/* ========== Biến theme ========== */
:root {
    --bs-book-primary: #2563eb;
    --bs-book-primary-rgb: 37, 99, 235;
    --book-accent: #7c3aed;
    --book-surface: #ffffff;
    --book-body-bg: #f1f5f9;
    --book-text: #1e293b;
    --book-muted: #64748b;
    --book-border: #e2e8f0;
    --book-shadow: 0 1px 3px rgba(15, 23, 42, 0.08);
    --book-shadow-lg: 0 18px 40px rgba(15, 23, 42, 0.12);
    --book-radius: 14px;
    --book-header-h: 72px;
}

body.dark-mode {
    --book-surface: #1e2936;
    --book-body-bg: #0f1419;
    --book-text: #e8eef7;
    --book-muted: #94a3b8;
    --book-border: #334155;
    --book-shadow: 0 1px 3px rgba(0, 0, 0, 0.35);
    --book-shadow-lg: 0 18px 40px rgba(0, 0, 0, 0.45);
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: 'Roboto', system-ui, sans-serif;
    color: var(--book-text);
    background-color: var(--book-body-bg);
    transition: background-color 0.25s ease, color 0.25s ease;
}

/* ========== Header ========== */
.header-section {
    border-bottom: 1px solid var(--book-border);
    background: var(--book-surface) !important;
    transition: box-shadow 0.2s ease, padding 0.2s ease;
}

.header-section.navbar-scrolled {
    box-shadow: var(--book-shadow-lg) !important;
    padding-top: 0 !important;
    padding-bottom: 0 !important;
}

.header-section .navbar {
    padding-top: 0.65rem;
    padding-bottom: 0.65rem;
    transition: padding 0.2s ease;
}

.navbar-brand {
    font-size: 1.35rem;
    letter-spacing: 0.02em;
    color: var(--book-text) !important;
    background: linear-gradient(120deg, var(--bs-book-primary), var(--book-accent));
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
}

.navbar-brand i {
    -webkit-text-fill-color: var(--bs-book-primary);
    color: var(--bs-book-primary);
}

.nav-link {
    font-weight: 500;
    color: var(--book-text) !important;
    border-radius: 8px;
    padding: 0.4rem 0.75rem !important;
    transition: color 0.2s, background-color 0.2s;
}

.nav-link:hover,
.nav-link:focus {
    color: var(--bs-book-primary) !important;
    background-color: rgba(var(--bs-book-primary-rgb), 0.08);
}

.nav-cart-link {
    color: var(--book-text) !important;
    transition: color 0.2s, transform 0.2s;
}

.nav-cart-link:hover {
    color: var(--bs-book-primary) !important;
    transform: scale(1.05);
}

.cart-count-badge {
    font-size: 0.65rem;
    min-width: 1.25rem;
    padding: 0.25em 0.4em;
}

.cart-count-empty {
    opacity: 0.85;
    font-weight: 600;
}

/* Giỏ hàng */
.cart-table-wrap {
    overflow: hidden;
}

.cart-table thead th {
    font-size: 0.8rem;
    text-transform: uppercase;
    letter-spacing: 0.04em;
    color: var(--book-muted);
}

.cart-qty-input {
    max-width: 4.5rem;
}

.cart-empty-state {
    background: var(--book-surface);
    border-color: var(--book-border) !important;
    box-shadow: var(--book-shadow);
}

.checkout-box {
    background: var(--book-surface);
    border: 1px solid var(--book-border);
    border-radius: var(--book-radius);
    box-shadow: var(--book-shadow);
}

.checkout-summary-list {
    max-height: 340px;
    overflow: auto;
}

body.dark-mode .cart-table thead {
    --bs-table-bg: #252f3d;
    color: var(--book-text);
}

body.dark-mode .cart-table tbody td,
body.dark-mode .cart-table tfoot th {
    background: transparent;
    color: var(--book-text);
    border-color: var(--book-border);
}

body.dark-mode .cart-table .table-group-divider {
    border-color: var(--book-border);
}

body.dark-mode .checkout-box {
    background: var(--book-surface);
    border-color: var(--book-border);
}

