/* ============================================
   FAKTURISANJE - MODERN DARK UI
   Color Palette: Dark BG, Green, Dark Blue, Cream
   ============================================ */

:root {
    /* Colors */
    --bg-dark: #0f1419;
    --bg-card: #1a1f2e;
    --bg-card-hover: #242938;
    
    --accent-green: #10b981;
    --accent-green-dark: #059669;
    --accent-blue: #0ea5e9;
    --accent-blue-dark: #0284c7;
    
    --cream: #faf8f3;
    --cream-dark: #e8e4db;
    
    --text-primary: #f9fafb;
    --text-secondary: #9ca3af;
    --text-muted: #6b7280;
    
    --border: #374151;
    --border-light: #4b5563;
    
    /* Spacing */
    --spacing-xs: 0.5rem;
    --spacing-sm: 0.75rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --spacing-2xl: 3rem;
    
    /* Border radius */
    --radius-sm: 0.375rem;
    --radius-md: 0.5rem;
    --radius-lg: 0.75rem;
    --radius-xl: 1rem;
    
    /* Shadows */
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.4);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.5);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.6);
    
    /* Transitions */
    --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

/* ============================================
   RESET & BASE
   ============================================ */

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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    background: var(--bg-dark);
    color: var(--text-primary);
    line-height: 1.6;
    font-size: 16px;
    font-weight: 400;
    min-height: 100vh;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

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

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

/* ============================================
   HEADER / NAVBAR
   ============================================ */

header {
    background: var(--bg-card);
    border-bottom: 2px solid var(--border);
    padding: var(--spacing-lg) var(--spacing-xl);
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: var(--spacing-lg);
    flex-wrap: wrap;
    position: sticky;
    top: 0;
    z-index: 1000;
    box-shadow: var(--shadow-md);
}

.brand {
    font-weight: 600;
    font-size: 1.5rem;
    background: linear-gradient(135deg, var(--accent-green), var(--accent-blue));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    letter-spacing: -0.5px;
}

.brand a {
    background: linear-gradient(135deg, var(--accent-green), var(--accent-blue));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

nav {
    display: flex;
    gap: var(--spacing-lg);
    align-items: center;
}

nav a {
    color: var(--text-secondary);
    font-weight: 400;
    padding: var(--spacing-sm) var(--spacing-md);
    border-radius: var(--radius-md);
    transition: var(--transition);
    position: relative;
}

nav a:hover {
    color: var(--text-primary);
    background: var(--bg-card-hover);
}

nav a::after {
    content: '';
    position: absolute;
    bottom: -2px;
    left: 50%;
    width: 0;
    height: 2px;
    background: linear-gradient(90deg, var(--accent-green), var(--accent-blue));
    transition: var(--transition);
    transform: translateX(-50%);
}

nav a:hover::after {
    width: 80%;
}

.logout-form {
    margin: 0;
}

.logout-form button {
    background: transparent;
    border: 1px solid var(--border);
    color: var(--text-secondary);
    padding: var(--spacing-sm) var(--spacing-lg);
    border-radius: var(--radius-md);
    cursor: pointer;
    font-weight: 400;
    transition: var(--transition);
    font-size: 0.95rem;
}

.logout-form button:hover {
    background: rgba(239, 68, 68, 0.1);
    border-color: #ef4444;
    color: #ef4444;
}

/* ============================================
   MAIN CONTAINER
   ============================================ */

main {
    padding: var(--spacing-2xl) var(--spacing-xl);
    max-width: 1400px;
    margin: 0 auto;
}

.container {
    width: 100%;
}

/* ============================================
   PAGE HEADER
   ============================================ */

.page-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: var(--spacing-2xl);
    flex-wrap: wrap;
    gap: var(--spacing-lg);
}

.page-header h1 {
    font-size: 2.5rem;
    font-weight: 600;
    background: linear-gradient(135deg, var(--cream), var(--text-primary));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    letter-spacing: -1px;
}

/* ============================================
   BUTTONS
   ============================================ */

.btn {
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-md) var(--spacing-xl);
    border-radius: var(--radius-lg);
    font-weight: 500;
    font-size: 1rem;
    cursor: pointer;
    border: none;
    transition: var(--transition);
    text-decoration: none;
    position: relative;
    overflow: hidden;
}

.btn::before {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    width: 0;
    height: 0;
    border-radius: 50%;
    background: rgba(255, 255, 255, 0.1);
    transform: translate(-50%, -50%);
    transition: width 0.6s, height 0.6s;
}

.btn:hover::before {
    width: 300px;
    height: 300px;
}

.btn-primary {
    background: linear-gradient(135deg, var(--accent-green), var(--accent-green-dark));
    color: white;
    box-shadow: var(--shadow-md);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

