:root {
    --font-sans: Arial, Helvetica, sans-serif;

    --color-ink: #F5F5F5;
    --color-text: #D1D5DB;
    --color-muted: #9CA3AF;
    --color-soft: #6B7280;
    --color-surface: #1F2937;
    --color-canvas: #111827;
    --color-panel: #1E293B;
    --color-border: #374151;

    --color-accent: #3B82F6;
    --color-accent-strong: #2563EB;
    --color-accent-soft: #1E3A8A;
    --color-gold: #FBBF24;
    --color-ruby: #EF4444;

    --color-success: #22C55E;
    --color-success-soft: #14532D;
    --color-warning: #F59E0B;
    --color-warning-soft: #78350F;
    --color-danger: #EF4444;
    --color-danger-soft: #7F1D1D;

    --shadow-sm: 0 8px 22px rgba(0,0,0,.35);
    --shadow-md: 0 18px 45px rgba(0,0,0,.45);

    --radius-sm: 8px;
    --radius-md: 10px;
    --radius-lg: 12px;

    --container: 1180px;
    --space-page: clamp(28px, 5vw, 64px);
}

*,
*::before,
*::after {
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
}

body {
    margin: 0;
    background: var(--color-canvas);
    color: var(--color-text);
    font-family: var(--font-sans);
    font-size: 16px;
    line-height: 1.6;
}

img {
    display: block;
    max-width: 100%;
}

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

a:hover {
    color: var(--color-accent);
}

button,
input,
select,
textarea {
    font: inherit;
}

button {
    cursor: pointer;
}

button:disabled,
.button[aria-disabled="true"],
button[disabled] {
    cursor: not-allowed;
    opacity: 0.58;
}

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

.site-main {
    min-height: 60vh;
}

.sr-only {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    white-space: nowrap;
    border: 0;
    clip: rect(0, 0, 0, 0);
}

.skip-link {
    position: fixed;
    top: 14px;
    left: 14px;
    z-index: 1000;
    transform: translateY(-160%);
    padding: 10px 14px;
    border-radius: var(--radius-sm);
    background: var(--color-ink);
    color: #ffffff;
}

.skip-link:focus {
    transform: translateY(0);
}

.eyebrow {
    margin: 0 0 8px;
    color: var(--color-accent);
    font-size: 0.78rem;
    font-weight: 700;
    letter-spacing: 0;
    text-transform: uppercase;
}

h1,
h2,
h3,
h4 {
    margin: 0;
    color: var(--color-ink);
    line-height: 1.18;
    letter-spacing: 0;
}

h1 {
    font-size: clamp(2rem, 4vw, 4rem);
}

h2 {
    font-size: clamp(1.45rem, 2.5vw, 2.2rem);
}

h3 {
    font-size: 1.05rem;
}

p {
    margin: 0;
}

.button,
button.button {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    min-height: 44px;
    padding: 11px 18px;
    border: 1px solid var(--color-accent);
    border-radius: var(--radius-sm);
    background: var(--color-accent);
    color: #ffffff;
    font-weight: 700;
    line-height: 1;
    text-align: center;
    transition: background 160ms ease, border-color 160ms ease, transform 160ms ease, box-shadow 160ms ease;
}

.button:hover {
    background: var(--color-accent-strong);
    border-color: var(--color-accent-strong);
    color: #ffffff;
    box-shadow: var(--shadow-sm);
    transform: translateY(-1px);
}

.button--secondary {
    background: var(--color-surface);
    color: var(--color-accent);
}

.button--secondary:hover {
    background: var(--color-accent-soft);
    color: var(--color-accent-strong);
}

.button--active {
    background: var(--color-ink);
    color: #ffffff;
    border-color: var(--color-ink);
    box-shadow: 0 0 0 1px rgba(255, 255, 255, 0.1);
}

/* keep hero buttons default; provide boxed active styles for filter links and category cards */
.filter-link {
    display: inline-block;
    padding: 6px 10px;
    border-radius: var(--radius-sm);
    border: 1px solid transparent;
    transition: background 120ms ease, border-color 120ms ease, color 120ms ease;
}

.filter-link.is-active {
    border-color: var(--color-accent);
    background: rgba(59,130,246,0.06);
    color: var(--color-accent);
}

.category-card.is-active {
    border-color: var(--color-accent);
    background: rgba(59,130,246,0.04);
    box-shadow: var(--shadow-sm);
    transform: translateY(-2px);
}

