/**
 * ChemSurplus Design System
 * Professional B2B Chemical Marketplace
 */

/* ========================================
   CSS Variables & Design Tokens
   ======================================== */
:root {
    /* Colors */
    --color-primary: #2563eb;
    --color-primary-dark: #1e40af;
    --color-primary-light: #3b82f6;
    --color-secondary: #64748b;
    --color-secondary-dark: #475569;
    --color-accent: #0891b2;
    
    --color-success: #10b981;
    --color-warning: #f59e0b;
    --color-error: #ef4444;
    --color-info: #3b82f6;
    
    --color-text-primary: #0f172a;
    --color-text-secondary: #475569;
    --color-text-muted: #94a3b8;
    
    --color-bg-primary: #ffffff;
    --color-bg-secondary: #f8fafc;
    --color-bg-tertiary: #f1f5f9;
    
    --color-border: #e2e8f0;
    --color-border-light: #f1f5f9;
    
    /* Typography */
    --font-primary: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    --font-heading: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    
    --font-size-xs: 0.75rem;
    --font-size-sm: 0.875rem;
    --font-size-base: 1rem;
    --font-size-lg: 1.125rem;
    --font-size-xl: 1.25rem;
    --font-size-2xl: 1.5rem;
    --font-size-3xl: 1.875rem;
    --font-size-4xl: 2.25rem;
    --font-size-5xl: 3rem;
    
    --font-weight-normal: 400;
    --font-weight-medium: 500;
    --font-weight-semibold: 600;
    --font-weight-bold: 700;
    
    --line-height-tight: 1.25;
    --line-height-normal: 1.5;
    --line-height-relaxed: 1.75;
    
    /* Spacing */
    --spacing-xs: 0.25rem;
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --spacing-2xl: 3rem;
    --spacing-3xl: 4rem;
    --spacing-4xl: 6rem;
    
    /* Border Radius */
    --radius-sm: 0.375rem;
    --radius-md: 0.5rem;
    --radius-lg: 0.75rem;
    --radius-xl: 1rem;
    --radius-full: 9999px;
    
    /* Shadows */
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
    
    /* Transitions */
    --transition-fast: 150ms ease;
    --transition-base: 250ms ease;
    --transition-slow: 350ms ease;
    
    /* Container */
    --container-max-width: 1280px;
    --container-padding: var(--spacing-lg);
}

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

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

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

/* ========================================
   Typography
   ======================================== */
h1, h2, h3, h4, h5, h6 {
    font-family: var(--font-heading);
    font-weight: var(--font-weight-bold);
    line-height: var(--line-height-tight);
    color: var(--color-text-primary);
    margin-bottom: var(--spacing-md);
}

h1 { font-size: var(--font-size-5xl); }
h2 { font-size: var(--font-size-4xl); }
h3 { font-size: var(--font-size-3xl); }
h4 { font-size: var(--font-size-2xl); }
h5 { font-size: var(--font-size-xl); }
h6 { font-size: var(--font-size-lg); }

p {
    margin-bottom: var(--spacing-md);
    color: var(--color-text-secondary);
}

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

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

/* ========================================
   Layout
   ======================================== */
.container {
    max-width: var(--container-max-width);
    margin: 0 auto;
    padding: 0 var(--container-padding);
}

.container-fluid {
    width: 100%;
    padding: 0 var(--container-padding);
}

/* ========================================
   Header & Navigation
   ======================================== */
.header {
    background: var(--color-bg-primary);
    border-bottom: 1px solid var(--color-border);
    position: sticky;
    top: 0;
    z-index: 100;
    box-shadow: var(--shadow-sm);
}

.header-content {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: var(--spacing-sm) 0;
}

.logo {
    font-size: var(--font-size-2xl);
    font-weight: var(--font-weight-bold);
    color: var(--color-primary);
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
}

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

.logo-img {
    height: 5rem;
    width: auto;
    display: block;
}

.nav {
    display: flex;
    align-items: center;
    gap: 2.25rem;
}

.nav-link {
    font-weight: var(--font-weight-medium);
    color: var(--color-text-secondary);
    padding: var(--spacing-sm) 0;
    position: relative;
}

.nav-link:hover,
.nav-link.active {
    color: var(--color-primary);
}

.nav-link.active::after {
    content: '';
    position: absolute;
    bottom: -2px;
    left: 0;
    right: 0;
    height: 2px;
    background: var(--color-primary);
}

.mobile-menu-toggle {
    display: none;
    background: none;
    border: none;
    cursor: pointer;
    padding: var(--spacing-sm);
}