.btn-secondary {
    background: linear-gradient(135deg, var(--accent-blue), var(--accent-blue-dark));
    color: white;
    box-shadow: var(--shadow-md);
}

.btn-secondary:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

.btn-outline {
    background: transparent;
    border: 2px solid var(--border-light);
    color: var(--text-primary);
}

.btn-outline:hover {
    background: var(--bg-card-hover);
    border-color: var(--accent-green);
    transform: translateY(-2px);
}

.btn-danger {
    background: linear-gradient(135deg, #ef4444, #dc2626);
    color: white;
    box-shadow: var(--shadow-md);
}

.btn-danger:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

/* ============================================
   ALERTS / MESSAGES
   ============================================ */

.alert {
    padding: var(--spacing-lg);
    border-radius: var(--radius-lg);
    margin-bottom: var(--spacing-xl);
    border-left: 4px solid;
    animation: slideIn 0.3s ease-out;
}

@keyframes slideIn {
    from {
        opacity: 0;
        transform: translateY(-10px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.alert-success {
    background: rgba(16, 185, 129, 0.1);
    border-color: var(--accent-green);
    color: var(--accent-green);
}

.alert-error {
    background: rgba(239, 68, 68, 0.1);
    border-color: #ef4444;
    color: #ef4444;
}

.alert-info {
    background: rgba(14, 165, 233, 0.1);
    border-color: var(--accent-blue);
    color: var(--accent-blue);
}

/* ============================================
   CARDS GRID (for Clients, Invoices)
   ============================================ */

.cards-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
    gap: var(--spacing-xl);
    margin-top: var(--spacing-xl);
}

.card {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius-xl);
    padding: var(--spacing-xl);
    transition: var(--transition);
    cursor: pointer;
    position: relative;
    overflow: hidden;
}

.card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 4px;
    background: linear-gradient(90deg, var(--accent-green), var(--accent-blue));
    transform: scaleX(0);
    transform-origin: left;
    transition: var(--transition);
}

.card:hover::before {
    transform: scaleX(1);
}

.card:hover {
    transform: translateY(-8px);
    box-shadow: var(--shadow-xl);
    border-color: var(--border-light);
    background: var(--bg-card-hover);
}

.card-title {
    font-size: 1.5rem;
    font-weight: 600;
    color: var(--cream);
    margin-bottom: var(--spacing-sm);
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
}

.card-meta {
    color: var(--text-muted);
    font-size: 0.9rem;
    margin-bottom: var(--spacing-lg);
    opacity: 0;
    transform: translateY(10px);
    transition: var(--transition);
}

.card:hover .card-meta {
    opacity: 1;
    transform: translateY(0);
}

.card-actions {
    display: flex;
    gap: var(--spacing-md);
    margin-top: var(--spacing-lg);
    opacity: 0;
    transform: translateY(10px);
    transition: var(--transition);
    transition-delay: 0.1s;
}

.card:hover .card-actions {
    opacity: 1;
    transform: translateY(0);
}

.card-action-link {
    color: var(--accent-green);
    font-weight: 400;
    padding: var(--spacing-sm) var(--spacing-md);
    border-radius: var(--radius-md);
    transition: var(--transition);
    font-size: 0.95rem;
}

.card-action-link:hover {
    background: rgba(16, 185, 129, 0.1);
}

/* ============================================
   EMPTY STATE
   ============================================ */

.empty-state {
    text-align: center;
    padding: var(--spacing-2xl) var(--spacing-xl);
    background: var(--bg-card);
    border: 2px dashed var(--border);
    border-radius: var(--radius-xl);
    margin-top: var(--spacing-xl);
}

.empty-state-icon {
    font-size: 4rem;
    margin-bottom: var(--spacing-lg);
    opacity: 0.3;
}

.empty-state h3 {
    font-size: 1.5rem;
    color: var(--text-secondary);
    margin-bottom: var(--spacing-md);
}

.empty-state p {
    color: var(--text-muted);
    margin-bottom: var(--spacing-xl);
}

/* ============================================
   INVOICES GRID (2 columns)
   ============================================ */

.invoices-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: var(--spacing-xl);
    margin-top: var(--spacing-xl);
}

.invoice-card {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius-xl);
    padding: var(--spacing-xl);
    transition: var(--transition);
    position: relative;
    overflow: hidden;
    display: flex;
    flex-direction: column;
    gap: var(--spacing-lg);
}

.invoice-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 4px;
    background: linear-gradient(90deg, var(--accent-green), var(--accent-blue));
    transform: scaleX(0);
    transform-origin: left;
    transition: var(--transition);
}

