/* ==========================================================================
   Library Management System - Main Stylesheet
   ========================================================================== */

/* --------------------------------------------------------------------------
   CSS Custom Properties (Design Tokens)
   -------------------------------------------------------------------------- */

:root {
    /* Typography */
    --font-family: 'Open Sans', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;

    /* Font Sizes */
    --text-xs: 0.75rem;
    --text-sm: 0.875rem;
    --text-base: 1rem;
    --text-lg: 1.125rem;
    --text-xl: 1.25rem;
    --text-2xl: 1.5rem;
    --text-3xl: 1.875rem;

    /* Spacing */
    --space-1: 0.25rem;
    --space-2: 0.5rem;
    --space-3: 0.75rem;
    --space-4: 1rem;
    --space-5: 1.25rem;
    --space-6: 1.5rem;
    --space-8: 2rem;

    /* Layout */
    --sidebar-width: 250px;
    --sidebar-collapsed-width: 70px;
    --header-height: 60px;
    --bottom-nav-height: 60px;

    /* Light Theme (Default) */
    --color-bg-primary: #ffffff;
    --color-bg-secondary: #f8f9fa;
    --color-bg-tertiary: #e9ecef;
    --color-bg-sidebar: #1a1a2e;

    --color-text-primary: #212529;
    --color-text-secondary: #6c757d;
    --color-text-muted: #adb5bd;
    --color-text-inverse: #ffffff;

    --color-border: #dee2e6;
    --color-border-light: #e9ecef;

    --color-accent: #0d6efd;
    --color-accent-hover: #0b5ed7;
    --color-accent-light: rgba(13, 110, 253, 0.1);

    --color-success: #198754;
    --color-success-light: rgba(25, 135, 84, 0.1);
    --color-warning: #ffc107;
    --color-warning-light: rgba(255, 193, 7, 0.1);
    --color-error: #dc3545;
    --color-error-light: rgba(220, 53, 69, 0.1);
    --color-info: #0dcaf0;
    --color-info-light: rgba(13, 202, 240, 0.1);

    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 15px rgba(0, 0, 0, 0.1);

    --radius-sm: 4px;
    --radius-md: 6px;
    --radius-lg: 8px;
    --radius-full: 9999px;

    --transition-fast: 0.15s ease;
    --transition-normal: 0.3s ease;
}

/* Dark Theme */
[data-theme="dark"] {
    --color-bg-primary: #1a1a2e;
    --color-bg-secondary: #16213e;
    --color-bg-tertiary: #0f3460;
    --color-bg-sidebar: #0d0d1a;

    --color-text-primary: #e9ecef;
    --color-text-secondary: #adb5bd;
    --color-text-muted: #6c757d;

    --color-border: #2d3748;
    --color-border-light: #1e2a3a;

    --color-accent: #4dabf7;
    --color-accent-hover: #74c0fc;
    --color-accent-light: rgba(77, 171, 247, 0.15);

    --color-success: #51cf66;
    --color-success-light: rgba(81, 207, 102, 0.15);
    --color-warning: #fcc419;
    --color-warning-light: rgba(252, 196, 25, 0.15);
    --color-error: #ff6b6b;
    --color-error-light: rgba(255, 107, 107, 0.15);
    --color-info: #22d3ee;
    --color-info-light: rgba(34, 211, 238, 0.15);

    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.4);
    --shadow-lg: 0 10px 15px rgba(0, 0, 0, 0.5);
}

/* --------------------------------------------------------------------------
   Base Styles
   -------------------------------------------------------------------------- */

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

html {
    font-size: 16px;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

body {
    font-family: var(--font-family);
    font-size: var(--text-base);
    line-height: 1.6;
    color: var(--color-text-primary);
    background: var(--color-bg-secondary);
}

a {
    color: var(--color-accent);
    text-decoration: none;
}

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

/* --------------------------------------------------------------------------
   App Container
   -------------------------------------------------------------------------- */

.app-container {
    display: flex;
    min-height: 100vh;
}

/* --------------------------------------------------------------------------
   Sidebar
   -------------------------------------------------------------------------- */

.sidebar {
    position: fixed;
    left: 0;
    top: 0;
    bottom: 0;
    width: var(--sidebar-width);
    background: var(--color-bg-sidebar);
    color: var(--color-text-inverse);
    display: flex;
    flex-direction: column;
    z-index: 100;
    transition: width var(--transition-normal), transform var(--transition-normal);
}

.sidebar.collapsed {
    width: var(--sidebar-collapsed-width);
}

.sidebar.collapsed .sidebar-title,
.sidebar.collapsed .nav-label {
    opacity: 0;
    width: 0;
    overflow: hidden;
}