.button--active:hover {
    background: #111111;
    border-color: #111111;
}

.button--small {
    min-height: 36px;
    padding: 8px 12px;
    font-size: 0.9rem;
}

.text-link,
.text-button {
    border: 0;
    background: transparent;
    color: var(--color-accent);
    font-weight: 700;
    text-decoration: underline;
    text-underline-offset: 3px;
}

.text-button--danger {
    color: var(--color-danger);
}

.notice {
    margin: 18px 0;
    padding: 14px 16px;
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    background: var(--color-surface);
    color: var(--color-text);
}

.notice--success {
    border-color: #b7ddcb;
    background: var(--color-success-soft);
    color: var(--color-success);
}

.notice--warning {
    border-color: #ecd29b;
    background: var(--color-warning-soft);
    color: var(--color-warning);
}

.notice--danger {
    border-color: #edb8b1;
    background: var(--color-danger-soft);
    color: var(--color-danger);
}

.section-block,
.page-title-block {
    padding-block: var(--space-page);
}

.page-title-block p:last-child {
    max-width: 680px;
    margin-top: 10px;
    color: var(--color-muted);
}

.section-heading {
    display: flex;
    align-items: end;
    justify-content: space-between;
    gap: 20px;
    margin-bottom: 24px;
}

.hero-section {
    padding: clamp(40px, 7vw, 86px) 0;
    background: linear-gradient(180deg, #ffffff 0%, var(--color-panel) 100%);
    border-bottom: 1px solid var(--color-border);
}

.hero-section__grid {
    display: grid;
    grid-template-columns: minmax(0, 1.35fr) minmax(280px, 0.65fr);
    gap: clamp(28px, 5vw, 64px);
    align-items: center;
}

.hero-section__copy {
    max-width: 640px;
    margin-top: 18px;
    color: var(--color-muted);
    font-size: 1.1rem;
}

.hero-section__actions {
    display: flex;
    flex-wrap: wrap;
    gap: 12px;
    margin-top: 28px;
}

.hero-panel {
    display: grid;
    gap: 12px;
}

.hero-panel__item {
    padding: 20px;
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    background: var(--color-surface);
    box-shadow: var(--shadow-sm);
}

.hero-panel__value {
    display: block;
    color: var(--color-ink);
    font-size: 1.8rem;
    font-weight: 800;
}

.hero-panel__label {
    color: var(--color-muted);
}

.book-grid,
.category-grid,
.wishlist-grid,
.profile-overview {
    display: grid;
    grid-template-columns: repeat(4, minmax(0, 1fr));
    gap: 18px;
}

.book-card,
.category-card,
.wishlist-card,
.profile-stat,
.auth-benefit,
.review-card,
.cart-item,
.checkout-panel,
.checkout-summary,
.cart-summary,
.profile-panel {
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    background: var(--color-surface);
    box-shadow: var(--shadow-sm);
}

.book-card {
    overflow: hidden;
    transition: transform 160ms ease, box-shadow 160ms ease;
}

.book-card:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.book-card__cover {
    display: block;
    aspect-ratio: 3 / 4;
    background: var(--color-panel);
}

.book-card__cover img {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.book-card__body {
    display: grid;
    gap: 8px;
    padding: 16px;
}

.book-card__category,
.cart-item__category,
.wishlist-card__category {
    color: var(--color-accent);
    font-size: 0.78rem;
    font-weight: 700;
    text-transform: uppercase;
}

.book-card__author,
.book-card__meta,
.wishlist-card__author,
.wishlist-card__description,
.wishlist-card__meta,
.cart-item__author,
.cart-item__stock {
    color: var(--color-muted);
    font-size: 0.92rem;
}

.book-card__footer,
.wishlist-card__actions,
.cart-item__actions {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 12px;
    margin-top: 8px;
}

.book-card__price,
.wishlist-card__price strong {
    color: var(--color-ink);
    font-weight: 800;
}

.category-card {
    display: grid;
    gap: 8px;
    padding: 18px;
    transition: border-color 160ms ease, transform 160ms ease;
}

.category-card:hover {
    border-color: var(--color-accent);
    transform: translateY(-1px);
}

.category-card__name {
    color: var(--color-ink);
    font-weight: 800;
}

.category-card__count,
.category-card__description {
    color: var(--color-muted);
    font-size: 0.92rem;
}