/* ========================================
   Buttons
   ======================================== */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-sm);
    padding: 0.75rem 1.5rem;
    font-size: var(--font-size-base);
    font-weight: var(--font-weight-medium);
    line-height: 1;
    border-radius: var(--radius-md);
    border: none;
    cursor: pointer;
    transition: all var(--transition-base);
    text-decoration: none;
}

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

.btn-primary:hover {
    background: var(--color-primary-dark);
    color: white;
    transform: translateY(-1px);
    box-shadow: var(--shadow-md);
}

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

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

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

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

.btn-lg {
    padding: 1rem 2rem;
    font-size: var(--font-size-lg);
}

.btn-sm {
    padding: 0.5rem 1rem;
    font-size: var(--font-size-sm);
}

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

/* ========================================
   Cards
   ======================================== */
.card {
    background: var(--color-bg-primary);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-md);
    overflow: hidden;
    transition: all var(--transition-base);
}

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

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

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

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

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

.form-label {
    display: block;
    font-weight: var(--font-weight-medium);
    color: var(--color-text-primary);
    margin-bottom: var(--spacing-sm);
}

.form-label.required::after {
    content: ' *';
    color: var(--color-error);
}

.form-input,
.form-select,
.form-textarea {
    width: 100%;
    padding: 0.75rem 1rem;
    font-size: var(--font-size-base);
    font-family: inherit;
    color: var(--color-text-primary);
    background: var(--color-bg-primary);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    transition: all var(--transition-fast);
}

.form-input:focus,
.form-select:focus,
.form-textarea:focus {
    outline: none;
    border-color: var(--color-primary);
    box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}

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

.form-error {
    color: var(--color-error);
    font-size: var(--font-size-sm);
    margin-top: var(--spacing-xs);
}

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

/* ========================================
   Grid System
   ======================================== */
.grid {
    display: grid;
    gap: var(--spacing-lg);
}

.grid-cols-1 { grid-template-columns: repeat(1, 1fr); }
.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); }
.grid-cols-6 { grid-template-columns: repeat(6, 1fr); }

/* ========================================
   Hero Section
   ======================================== */
.hero {
    position: relative;
    min-height: 600px;
    display: flex;
    align-items: center;
    justify-content: center;
    text-align: center;
    overflow: hidden;
    background: linear-gradient(135deg, rgba(15, 23, 42, 0.95) 0%, rgba(30, 64, 175, 0.85) 100%);
}

.hero-background {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: 0;
}

.hero-background img {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.hero-overlay {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: linear-gradient(135deg, rgba(15, 23, 42, 0.85) 0%, rgba(30, 64, 175, 0.75) 100%);
    z-index: 1;
}

.hero-content {
    position: relative;
    z-index: 2;
    max-width: 900px;
    padding: var(--spacing-2xl) var(--spacing-lg);
}

.hero-title {
    font-size: var(--font-size-5xl);
    color: white;
    margin-bottom: var(--spacing-lg);
    text-shadow: 0 2px 4px rgba(0, 0, 0, 0.3);
}

.hero-subtitle {
    font-size: var(--font-size-xl);
    color: rgba(255, 255, 255, 0.95);
    margin-bottom: var(--spacing-2xl);
    line-height: var(--line-height-relaxed);
}

.hero-actions {
    display: flex;
    gap: var(--spacing-md);
    justify-content: center;
    flex-wrap: wrap;
}

.hero .btn-secondary {
    color: white;
    border-color: white;
}

.hero .btn-secondary:hover {
    background: white;
    color: #000;
    border-color: white;
}

/* ========================================
   Sections
   ======================================== */
.section {
    padding: var(--spacing-3xl) 0;
}

.section-header {
    text-align: center;
    margin-bottom: var(--spacing-3xl);
}

.section-title {
    font-size: var(--font-size-4xl);
    margin-bottom: var(--spacing-md);
}

.section-subtitle {
    font-size: var(--font-size-lg);
    color: var(--color-text-secondary);
    max-width: 700px;
    margin: 0 auto;
}

.section-alt {
    background: linear-gradient(135deg, #f8fafc 0%, #e0e7ff 100%);
}

/* ========================================
   Trust Badges
   ======================================== */
.trust-badges {
    display: flex;
    gap: var(--spacing-2xl);
    justify-content: center;
    flex-wrap: wrap;
    margin-top: var(--spacing-2xl);
}

