/* =========================
   RESET
========================= */

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

html {
    scroll-behavior: smooth;
}

body {
    font-family:
        "Hind Siliguri",
        "Noto Sans Bengali",
        Arial,
        sans-serif;

    background: #f8fafc;
    color: #172033;
    line-height: 1.7;
}

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

button,
input {
    font: inherit;
}


/* =========================
   VARIABLES
========================= */

:root {

    --primary: #155e75;
    --primary-dark: #0c4a5c;
    --primary-light: #e6f5f8;

    --accent: #f59e0b;

    --dark: #172033;
    --muted: #667085;

    --white: #ffffff;

    --border: #e5e7eb;

    --bg: #f8fafc;

    --radius: 18px;

    --shadow:
        0 10px 35px rgba(15, 23, 42, 0.07);
}


/* =========================
   COMMON
========================= */

.container {
    width: min(1180px, calc(100% - 32px));
    margin: auto;
}

.section {
    padding: 85px 0;
}

.section-header {
    display: flex;
    justify-content: space-between;
    align-items: end;
    gap: 30px;
    margin-bottom: 40px;
}

.section-label {
    display: inline-block;

    color: var(--primary);
    font-size: 13px;
    font-weight: 800;

    letter-spacing: 1.5px;

    margin-bottom: 8px;
}

.section-header h2,
.about-section h2 {
    font-size: 34px;
    line-height: 1.2;
}

.section-header p {
    color: var(--muted);
    max-width: 450px;
}

.view-all {
    color: var(--primary);
    font-weight: 700;
}


/* =========================
   HEADER
========================= */

.header {
    position: sticky;
    top: 0;

    z-index: 1000;

    background:
        rgba(255, 255, 255, 0.95);

    backdrop-filter: blur(12px);

    border-bottom: 1px solid var(--border);
}

.nav-container {
    min-height: 78px;

    display: flex;
    align-items: center;
    justify-content: space-between;
}

.logo {
    display: flex;
    align-items: center;
    gap: 10px;
}

.logo-icon {
    font-size: 34px;
}

.logo strong {
    display: block;
    font-size: 18px;
    color: var(--dark);
}

.logo small {
    display: block;

    color: var(--muted);
    font-size: 11px;
}

.nav {
    display: flex;
    gap: 28px;
    align-items: center;
}

.nav a {
    font-size: 15px;
    font-weight: 600;
    color: #344054;

    transition: 0.2s;
}

.nav a:hover {
    color: var(--primary);
}

.menu-btn {
    display: none;

    border: 0;
    background: transparent;

    font-size: 28px;

    cursor: pointer;
}


/* =========================
   HERO
========================= */

.hero {
    background:
        linear-gradient(
            135deg,
            #eff9fb 0%,
            #ffffff 50%,
            #f8fafc 100%
        );

    overflow: hidden;
}

.hero-content {
    min-height: 650px;

    display: grid;
    grid-template-columns: 1.1fr 0.9fr;

    align-items: center;

    gap: 50px;
}

.hero-badge {
    display: inline-block;

    padding: 7px 13px;

    background: var(--primary-light);

    color: var(--primary);

    border-radius: 50px;

    font-size: 13px;
    font-weight: 700;

    margin-bottom: 20px;
}

.hero h1 {
    font-size: clamp(40px, 5vw, 68px);

    line-height: 1.08;

    letter-spacing: -1.5px;

    margin-bottom: 25px;
}

.hero h1 span {
    color: var(--primary);
}

.hero-text > p {
    max-width: 650px;

    color: var(--muted);

    font-size: 18px;

    margin-bottom: 30px;
}

.search-box {
    display: flex;

    max-width: 620px;

    padding: 6px;

    background: var(--white);

    border: 1px solid var(--border);

    border-radius: 14px;

    box-shadow: var(--shadow);
}

.search-box input {
    flex: 1;

    border: 0;
    outline: 0;

    padding: 14px 16px;

    background: transparent;

    min-width: 0;
}

.search-box button {
    border: 0;

    background: var(--primary);

    color: white;

    padding: 0 24px;

    border-radius: 10px;

    font-weight: 700;

    cursor: pointer;

    transition: 0.2s;
}

.search-box button:hover {
    background: var(--primary-dark);
}

.hero-tags {
    display: flex;

    gap: 8px;

    flex-wrap: wrap;

    margin-top: 20px;
}

.hero-tags span {
    background: white;

    border: 1px solid var(--border);

    padding: 4px 12px;

    border-radius: 50px;

    font-size: 12px;

    color: var(--muted);
}


/* =========================
   HERO VISUAL
========================= */

.hero-visual {
    display: flex;
    justify-content: center;
    align-items: center;
}