.empty-state {
    padding: clamp(26px, 5vw, 48px);
    border: 1px dashed var(--color-border);
    border-radius: var(--radius-md);
    background: var(--color-panel);
    text-align: center;
}

.empty-state p {
    max-width: 560px;
    margin: 10px auto 20px;
    color: var(--color-muted);
}

.empty-state--compact {
    padding: 24px;
}

.breadcrumbs {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
    margin-bottom: 26px;
    color: var(--color-muted);
    font-size: 0.92rem;
}

.product-detail {
    padding-block: var(--space-page);
}

.product-detail__grid,
.product-information__grid,
.cart-layout,
.checkout-layout,
.profile-layout,
.auth-layout__grid {
    display: grid;
    grid-template-columns: minmax(0, 1fr) 360px;
    gap: 28px;
    align-items: start;
}

.product-detail__grid {
    grid-template-columns: minmax(260px, 390px) minmax(0, 1fr);
}

.product-detail__media {
    padding: 20px;
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    background: var(--color-surface);
    box-shadow: var(--shadow-sm);
}

.product-detail__cover {
    width: 100%;
    aspect-ratio: 3 / 4;
    object-fit: cover;
    border-radius: var(--radius-sm);
    background: var(--color-panel);
}

.product-detail__content {
    display: grid;
    gap: 16px;
}

.product-detail__author,
.product-detail__summary {
    color: var(--color-muted);
}

.product-detail__rating,
.product-purchase-panel,
.product-description,
.product-specs {
    display: grid;
    gap: 16px;
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    background: var(--color-surface);
    padding: 18px;
}

.product-price {
    display: flex;
    align-items: center;
    flex-wrap: wrap;
    gap: 10px;
    margin-bottom: 10px;
}

.product-price__current {
    color: var(--color-ink);
    font-size: 1.7rem;
    font-weight: 800;
}

.product-price__previous,
.wishlist-card__price span,
.cart-item__price span {
    color: var(--color-muted);
    text-decoration: line-through;
}

.product-price__badge,
.nav-count,
.status-pill {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    min-height: 24px;
    padding: 4px 8px;
    border-radius: 999px;
    background: var(--color-accent-soft);
    color: var(--color-accent);
    font-size: 0.78rem;
    font-weight: 800;
}

.stock-status {
    margin-bottom: 16px;
    font-weight: 800;
}

.stock-status--available {
    color: var(--color-success);
}

.stock-status--empty,
.cart-item__alert {
    color: var(--color-danger);
}

.product-action-form,
.wishlist-form,
.quantity-form,
.auth-form,
.profile-form,
.admin-form {
    display: grid;
    gap: 14px;
}

.form-grid {
    display: grid;
    gap: 14px;
}

.form-grid--two {
    grid-template-columns: repeat(2, minmax(0, 1fr));
}

.form-grid--three {
    grid-template-columns: repeat(3, minmax(0, 1fr));
}

.form-field {
    display: grid;
    gap: 7px;
}

.form-field label,
.quantity-form label {
    color: var(--color-ink);
    font-size: 0.9rem;
    font-weight: 800;
}

.form-field label span {
    color: var(--color-muted);
    font-weight: 500;
}

input,
select,
textarea {
    width: 100%;
    min-height: 44px;
    border: 1px solid var(--color-border);
    border-radius: var(--radius-sm);
    background: #ffffff;
    color: var(--color-text);
    padding: 10px 12px;
    outline: none;
    transition: border-color 160ms ease, box-shadow 160ms ease;
}

.auth-form input,
.auth-form select,
.auth-form textarea {
    color: #111111;
}

.auth-form input::placeholder,
.auth-form textarea::placeholder {
    color: white;
}

input[type="number"]::placeholder,
input[type="number"]:-ms-input-placeholder,
input[type="number"]::-ms-input-placeholder,
input[type="number"]::-webkit-input-placeholder {
    color: #111111;
    opacity: 0.8;
}

textarea {
    resize: vertical;
}

input:focus,
select:focus,
textarea:focus {
    border-color: var(--color-accent);
    box-shadow: 0 0 0 4px rgba(47, 93, 80, 0.12);
}

.form-help {
    color: var(--color-muted);
    font-size: 0.88rem;
}

.checkbox-field,
.payment-option {
    display: flex;
    align-items: flex-start;
    gap: 10px;
}