.sidebar.collapsed .sidebar-header {
    justify-content: center;
}

.sidebar.collapsed .nav-item {
    justify-content: center;
    padding: var(--space-3);
}

.sidebar.collapsed .toggle-icon {
    transform: rotate(180deg);
}

.sidebar-header {
    display: flex;
    align-items: center;
    gap: var(--space-3);
    padding: var(--space-5);
    border-bottom: 1px solid rgba(255, 255, 255, 0.1);
}

.sidebar-logo {
    width: 40px;
    height: 40px;
    background: var(--color-accent);
    border-radius: var(--radius-md);
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 700;
    font-size: var(--text-sm);
    flex-shrink: 0;
}

.sidebar-title {
    font-size: var(--text-lg);
    font-weight: 600;
    white-space: nowrap;
    transition: opacity var(--transition-normal);
}

.sidebar-nav {
    flex: 1;
    padding: var(--space-4) 0;
    overflow-y: auto;
}

.nav-item {
    display: flex;
    align-items: center;
    gap: var(--space-3);
    padding: var(--space-3) var(--space-5);
    color: rgba(255, 255, 255, 0.7);
    transition: all var(--transition-fast);
    border-left: 3px solid transparent;
}

.nav-item:hover {
    background: rgba(255, 255, 255, 0.05);
    color: var(--color-text-inverse);
}

.nav-item.active {
    background: rgba(255, 255, 255, 0.1);
    color: var(--color-text-inverse);
    border-left-color: var(--color-accent);
}

.nav-item.disabled {
    opacity: 0.4;
    cursor: not-allowed;
    pointer-events: none;
}

.nav-icon {
    font-size: var(--text-xl);
    width: 24px;
    text-align: center;
    flex-shrink: 0;
}

.nav-label {
    white-space: nowrap;
    transition: opacity var(--transition-normal);
}

/* Navigation Groups */
.nav-group {
    margin-top: var(--space-3);
    padding-top: var(--space-2);
    border-top: 1px solid rgba(255, 255, 255, 0.1);
}

.nav-group-label {
    display: block;
    padding: var(--space-2) var(--space-5);
    font-size: var(--text-xs);
    text-transform: uppercase;
    letter-spacing: 0.05em;
    color: rgba(255, 255, 255, 0.4);
}

.sidebar.collapsed .nav-group-label {
    display: none;
}

.nav-group .nav-item {
    padding-left: var(--space-6);
}

.sidebar.collapsed .nav-group .nav-item {
    padding-left: var(--space-5);
}

.sidebar-footer {
    padding: var(--space-4);
    border-top: 1px solid rgba(255, 255, 255, 0.1);
}

.sidebar-toggle {
    width: 100%;
    padding: var(--space-2);
    background: rgba(255, 255, 255, 0.1);
    border: none;
    border-radius: var(--radius-md);
    color: var(--color-text-inverse);
    cursor: pointer;
    transition: background var(--transition-fast);
}

.sidebar-toggle:hover {
    background: rgba(255, 255, 255, 0.2);
}

.toggle-icon {
    display: inline-block;
    transition: transform var(--transition-normal);
}

/* --------------------------------------------------------------------------
   Main Wrapper
   -------------------------------------------------------------------------- */

.main-wrapper {
    flex: 1;
    margin-left: var(--sidebar-width);
    display: flex;
    flex-direction: column;
    min-height: 100vh;
    transition: margin-left var(--transition-normal);
}

.sidebar.collapsed ~ .main-wrapper {
    margin-left: var(--sidebar-collapsed-width);
}

/* --------------------------------------------------------------------------
   Top Header
   -------------------------------------------------------------------------- */

.top-header {
    position: sticky;
    top: 0;
    height: var(--header-height);
    background: var(--color-bg-primary);
    border-bottom: 1px solid var(--color-border);
    display: flex;
    align-items: center;
    padding: 0 var(--space-6);
    gap: var(--space-4);
    z-index: 50;
}

.mobile-menu-btn {
    display: none;
    background: none;
    border: none;
    font-size: var(--text-xl);
    color: var(--color-text-primary);
    cursor: pointer;
    padding: var(--space-2);
}

.header-search {
    flex: 1;
    max-width: 400px;
}

.search-form {
    display: flex;
    align-items: center;
    background: var(--color-bg-secondary);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-full);
    overflow: hidden;
}

.search-input {
    flex: 1;
    border: none;
    background: transparent;
    padding: var(--space-2) var(--space-4);
    font-family: var(--font-family);
    font-size: var(--text-sm);
    color: var(--color-text-primary);
    outline: none;
}

