/**
 * Linkchanger - Hauptstylesheet
 * 
 * Responsive CSS Framework für das Backend.
 * Mobile-First Approach mit Breakpoints:
 * - Mobile: < 768px
 * - Tablet: 768px - 1024px
 * - Desktop: > 1024px
 * 
 * @version 1.0.0
 */

/* ============================================
   CSS VARIABLES (Design Tokens)
   ============================================ */
:root {
    /* Farben */
    --color-primary: #4f46e5;
    --color-primary-dark: #4338ca;
    --color-primary-light: #818cf8;
    
    --color-success: #10b981;
    --color-warning: #f59e0b;
    --color-danger: #ef4444;
    --color-info: #3b82f6;
    
    --color-gray-50: #f9fafb;
    --color-gray-100: #f3f4f6;
    --color-gray-200: #e5e7eb;
    --color-gray-300: #d1d5db;
    --color-gray-400: #9ca3af;
    --color-gray-500: #6b7280;
    --color-gray-600: #4b5563;
    --color-gray-700: #374151;
    --color-gray-800: #1f2937;
    --color-gray-900: #111827;
    
    /* Typografie */
    --font-sans: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    --font-mono: 'SF Mono', Monaco, 'Cascadia Code', 'Consolas', monospace;
    
    /* Spacing */
    --spacing-xs: 0.25rem;
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --spacing-2xl: 3rem;
    
    /* Border Radius */
    --radius-sm: 0.25rem;
    --radius-md: 0.375rem;
    --radius-lg: 0.5rem;
    --radius-xl: 0.75rem;
    --radius-full: 9999px;
    
    /* Shadows */
    --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
    --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1);
    --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1);
    
    /* Transitions */
    --transition-fast: 150ms ease;
    --transition-normal: 250ms ease;
}

/* ============================================
   RESET & BASE
   ============================================ */
*, *::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-sans);
    font-size: 1rem;
    line-height: 1.5;
    color: var(--color-gray-800);
    background-color: var(--color-gray-100);
    min-height: 100vh;
}

a {
    color: var(--color-primary);
    text-decoration: none;
    transition: color var(--transition-fast);
}

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

img {
    max-width: 100%;
    height: auto;
}

/* ============================================
   LAYOUT
   ============================================ */
.app-container {
    display: flex;
    min-height: 100vh;
}

/* Sidebar */
.sidebar {
    width: 260px;
    background: var(--color-gray-800);
    color: white;
    position: fixed;
    height: 100vh;
    overflow-y: auto;
    transition: transform var(--transition-normal);
    z-index: 100;
}

.sidebar-header {
    padding: var(--spacing-lg);
    border-bottom: 1px solid var(--color-gray-700);
}

.sidebar-logo {
    font-size: 1.5rem;
    font-weight: 700;
    color: white;
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
}

.sidebar-nav {
    padding: var(--spacing-md) 0;
}

.nav-item {
    display: block;
    padding: var(--spacing-sm) var(--spacing-lg);
    color: var(--color-gray-300);
    transition: all var(--transition-fast);
    border-left: 3px solid transparent;
}

.nav-item:hover,
.nav-item.active {
    background: var(--color-gray-700);
    color: white;
    border-left-color: var(--color-primary);
}

.nav-item svg {
    width: 20px;
    height: 20px;
    margin-right: var(--spacing-sm);
    vertical-align: middle;
}

/* Main Content */
.main-content {
    flex: 1;
    margin-left: 260px;
    min-height: 100vh;
}

.topbar {
    background: white;
    padding: var(--spacing-md) var(--spacing-xl);
    display: flex;
    justify-content: space-between;
    align-items: center;
    border-bottom: 1px solid var(--color-gray-200);
    position: sticky;
    top: 0;
    z-index: 50;
}

.topbar-title {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--color-gray-800);
}

.topbar-actions {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
}

.content-area {
    padding: var(--spacing-xl);
}

/* Mobile Menu Toggle */
.mobile-menu-toggle {
    display: none;
    background: none;
    border: none;
    color: var(--color-gray-600);
    cursor: pointer;
    padding: var(--spacing-sm);
}

/* ============================================
   CARDS
   ============================================ */
.card {
    background: white;
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-sm);
    overflow: hidden;
}