.checkbox-field input,
.payment-option input {
    width: auto;
    min-height: auto;
    margin-top: 5px;
}

.payment-options {
    display: grid;
    gap: 12px;
    padding: 0;
    border: 0;
}

.payment-option {
    padding: 14px;
    border: 1px solid var(--color-border);
    border-radius: var(--radius-sm);
    background: var(--color-panel);
}

.payment-option small {
    display: block;
    color: var(--color-muted);
}

.product-specs dl,
.summary-list,
.admin-metric-list {
    display: grid;
    gap: 0;
    margin: 0;
}

.product-specs dl div,
.summary-list div,
.admin-metric-list div {
    display: flex;
    justify-content: space-between;
    gap: 16px;
    padding: 12px 0;
    border-bottom: 1px solid var(--color-border);
}

.product-specs dt,
.summary-list dt,
.admin-metric-list dt {
    color: var(--color-muted);
}

.product-specs dd,
.summary-list dd,
.admin-metric-list dd {
    margin: 0;
    color: var(--color-ink);
    font-weight: 800;
    text-align: right;
}

.summary-list__total {
    font-size: 1.1rem;
}

.review-list,
.cart-item-list,
.order-history-list,
.checkout-summary__items {
    display: grid;
    gap: 14px;
}

.review-card {
    padding: 18px;
}

.review-card__header,
.cart-item__header,
.order-history-card,
.checkout-summary__item {
    display: flex;
    justify-content: space-between;
    gap: 18px;
}

.review-card time {
    display: block;
    margin-top: 12px;
    color: var(--color-muted);
    font-size: 0.88rem;
}

.cart-layout__main,
.profile-layout__main {
    display: grid;
    gap: 20px;
}

.cart-item {
    display: grid;
    grid-template-columns: 120px minmax(0, 1fr);
    gap: 18px;
    padding: 16px;
}

.cart-item__cover {
    aspect-ratio: 3 / 4;
    border-radius: var(--radius-sm);
    overflow: hidden;
    background: var(--color-panel);
}

.cart-item__cover img {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.cart-item__content {
    display: grid;
    gap: 12px;
}

.cart-item__price,
.cart-item__line-total {
    display: grid;
    gap: 4px;
    text-align: right;
}

.quantity-form {
    grid-template-columns: auto 90px auto;
    align-items: end;
}

.cart-summary,
.checkout-summary {
    position: sticky;
    top: 20px;
    padding: 20px;
}

.cart-summary__checkout,
.cart-summary__continue,
.checkout-summary__cart-link {
    width: 100%;
    margin-top: 14px;
}

.cart-summary__note,
.checkout-summary__note {
    margin-top: 14px;
    color: var(--color-muted);
    font-size: 0.9rem;
}

.checkout-form {
    display: grid;
    gap: 18px;
}

.checkout-panel,
.profile-panel {
    padding: 20px;
}

.checkout-summary__item {
    padding: 12px 0;
    border-bottom: 1px solid var(--color-border);
}

.checkout-summary__warning {
    color: var(--color-danger);
    font-weight: 800;
}

.auth-layout {
    padding-block: var(--space-page);
}

.auth-layout__grid {
    grid-template-columns: minmax(0, 0.9fr) minmax(340px, 0.7fr);
}

.auth-intro {
    display: grid;
    align-content: start;
    gap: 18px;
}

.auth-intro > p {
    max-width: 620px;
    color: var(--color-muted);
}

.auth-benefits {
    display: grid;
    gap: 14px;
    margin-top: 14px;
}

.auth-benefit {
    padding: 18px;
}

.auth-benefit p {
    margin-top: 6px;
    color: var(--color-muted);
}

.auth-card {
    padding: 24px;
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    background: var(--color-surface);
    box-shadow: var(--shadow-md);
}

.auth-card__header,
.auth-card__footer {
    display: grid;
    gap: 8px;
}

.auth-card__footer {
    margin-top: 20px;
    color: var(--color-muted);
}

.auth-form {
    margin-top: 18px;
}

.profile-overview {
    padding-bottom: 20px;
}

.profile-stat {
    padding: 18px;
}

.profile-stat__value {
    display: block;
    color: var(--color-ink);
    font-size: 1.35rem;
    font-weight: 800;
}

