* {
    box-sizing: border-box;
}

html,
body {
    margin: 0;
    padding: 0;
}

:root {
    --bg: #0b0f14;
    --surface: #111720;
    --surface-2: #161d27;
    --border: #252e3a;
    --text: #f1f5f9;
    --muted: #9aa6b5;
    --primary: #ab5628;
    --primary-hover: #eb7825;
    --header: #0d1219;
}

body {
    font-family: "Noto Sans Bengali", "SolaimanLipi", Arial, sans-serif;
    background: var(--bg);
    color: var(--text);
    line-height: 1.7;
}

a {
    text-decoration: none;
    color: inherit;
}

.container {
    width: min(1080px, 92%);
    margin: auto;
}

.site-header {
    width: 100%;
    background: #0d1219;
    border-bottom: 1px solid #252e3a;
}

.header-inner {
    height: 68px;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.logo {
    font-size: 21px;
    font-weight: 700;
    color: #fff;
}

.logo span {
    color: var(--primary);
}

.back-link {
    color: var(--muted);
    font-size: 14px;
    transition: .2s ease;
    padding: 2px 5px 0 5px;
    border: solid 1px #1f213b;
    border-radius: 5px;
}

.back-link:hover {
    color: #fff;
}

footer {
    margin-top: 45px;
    padding: 28px 0;
    background: #080b0f;
    border-top: 1px solid var(--border);
    color: #788492;
    text-align: center;
    font-size: 12px;
}

footer strong {
    color: #dce3eb;
}


/* =========================================================
   BOOK INDEX
   ========================================================= */

.book-index .page-header {
    margin: 45px auto 28px;
    background: linear-gradient(145deg, #111821, #0f151d);
    border: 1px solid var(--border);
    border-radius: 13px;
    padding: 30px 34px;
    box-shadow: 0 15px 35px rgba(0, 0, 0, .22);
}

.book-index .page-header h1 {
    margin: 0 0 6px;
    color: #fff;
    font-size: 28px;
    line-height: 1.4;
}

.book-index .page-header p {
    margin: 0;
    color: var(--muted);
    font-size: 14px;
}

.book-index .publication {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: 13px;
    padding: 28px;
    display: grid;
    grid-template-columns: 190px 1fr;
    gap: 30px;
    transition: border-color .2s ease, transform .2s ease, box-shadow .2s ease;
}

.book-index .publication:hover {
    border-color: #34445a;
    transform: translateY(-2px);
    box-shadow: 0 15px 35px rgba(0, 0, 0, .25);
}

.book-index .publication-cover {
    text-align: center;
}

.book-index .publication-cover img {
    width: 175px;
    max-width: 100%;
    border-radius: 5px;
    display: block;
    margin: auto;
    box-shadow: 0 20px 40px rgba(0, 0, 0, .5);
}

.book-index .publication-info h2 {
    margin: 0 0 7px;
    color: #fff;
    font-size: 25px;
    line-height: 1.4;
}

.book-index .subtitle {
    color: #aab5c3;
    font-size: 14px;
    margin-bottom: 17px;
}

.book-index .author {
    color: #c4ccd6;
    font-size: 13px;
    margin-bottom: 17px;
}

.book-index .author strong {
    color: #fff;
}

.book-index .book-meta {
    display: flex;
    flex-wrap: wrap;
    gap: 7px;
    margin-bottom: 18px;
}

.book-index .meta-item {
    background: #171f2a;
    border: 1px solid #283342;
    color: #aeb9c7;
    padding: 4px 9px;
    border-radius: 5px;
    font-size: 11px;
}

.book-index .description {
    color: var(--muted);
    font-size: 13px;
    margin: 0 0 20px;
    max-width: 720px;
}

.book-index .book-btn {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    background: var(--primary);
    color: #fff;
    padding: 9px 17px;
    border-radius: 6px;
    font-size: 13px;
    font-weight: 600;
    transition: background .2s ease, transform .2s ease, box-shadow .2s ease;
}

.book-index .book-btn:hover {
    background: var(--primary-hover);
    transform: translateY(-2px);
    box-shadow: 0 8px 22px rgba(255, 143, 0, .28);
}

.book-index .free-notice {
    margin-top: 22px;
    background: #11161d;
    border: 1px solid var(--border);
    border-left: 3px solid var(--primary);
    border-radius: 8px;
    padding: 16px 20px;
}

.book-index .free-notice strong {
    display: block;
    color: #fff;
    font-size: 14px;
    margin-bottom: 3px;
}

.book-index .free-notice span {
    color: #929eac;
    font-size: 12px;
}


/* =========================================================
   BOOK DETAIL
   ========================================================= */

.book-detail .book-hero {
    background: linear-gradient(145deg, #111821, #0f151d);
    margin: 45px auto 28px;
    padding: 45px;
    border: 1px solid var(--border);
    border-radius: 16px;
    display: grid;
    grid-template-columns: 270px 1fr;
    gap: 55px;
    align-items: center;
    box-shadow: 0 20px 50px rgba(0, 0, 0, .35);
}

