/* ============================================
   MODERN DESIGN SYSTEM - Inventory Management
   ============================================ */

:root {
    /* Color Palette */
    --primary: #6366f1;
    --primary-dark: #4f46e5;
    --primary-light: #818cf8;
    --secondary: #0ea5e9;
    --success: #10b981;
    --warning: #f59e0b;
    --danger: #ef4444;
    --danger-dark: #dc2626;
    
    /* Neutrals */
    --gray-50: #f9fafb;
    --gray-100: #f3f4f6;
    --gray-200: #e5e7eb;
    --gray-300: #d1d5db;
    --gray-400: #9ca3af;
    --gray-500: #6b7280;
    --gray-600: #4b5563;
    --gray-700: #374151;
    --gray-800: #1f2937;
    --gray-900: #111827;
    
    /* Backgrounds */
    --bg-primary: #ffffff;
    --bg-secondary: #f9fafb;
    --bg-tertiary: #f3f4f6;
    
    /* Shadows */
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow: 0 1px 3px 0 rgba(0, 0, 0, 0.1), 0 1px 2px -1px rgba(0, 0, 0, 0.1);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -2px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -4px rgba(0, 0, 0, 0.1);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 8px 10px -6px rgba(0, 0, 0, 0.1);
    
    /* Border Radius */
    --radius-sm: 0.375rem;
    --radius: 0.5rem;
    --radius-md: 0.75rem;
    --radius-lg: 1rem;
    --radius-xl: 1.5rem;
    --radius-full: 9999px;
    
    /* Transitions */
    --transition-fast: 150ms cubic-bezier(0.4, 0, 0.2, 1);
    --transition: 200ms cubic-bezier(0.4, 0, 0.2, 1);
    --transition-slow: 300ms cubic-bezier(0.4, 0, 0.2, 1);
}

/* ============================================
   BASE STYLES
   ============================================ */

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

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    line-height: 1.6;
    color: var(--gray-800);
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    background-attachment: fixed;
    min-height: 100vh;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

/* ============================================
   NAVIGATION
   ============================================ */

nav {
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    color: var(--gray-800);
    padding: 1rem 2rem;
    box-shadow: var(--shadow-md);
    display: flex;
    justify-content: space-between;
    align-items: center;
    position: sticky;
    top: 0;
    z-index: 100;
    border-bottom: 1px solid var(--gray-200);
}

nav h1 {
    margin: 0;
    font-size: 1.5rem;
    font-weight: 700;
    background: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

nav ul {
    list-style: none;
    display: flex;
    gap: 0.5rem;
    margin: 0;
    flex-wrap: wrap;
}

nav a {
    color: var(--gray-700);
    text-decoration: none;
    transition: all var(--transition);
    padding: 0.5rem 1rem;
    border-radius: var(--radius);
    font-weight: 500;
    font-size: 0.95rem;
}

nav a:hover {
    background: var(--gray-100);
    color: var(--primary);
    transform: translateY(-1px);
}

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

.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    padding: 0.625rem 1.25rem;
    background: var(--primary);
    color: white;
    text-decoration: none;
    border-radius: var(--radius);
    border: none;
    cursor: pointer;
    font-size: 0.95rem;
    font-weight: 500;
    transition: all var(--transition);
    box-shadow: var(--shadow-sm);
    white-space: nowrap;
}

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

.btn:active {
    transform: translateY(0);
}

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

.btn-success:hover {
    background: #059669;
}

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

.btn-danger:hover {
    background: var(--danger-dark);
}

.btn-secondary {
    background: var(--gray-600);
}

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

.btn-outline {
    background: transparent;
    border: 2px solid var(--gray-300);
    color: var(--gray-700);
}

.btn-outline:hover {
    background: var(--gray-100);
    border-color: var(--gray-400);
}

/* ============================================
   CARDS
   ============================================ */

.card {
    background: var(--bg-primary);
    padding: 1.5rem;
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow);
    margin-bottom: 1.5rem;
    transition: all var(--transition);
    border: 1px solid var(--gray-200);
}

.card:hover {
    box-shadow: var(--shadow-md);
    transform: translateY(-2px);
}

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

.container {
    max-width: 1400px;
    margin: 2rem auto;
    padding: 0 2rem;
}

/* ============================================
   TABLES
   ============================================ */

table {
    width: 100%;
    background: var(--bg-primary);
    border-collapse: separate;
    border-spacing: 0;
    box-shadow: var(--shadow);
    margin: 1rem 0;
    border-radius: var(--radius-lg);
    overflow: hidden;
    border: 1px solid var(--gray-200);
}

th, td {
    padding: 1rem;
    text-align: left;
    border-bottom: 1px solid var(--gray-200);
}

th {
    background: linear-gradient(135deg, var(--gray-800) 0%, var(--gray-700) 100%);
    color: white;
    font-weight: 600;
    text-transform: uppercase;
    font-size: 0.75rem;
    letter-spacing: 0.05em;
}