.book-stack {
    width: 350px;
    height: 420px;

    position: relative;
}

.hero-book {
    position: absolute;

    width: 220px;
    height: 290px;

    left: 65px;
    top: 65px;

    border-radius: 10px 20px 20px 10px;

    background:
        linear-gradient(
            135deg,
            #155e75,
            #0e7490
        );

    color: white;

    box-shadow:
        25px 25px 40px rgba(15, 23, 42, 0.2);

    display: flex;

    flex-direction: column;

    align-items: center;
    justify-content: center;

    gap: 5px;

    text-align: center;
}

.hero-book span {
    font-size: 60px;

    margin-bottom: 20px;
}

.hero-book strong {
    font-size: 22px;
}

.hero-book small {
    margin-top: 20px;

    opacity: 0.8;
}

.floating-book {
    position: absolute;

    width: 90px;
    height: 120px;

    display: flex;

    align-items: center;
    justify-content: center;

    font-size: 40px;

    border-radius: 8px;

    box-shadow: var(--shadow);

    background: white;
}

.book-one {
    top: 20px;
    right: 20px;

    transform: rotate(12deg);
}

.book-two {
    bottom: 30px;
    left: 10px;

    transform: rotate(-12deg);
}

.book-three {
    bottom: 0;
    right: 30px;

    transform: rotate(8deg);
}


/* =========================
   CATEGORY
========================= */

.category-grid {
    display: grid;

    grid-template-columns:
        repeat(4, 1fr);

    gap: 18px;
}

.category-card {
    border: 1px solid var(--border);

    background: white;

    border-radius: var(--radius);

    padding: 25px;

    text-align: left;

    cursor: pointer;

    transition:
        transform 0.2s,
        box-shadow 0.2s,
        border 0.2s;
}

.category-card:hover {
    transform: translateY(-5px);

    border-color: #a7d9e3;

    box-shadow: var(--shadow);
}

.category-icon {
    width: 52px;
    height: 52px;

    display: flex;

    align-items: center;
    justify-content: center;

    background: var(--primary-light);

    border-radius: 14px;

    font-size: 25px;

    margin-bottom: 18px;
}

.category-card h3 {
    font-size: 19px;

    margin-bottom: 4px;
}

.category-card p {
    font-size: 13px;

    color: var(--muted);
}


/* =========================
   BOOKS
========================= */

.featured-section {
    background: white;
}

.books-grid {
    display: grid;

    grid-template-columns:
        repeat(3, 1fr);

    gap: 22px;
}

.book-card {
    overflow: hidden;

    background: white;

    border: 1px solid var(--border);

    border-radius: var(--radius);

    transition: 0.25s;
}

.book-card:hover {
    transform: translateY(-5px);

    box-shadow: var(--shadow);
}

.book-cover {
    height: 230px;

    display: flex;

    flex-direction: column;

    align-items: center;
    justify-content: center;

    position: relative;

    color: white;
}

.cover-blue {
    background:
        linear-gradient(
            135deg,
            #075985,
            #0e7490
        );
}

.cover-green {
    background:
        linear-gradient(
            135deg,
            #166534,
            #15803d
        );
}

.cover-orange {
    background:
        linear-gradient(
            135deg,
            #c2410c,
            #ea580c
        );
}

.cover-purple {
    background:
        linear-gradient(
            135deg,
            #6b21a8,
            #9333ea
        );
}

.cover-red {
    background:
        linear-gradient(
            135deg,
            #991b1b,
            #dc2626
        );
}

.cover-dark {
    background:
        linear-gradient(
            135deg,
            #1e293b,
            #334155
        );
}