.search-form-nav .form-control {
    min-width: 180px;
    border-radius: 999px;
    border: 1px solid var(--book-border);
    background: var(--book-body-bg);
    padding-left: 1rem;
    padding-right: 1rem;
}

.search-form-nav .form-control:focus {
    border-color: var(--bs-book-primary);
    box-shadow: 0 0 0 3px rgba(var(--bs-book-primary-rgb), 0.2);
    background: var(--book-surface);
}

/* ========== Main layout ========== */
.site-main {
    padding-top: 1.5rem;
    padding-bottom: 3rem;
}

@media (min-width: 768px) {
    .sidebar-sticky {
        position: sticky;
        top: calc(var(--book-header-h) + 1rem);
        align-self: flex-start;
    }
}

.menu-title {
    font-size: 0.82rem;
    font-weight: 700;
    letter-spacing: 0.08em;
    color: var(--book-muted);
    margin-bottom: 0.65rem;
    text-transform: uppercase;
}

.menu-title--in-box {
    padding: 1rem 1rem 0.5rem;
    margin-bottom: 0;
    border-bottom: none;
}

.sidebar-panel {
    background: var(--book-surface);
    border-radius: var(--book-radius);
    box-shadow: var(--book-shadow);
    border: 1px solid var(--book-border);
    overflow: hidden;
    transition: background-color 0.25s ease, border-color 0.25s ease;
}

.sidebar-panel .list-group {
    border-radius: 0;
}

.sidebar-panel .list-group-item {
    border-color: var(--book-border);
    color: var(--book-text);
    background: transparent;
    padding: 0.75rem 1rem;
    transition: background 0.2s, color 0.2s, padding-left 0.2s;
}

.sidebar-panel .list-group-item:hover {
    background: rgba(var(--bs-book-primary-rgb), 0.08);
    color: var(--bs-book-primary);
    padding-left: 1.25rem;
}

.sidebar-panel .list-group-item i {
    opacity: 0.7;
}

/* ========== Hero ========== */
.hero-banner {
    background: linear-gradient(135deg, #e0e7ff 0%, #fae8ff 45%, #e0f2fe 100%);
    border-radius: var(--book-radius);
    padding: 2.5rem 2rem;
    border: 1px solid rgba(99, 102, 241, 0.15);
    box-shadow: var(--book-shadow);
}

body.dark-mode .hero-banner {
    background: linear-gradient(135deg, #1e1b4b 0%, #312e81 40%, #0c4a6e 100%);
    border-color: rgba(129, 140, 248, 0.25);
}

.hero-banner h1 {
    color: var(--book-text);
}

body.dark-mode .hero-banner h1 {
    color: #f8fafc !important;
}

.hero-banner .lead {
    color: var(--book-muted);
}

body.dark-mode .hero-banner .lead {
    color: #cbd5e1 !important;
}

body.dark-mode .hero-banner .text-dark {
    color: #f8fafc !important;
}

/* ========== Thẻ sách ========== */
.book-card {
    transition: transform 0.3s ease, box-shadow 0.3s ease;
    border-radius: var(--book-radius);
    background: var(--book-surface);
    border: 1px solid var(--book-border) !important;
}

.book-card:hover {
    transform: translateY(-8px);
    box-shadow: var(--book-shadow-lg) !important;
}

.img-hover {
    transition: transform 0.45s ease;
}

.book-card:hover .img-hover {
    transform: scale(1.04);
}

.card-badge {
    position: absolute;
    top: 12px;
    left: 12px;
    z-index: 2;
    color: #fff;
    padding: 0.2rem 0.65rem;
    border-radius: 999px;
    font-size: 11px;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.03em;
}

.book-img,
.card-img-top.book-img {
    height: 240px;
    object-fit: contain;
    width: 100%;
    display: block;
    margin: 0 auto;
    background: #f8fafc;
    border-bottom: 1px solid rgba(15, 23, 42, 0.06);
}

.btn-add-cart {
    border-radius: 10px;
    font-weight: 600;
    transition: background 0.2s, color 0.2s, border-color 0.2s;
}

.btn-add-cart:hover {
    background-color: var(--bs-book-primary);
    border-color: var(--bs-book-primary);
    color: #fff;
}