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

tr:hover {
    background: var(--gray-50);
}

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

.form-group {
    margin-bottom: 1.25rem;
}

label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: 600;
    color: var(--gray-700);
    font-size: 0.9rem;
}

input, select, textarea {
    width: 100%;
    padding: 0.75rem 1rem;
    border: 2px solid var(--gray-300);
    border-radius: var(--radius);
    font-size: 1rem;
    transition: all var(--transition);
    background: var(--bg-primary);
    color: var(--gray-800);
}

input:focus, select:focus, textarea:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.1);
}

textarea {
    resize: vertical;
    min-height: 120px;
}

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

.alert {
    padding: 1rem 1.25rem;
    margin-bottom: 1.5rem;
    border-radius: var(--radius);
    border-left: 4px solid;
    animation: slideIn 0.3s ease-out;
}

@keyframes slideIn {
    from {
        opacity: 0;
        transform: translateX(-20px);
    }
    to {
        opacity: 1;
        transform: translateX(0);
    }
}

.alert-success {
    background: #d1fae5;
    color: #065f46;
    border-color: var(--success);
}

.alert-error {
    background: #fee2e2;
    color: #991b1b;
    border-color: var(--danger);
}

.alert-warning {
    background: #fef3c7;
    color: #92400e;
    border-color: var(--warning);
}

.alert-link {
    color: inherit;
    font-weight: bold;
    text-decoration: underline;
}

/* ============================================
   BADGES
   ============================================ */

.badge {
    display: inline-flex;
    align-items: center;
    padding: 0.25rem 0.75rem;
    border-radius: var(--radius-full);
    font-size: 0.875rem;
    font-weight: 600;
}

.badge-success {
    background: #d1fae5;
    color: #065f46;
}

.badge-warning {
    background: #fef3c7;
    color: #92400e;
}

.badge-danger {
    background: #fee2e2;
    color: #991b1b;
}

.badge-info {
    background: #dbeafe;
    color: #1e40af;
}

/* ============================================
   LOADING STATES
   ============================================ */

@keyframes spin {
    to {
        transform: rotate(360deg);
    }
}

@keyframes pulse {
    0%, 100% {
        opacity: 1;
    }
    50% {
        opacity: 0.5;
    }
}

.loading {
    display: inline-block;
    width: 20px;
    height: 20px;
    border: 3px solid var(--gray-300);
    border-top-color: var(--primary);
    border-radius: 50%;
    animation: spin 0.8s linear infinite;
}

.loading-text {
    animation: pulse 1.5s ease-in-out infinite;
}

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

@media (max-width: 1024px) {
    .container {
        padding: 0 1.5rem;
        margin: 1.5rem auto;
    }
    
    nav {
        padding: 1rem 1.5rem;
        flex-direction: column;
        gap: 1rem;
    }
    
    nav ul {
        width: 100%;
        justify-content: center;
    }
}

@media (max-width: 768px) {
    .container {
        padding: 0 1rem;
        margin: 1rem auto;
    }
    
    nav ul {
        flex-direction: column;
        gap: 0.25rem;
    }
    
    nav a {
        width: 100%;
        text-align: center;
    }
    
    table {
        font-size: 0.875rem;
    }
    
    th, td {
        padding: 0.75rem 0.5rem;
    }
    
    .card {
        padding: 1rem;
    }
    
    h2 {
        font-size: 1.5rem;
    }
}

@media (max-width: 480px) {
    nav h1 {
        font-size: 1.25rem;
    }
    
    .btn {
        width: 100%;
        justify-content: center;
    }
    
    table {
        display: block;
        overflow-x: auto;
        white-space: nowrap;
    }
}

/* ============================================
   ANIMATIONS
   ============================================ */

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

.fade-in {
    animation: fadeIn 0.4s ease-out;
}

@keyframes scaleIn {
    from {
        opacity: 0;
        transform: scale(0.95);
    }
    to {
        opacity: 1;
        transform: scale(1);
    }
}

.scale-in {
    animation: scaleIn 0.3s ease-out;
}

/* ============================================
   UTILITY CLASSES
   ============================================ */

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

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

.mt-1 { margin-top: 0.5rem; }
.mt-2 { margin-top: 1rem; }
.mt-3 { margin-top: 1.5rem; }
.mt-4 { margin-top: 2rem; }

.mb-1 { margin-bottom: 0.5rem; }
.mb-2 { margin-bottom: 1rem; }
.mb-3 { margin-bottom: 1.5rem; }
.mb-4 { margin-bottom: 2rem; }

.flex {
    display: flex;
}

.flex-wrap {
    flex-wrap: wrap;
}

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

.justify-between {
    justify-content: space-between;
}

.gap-1 { gap: 0.5rem; }
.gap-2 { gap: 1rem; }
.gap-3 { gap: 1.5rem; }

.grid {
    display: grid;
}

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

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

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

@media (max-width: 768px) {
    .grid-cols-2,
    .grid-cols-3,
    .grid-cols-4 {
        grid-template-columns: 1fr;
    }
}