.book-emoji {
    font-size: 65px;
}

.book-category {
    position: absolute;

    bottom: 15px;
    left: 15px;

    padding: 4px 10px;

    background: rgba(255, 255, 255, 0.18);

    backdrop-filter: blur(5px);

    border-radius: 50px;

    font-size: 11px;

    font-weight: 800;

    letter-spacing: 1px;
}

.book-info {
    padding: 22px;
}

.book-type {
    color: var(--primary);

    font-size: 12px;

    font-weight: 700;
}

.book-info h3 {
    font-size: 19px;

    line-height: 1.4;

    margin: 6px 0 8px;
}

.book-info p {
    font-size: 13px;
    color: var(--muted);
    margin-bottom: 5px;
}

.book-info .book-description {
    margin-top: 8px;
    min-height: 45px;
}

.book-author strong,
.publisher strong {
    color: var(--dark);
}

.book-author {
    margin-bottom: 2px !important;
}

.publisher {
    font-size: 12px !important;
}

.book-meta {
    display: flex;

    justify-content: space-between;

    align-items: center;

    margin: 15px 0;
}

.book-meta span {
    font-size: 12px;

    color: #b45309;
}

.book-meta strong {
    color: var(--dark);

    font-size: 14px;
}

.book-btn {
    display: block;

    text-align: center;

    background: var(--primary);

    color: white;

    padding: 11px;

    border-radius: 10px;

    font-size: 14px;

    font-weight: 700;

    transition: 0.2s;
}

.book-btn:hover {
    background: var(--primary-dark);
}

.no-results {
    display: none;

    text-align: center;

    padding: 70px 20px;
}

.no-results div {
    font-size: 55px;
}

.no-results h3 {
    margin-top: 10px;
}

.no-results p {
    color: var(--muted);
}


/* =========================
   GUIDE
========================= */

.guide-section {
    background: #f8fafc;
}

.guide-grid {
    display: grid;

    grid-template-columns:
        repeat(3, 1fr);

    gap: 22px;
}

.guide-card {
    background: white;

    border: 1px solid var(--border);

    border-radius: var(--radius);

    padding: 30px;
}

.guide-number {
    color: var(--primary);

    font-size: 30px;

    font-weight: 900;

    margin-bottom: 15px;
}

.guide-card h3 {
    font-size: 21px;

    margin-bottom: 10px;
}

.guide-card p {
    color: var(--muted);

    font-size: 14px;

    margin-bottom: 18px;
}

.guide-card a {
    color: var(--primary);

    font-weight: 700;

    font-size: 14px;
}


/* =========================
   ARTICLES
========================= */

.article-grid {
    display: grid;

    grid-template-columns:
        repeat(3, 1fr);

    gap: 22px;
}

.article-card {
    background: white;

    border: 1px solid var(--border);

    border-radius: var(--radius);

    overflow: hidden;
}

.article-image {
    height: 180px;

    background: var(--primary-light);

    display: flex;

    align-items: center;
    justify-content: center;

    font-size: 65px;
}

.article-content {
    padding: 24px;
}

.article-content > span {
    color: var(--primary);

    font-size: 12px;

    font-weight: 800;
}

.article-content h3 {
    font-size: 20px;

    line-height: 1.4;

    margin: 8px 0;
}

.article-content p {
    color: var(--muted);

    font-size: 14px;

    margin-bottom: 15px;
}

.article-content a {
    color: var(--primary);

    font-weight: 700;

    font-size: 14px;
}


/* =========================
   CTA
========================= */

.cta-section {
    padding: 60px 0;
}

.cta-box {
    background:
        linear-gradient(
            135deg,
            #0c4a5c,
            #155e75
        );

    border-radius: 25px;

    color: white;

    padding: 50px;

    display: flex;

    justify-content: space-between;

    align-items: center;

    gap: 30px;
}

.cta-box span {
    opacity: 0.8;

    font-size: 14px;
}

.cta-box h2 {
    font-size: 32px;

    line-height: 1.3;

    margin: 8px 0;
}

.cta-box p {
    opacity: 0.85;

    max-width: 650px;
}

.cta-buttons {
    display: flex;

    gap: 10px;

    flex-shrink: 0;
}

.whatsapp-btn,
.outline-btn {
    padding: 12px 20px;

    border-radius: 10px;

    font-weight: 700;

    white-space: nowrap;
}

.whatsapp-btn {
    background: white;

    color: var(--primary);
}

.outline-btn {
    border: 1px solid rgba(255,255,255,0.5);

    color: white;
}


/* =========================
   ABOUT
========================= */

.about-section {
    background: white;
}

.about-content {
    display: grid;

    grid-template-columns: 0.8fr 1.2fr;