.card-header {
    padding: var(--spacing-lg);
    border-bottom: 1px solid var(--color-gray-200);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.card-title {
    font-size: 1.125rem;
    font-weight: 600;
    color: var(--color-gray-800);
}

.card-body {
    padding: var(--spacing-lg);
}

/* ============================================
   STATS CARDS
   ============================================ */
.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: var(--spacing-lg);
    margin-bottom: var(--spacing-xl);
}

.stat-card {
    background: white;
    border-radius: var(--radius-lg);
    padding: var(--spacing-lg);
    box-shadow: var(--shadow-sm);
}

.stat-card-icon {
    width: 48px;
    height: 48px;
    border-radius: var(--radius-lg);
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: var(--spacing-md);
}

.stat-card-icon.primary { background: rgba(79, 70, 229, 0.1); color: var(--color-primary); }
.stat-card-icon.success { background: rgba(16, 185, 129, 0.1); color: var(--color-success); }
.stat-card-icon.warning { background: rgba(245, 158, 11, 0.1); color: var(--color-warning); }
.stat-card-icon.info { background: rgba(59, 130, 246, 0.1); color: var(--color-info); }

.stat-card-value {
    font-size: 2rem;
    font-weight: 700;
    color: var(--color-gray-800);
    line-height: 1;
}

.stat-card-label {
    color: var(--color-gray-500);
    font-size: 0.875rem;
    margin-top: var(--spacing-xs);
}

/* ============================================
   BUTTONS
   ============================================ */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-sm) var(--spacing-lg);
    font-size: 0.875rem;
    font-weight: 500;
    border-radius: var(--radius-md);
    border: 1px solid transparent;
    cursor: pointer;
    transition: all var(--transition-fast);
    text-decoration: none;
    white-space: nowrap;
}

.btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

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

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

.btn-secondary {
    background: var(--color-gray-100);
    color: var(--color-gray-700);
    border-color: var(--color-gray-300);
}

.btn-secondary:hover {
    background: var(--color-gray-200);
    color: var(--color-gray-700);
}

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

.btn-danger:hover {
    background: #dc2626;
    color: white;
}

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

.btn-sm {
    padding: var(--spacing-xs) var(--spacing-sm);
    font-size: 0.75rem;
}

.btn-lg {
    padding: var(--spacing-md) var(--spacing-xl);
    font-size: 1rem;
}

.btn-block {
    width: 100%;
}

/* ============================================
   FORMS
   ============================================ */
.form-group {
    margin-bottom: var(--spacing-lg);
}

.form-label {
    display: block;
    font-size: 0.875rem;
    font-weight: 500;
    color: var(--color-gray-700);
    margin-bottom: var(--spacing-sm);
}

.form-control {
    width: 100%;
    padding: var(--spacing-sm) var(--spacing-md);
    font-size: 1rem;
    border: 1px solid var(--color-gray-300);
    border-radius: var(--radius-md);
    background: white;
    transition: border-color var(--transition-fast), box-shadow var(--transition-fast);
}

.form-control:focus {
    outline: none;
    border-color: var(--color-primary);
    box-shadow: 0 0 0 3px rgba(79, 70, 229, 0.1);
}

.form-control::placeholder {
    color: var(--color-gray-400);
}

.form-hint {
    font-size: 0.75rem;
    color: var(--color-gray-500);
    margin-top: var(--spacing-xs);
}

.form-checkbox {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
}

.form-checkbox input[type="checkbox"] {
    width: 1rem;
    height: 1rem;
    accent-color: var(--color-primary);
}

/* ============================================
   ALERTS
   ============================================ */
.alert {
    padding: var(--spacing-md) var(--spacing-lg);
    border-radius: var(--radius-md);
    margin-bottom: var(--spacing-lg);
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
}

.alert-success {
    background: rgba(16, 185, 129, 0.1);
    color: #065f46;
    border: 1px solid rgba(16, 185, 129, 0.2);
}

.alert-error {
    background: rgba(239, 68, 68, 0.1);
    color: #991b1b;
    border: 1px solid rgba(239, 68, 68, 0.2);
}

