*{
    margin:0;
    padding:0;
    box-sizing:border-box;
}

body{
    font-family:Arial, Helvetica, sans-serif;
    background:#f5f7fb;
    color:#222;
}

.detail-container{
    max-width:1100px;
    margin:50px auto;
    background:#fff;
    padding:40px;
    border-radius:16px;
    box-shadow:0 10px 30px rgba(0,0,0,.08);
}

.back-link{
    display:inline-block;
    margin-bottom:30px;
    text-decoration:none;
    color:#1d4ed8;
    font-weight:bold;
}

.detail-title{
    font-size:34px;
    margin-bottom:25px;
}

.info-grid{
    display:grid;
    grid-template-columns:repeat(2,1fr);
    gap:15px;
    margin-bottom:35px;
}

.info-item{
    padding:15px;
    background:#f8fafc;
    border-radius:10px;
}

.section-title{
    margin:35px 0 20px;
    font-size:24px;
}

.description{
    line-height:1.8;
}

#pdfViewer{
    width:100%;
    height:700px;
    border:1px solid #ddd;
    border-radius:12px;
    margin-top:20px;
}

.download-btn{
    display:inline-block;
    margin-top:30px;
    padding:15px 35px;
    background:#2563eb;
    color:white;
    text-decoration:none;
    border-radius:10px;
    font-weight:bold;
}

.detail-layout{
    display:grid;
    grid-template-columns:380px 1fr;
    gap:40px;
    align-items:start;
}

.detail-left{
    position:sticky;
    top:30px;
}

.detail-right{
    width:100%;
}

@media(max-width:992px){

    .detail-layout{

        grid-template-columns:1fr;

    }

    .detail-left{

        position:static;

    }

}

.related-section{
    margin-top:70px;
}

.related-section h2{
    margin-bottom:25px;
}

.related-grid{
    display:grid;
    grid-template-columns:repeat(auto-fill,minmax(260px,1fr));
    gap:20px;
}


.related-card{
    display:block;
    padding:20px;
    border:1px solid #ddd;
    border-radius:12px;
    text-decoration:none;
    color:#222;
    transition:.25s;
    background:#fff;
}

.related-card:hover{
    transform:translateY(-4px);
    box-shadow:0 10px 20px rgba(0,0,0,.08);
}

.related-card h3{
    margin-bottom:10px;
}

.related-card p{
    color:#666;
    margin-bottom:8px;
}

.related-card small{
    color:#999;
}