.book-title {
    color: var(--book-text) !important;
}

.book-title:hover {
    color: var(--bs-book-primary) !important;
}

/* ========== Chi tiết sách ========== */
.book-detail-container {
    background: var(--book-surface) !important;
    border: 1px solid var(--book-border);
    border-radius: var(--book-radius);
    box-shadow: var(--book-shadow);
    transition: background 0.25s, border-color 0.25s;
}

.p-back-btn:hover {
    color: var(--book-accent) !important;
}

/* ========== Footer ========== */
.site-footer {
    border-top: 1px solid var(--book-border);
    transition: background 0.25s, color 0.25s;
}

body.dark-mode .site-footer {
    background: #0c1017 !important;
    color: #e8eef7 !important;
    border-top-color: var(--book-border);
}

body.dark-mode .site-footer .text-secondary {
    color: var(--book-muted) !important;
}

body.dark-mode .site-footer hr {
    border-color: var(--book-border);
    opacity: 1;
}

.site-footer a.text-secondary:hover {
    color: #fff !important;
}

.footer-heading {
    font-size: 0.95rem;
    font-weight: 700;
    margin-bottom: 1rem;
    letter-spacing: 0.04em;
}

/* ========== Dark mode – bootstrap leftovers ========== */
body.dark-mode .header-section,
body.dark-mode .bg-white {
    background-color: var(--book-surface) !important;
    border-bottom-color: var(--book-border) !important;
}

body.dark-mode .navbar-toggler {
    border-color: var(--book-border);
}

body.dark-mode .navbar-toggler-icon {
    filter: invert(1) grayscale(100%);
}

body.dark-mode .dropdown-menu {
    background: var(--book-surface);
    border-color: var(--book-border);
}

body.dark-mode .dropdown-item {
    color: var(--book-text);
}

body.dark-mode .dropdown-item:hover {
    background: rgba(var(--bs-book-primary-rgb), 0.15);
    color: var(--bs-book-primary);
}

body.dark-mode .dropdown-item-text,
body.dark-mode .dropdown-divider {
    color: var(--book-muted);
    border-color: var(--book-border);
}

body.dark-mode .form-control {
    background-color: #293548;
    color: var(--book-text);
    border-color: var(--book-border);
}

body.dark-mode .list-group-item {
    background-color: transparent;
    color: var(--book-text);
    border-color: var(--book-border);
}

body.dark-mode .book-card {
    background-color: var(--book-surface);
}

body.dark-mode .book-title {
    color: #f1f5f9 !important;
}

body.dark-mode .book-title:hover {
    color: #93c5fd !important;
}

body.dark-mode .text-dark {
    color: #f1f5f9 !important;
}

body.dark-mode .alert-info {
    background: #164e63;
    border-color: #0e7490;
    color: #cffafe;
}

body.dark-mode .alert-warning {
    background: #713f12;
    border-color: #ca8a04;
    color: #fef9c3;
}

body.dark-mode .book-detail-container .text-muted {
    color: var(--book-muted) !important;
}

body.dark-mode .book-detail-container hr {
    border-color: var(--book-border);
}

/* ========== Pagination ========== */
.pager-wrap {
    margin-top: 1.25rem;
    margin-bottom: 0.75rem;
}

.pager-wrap .pagination {
    gap: 0.3rem;
    margin-bottom: 0;
    flex-wrap: wrap;
    justify-content: center;
    background: #fff;
    border: 1px solid #d9dee7;
    border-radius: 6px;
    padding: 0.4rem;
    box-shadow: 0 1px 2px rgba(15, 23, 42, 0.06);
}

.pager-wrap .pagination > li {
    display: inline-flex;
}

.pager-wrap .pagination > li > a,
.pager-wrap .pagination > li > span {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    min-width: 2rem;
    height: 2rem;
    padding: 0 0.55rem;
    border-radius: 4px;
    border: 1px solid transparent;
    background: transparent;
    color: #7b8798;
    text-decoration: none;
    font-weight: 600;
    line-height: 1;
    transition: all 0.2s ease;
    box-shadow: none;
}

