { word-break: break-all; }
.ref-list a { color: #555; }

.back-matter .ref-list {
    margin-bottom: 60px;
}

.about-toc {
  display: flex;
  justify-content: center;
  gap: 200px; /* 두 항목 사이의 간격 (원하는 만큼 조절) */
  border-bottom: 2px solid #1d2088;
  padding-top: 20px;
  padding-bottom: 20px;
}

.about-toc a {
  color: #007bff;
}

<!-- toc -->
.toc { margin-bottom: 30px; }
.toc h2 {
    padding: 30px 0 10px 0;
}
.toc ul { list-style-type: none; padding-left: 20px; }
.toc>ul>li {
    margin-top: 20px;
}
.toc>ul>li:first-child {
    margin-top: 0px;
}
.toc li { margin-bottom: 5px; }

.toc ul ul {
    padding-left: 0px;
}
.toc li a i {
    font-size: 0.85rem;
    display: block;
}


/* references 링크에 대한 스타일 */
.black-link { color: #000; }

.publisher {
    text-align: center;
    margin-top: 40px;
}
.publisher img {
    width: 130px;
}

@media screen and (max-width: 767px) {
    .container { 
        font-size: 1.4rem;
    }
    .cover-title {
        flex-wrap: wrap;
    }

    .img-container {
        width: 100%;
        margin: 0;
    }
    .book-title { 
        font-size: 1.6rem;
        margin-bottom: 10%;
    }
    .book-author {
        font-size: 1.2rem;c
    }
    .about-toc {
        text-align: center;
        gap: 20%;
        line-height: 1.8rem;
    }
    .toc h2 {
        font-size: 1.6rem;
    }
    .toc li {
        line-height: 1.8rem;
    }
    .toc li a i {
        font-size: 1.12rem;
        line-height: 1.2rem;
    }

    .toc ul ul li {
        margin-top: 10px;
    }
    li.mt-top {
        margin-top: 30px!important;
    }
    .toc ul ul li:first-child {
        margin-top: 20px;
    }

}