/* ===== CSS Custom Properties — Dark Emerald Palette ===== */
:root {
    --bg-primary:     #080d0b;
    --bg-secondary:   #0d1a14;
    --bg-tertiary:    #112219;
    --bg-elevated:    #162d22;
    --bg-card:        #0f1d17;
    --bg-card-hover:  #132416;

    --emerald-300:    #6ee7b7;
    --emerald-400:    #34d399;
    --emerald-500:    #10b981;
    --emerald-600:    #059669;
    --emerald-700:    #047857;
    --emerald-900:    #064e3b;

    --danger:         #ef4444;
    --danger-hover:   #dc2626;
    --danger-bg:      #1f0a0a;
    --danger-border:  #7f1d1d;

    --text-primary:   #dff0e8;
    --text-secondary: #8db09a;
    --text-muted:     #4d7060;

    --border:         #1a3327;
    --border-light:   #254d3a;
    --border-accent:  #10b981;

    --radius-sm:  4px;
    --radius-md:  8px;
    --radius-lg:  12px;
    --radius-pill: 9999px;

    --shadow-card: 0 4px 24px rgba(0,0,0,0.5), 0 0 0 1px var(--border);
    --shadow-glow: 0 0 16px rgba(16, 185, 129, 0.25);
    --transition:  0.18s ease;
}

/* ===== Base Reset & Typography ===== */
*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    line-height: 1.65;
    color: var(--text-primary);
    background-color: var(--bg-primary);
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

a {
    color: var(--emerald-400);
    text-decoration: none;
    transition: color var(--transition);
}

a:hover {
    color: var(--emerald-300);
    text-decoration: none;
}

h1 {
    font-size: 1.85rem;
    font-weight: 700;
    letter-spacing: -0.02em;
    color: var(--text-primary);
    margin-bottom: 1.25rem;
}

h2 {
    font-size: 1.2rem;
    font-weight: 600;
    letter-spacing: -0.01em;
    color: var(--text-primary);
    margin-top: 1.75rem;
    margin-bottom: 0.875rem;
}

p {
    margin-bottom: 0.875rem;
    color: var(--text-secondary);
}

strong {
    color: var(--text-primary);
    font-weight: 600;
}

/* ===== Navigation ===== */
nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0 2rem;
    height: 60px;
    background-color: var(--bg-elevated);
    border-bottom: 1px solid var(--border);
    position: sticky;
    top: 0;
    z-index: 100;
    backdrop-filter: blur(8px);
}

.nav-brand {
    font-size: 1.15rem;
    font-weight: 800;
    letter-spacing: -0.03em;
    color: var(--emerald-400);
    text-shadow: var(--shadow-glow);
    text-decoration: none;
    transition: color var(--transition), text-shadow var(--transition);
}

.nav-brand:hover {
    color: var(--emerald-300);
    text-shadow: 0 0 24px rgba(16,185,129,0.5);
}

.nav-links {
    display: flex;
    align-items: center;
    gap: 0.25rem;
}

nav a:not(.nav-brand) {
    color: var(--text-secondary);
    font-weight: 500;
    font-size: 0.9rem;
    padding: 0.35rem 0.75rem;
    border-radius: var(--radius-sm);
    transition: color var(--transition), background-color var(--transition);
}

nav a:not(.nav-brand):hover {
    color: var(--emerald-400);
    background-color: rgba(16,185,129,0.08);
    text-decoration: none;
}

.nav-username {
    color: var(--text-muted);
    font-size: 0.85rem;
    font-weight: 500;
    padding: 0.35rem 0.75rem;
    border: 1px solid var(--border);
    border-radius: var(--radius-pill);
    background: var(--bg-tertiary);
}

/* ===== Logout Button (nav) ===== */
nav form {
    display: inline;
    margin: 0;
}

.logout-btn {
    background: none;
    border: 1px solid var(--border);
    padding: 0.3rem 0.75rem;
    border-radius: var(--radius-sm);
    color: var(--text-secondary);
    font-weight: 500;
    font-size: 0.9rem;
    cursor: pointer;
    font-family: inherit;
    transition: color var(--transition), border-color var(--transition), background-color var(--transition);
}

.logout-btn:hover {
    color: var(--danger);
    border-color: var(--danger-border);
    background-color: rgba(239,68,68,0.07);
}

/* ===== Main Content ===== */
main {
    max-width: 1040px;
    margin: 2.5rem auto;
    padding: 0 1.5rem;
    flex: 1;
    width: 100%;
}