.alert-warning {
    background: rgba(245, 158, 11, 0.1);
    color: #92400e;
    border: 1px solid rgba(245, 158, 11, 0.2);
}

.alert-info {
    background: rgba(59, 130, 246, 0.1);
    color: #1e40af;
    border: 1px solid rgba(59, 130, 246, 0.2);
}

/* ============================================
   TABLES
   ============================================ */
.table-responsive {
    overflow-x: auto;
    -webkit-overflow-scrolling: touch;
}

.table {
    width: 100%;
    border-collapse: collapse;
}

.table th,
.table td {
    padding: var(--spacing-md);
    text-align: left;
    border-bottom: 1px solid var(--color-gray-200);
}

.table th {
    font-weight: 600;
    color: var(--color-gray-600);
    font-size: 0.75rem;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    background: var(--color-gray-50);
}

.table tbody tr:hover {
    background: var(--color-gray-50);
}

.table-actions {
    display: flex;
    gap: var(--spacing-sm);
}

/* ============================================
   LINKS TABLE SPECIFIC
   ============================================ */
.link-url {
    font-family: var(--font-mono);
    font-size: 0.875rem;
    color: var(--color-gray-600);
    max-width: 300px;
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
}

.link-short {
    font-family: var(--font-mono);
    font-size: 0.875rem;
    color: var(--color-primary);
    font-weight: 500;
}

.link-title {
    font-weight: 500;
    color: var(--color-gray-800);
}

.link-clicks {
    font-weight: 600;
    color: var(--color-gray-600);
}

/* Status Badge */
.badge {
    display: inline-flex;
    align-items: center;
    padding: var(--spacing-xs) var(--spacing-sm);
    font-size: 0.75rem;
    font-weight: 500;
    border-radius: var(--radius-full);
}

.badge-success {
    background: rgba(16, 185, 129, 0.1);
    color: var(--color-success);
}

.badge-danger {
    background: rgba(239, 68, 68, 0.1);
    color: var(--color-danger);
}

.badge-warning {
    background: rgba(245, 158, 11, 0.1);
    color: var(--color-warning);
}

/* ============================================
   PAGINATION
   ============================================ */
.pagination {
    display: flex;
    gap: var(--spacing-xs);
    justify-content: center;
    margin-top: var(--spacing-lg);
}

.pagination-item {
    padding: var(--spacing-sm) var(--spacing-md);
    border: 1px solid var(--color-gray-300);
    border-radius: var(--radius-md);
    color: var(--color-gray-600);
    font-size: 0.875rem;
    transition: all var(--transition-fast);
}

.pagination-item:hover {
    background: var(--color-gray-100);
    color: var(--color-gray-800);
}

.pagination-item.active {
    background: var(--color-primary);
    border-color: var(--color-primary);
    color: white;
}

.pagination-item.disabled {
    opacity: 0.5;
    pointer-events: none;
}

/* ============================================
   PROGRESS BAR
   ============================================ */
.progress {
    height: 8px;
    background: var(--color-gray-200);
    border-radius: var(--radius-full);
    overflow: hidden;
}

.progress-bar {
    height: 100%;
    background: var(--color-primary);
    border-radius: var(--radius-full);
    transition: width var(--transition-normal);
}

.progress-bar.warning {
    background: var(--color-warning);
}

.progress-bar.danger {
    background: var(--color-danger);
}

/* ============================================
   EMPTY STATE
   ============================================ */
.empty-state {
    text-align: center;
    padding: var(--spacing-2xl);
    color: var(--color-gray-500);
}

.empty-state-icon {
    width: 64px;
    height: 64px;
    margin: 0 auto var(--spacing-lg);
    color: var(--color-gray-300);
}

.empty-state-title {
    font-size: 1.125rem;
    font-weight: 600;
    color: var(--color-gray-700);
    margin-bottom: var(--spacing-sm);
}

/* ============================================
   AUTH PAGES (Login, Register)
   ============================================ */
.auth-container {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: var(--spacing-lg);
    background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-primary-dark) 100%);
}

.auth-card {
    width: 100%;
    max-width: 420px;
    background: white;
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-lg);
    padding: var(--spacing-xl);
}

.auth-logo {
    text-align: center;
    margin-bottom: var(--spacing-xl);
}

.auth-logo h1 {
    font-size: 1.75rem;
    font-weight: 700;
    color: var(--color-gray-800);
}

