:root {
    --color-fondo: #f4f4f4;
    --color-card: #ffffff;
    --color-texto: #222222;
    --color-primario: #333333;
    --color-borde: #cccccc;
    --color-item: #fafafa;
}

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

body {
    background: var(--color-fondo);
    color: var(--color-texto);
    font-family: sans-serif;
}

.header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 15px 20px;
    background: #ddd;
    border-bottom: 1px solid var(--color-borde);
    flex-wrap: wrap;
    gap: 10px;
}

.nav {
    display: flex;
    gap: 10px;
}

.nav a {
    text-decoration: none;
    color: var(--color-primario);
    padding: 4px 8px;
}

.nav a.active {
    font-weight: bold;
    border-bottom: 2px solid var(--color-primario);
}

.btn-logout {
    background: #721c24;
    color: var(--color-card);
    border: none;
    padding: 6px 12px;
    cursor: pointer;
}

.main-container {
    padding: 20px;
    max-width: 1200px;
    margin: 0 auto;
}

.card {
    background: var(--color-card);
    border: 1px solid var(--color-borde);
    padding: 15px;
    display: flex;
    flex-direction: column;
    gap: 10px;
}

.marcas-grid {
    display: grid;
    grid-template-columns: 1fr;
    gap: 10px;
    width: 100%;
}

@media (min-width: 768px) {
    .marcas-grid {
        grid-template-columns: 1fr 1fr;
    }
}

@media (min-width: 1024px) {
    .marcas-grid {
        grid-template-columns: 1fr 1fr 1fr;
    }
}

.marca-item {
    padding: 10px;
    background: var(--color-item);
    border: 1px solid var(--color-borde);
    display: flex;
    flex-direction: column;
    gap: 4px;
    min-width: 0;
}