    gap: 80px;

    align-items: start;
}

.about-content p {
    color: var(--muted);

    margin-bottom: 15px;
}


/* =========================
   FOOTER
========================= */

.footer {
    background: #111827;

    color: white;

    padding-top: 60px;
}

.footer-grid {
    display: grid;

    grid-template-columns:
        2fr 1fr 1fr 1fr;

    gap: 40px;

    padding-bottom: 50px;
}

.footer-logo {
    font-size: 20px;

    font-weight: 800;

    margin-bottom: 10px;
}

.footer p {
    color: #9ca3af;

    font-size: 14px;
}

.footer h4 {
    margin-bottom: 15px;
}

.footer a {
    display: block;

    color: #9ca3af;

    font-size: 14px;

    margin: 7px 0;

    transition: 0.2s;
}

.footer a:hover {
    color: white;
}

.footer-bottom {
    border-top: 1px solid #273142;

    padding: 20px 0;
}

.footer-bottom .container {
    display: flex;

    justify-content: space-between;

    gap: 20px;
}

.affiliate-note {
    font-size: 12px !important;
}


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

@media (max-width: 950px) {

    .hero-content {
        grid-template-columns: 1fr;

        padding: 70px 0;
    }

    .hero-visual {
        display: none;
    }

    .category-grid {
        grid-template-columns:
            repeat(2, 1fr);
    }

    .books-grid {
        grid-template-columns:
            repeat(2, 1fr);
    }

    .guide-grid,
    .article-grid {
        grid-template-columns:
            repeat(2, 1fr);
    }

    .footer-grid {
        grid-template-columns:
            repeat(2, 1fr);
    }

    .cta-box {
        flex-direction: column;

        align-items: flex-start;
    }

    .about-content {
        grid-template-columns: 1fr;

        gap: 25px;
    }
}


@media (max-width: 700px) {

    .container {
        width:
            min(100% - 24px, 1180px);
    }

    .section {
        padding: 60px 0;
    }

    .nav {
        display: none;

        position: absolute;

        top: 78px;
        left: 0;
        right: 0;

        background: white;

        border-bottom: 1px solid var(--border);

        padding: 20px;

        flex-direction: column;

        align-items: flex-start;

        gap: 15px;
    }

    .nav.active {
        display: flex;
    }

    .menu-btn {
        display: block;
    }

    .hero-content {
        min-height: auto;

        padding: 60px 0;
    }

    .hero h1 {
        font-size: 42px;
    }

    .hero-text > p {
        font-size: 16px;
    }

    .search-box {
        flex-direction: column;

        padding: 8px;
    }

    .search-box button {
        height: 48px;
    }

    .section-header {
        display: block;
    }

    .section-header h2,
    .about-section h2 {
        font-size: 28px;
    }

    .section-header p {
        margin-top: 10px;
    }

    .category-grid {
        grid-template-columns:
            repeat(2, 1fr);

        gap: 12px;
    }

    .category-card {
        padding: 18px;
    }

    .category-card h3 {
        font-size: 16px;
    }

    .category-icon {
        width: 45px;
        height: 45px;
    }

    .books-grid,
    .guide-grid,
    .article-grid {
        grid-template-columns: 1fr;
    }

    .cta-box {
        padding: 30px 22px;
    }

    .cta-box h2 {
        font-size: 25px;
    }

    .cta-buttons {
        flex-wrap: wrap;
    }

    .footer-grid {
        grid-template-columns: 1fr 1fr;

        gap: 30px;
    }

    .footer-bottom .container {
        flex-direction: column;

        gap: 5px;
    }
}


@media (max-width: 420px) {

    .category-grid {
        grid-template-columns: 1fr;
    }

    .hero h1 {
        font-size: 36px;
    }

    .footer-grid {
        grid-template-columns: 1fr;
    }

}
.bcs-subject-filter {
    display: flex;
    gap: 10px;
    flex-wrap: wrap;
    margin: 0 0 30px;
}

.bcs-subject-filter button {
    border: 1px solid var(--border);
    background: white;
    color: var(--dark);
    padding: 8px 15px;
    border-radius: 50px;
    cursor: pointer;
    font-weight: 600;
    transition: 0.2s;
}

.bcs-subject-filter button:hover {
    background: var(--primary);
    color: white;
    border-color: var(--primary);
}