/* ===== Page Header ===== */
.page-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: 1.75rem;
    padding-bottom: 1rem;
    border-bottom: 1px solid var(--border);
}

.page-header h1 {
    margin-bottom: 0;
}

/* ===== Messages (Django flash messages) ===== */
ul.messages {
    list-style: none;
    margin-bottom: 1.75rem;
}

ul.messages li {
    padding: 0.8rem 1.1rem;
    border-radius: var(--radius-md);
    margin-bottom: 0.5rem;
    border: 1px solid transparent;
    font-size: 0.9rem;
    font-weight: 500;
}

ul.messages li.success {
    background-color: rgba(16,185,129,0.12);
    color: var(--emerald-300);
    border-color: rgba(16,185,129,0.3);
}

ul.messages li.error {
    background-color: rgba(239,68,68,0.1);
    color: #fca5a5;
    border-color: rgba(239,68,68,0.3);
}

ul.messages li.warning {
    background-color: rgba(245,158,11,0.1);
    color: #fcd34d;
    border-color: rgba(245,158,11,0.3);
}

ul.messages li.info {
    background-color: rgba(59,130,246,0.1);
    color: #93c5fd;
    border-color: rgba(59,130,246,0.3);
}

/* ===== Cards ===== */
.card {
    background-color: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius-lg);
    padding: 1.75rem;
    box-shadow: var(--shadow-card);
}

.card-sm {
    padding: 1.25rem;
}

/* ===== Book Grid (Catalogue) ===== */
.book-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 1.25rem;
    margin-bottom: 2rem;
}

@media (max-width: 768px) {
    .book-grid { grid-template-columns: repeat(2, 1fr); }
}

@media (max-width: 500px) {
    .book-grid { grid-template-columns: 1fr; }
}

.book-card {
    background-color: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius-lg);
    padding: 1.25rem;
    display: flex;
    flex-direction: column;
    gap: 0.6rem;
    transition: border-color var(--transition), box-shadow var(--transition), transform var(--transition);
    text-decoration: none;
}

.book-card:hover {
    border-color: var(--emerald-700);
    box-shadow: 0 6px 28px rgba(0,0,0,0.5), 0 0 0 1px var(--emerald-700);
    transform: translateY(-2px);
    text-decoration: none;
}

.book-card-title {
    font-size: 1rem;
    font-weight: 700;
    color: var(--text-primary);
    line-height: 1.35;
}

.book-card-author {
    font-size: 0.85rem;
    color: var(--text-secondary);
}

.book-card-footer {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-top: auto;
    padding-top: 0.75rem;
    border-top: 1px solid var(--border);
}

.book-card-genres {
    display: flex;
    flex-wrap: wrap;
    gap: 0.35rem;
}

/* ===== Badges ===== */
.badge {
    display: inline-flex;
    align-items: center;
    gap: 0.3rem;
    padding: 0.2rem 0.6rem;
    border-radius: var(--radius-pill);
    font-size: 0.72rem;
    font-weight: 600;
    letter-spacing: 0.03em;
    text-transform: uppercase;
    line-height: 1;
}

.badge-genre {
    background-color: rgba(16,185,129,0.1);
    color: var(--emerald-400);
    border: 1px solid rgba(16,185,129,0.2);
}

.badge-available {
    background-color: rgba(16,185,129,0.12);
    color: var(--emerald-300);
    border: 1px solid rgba(16,185,129,0.25);
}

.badge-unavailable {
    background-color: rgba(239,68,68,0.1);
    color: #fca5a5;
    border: 1px solid rgba(239,68,68,0.25);
}

.badge-active {
    background-color: rgba(16,185,129,0.12);
    color: var(--emerald-300);
    border: 1px solid rgba(16,185,129,0.25);
}

.badge-returned {
    background-color: rgba(255,255,255,0.05);
    color: var(--text-muted);
    border: 1px solid var(--border);
}

.badge::before {
    content: '';
    display: inline-block;
    width: 6px;
    height: 6px;
    border-radius: 50%;
    background-color: currentColor;
    flex-shrink: 0;
}

.badge-genre::before,
.badge-returned::before {
    display: none;
}

/* ===== Availability dot in book cards ===== */
.avail-indicator {
    display: flex;
    align-items: center;
    gap: 0.4rem;
    font-size: 0.8rem;
    font-weight: 600;
}