.search-input::placeholder {
    color: var(--color-text-muted);
}

.search-btn {
    background: none;
    border: none;
    padding: var(--space-2) var(--space-3);
    cursor: pointer;
    color: var(--color-text-secondary);
}

.header-actions {
    display: flex;
    align-items: center;
    gap: var(--space-3);
}

/* Theme Toggle */
.theme-toggle {
    background: var(--color-bg-secondary);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-full);
    width: 40px;
    height: 40px;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: var(--text-lg);
    transition: background var(--transition-fast);
}

.theme-toggle:hover {
    background: var(--color-bg-tertiary);
}

.theme-icon-dark {
    display: none;
}

[data-theme="dark"] .theme-icon-light {
    display: none;
}

[data-theme="dark"] .theme-icon-dark {
    display: inline;
}

/* User Menu */
.user-menu {
    position: relative;
}

.user-btn {
    display: flex;
    align-items: center;
    gap: var(--space-2);
    background: none;
    border: none;
    cursor: pointer;
    padding: var(--space-1);
}

.user-avatar {
    width: 36px;
    height: 36px;
    background: var(--color-accent);
    color: white;
    border-radius: var(--radius-full);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: var(--text-sm);
    font-weight: 600;
}

.user-name {
    color: var(--color-text-primary);
    font-weight: 500;
}

.user-dropdown {
    position: absolute;
    top: 100%;
    right: 0;
    margin-top: var(--space-2);
    background: var(--color-bg-primary);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-lg);
    min-width: 200px;
    opacity: 0;
    visibility: hidden;
    transform: translateY(-10px);
    transition: all var(--transition-fast);
    z-index: 200;
}

.user-dropdown.show {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}

.dropdown-header {
    padding: var(--space-3) var(--space-4);
    border-bottom: 1px solid var(--color-border);
    display: flex;
    flex-direction: column;
    gap: var(--space-1);
}

.dropdown-header strong {
    font-size: var(--text-sm);
}

.dropdown-item {
    display: block;
    padding: var(--space-2) var(--space-4);
    color: var(--color-text-primary);
    font-size: var(--text-sm);
    transition: background var(--transition-fast);
}

.dropdown-item:hover {
    background: var(--color-bg-secondary);
    color: var(--color-text-primary);
}

.dropdown-item-danger {
    color: var(--color-error);
}

.dropdown-item-danger:hover {
    background: var(--color-error-light);
    color: var(--color-error);
}

.dropdown-divider {
    border: none;
    border-top: 1px solid var(--color-border);
    margin: var(--space-1) 0;
}

/* Role Badge */
.role-badge {
    display: inline-block;
    padding: 2px var(--space-2);
    border-radius: var(--radius-full);
    font-size: var(--text-xs);
    font-weight: 600;
    text-transform: uppercase;
}

.role-admin {
    background: var(--color-error-light);
    color: var(--color-error);
}

.role-staff {
    background: var(--color-accent-light);
    color: var(--color-accent);
}

.role-patron {
    background: var(--color-success-light);
    color: var(--color-success);
}

/* --------------------------------------------------------------------------
   Main Content
   -------------------------------------------------------------------------- */

.main-content {
    flex: 1;
    padding: var(--space-6);
}

/* --------------------------------------------------------------------------
   Messages
   -------------------------------------------------------------------------- */

.messages {
    margin-bottom: var(--space-4);
}

.message {
    padding: var(--space-3) var(--space-4);
    border-radius: var(--radius-md);
    margin-bottom: var(--space-2);
    display: flex;
    justify-content: space-between;
    align-items: center;
    font-size: var(--text-sm);
}

.message-success {
    background: var(--color-success-light);
    color: var(--color-success);
    border: 1px solid var(--color-success);
}

.message-info {
    background: var(--color-info-light);
    color: var(--color-info);
    border: 1px solid var(--color-info);
}

.message-warning {
    background: var(--color-warning-light);
    color: var(--color-warning);
    border: 1px solid var(--color-warning);
}

.message-error {
    background: var(--color-error-light);
    color: var(--color-error);
    border: 1px solid var(--color-error);
}

.message-close {
    background: none;
    border: none;
    font-size: var(--text-lg);
    cursor: pointer;
    opacity: 0.7;
    color: inherit;
}

.message-close:hover {
    opacity: 1;
}

/* --------------------------------------------------------------------------
   Bottom Navigation (Mobile)
   -------------------------------------------------------------------------- */

.bottom-nav {
    display: none;
    position: fixed;
    bottom: 0;
    left: 0;
    right: 0;
    height: var(--bottom-nav-height);
    background: var(--color-bg-primary);
    border-top: 1px solid var(--color-border);
    z-index: 100;
}

