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The tagline is normally hidden because it doesn’t fit well, but you can add the CSS below to make it appear. This will also limit the width of the tagline so that it doesn’t interfere with the menu button. The only caveat is that it will take up two lines rather than one (like this).
@media all and (max-width: 549px) {
.site-header .tagline {
display: block;
max-width: 280px;
}
}
Please copy and paste this into the Customizer (Appearance > Customize), and it will take affect right away.