.profile-stat__label {
    color: var(--color-muted);
}

.profile-layout {
    padding-bottom: var(--space-page);
}

.profile-layout__side {
    display: grid;
    gap: 18px;
}

.profile-links {
    display: grid;
    gap: 10px;
}

.profile-links a {
    padding: 12px 0;
    border-bottom: 1px solid var(--color-border);
    color: var(--color-accent);
    font-weight: 800;
}

.order-history-card {
    align-items: center;
    padding: 16px;
    border: 1px solid var(--color-border);
    border-radius: var(--radius-sm);
}

.order-history-card__date,
.order-history-card__items {
    color: var(--color-muted);
    font-size: 0.92rem;
}

.wishlist-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
}

.wishlist-card {
    display: grid;
    grid-template-columns: 150px minmax(0, 1fr);
    overflow: hidden;
}

.wishlist-card__cover {
    background: var(--color-panel);
}

.wishlist-card__cover img {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.wishlist-card__content {
    display: grid;
    gap: 8px;
    padding: 18px;
}

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

.site-footer {
    margin-top: var(--space-page);
    background: linear-gradient(180deg, var(--color-panel) 0%, #101827 100%);
    color: var(--color-text);
    border-top: 1px solid var(--color-border);
}

.site-footer__grid {
    display: grid;
    grid-template-columns: 1.4fr repeat(4, 1fr);
    gap: 28px;
    padding-block: 44px;
}

.site-footer h3,
.footer-brand__name {
    color: #ffffff;
}

.footer-brand {
    display: inline-flex;
    align-items: center;
    gap: 10px;
    font-weight: 800;
}

.footer-brand__mark {
    display: inline-grid;
    place-items: center;
    width: 38px;
    height: 38px;
    border-radius: var(--radius-sm);
    background: var(--color-accent);
    color: #ffffff;
}

.site-footer__description,
.site-footer__contact,
.site-footer__section p,
.site-footer__bottom {
    color: var(--color-muted);
}

.site-footer__contact {
    display: grid;
    margin-top: 16px;
    font-style: normal;
}

.footer-link-list {
    display: grid;
    gap: 10px;
    padding: 0;
    margin: 14px 0 0;
    list-style: none;
}

.footer-service-link {
    display: inline-block;
    margin-top: 12px;
    color: var(--color-accent);
    font-weight: 800;
}

.site-footer__bottom {
    border-top: 1px solid rgba(148, 163, 184, 0.18);
.site-footer__bottom-inner {
    display: flex;
    justify-content: space-between;
    gap: 16px;
    padding-block: 18px;
    font-size: 0.9rem;
}

.responsive-table {
    width: 100%;
    overflow-x: auto;
}

.pagination {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
    margin-top: 22px;
}

.pagination a {
    display: inline-grid;
    place-items: center;
    min-width: 38px;
    min-height: 38px;
    border: 1px solid var(--color-border);
    border-radius: var(--radius-sm);
    background: var(--color-surface);
    font-weight: 800;
}

.pagination a.is-active {
    border-color: var(--color-accent);
    background: var(--color-accent);
    color: #ffffff;
}

@media (max-width: 1040px) {
    .book-grid,
    .category-grid,
    .profile-overview {
        grid-template-columns: repeat(3, minmax(0, 1fr));
    }

    .hero-section__grid,
    .product-detail__grid,
    .product-information__grid,
    .cart-layout,
    .checkout-layout,
    .profile-layout,
    .auth-layout__grid {
        grid-template-columns: 1fr;
    }

    .cart-summary,
    .checkout-summary {
        position: static;
    }

    .site-footer__grid {
        grid-template-columns: repeat(2, minmax(0, 1fr));
    }
}

@media (max-width: 760px) {
    body {
        font-size: 15px;
    }

    .section-heading,
    .cart-item__header,
    .cart-item__actions,
    .review-card__header,
    .order-history-card,
    .checkout-summary__item,
    .site-footer__bottom-inner {
        align-items: flex-start;
        flex-direction: column;
    }

    .book-grid,
    .category-grid,
    .wishlist-grid,
    .profile-overview,
    .form-grid--two,
    .form-grid--three {
        grid-template-columns: 1fr;
    }

    .cart-item,
    .wishlist-card {
        grid-template-columns: 1fr;
    }

    .cart-item__cover,
    .wishlist-card__cover {
        max-width: 190px;
    }

    .quantity-form {
        grid-template-columns: 1fr;
    }

    .site-footer__grid {
        grid-template-columns: 1fr;
    }