.trust-badge {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    color: rgba(255, 255, 255, 0.95);
    font-weight: var(--font-weight-medium);
}

.trust-badge svg {
    width: 24px;
    height: 24px;
}

/* ========================================
   Feature Cards
   ======================================== */
.feature-card {
    text-align: center;
    padding: var(--spacing-xl);
}

.feature-icon {
    width: 64px;
    height: 64px;
    margin: 0 auto var(--spacing-lg);
    display: flex;
    align-items: center;
    justify-content: center;
    background: linear-gradient(135deg, var(--color-primary-light), var(--color-primary));
    border-radius: var(--radius-xl);
    color: white;
}

.feature-icon svg {
    width: 32px;
    height: 32px;
}

.feature-title {
    font-size: var(--font-size-xl);
    margin-bottom: var(--spacing-sm);
}

.feature-description {
    color: var(--color-text-secondary);
}

/* ========================================
   Table
   ======================================== */
.table-container {
    overflow-x: auto;
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-md);
}

.table {
    width: 100%;
    border-collapse: collapse;
    background: var(--color-bg-primary);
}

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

.table th {
    padding: var(--spacing-md) var(--spacing-lg);
    text-align: left;
    font-weight: var(--font-weight-semibold);
    color: var(--color-text-primary);
    border-bottom: 2px solid var(--color-border);
}

.table td {
    padding: var(--spacing-md) var(--spacing-lg);
    border-bottom: 1px solid var(--color-border-light);
}

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

/* ========================================
   Badges
   ======================================== */
.badge {
    display: inline-flex;
    align-items: center;
    padding: 0.25rem 0.75rem;
    font-size: var(--font-size-sm);
    font-weight: var(--font-weight-medium);
    border-radius: var(--radius-full);
}

.badge-primary {
    background: rgba(37, 99, 235, 0.1);
    color: var(--color-primary);
}

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

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

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

/* ========================================
   Pagination
   ======================================== */
.pagination {
    display: flex;
    gap: var(--spacing-sm);
    justify-content: center;
    align-items: center;
    margin-top: var(--spacing-2xl);
}

.pagination-link {
    padding: 0.5rem 1rem;
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    color: var(--color-text-primary);
    font-weight: var(--font-weight-medium);
    transition: all var(--transition-fast);
}

.pagination-link:hover {
    background: var(--color-bg-secondary);
    border-color: var(--color-primary);
    color: var(--color-primary);
}

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

.pagination-ellipsis {
    padding: 0.5rem;
    color: var(--color-text-muted);
}

/* ========================================
   Footer
   ======================================== */
.footer {
    background: var(--color-text-primary);
    color: white;
    padding: var(--spacing-3xl) 0 var(--spacing-xl);
}

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

.footer-section h4 {
    color: white;
    margin-bottom: var(--spacing-md);
}

.footer-section p {
    color: white;
}

.footer-links {
    list-style: none;
}

.footer-links li {
    margin-bottom: var(--spacing-sm);
}

.footer-links a {
    color: white;
}

.footer-links a:hover {
    color: rgba(255, 255, 255, 0.8);
}

.footer-bottom {
    padding-top: var(--spacing-xl);
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    text-align: center;
    color: white;
}

.footer-bottom a {
    color: white;
}

.footer-bottom a:hover {
    color: rgba(255, 255, 255, 0.8);
}

.footer input::placeholder {
    color: rgba(255, 255, 255, 0.6);
}

/* ========================================
   Utilities
   ======================================== */
.text-center { text-align: center; }
.text-left { text-align: left; }
.text-right { text-align: right; }

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

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

.hidden { display: none; }

/* ========================================
   Responsive Design
   ======================================== */
@media (max-width: 768px) {
    :root {
        --font-size-5xl: 2rem;
        --font-size-4xl: 1.75rem;
        --font-size-3xl: 1.5rem;
    }
    
    .nav {
        display: none;
    }
    
    .mobile-menu-toggle {
        display: block;
    }
    
    .grid-cols-2,
    .grid-cols-3,
    .grid-cols-4,
    .grid-cols-6 {
        grid-template-columns: 1fr;
    }
    
    .hero {
        min-height: 500px;
    }
    
    .hero-actions {
        flex-direction: column;
    }
    
    .section {
        padding: var(--spacing-2xl) 0;
    }
}

@media (min-width: 769px) and (max-width: 1024px) {
    .grid-cols-3,
    .grid-cols-4,
    .grid-cols-6 {
        grid-template-columns: repeat(2, 1fr);
    }
}