.mail-preview-modal {
    padding: 12px;
}

.mail-preview-modal > section {
    width: min(1440px, calc(100vw - 24px));
    height: calc(100vh - 24px);
}

@media (max-width: 620px) {
    .mail-preview-modal {
        padding: 0;
    }

    .mail-preview-modal > section {
        width: 100%;
        height: 100%;
    }
}