.avail-dot {
    width: 8px;
    height: 8px;
    border-radius: 50%;
    flex-shrink: 0;
}

.avail-dot.green { background-color: var(--emerald-400); box-shadow: 0 0 6px var(--emerald-600); }
.avail-dot.red   { background-color: #ef4444; box-shadow: 0 0 6px rgba(239,68,68,0.5); }
.avail-count     { color: var(--text-muted); }

/* ===== Tables ===== */
table {
    width: 100%;
    border-collapse: collapse;
    margin-bottom: 1.5rem;
    background-color: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius-lg);
    overflow: hidden;
}

th, td {
    padding: 0.7rem 1rem;
    text-align: left;
    border-bottom: 1px solid var(--border);
}

td {
    color: var(--text-secondary);
    font-size: 0.9rem;
}

thead th {
    background-color: var(--bg-tertiary);
    font-weight: 600;
    font-size: 0.78rem;
    letter-spacing: 0.06em;
    text-transform: uppercase;
    color: var(--text-muted);
    border-bottom: 1px solid var(--border-light);
}

tbody tr:last-child td {
    border-bottom: none;
}

tbody tr {
    transition: background-color var(--transition);
}

tbody tr:hover {
    background-color: var(--bg-tertiary);
}

tbody tr:hover td {
    color: var(--text-primary);
}

/* ===== Forms ===== */
.form-card {
    background-color: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius-lg);
    padding: 2rem;
    box-shadow: var(--shadow-card);
    max-width: 600px;
}

.auth-card {
    background-color: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius-lg);
    padding: 2.5rem;
    box-shadow: var(--shadow-card);
    max-width: 420px;
    margin: 0 auto;
}

.auth-card h1 {
    text-align: center;
    margin-bottom: 1.75rem;
    color: var(--emerald-400);
}

.auth-footer {
    text-align: center;
    margin-top: 1.25rem;
    font-size: 0.88rem;
    color: var(--text-muted);
}

form {
    margin-bottom: 1rem;
}

form p {
    margin-bottom: 0.875rem;
}

form p label {
    display: block;
    font-weight: 600;
    font-size: 0.85rem;
    margin-bottom: 0.35rem;
    color: var(--text-secondary);
    letter-spacing: 0.02em;
}

input[type="text"],
input[type="password"],
input[type="email"],
input[type="number"],
select,
textarea {
    width: 100%;
    padding: 0.55rem 0.875rem;
    background-color: var(--bg-tertiary);
    border: 1px solid var(--border-light);
    border-radius: var(--radius-md);
    font-size: 0.95rem;
    font-family: inherit;
    color: var(--text-primary);
    transition: border-color var(--transition), box-shadow var(--transition);
    -webkit-appearance: none;
}

input:focus,
select:focus,
textarea:focus {
    outline: none;
    border-color: var(--emerald-600);
    box-shadow: 0 0 0 3px rgba(16,185,129,0.18);
}

select option {
    background-color: var(--bg-secondary);
    color: var(--text-primary);
}

/* ===== Buttons ===== */
.btn,
button[type="submit"] {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 0.4rem;
    padding: 0.55rem 1.35rem;
    border-radius: var(--radius-md);
    font-size: 0.92rem;
    font-weight: 600;
    font-family: inherit;
    cursor: pointer;
    border: none;
    transition: background-color var(--transition), box-shadow var(--transition), transform var(--transition), color var(--transition), border-color var(--transition);
    text-decoration: none;
    line-height: 1;
    white-space: nowrap;
}

button[type="submit"] {
    background-color: var(--emerald-600);
    color: #fff;
    border: 1px solid var(--emerald-500);
}

button[type="submit"]:hover {
    background-color: var(--emerald-500);
    box-shadow: var(--shadow-glow);
}

button[type="submit"]:active {
    transform: scale(0.98);
}

/* Button variants via class */
.btn-primary {
    background-color: var(--emerald-600);
    color: #fff;
    border: 1px solid var(--emerald-500);
}

.btn-primary:hover {
    background-color: var(--emerald-500);
    box-shadow: var(--shadow-glow);
    color: #fff;
}

.btn-danger {
    background-color: transparent;
    color: #fca5a5;
    border: 1px solid var(--danger-border);
}

.btn-danger:hover {
    background-color: var(--danger-hover);
    border-color: var(--danger);
    color: #fff;
}

button.btn-danger {
    background-color: var(--danger-hover);
    color: #fff;
    border: 1px solid var(--danger);
}

button.btn-danger:hover {
    background-color: var(--danger);
    box-shadow: 0 0 16px rgba(239,68,68,0.3);
}

