:root {
    --bg-primary: #ffffff;
    --bg-secondary: #f8f9fa;
    --bg-card: #ffffff;
    --text-primary: #212529;
    --text-secondary: #6c757d;
    --border-color: #dee2e6;
    --accent: #4f46e5;
    --accent-hover: #4338ca;
    --success: #10b981;
    --danger: #ef4444;
    --warning: #f59e0b;
    --shadow: rgba(0, 0, 0, 0.1);
}

[data-theme="dark"] {
    --bg-primary: #1a1a1a;
    --bg-secondary: #2d2d2d;
    --bg-card: #242424;
    --text-primary: #e5e5e5;
    --text-secondary: #a3a3a3;
    --border-color: #404040;
    --shadow: rgba(0, 0, 0, 0.3);
}

* {
    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-primary);
    color: var(--text-primary);
    line-height: 1.6;
    transition: background-color 0.3s, color 0.3s;
}

/* HEADER */
header {
    background: var(--bg-card);
    border-bottom: 1px solid var(--border-color);
    padding: 1rem 0;
    position: sticky;
    top: 0;
    z-index: 100;
    box-shadow: 0 2px 8px var(--shadow);
}

.header-content {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 1rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--accent);
    text-decoration: none;
}

.theme-toggle {
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: 20px;
    padding: 0.5rem 1rem;
    cursor: pointer;
    font-size: 1.2rem;
    transition: all 0.3s;
}

.theme-toggle:hover {
    background: var(--accent);
    color: white;
    transform: scale(1.05);
}

/* CONTAINER */
.container {
    max-width: 1200px;
    margin: 2rem auto;
    padding: 0 1rem;
}

/* GRID DE ARTÍCULOS */
.articles-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    gap: 1.5rem;
    margin-top: 2rem;
}

.article-card {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    overflow: hidden;
    transition: all 0.3s;
    box-shadow: 0 2px 8px var(--shadow);
}

.article-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 16px var(--shadow);
}

.article-image {
    width: 100%;
    height: 200px;
    object-fit: cover;
    background: var(--bg-secondary);
}

.article-content {
    padding: 1rem;
}

.article-title {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
    color: var(--text-primary);
}

.article-description {
    color: var(--text-secondary);
    font-size: 0.9rem;
    margin-bottom: 1rem;
    display: -webkit-box;
    -webkit-line-clamp: 3;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

.article-footer {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding-top: 1rem;
    border-top: 1px solid var(--border-color);
}

.article-price {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--accent);
}

.badge {
    display: inline-block;
    padding: 0.25rem 0.75rem;
    border-radius: 20px;
    font-size: 0.75rem;
    font-weight: 600;
}

.badge-estado {
    background: var(--bg-secondary);
    color: var(--text-primary);
}

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

/* BOTONES */
.btn {
    display: inline-block;
    padding: 0.75rem 1.5rem;
    border-radius: 8px;
    text-decoration: none;
    font-weight: 600;
    transition: all 0.3s;
    border: none;
    cursor: pointer;
    font-size: 1rem;
}

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

.btn-primary:hover {
    background: var(--accent-hover);
    transform: translateY(-2px);
}

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

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

/* FORMULARIOS */
.form-group {
    margin-bottom: 1.5rem;
}

.form-label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: 600;
    color: var(--text-primary);
}

.form-control {
    width: 100%;
    padding: 0.75rem;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    background: var(--bg-card);
    color: var(--text-primary);
    font-size: 1rem;
    transition: all 0.3s;
}

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

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

/* MENSAJES */
.message-box {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    padding: 1.5rem;
    margin-bottom: 1.5rem;
}

.message-header {
    display: flex;
    justify-content: space-between;
    margin-bottom: 1rem;
    padding-bottom: 1rem;
    border-bottom: 1px solid var(--border-color);
}

.message-response {
    background: var(--bg-secondary);
    padding: 1rem;
    border-radius: 8px;
    margin-top: 1rem;
    border-left: 4px solid var(--accent);
}

/* ADMIN STYLES */
.admin-nav {
    background: var(--bg-card);
    border-radius: 12px;
    padding: 1rem;
    margin-bottom: 2rem;
    display: flex;
    gap: 1rem;
    flex-wrap: wrap;
    box-shadow: 0 2px 8px var(--shadow);
}

.admin-nav a {
    padding: 0.5rem 1rem;
    border-radius: 6px;
    text-decoration: none;
    color: var(--text-primary);
    transition: all 0.3s;
}

.admin-nav a:hover,
.admin-nav a.active {
    background: var(--accent);
    color: white;
}

.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 1rem;
    margin-bottom: 2rem;
}

.stat-card {
    background: var(--bg-card);
    padding: 1.5rem;
    border-radius: 12px;
    border: 1px solid var(--border-color);
    box-shadow: 0 2px 8px var(--shadow);
}

.stat-number {
    font-size: 2rem;
    font-weight: 700;
    color: var(--accent);
}

.stat-label {
    color: var(--text-secondary);
    font-size: 0.9rem;
}

/* TABLA */
.table {
    width: 100%;
    background: var(--bg-card);
    border-radius: 12px;
    overflow: hidden;
    box-shadow: 0 2px 8px var(--shadow);
}

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

.table th {
    background: var(--bg-secondary);
    font-weight: 600;
}

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

/* RESPONSIVE */
@media (max-width: 768px) {
    .articles-grid {
        grid-template-columns: 1fr;
    }
    
    .admin-nav {
        flex-direction: column;
    }
    
    .table {
        font-size: 0.9rem;
    }
}

/* ALERTS */
.alert {
    padding: 1rem;
    border-radius: 8px;
    margin-bottom: 1rem;
}

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

.alert-danger {
    background: rgba(239, 68, 68, 0.1);
    border: 1px solid var(--danger);
    color: var(--danger);
}

.alert-info {
    background: rgba(79, 70, 229, 0.1);
    border: 1px solid var(--accent);
    color: var(--accent);
}