.book-detail .book-cover {
    text-align: center;
}

.book-detail .book-cover img {
    width: 245px;
    max-width: 100%;
    border-radius: 5px;
    box-shadow: 0 20px 45px rgba(0, 0, 0, .55);
}

.book-detail .book-info h1 {
    font-size: 38px;
    line-height: 1.3;
    color: #fff;
    margin-bottom: 10px;
}

.book-detail .subtitle {
    color: #aab5c3;
    font-size: 16px;
    margin-bottom: 22px;
}

.book-detail .author {
    color: #c4ccd6;
    font-size: 15px;
    margin-bottom: 20px;
}

.book-detail .author strong {
    color: #fff;
}

.book-detail .book-meta {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
    margin-bottom: 25px;
}

.book-detail .meta-item {
    background: #171f2a;
    border: 1px solid #283342;
    color: #aeb9c7;
    padding: 5px 11px;
    border-radius: 5px;
    font-size: 12px;
}

.book-detail .download-btn {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    background: var(--primary);
    color: #fff;
    padding: 11px 22px;
    border-radius: 6px;
    font-size: 14px;
    font-weight: 600;
    transition: background .2s ease, transform .2s ease, box-shadow .2s ease;
}

.book-detail .download-btn:hover {
    background: var(--primary-hover);
    transform: translateY(-2px);
    box-shadow: 0 8px 22px rgba(255, 143, 0, .28);
}

.book-detail .book-price {
    display: inline-block;
    color: #fff;
    background: #171f2a;
    border: 1px solid #283342;
    padding: 9px 16px;
    border-radius: 6px;
    font-size: 14px;
    font-weight: 600;
}

.book-detail .section {
    background: var(--surface);
    margin-bottom: 22px;
    padding: 30px 34px;
    border: 1px solid var(--border);
    border-radius: 13px;
}

.book-detail .section-title {
    font-size: 21px;
    color: #fff;
    margin-bottom: 13px;
}

.book-detail .section p {
    color: var(--muted);
    font-size: 14px;
}

.book-detail .contents-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 13px;
    margin-top: 18px;
}

.book-detail .chapter {
    background: var(--surface-2);
    border: 1px solid var(--border);
    border-radius: 8px;
    padding: 16px;
    transition: border-color .2s ease, transform .2s ease;
}

.book-detail .chapter:hover {
    border-color: #34445a;
    transform: translateY(-2px);
}

.book-detail .chapter strong {
    display: block;
    color: #e8edf4;
    font-size: 14px;
    margin-bottom: 5px;
}

.book-detail .chapter span {
    color: #8e9baa;
    font-size: 12px;
}

.book-detail .download-section {
    background: linear-gradient(145deg, #111c2b, #101823);
    border-color: #243a58;
    text-align: center;
}

.book-detail .download-section .section-title {
    color: #fff;
}

.book-detail .download-section p {
    margin-bottom: 20px;
}

.book-detail .notice {
    background: #11161d;
    border-left: 3px solid var(--primary);
}

.book-detail .notice .section-title {
    font-size: 19px;
}

.book-detail .notice p {
    font-size: 13px;
}

.book-detail .author-box {
    display: flex;
    align-items: center;
    gap: 18px;
}

.book-detail .author-icon {
    width: 54px;
    height: 54px;
    flex-shrink: 0;
    border-radius: 50%;
    background: #2f2f2f;
    border: 1px solid #483f3a;
    display: flex;
    align-items: center;
    justify-content: center;
    overflow: hidden;
}

.book-detail .author-icon img {
    width: 90%;
    height: 90%;
    object-fit: contain;
    padding: 7px;
}

.book-detail .author-box h3 {
    color: #fff;
    font-size: 17px;
    margin-bottom: 2px;
}

.book-detail .author-box p {
    color: #929eac;
    font-size: 13px;
}


/* =========================================================
   RESPONSIVE
   ========================================================= */

@media (max-width: 768px) {

    .header-inner {
        height: 60px;
    }

    .logo {
        font-size: 19px;
    }


    /* Book Index */

    .book-index .page-header {
        margin-top: 30px;
        padding: 24px 20px;
    }

    .book-index .page-header h1 {
        font-size: 24px;
    }

    .book-index .publication {
        grid-template-columns: 1fr;
        padding: 24px 20px;
        gap: 25px;
        text-align: center;
    }

    .book-index .publication-cover img {
        width: 180px;
    }

    .book-index .publication-info h2 {
        font-size: 23px;
    }

    .book-index .book-meta {
        justify-content: center;
    }

    .book-index .description {
        text-align: left;
    }

    .book-index .free-notice {
        text-align: left;
    }


    /* Book Detail */

    .book-detail .book-hero {
        grid-template-columns: 1fr;
        text-align: center;
        padding: 30px 20px;
        gap: 28px;
    }

    .book-detail .book-cover img {
        width: 210px;
    }

    .book-detail .book-info h1 {
        font-size: 29px;
    }

    .book-detail .book-meta {
        justify-content: center;
    }

    .book-detail .contents-grid {
        grid-template-columns: 1fr;
    }

    .book-detail .section {
        padding: 24px 20px;
    }

    .book-detail .author-box {
        align-items: flex-start;
    }

}