.bottom-nav-item {
    flex: 1;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 2px;
    color: var(--color-text-secondary);
    font-size: var(--text-xs);
    transition: color var(--transition-fast);
}

.bottom-nav-item:hover,
.bottom-nav-item.active {
    color: var(--color-accent);
}

.bottom-nav-item.disabled {
    opacity: 0.4;
    pointer-events: none;
}

.bottom-nav-icon {
    font-size: var(--text-xl);
}

.bottom-nav-label {
    font-weight: 500;
}

/* Sidebar Overlay (Mobile) */
.sidebar-overlay {
    display: none;
    position: fixed;
    inset: 0;
    background: rgba(0, 0, 0, 0.5);
    z-index: 99;
    opacity: 0;
    transition: opacity var(--transition-normal);
}

.sidebar-overlay.show {
    opacity: 1;
}

/* --------------------------------------------------------------------------
   Responsive Styles
   -------------------------------------------------------------------------- */

@media (max-width: 1024px) {
    .sidebar {
        transform: translateX(-100%);
    }

    .sidebar.mobile-open {
        transform: translateX(0);
    }

    .sidebar-overlay {
        display: block;
    }

    .main-wrapper {
        margin-left: 0;
    }

    .sidebar.collapsed ~ .main-wrapper {
        margin-left: 0;
    }

    .mobile-menu-btn {
        display: block;
    }

    .sidebar-toggle {
        display: none;
    }
}

@media (max-width: 768px) {
    .bottom-nav {
        display: flex;
    }

    .main-content {
        padding-bottom: calc(var(--bottom-nav-height) + var(--space-6));
    }

    .user-name {
        display: none;
    }

    .header-search {
        display: none;
    }
}

/* --------------------------------------------------------------------------
   Utility Classes
   -------------------------------------------------------------------------- */

.text-center { text-align: center; }
.text-right { text-align: right; }
.text-muted { color: var(--color-text-muted); }
.text-success { color: var(--color-success); }
.text-error { color: var(--color-error); }
.text-warning { color: var(--color-warning); }

.mt-1 { margin-top: var(--space-1); }
.mt-2 { margin-top: var(--space-2); }
.mt-4 { margin-top: var(--space-4); }
.mt-6 { margin-top: var(--space-6); }
.mb-1 { margin-bottom: var(--space-1); }
.mb-2 { margin-bottom: var(--space-2); }
.mb-4 { margin-bottom: var(--space-4); }
.mb-6 { margin-bottom: var(--space-6); }

/* --------------------------------------------------------------------------
   Components
   -------------------------------------------------------------------------- */

/* Page Header */
.page-header {
    margin-bottom: var(--space-6);
}

.page-header h1 {
    font-size: var(--text-2xl);
    font-weight: 600;
    margin-bottom: var(--space-1);
}

.page-header p {
    color: var(--color-text-secondary);
}

.page-header-actions {
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: var(--space-4);
}

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

.card-header {
    padding: var(--space-4);
    border-bottom: 1px solid var(--color-border);
    font-weight: 600;
}

.card-body {
    padding: var(--space-4);
}

.card-footer {
    padding: var(--space-4);
    border-top: 1px solid var(--color-border);
    background: var(--color-bg-secondary);
}

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--space-2);
    padding: var(--space-2) var(--space-4);
    font-family: var(--font-family);
    font-size: var(--text-sm);
    font-weight: 600;
    border: none;
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: all var(--transition-fast);
    text-decoration: none;
}

.btn-primary {
    background: var(--color-accent);
    color: white;
}

.btn-primary:hover {
    background: var(--color-accent-hover);
    color: white;
}

.btn-secondary {
    background: var(--color-bg-secondary);
    color: var(--color-text-primary);
    border: 1px solid var(--color-border);
}

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

.btn-success {
    background: var(--color-success);
    color: white;
}

.btn-success:hover {
    filter: brightness(1.1);
    color: white;
}

.btn-danger {
    background: var(--color-error);
    color: white;
}

.btn-danger:hover {
    filter: brightness(1.1);
    color: white;
}

.btn-sm {
    padding: var(--space-1) var(--space-3);
    font-size: var(--text-xs);
}

.btn-lg {
    padding: var(--space-3) var(--space-6);
    font-size: var(--text-base);
}

/* Forms */
.form-group {
    margin-bottom: var(--space-4);
}

.form-label {
    display: block;
    margin-bottom: var(--space-1);
    font-size: var(--text-sm);
    font-weight: 500;
    color: var(--color-text-primary);
}