.pager-wrap .pagination > li > a:hover,
.pager-wrap .pagination > li > a:focus {
    background: #f5f8ff;
    color: var(--bs-book-primary);
    border-color: #dbe5fb;
    transform: none;
}

.pager-wrap .pagination > .active > a,
.pager-wrap .pagination > .active > span {
    background: #2f80ed;
    color: #fff;
    border-color: #2f80ed;
    box-shadow: none;
}

.pager-wrap .pagination > .disabled > a,
.pager-wrap .pagination > .disabled > span {
    color: #c0c6d1;
    opacity: 1;
    pointer-events: none;
}

body.dark-mode .pager-wrap .pagination {
    background: var(--book-surface);
    border-color: var(--book-border);
    box-shadow: none;
}

/* ========== Page header / breadcrumb ========== */
.page-hero {
    background: var(--book-surface);
    border-radius: var(--book-radius);
    padding: 1.25rem 1.5rem;
    margin-bottom: 1.5rem;
    border: 1px solid var(--book-border);
    box-shadow: var(--book-shadow);
}

.breadcrumb-book {
    --bs-breadcrumb-divider: '›';
    margin-bottom: 0.5rem;
    font-size: 0.875rem;
}

.breadcrumb-book .breadcrumb-item a {
    color: var(--bs-book-primary);
    text-decoration: none;
}

.breadcrumb-book .breadcrumb-item a:hover {
    text-decoration: underline;
}

/* ========== User icon & theme switch ========== */
.user-icon {
    font-size: 1.35rem;
    transition: color 0.2s, transform 0.2s;
    color: var(--book-text) !important;
}

.user-icon:hover {
    color: var(--bs-book-primary) !important;
    transform: scale(1.08);
}

.theme-switch-wrapper {
    display: flex;
    align-items: center;
}

.theme-switch {
    display: inline-block;
    height: 30px;
    position: relative;
    width: 60px;
    margin: 0;
}

.theme-switch input {
    display: none !important;
}

.slider {
    background-color: #cbd5e1;
    bottom: 0;
    cursor: pointer;
    left: 0;
    position: absolute;
    right: 0;
    top: 0;
    transition: 0.35s;
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0 8px;
    box-sizing: border-box;
    border-radius: 34px;
    box-shadow: inset 0 2px 4px rgba(0, 0, 0, 0.08);
}

.slider:before {
    background-color: #ffffff;
    bottom: 3px;
    content: "";
    height: 24px;
    left: 4px;
    position: absolute;
    transition: 0.35s;
    width: 24px;
    border-radius: 50%;
    z-index: 2;
    box-shadow: 0 2px 6px rgba(0, 0, 0, 0.15);
}

body.dark-mode .slider {
    background: #475569;
}

input:checked + .slider {
    background: linear-gradient(120deg, #1e3a8a, #6d28d9);
}

input:checked + .slider:before {
    transform: translateX(28px);
}

.slider .icon-on, .slider .icon-off {
    font-size: 12px;
    transition: opacity 0.3s;
    z-index: 1;
}

.slider .icon-on {
    opacity: 0;
}

.slider .icon-off {
    opacity: 1;
}

input:checked + .slider .icon-on {
    opacity: 1;
}

input:checked + .slider .icon-off {
    opacity: 0;
}

/* ========== Nút lên đầu trang ========== */
.btn-back-top {
    position: fixed;
    right: 1.25rem;
    bottom: 1.25rem;
    z-index: 1040;
    width: 48px;
    height: 48px;
    border-radius: 50%;
    border: none;
    background: var(--bs-book-primary);
    color: #fff;
    box-shadow: var(--book-shadow-lg);
    opacity: 0;
    visibility: hidden;
    transform: translateY(12px);
    transition: opacity 0.25s, transform 0.25s, visibility 0.25s;
}

.btn-back-top.is-visible {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}

.btn-back-top:hover {
    background: #1d4ed8;
    color: #fff;
}

.btn-back-top:focus-visible {
    outline: 3px solid rgba(var(--bs-book-primary-rgb), 0.45);
    outline-offset: 2px;
}

body.dark-mode .btn-back-top {
    background: var(--book-accent);
}

body.dark-mode .btn-back-top:hover {
    background: #8b5cf6;
}