.btn-ghost {
    background-color: transparent;
    color: var(--text-secondary);
    border: 1px solid var(--border-light);
}

.btn-ghost:hover {
    background-color: var(--bg-tertiary);
    border-color: var(--border-light);
    color: var(--text-primary);
}

.btn-sm {
    padding: 0.3rem 0.75rem;
    font-size: 0.8rem;
}

.btn-edit {
    color: var(--emerald-400);
    background-color: rgba(16,185,129,0.08);
    border: 1px solid rgba(16,185,129,0.2);
    border-radius: var(--radius-sm);
    padding: 0.25rem 0.65rem;
    font-size: 0.8rem;
    font-weight: 600;
    transition: background-color var(--transition), border-color var(--transition);
}

.btn-edit:hover {
    background-color: rgba(16,185,129,0.18);
    border-color: rgba(16,185,129,0.4);
    color: var(--emerald-300);
    text-decoration: none;
}

.btn-delete {
    color: #fca5a5;
    background-color: rgba(239,68,68,0.08);
    border: 1px solid rgba(239,68,68,0.2);
    border-radius: var(--radius-sm);
    padding: 0.25rem 0.65rem;
    font-size: 0.8rem;
    font-weight: 600;
    transition: background-color var(--transition), border-color var(--transition);
}

.btn-delete:hover {
    background-color: rgba(239,68,68,0.18);
    border-color: rgba(239,68,68,0.4);
    color: #fff;
    text-decoration: none;
}

.actions-cell {
    display: flex;
    gap: 0.4rem;
    align-items: center;
    flex-wrap: nowrap;
}

/* ===== Filter Tabs ===== */
.filter-bar {
    display: flex;
    align-items: center;
    gap: 0.4rem;
    margin-bottom: 1.25rem;
    flex-wrap: wrap;
}

.filter-label {
    font-size: 0.8rem;
    font-weight: 600;
    color: var(--text-muted);
    text-transform: uppercase;
    letter-spacing: 0.06em;
    margin-right: 0.25rem;
}

.filter-pill {
    display: inline-block;
    padding: 0.3rem 0.85rem;
    border-radius: var(--radius-pill);
    font-size: 0.82rem;
    font-weight: 600;
    color: var(--text-muted);
    border: 1px solid var(--border);
    background: var(--bg-card);
    transition: color var(--transition), border-color var(--transition), background-color var(--transition);
}

.filter-pill:hover {
    color: var(--emerald-400);
    border-color: rgba(16,185,129,0.4);
    background-color: rgba(16,185,129,0.06);
    text-decoration: none;
}

.filter-pill.active {
    background-color: rgba(16,185,129,0.14);
    color: var(--emerald-300);
    border-color: rgba(16,185,129,0.35);
}

/* ===== Detail View ===== */
.detail-card {
    background-color: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius-lg);
    padding: 2rem;
    box-shadow: var(--shadow-card);
    margin-bottom: 1.5rem;
}

.detail-grid {
    display: grid;
    grid-template-columns: 140px 1fr;
    gap: 0;
}

.detail-row {
    display: contents;
}

.detail-row .detail-label {
    padding: 0.65rem 0;
    font-size: 0.82rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.06em;
    color: var(--text-muted);
    border-bottom: 1px solid var(--border);
}

.detail-row .detail-value {
    padding: 0.65rem 0 0.65rem 1rem;
    color: var(--text-secondary);
    font-size: 0.95rem;
    border-bottom: 1px solid var(--border);
}

.detail-row:last-child .detail-label,
.detail-row:last-child .detail-value {
    border-bottom: none;
}

.detail-actions {
    display: flex;
    align-items: center;
    gap: 1rem;
    margin-bottom: 1.25rem;
}

/* ===== Book detail table override ===== */
.detail-card table {
    border: none;
    border-radius: 0;
    box-shadow: none;
    background: transparent;
    margin-bottom: 0;
}

.detail-card table th,
.detail-card table td {
    border-bottom: 1px solid var(--border);
}

.detail-card table th {
    font-size: 0.82rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.06em;
    color: var(--text-muted);
    background: transparent;
    width: 140px;
    padding-left: 0;
}

.detail-card table td {
    color: var(--text-secondary);
    padding-left: 1rem;
}