.invoice-card:hover::before {
    transform: scaleX(1);
}

.invoice-card:hover {
    transform: translateY(-8px);
    box-shadow: var(--shadow-xl);
    border-color: var(--border-light);
    background: var(--bg-card-hover);
}

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

.invoice-number {
    font-size: 1.5rem;
    font-weight: 600;
    color: var(--cream);
}

.invoice-date {
    color: var(--text-muted);
    font-size: 0.9rem;
}

.invoice-card-body {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
    flex-grow: 1;
}

.invoice-client,
.invoice-total {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-xs);
}

.invoice-label {
    color: var(--text-muted);
    font-size: 0.85rem;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.invoice-value {
    color: var(--text-primary);
    font-size: 1.1rem;
}

.invoice-amount {
    color: var(--accent-green);
    font-size: 1.5rem;
    font-weight: 600;
}

.invoice-card-actions {
    display: flex;
    gap: var(--spacing-md);
    padding-top: var(--spacing-md);
    border-top: 1px solid var(--border);
}

.invoice-card-actions .btn {
    flex: 1;
    justify-content: center;
    padding: var(--spacing-sm) var(--spacing-md);
    font-size: 0.9rem;
}

/* ============================================
   TABLES (for Invoices list)
   ============================================ */

.table-container {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius-xl);
    overflow: hidden;
    margin-top: var(--spacing-xl);
}

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

thead {
    background: rgba(16, 185, 129, 0.05);
}

thead th {
    text-align: left;
    padding: var(--spacing-lg);
    font-weight: 500;
    color: var(--accent-green);
    text-transform: uppercase;
    font-size: 0.85rem;
    letter-spacing: 0.5px;
}

tbody tr {
    border-bottom: 1px solid var(--border);
    transition: var(--transition);
}

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

tbody td {
    padding: var(--spacing-lg);
    color: var(--text-primary);
}

tbody td a {
    color: var(--accent-blue);
    font-weight: 400;
}

tbody td a:hover {
    text-decoration: underline;
}

/* ============================================
   FORMS
   ============================================ */

.form-container {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius-xl);
    padding: var(--spacing-2xl);
    max-width: 800px;
    margin: var(--spacing-xl) auto;
}

.form-group {
    margin-bottom: var(--spacing-xl);
}

.form-label {
    display: block;
    margin-bottom: var(--spacing-sm);
    color: var(--cream);
    font-weight: 500;
    font-size: 0.95rem;
}

.form-input,
.form-select,
.form-textarea {
    width: 100%;
    padding: var(--spacing-md);
    background: var(--bg-dark);
    border: 2px solid var(--border);
    border-radius: var(--radius-md);
    color: var(--text-primary);
    font-size: 1rem;
    transition: var(--transition);
    font-family: inherit;
}

.form-input:focus,
.form-select:focus,
.form-textarea:focus {
    outline: none;
    border-color: var(--accent-green);
    box-shadow: 0 0 0 3px rgba(16, 185, 129, 0.1);
}

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

.form-error {
    color: #ef4444;
    font-size: 0.9rem;
    margin-top: var(--spacing-sm);
}

.form-actions {
    display: flex;
    gap: var(--spacing-md);
    margin-top: var(--spacing-2xl);
}

/* ============================================
   INVOICE FORM GRID
   ============================================ */

.invoice-form-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--spacing-lg);
    margin-bottom: var(--spacing-xl);
}

/* ============================================
   INVOICE ITEMS (Dynamic rows)
   ============================================ */

.invoice-items {
    margin-top: var(--spacing-xl);
}

.invoice-item-row {
    display: grid;
    grid-template-columns: 2fr 1fr 1fr 1fr auto;
    gap: var(--spacing-md);
    align-items: end;
    margin-bottom: var(--spacing-md);
    padding: var(--spacing-md);
    background: var(--bg-dark);
    border-radius: var(--radius-md);
    border: 1px solid var(--border);
}

.invoice-item-row:hover {
    border-color: var(--border-light);
}

.btn-remove {
    background: transparent;
    border: 2px solid #ef4444;
    color: #ef4444;
    padding: var(--spacing-sm) var(--spacing-md);
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: var(--transition);
    font-weight: 500;
}

.btn-remove:hover {
    background: #ef4444;
    color: white;
}

.btn-add {
    background: transparent;
    border: 2px dashed var(--accent-green);
    color: var(--accent-green);
    padding: var(--spacing-md) var(--spacing-xl);
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: var(--transition);
    font-weight: 500;
    margin-top: var(--spacing-md);
    width: 100%;
}

.btn-add:hover {
    background: rgba(16, 185, 129, 0.1);
    border-style: solid;
}