.auth-title {
    font-size: 1.5rem;
    font-weight: 600;
    color: var(--color-gray-800);
    margin-bottom: var(--spacing-lg);
    text-align: center;
}

.auth-footer {
    text-align: center;
    margin-top: var(--spacing-lg);
    color: var(--color-gray-500);
    font-size: 0.875rem;
}

/* ============================================
   COPY TO CLIPBOARD
   ============================================ */
.copy-btn {
    background: none;
    border: none;
    color: var(--color-gray-400);
    cursor: pointer;
    padding: var(--spacing-xs);
    border-radius: var(--radius-sm);
    transition: all var(--transition-fast);
}

.copy-btn:hover {
    color: var(--color-primary);
    background: var(--color-gray-100);
}

.copy-btn.copied {
    color: var(--color-success);
}

/* ============================================
   TOGGLE SWITCH
   ============================================ */
.toggle {
    position: relative;
    display: inline-block;
    width: 44px;
    height: 24px;
}

.toggle input {
    opacity: 0;
    width: 0;
    height: 0;
}

.toggle-slider {
    position: absolute;
    cursor: pointer;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-color: var(--color-gray-300);
    transition: var(--transition-fast);
    border-radius: var(--radius-full);
}

.toggle-slider:before {
    position: absolute;
    content: "";
    height: 18px;
    width: 18px;
    left: 3px;
    bottom: 3px;
    background-color: white;
    transition: var(--transition-fast);
    border-radius: 50%;
}

.toggle input:checked + .toggle-slider {
    background-color: var(--color-primary);
}

.toggle input:checked + .toggle-slider:before {
    transform: translateX(20px);
}

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

/* Tablet & Mobile */
@media (max-width: 1024px) {
    .sidebar {
        transform: translateX(-100%);
    }
    
    .sidebar.open {
        transform: translateX(0);
    }
    
    .main-content {
        margin-left: 0;
    }
    
    .mobile-menu-toggle {
        display: block;
    }
    
    /* Overlay for mobile menu */
    .sidebar-overlay {
        display: none;
        position: fixed;
        top: 0;
        left: 0;
        right: 0;
        bottom: 0;
        background: rgba(0, 0, 0, 0.5);
        z-index: 99;
    }
    
    .sidebar-overlay.show {
        display: block;
    }
}

/* Mobile Only */
@media (max-width: 768px) {
    .content-area {
        padding: var(--spacing-md);
    }
    
    .stats-grid {
        grid-template-columns: 1fr;
    }
    
    .card-header {
        flex-direction: column;
        align-items: flex-start;
        gap: var(--spacing-md);
    }
    
    .table th,
    .table td {
        padding: var(--spacing-sm);
        font-size: 0.875rem;
    }
    
    /* Hide less important columns on mobile */
    .table .hide-mobile {
        display: none;
    }
    
    .topbar {
        padding: var(--spacing-md);
    }
    
    .topbar-title {
        font-size: 1rem;
    }
    
    .btn {
        padding: var(--spacing-sm) var(--spacing-md);
    }
    
    .auth-card {
        padding: var(--spacing-lg);
    }
}

/* ============================================
   UTILITIES
   ============================================ */
.text-center { text-align: center; }
.text-right { text-align: right; }
.text-muted { color: var(--color-gray-500); }
.text-small { font-size: 0.875rem; }

.mb-0 { margin-bottom: 0; }
.mb-1 { margin-bottom: var(--spacing-sm); }
.mb-2 { margin-bottom: var(--spacing-md); }
.mb-3 { margin-bottom: var(--spacing-lg); }
.mb-4 { margin-bottom: var(--spacing-xl); }

.mt-0 { margin-top: 0; }
.mt-1 { margin-top: var(--spacing-sm); }
.mt-2 { margin-top: var(--spacing-md); }
.mt-3 { margin-top: var(--spacing-lg); }

.d-flex { display: flex; }
.align-center { align-items: center; }
.justify-between { justify-content: space-between; }
.gap-1 { gap: var(--spacing-sm); }
.gap-2 { gap: var(--spacing-md); }

.visually-hidden {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    border: 0;
}