.form-input {
    width: 100%;
    padding: var(--space-2) var(--space-3);
    font-family: var(--font-family);
    font-size: var(--text-base);
    color: var(--color-text-primary);
    background: var(--color-bg-primary);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    transition: border-color var(--transition-fast), box-shadow var(--transition-fast);
}

.form-input:focus {
    outline: none;
    border-color: var(--color-accent);
    box-shadow: 0 0 0 3px var(--color-accent-light);
}

.form-input::placeholder {
    color: var(--color-text-muted);
}

.form-input:disabled {
    background: var(--color-bg-secondary);
    cursor: not-allowed;
}

.form-select {
    appearance: none;
    background-image: url("data:image/svg+xml,%3csvg xmlns='http://www.w3.org/2000/svg' fill='none' viewBox='0 0 20 20'%3e%3cpath stroke='%236b7280' stroke-linecap='round' stroke-linejoin='round' stroke-width='1.5' d='M6 8l4 4 4-4'/%3e%3c/svg%3e");
    background-position: right var(--space-2) center;
    background-repeat: no-repeat;
    background-size: 1.5em 1.5em;
    padding-right: var(--space-8);
}

.form-textarea {
    min-height: 100px;
    resize: vertical;
}

.form-help {
    margin-top: var(--space-1);
    font-size: var(--text-xs);
    color: var(--color-text-muted);
}

.form-error {
    margin-top: var(--space-1);
    font-size: var(--text-xs);
    color: var(--color-error);
}

.form-row {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: var(--space-4);
}

/* Tables */
.table-container {
    overflow-x: auto;
}

.table {
    width: 100%;
    border-collapse: collapse;
    font-size: var(--text-sm);
}

.table th,
.table td {
    padding: var(--space-3) var(--space-4);
    text-align: left;
    border-bottom: 1px solid var(--color-border);
}

.table th {
    background: var(--color-bg-secondary);
    font-weight: 600;
    color: var(--color-text-secondary);
    text-transform: uppercase;
    font-size: var(--text-xs);
    letter-spacing: 0.05em;
}

.table tr:hover {
    background: var(--color-bg-secondary);
}

.table-actions {
    display: flex;
    gap: var(--space-2);
}

/* Badge */
.badge {
    display: inline-block;
    padding: 2px var(--space-2);
    font-size: var(--text-xs);
    font-weight: 600;
    border-radius: var(--radius-full);
    text-transform: uppercase;
}

.badge-success {
    background: var(--color-success-light);
    color: var(--color-success);
}

.badge-warning {
    background: var(--color-warning-light);
    color: var(--color-warning);
}

.badge-error {
    background: var(--color-error-light);
    color: var(--color-error);
}

.badge-info {
    background: var(--color-info-light);
    color: var(--color-info);
}

/* Empty State */
.empty-state {
    text-align: center;
    padding: var(--space-8);
    color: var(--color-text-muted);
}

.empty-state-icon {
    font-size: 3rem;
    margin-bottom: var(--space-4);
    opacity: 0.5;
}

.empty-state h3 {
    font-size: var(--text-lg);
    margin-bottom: var(--space-2);
    color: var(--color-text-primary);
}

/* Grid */
.grid {
    display: grid;
    gap: var(--space-4);
}

.grid-2 { grid-template-columns: repeat(2, 1fr); }
.grid-3 { grid-template-columns: repeat(3, 1fr); }
.grid-4 { grid-template-columns: repeat(4, 1fr); }

@media (max-width: 1024px) {
    .grid-4 { grid-template-columns: repeat(2, 1fr); }
    .grid-3 { grid-template-columns: repeat(2, 1fr); }
}

@media (max-width: 640px) {
    .grid-4,
    .grid-3,
    .grid-2 { grid-template-columns: 1fr; }
}

/* Book Card */
.book-card {
    background: var(--color-bg-primary);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    overflow: hidden;
    transition: box-shadow var(--transition-fast);
}

.book-card:hover {
    box-shadow: var(--shadow-md);
}

.book-card-cover {
    aspect-ratio: 2/3;
    background: var(--color-bg-tertiary);
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--color-text-muted);
    font-size: 3rem;
}

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

.book-card-body {
    padding: var(--space-4);
}

.book-card-title {
    font-size: var(--text-base);
    font-weight: 600;
    margin-bottom: var(--space-1);
    display: -webkit-box;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

.book-card-author {
    font-size: var(--text-sm);
    color: var(--color-text-secondary);
    margin-bottom: var(--space-2);
}

.book-card-meta {
    display: flex;
    justify-content: space-between;
    align-items: center;
    font-size: var(--text-xs);
    color: var(--color-text-muted);
}