/* ============================================
   DASHBOARD
   ============================================ */

.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--spacing-xl);
    margin-bottom: var(--spacing-2xl);
}

.stat-card {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius-xl);
    padding: var(--spacing-xl);
    position: relative;
    overflow: hidden;
}

.stat-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 4px;
    background: linear-gradient(90deg, var(--accent-green), var(--accent-blue));
}

.stat-label {
    color: var(--text-muted);
    font-size: 0.9rem;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    margin-bottom: var(--spacing-sm);
}

.stat-value {
    font-size: 2.5rem;
    font-weight: 600;
    color: var(--cream);
}

/* ============================================
   INVOICE SHOW (Preview)
   ============================================ */

.invoice-preview {
    background: var(--cream);
    color: #1f2937;
    border-radius: var(--radius-xl);
    padding: var(--spacing-2xl);
    max-width: 900px;
    margin: var(--spacing-xl) auto;
    box-shadow: var(--shadow-xl);
}

.invoice-preview h1,
.invoice-preview h2,
.invoice-preview h3 {
    color: #1f2937;
}

.invoice-preview table {
    background: white;
}

.invoice-preview thead {
    background: #f3f4f6;
}

.invoice-preview thead th {
    color: #1f2937;
}

.invoice-preview tbody td {
    color: #1f2937;
}

/* ============================================
   LOGIN PAGE
   ============================================ */

.login-container {
    display: flex;
    align-items: center;
    justify-content: center;
    min-height: 100vh;
    padding: var(--spacing-xl);
}

.login-box {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius-xl);
    padding: var(--spacing-2xl);
    width: 100%;
    max-width: 450px;
    box-shadow: var(--shadow-xl);
}

.login-box h1 {
    text-align: center;
    margin-bottom: var(--spacing-xl);
    background: linear-gradient(135deg, var(--accent-green), var(--accent-blue));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

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

@media (max-width: 768px) {
    header {
        padding: var(--spacing-md);
    }

    .brand {
        font-size: 1.25rem;
    }

    nav {
        flex-wrap: wrap;
        gap: var(--spacing-sm);
    }

    main {
        padding: var(--spacing-lg) var(--spacing-md);
    }

    .page-header h1 {
        font-size: 2rem;
    }

    .cards-grid {
        grid-template-columns: 1fr;
    }

    .invoices-grid {
        grid-template-columns: 1fr;
    }

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

    .invoice-item-row {
        grid-template-columns: 1fr;
    }

    .form-actions {
        flex-direction: column;
    }

    .btn {
        width: 100%;
        justify-content: center;
    }

    .stats-grid {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 480px) {
    .page-header {
        flex-direction: column;
        align-items: flex-start;
    }
}

/* ============================================
   SEARCH BAR
   ============================================ */

.search-bar {
    margin-bottom: var(--spacing-xl);
}

.search-form {
    display: flex;
    gap: var(--spacing-md);
    align-items: center;
    flex-wrap: wrap;
}

.search-input {
    flex: 1;
    min-width: 250px;
    padding: var(--spacing-md) var(--spacing-lg);
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius-md);
    color: var(--text-primary);
    font-size: 1rem;
    transition: var(--transition);
}

.search-input:focus {
    outline: none;
    border-color: var(--accent-blue);
    box-shadow: 0 0 0 3px rgba(14, 165, 233, 0.1);
}

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

.btn-search {
    padding: var(--spacing-md) var(--spacing-xl);
    background: var(--accent-blue);
    color: white;
    border: none;
    border-radius: var(--radius-md);
    font-size: 1rem;
    font-weight: 500;
    cursor: pointer;
    transition: var(--transition);
    white-space: nowrap;
}

.btn-search:hover {
    background: var(--accent-blue-dark);
    transform: translateY(-1px);
    box-shadow: var(--shadow-md);
}

.btn-clear {
    padding: var(--spacing-md) var(--spacing-lg);
    background: transparent;
    color: var(--text-secondary);
    border: 1px solid var(--border);
    border-radius: var(--radius-md);
    font-size: 0.95rem;
    cursor: pointer;
    transition: var(--transition);
    white-space: nowrap;
}

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

/* Mobile responsive search */
@media (max-width: 640px) {
    .search-form {
        flex-direction: column;
        align-items: stretch;
    }

    .search-input {
        width: 100%;
        min-width: 100%;
    }

    .btn-search,
    .btn-clear {
        width: 100%;
    }
}

/* ============================================
   UTILITIES
   ============================================ */

.text-center {
    text-align: center;
}

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

.mt-xl {
    margin-top: var(--spacing-xl);
}

.mb-xl {
    margin-bottom: var(--spacing-xl);
}

.hidden {
    display: none;
}