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

:root {
    --background: #f2f7fb;
    --text: #292b2e;
    --muted: #3f4449;
    --blue: #088dcb;
    --blue-dark: #0573a8;
}

body {
    min-height: 100vh;
    overflow-x: hidden;
    background: var(--background);
    color: var(--text);
    font-family: 'Roboto', Arial, sans-serif;
    line-height: 1.32;
}

a { color: inherit; text-decoration: none; }
img { display: block; max-width: 100%; }

.container { width: min(1160px, calc(100% - 48px)); margin: 0 auto; }
.detail-page { min-height: 100vh; padding: 100px 0 50px; }

.back-link {
    display: inline-block;
    color: #303236;
    font-size: .94rem;
    font-weight: 800;
    transition: color .2s ease;
}

.back-link:hover { color: var(--blue); }

.detail-grid {
    display: grid;
    grid-template-columns: 445px minmax(0, 1fr);
    align-items: start;
    gap: 73px;
    margin-top: 214px;
}

.cover-column { display: flex; align-items: center; flex-direction: column; }
.detail-cover { width: 100%; }
.detail-cover img { width: 100%; aspect-ratio: 210 / 297; object-fit: cover; }
.detail-content { min-width: 0; padding-top: 7px; }

.detail-content h1 {
    margin-bottom: 22px;
    font-size: 1.65rem;
    font-weight: 800;
    line-height: 1.12;
    overflow-wrap: anywhere;
}

.full-description {
    color: var(--muted);
    font-size: 1.03rem;
    line-height: 1.28;
    overflow-wrap: anywhere;
}

.date { margin-top: 34px; font-size: .93rem; }

.download-btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: fit-content;
    margin-top: 28px;
    padding: 8px 15px;
    border-radius: 9px;
    background: var(--blue);
    color: #fff;
    font-size: .9rem;
    font-weight: 500;
    box-shadow: 0 6px 15px rgba(8, 141, 203, .2);
    transition: transform .2s ease, background .2s ease;
}

.download-btn:hover { transform: translateY(-2px); background: var(--blue-dark); }
.download-btn.disabled { background: #9daab4; pointer-events: none; box-shadow: none; }

.empty-cover {
    display: grid;
    width: 100%;
    aspect-ratio: 210 / 297;
    place-items: center;
    padding: 20px;
    background: #e6edf3;
    color: #6c7780;
    text-align: center;
}

.books-mark {
    display: flex;
    align-items: flex-end;
    justify-content: center;
    gap: 3px;
    height: 48px;
    margin: 180px auto 0;
}

.books-mark i { display: block; width: 8px; height: 40px; background: #ed4436; }
.books-mark i:nth-child(2) { background: #153e70; transform: skew(-10deg); }
.books-mark i:nth-child(3) { background: #057fb4; }
.books-mark i:nth-child(4) { background: #d7912a; }
.books-mark i:nth-child(5) { background: #4cae57; }
.books-mark i:nth-child(6) { background: #22a34a; transform: skew(7deg); }
.books-mark i:nth-child(7) { background: #078fc0; }
.books-mark i:nth-child(8) { background: #d93431; }
.books-mark i:nth-child(9) { background: #709c59; }
.books-mark i:nth-child(10) { background: #dc3c31; }
.books-mark i:nth-child(11) { margin-left: 7px; background: #d48d26; transform: skew(-12deg); }
.books-mark i:nth-child(12) { background: #16a7d1; }
.books-mark i:nth-child(13) { background: #f2a91b; }
.books-mark i:nth-child(14) { background: #fdb515; transform: skew(-7deg); }
.books-mark i:nth-child(15) { background: #cb1871; }
.books-mark i:nth-child(16) { background: #ef6425; }

@media (max-width: 900px) {
    .detail-page { padding-top: 45px; }
    .detail-grid { grid-template-columns: 310px minmax(0, 1fr); gap: 40px; margin-top: 110px; }
    .books-mark { margin-top: 110px; }
}

@media (max-width: 680px) {
    .container { width: min(100% - 28px, 1160px); }
    .detail-page { padding: 28px 0 40px; }
    .detail-grid { grid-template-columns: 1fr; gap: 34px; margin-top: 55px; }
    .cover-column { width: min(280px, 84vw); margin: 0 auto; }
    .detail-content { padding-top: 0; }
    .detail-content h1 { font-size: 1.4rem; }
    .full-description { font-size: .96rem; }
    .download-btn { width: 100%; }
    .books-mark { margin-top: 80px; }
}