.detail-card table thead {
    display: none;
}

.detail-card table tbody tr:last-child td,
.detail-card table tbody tr:last-child th {
    border-bottom: none;
}

.detail-card table tbody tr:hover {
    background-color: transparent;
}

/* ===== Checkout / CTA area ===== */
.checkout-area {
    background-color: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius-lg);
    padding: 1.5rem;
    margin-bottom: 1.25rem;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 1rem;
}

.checkout-area p {
    margin: 0;
}

/* ===== Danger / Delete Confirmation ===== */
.danger-card {
    background-color: rgba(239,68,68,0.06);
    border: 1px solid var(--danger-border);
    border-radius: var(--radius-lg);
    padding: 2rem;
    max-width: 500px;
}

.danger-card p {
    color: #fca5a5;
    margin-bottom: 1.5rem;
}

/* ===== Empty states ===== */
.empty-state {
    text-align: center;
    padding: 3.5rem 1rem;
    color: var(--text-muted);
    border: 1px dashed var(--border);
    border-radius: var(--radius-lg);
    margin-bottom: 1.5rem;
}

.empty-state p {
    color: var(--text-muted);
    font-size: 0.95rem;
    margin: 0;
}

/* ===== Back / utility links ===== */
.back-link {
    display: inline-flex;
    align-items: center;
    gap: 0.35rem;
    font-size: 0.87rem;
    color: var(--text-muted);
    margin-bottom: 1.25rem;
    transition: color var(--transition);
}

.back-link::before {
    content: '←';
}

.back-link:hover {
    color: var(--emerald-400);
    text-decoration: none;
}

/* ===== Error Lists ===== */
.errors {
    background-color: rgba(239,68,68,0.1);
    color: #fca5a5;
    border: 1px solid rgba(239,68,68,0.3);
    border-radius: var(--radius-md);
    padding: 0.875rem 1.1rem;
    margin-bottom: 1rem;
    font-size: 0.9rem;
}

.errors ul {
    list-style: none;
}

/* ===== Error Pages (403, 404, 500) ===== */
.error-page {
    text-align: center;
    padding: 5rem 1rem;
}

.error-code {
    font-size: 5rem;
    font-weight: 900;
    letter-spacing: -0.04em;
    color: var(--emerald-700);
    line-height: 1;
    margin-bottom: 0.5rem;
    text-shadow: 0 0 40px rgba(16,185,129,0.2);
}

.error-page h1 {
    font-size: 1.4rem;
    color: var(--text-secondary);
    font-weight: 500;
    margin-bottom: 1.25rem;
}

.error-page p {
    margin-bottom: 2rem;
}

/* ===== Footer ===== */
footer {
    margin-top: auto;
    padding: 1.25rem 2rem;
    border-top: 1px solid var(--border);
    text-align: center;
    font-size: 0.8rem;
    color: var(--text-muted);
}

/* ===== Inline form (table actions) ===== */
form.inline-form {
    display: inline;
    margin: 0;
}

form.inline-form button[type="submit"] {
    padding: 0.25rem 0.65rem;
    font-size: 0.8rem;
    font-weight: 600;
    background-color: transparent;
    color: #fca5a5;
    border: 1px solid rgba(239,68,68,0.2);
    border-radius: var(--radius-sm);
}

form.inline-form button[type="submit"]:hover {
    background-color: var(--danger-hover);
    border-color: var(--danger);
    color: #fff;
    box-shadow: none;
}

/* ===== Add/Action button (above tables) ===== */
.action-btn {
    display: inline-flex;
    align-items: center;
    gap: 0.4rem;
    padding: 0.5rem 1.1rem;
    background-color: var(--emerald-700);
    color: #fff;
    border: 1px solid var(--emerald-600);
    border-radius: var(--radius-md);
    font-size: 0.88rem;
    font-weight: 600;
    transition: background-color var(--transition), box-shadow var(--transition);
    margin-bottom: 1.25rem;
}

.action-btn::before {
    content: '+';
    font-size: 1rem;
    font-weight: 700;
    line-height: 1;
}

.action-btn:hover {
    background-color: var(--emerald-500);
    box-shadow: var(--shadow-glow);
    color: #fff;
    text-decoration: none;
}

/* ===== Loan section title ===== */
.section-title {
    font-size: 0.78rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.08em;
    color: var(--text-muted);
    margin-top: 2rem;
    margin-bottom: 0.875rem;
    padding-bottom: 0.5rem;
    border-bottom: 1px solid var(--border);
}