/* Recupera ancho útil en Estado Cero sin alterar la medida de lectura de escritorio. */
@media (max-width: 720px) {
    .hero {
        width: 100%;
        padding: 3.5rem 1rem 2.5rem;
    }

    .hero-grid {
        gap: 1.5rem;
    }

    .meta-card {
        padding: 1.1rem;
    }

    body > main {
        width: 100%;
        max-width: 100%;
        margin-bottom: 3rem;
        padding-inline: .75rem;
    }

    .article-shell {
        width: 100%;
        max-width: 100%;
    }

    .article-tools {
        padding: .85rem 1rem;
    }

    .article {
        padding: 1.5rem;
    }

    .article > section {
        margin-block: 2.4rem;
    }

    .abstract {
        margin-bottom: 2.5rem;
        padding: 1.15rem;
        border-left-width: 3px;
    }

    .keywords {
        margin-bottom: 2.6rem;
        padding-bottom: 1.7rem;
    }

    .keyword-list {
        gap: .45rem;
    }

    .keyword-list span {
        padding: .38rem .58rem;
    }

    .quote,
    .equation-box,
    .note {
        padding: 1.15rem;
    }

    .concept-card {
        min-height: 0;
        padding: 1.1rem;
    }

    .numbered-title {
        grid-template-columns: 2.35rem minmax(0, 1fr);
        gap: .75rem;
    }
}

@media (max-width: 420px) {
    body > main {
        padding-inline: 0;
    }

    .article-shell {
        border-right: 0;
        border-left: 0;
    }

    .article-tools {
        padding-inline: 1.25rem;
    }

    .article {
        padding: 1.35rem 1.25rem;
    }

    .abstract {
        margin-right: -.25rem;
        margin-left: -.25rem;
        padding: 1rem;
    }

    .numbered-title {
        grid-template-columns: 1fr;
        gap: .45rem;
    }

    .quote {
        margin-right: -.25rem;
        margin-left: -.25rem;
    }
}