Bản mẫu:BKTT:Toàn bộ/styles.css
.q1 {
background-image: url(https://upload.wikimedia.org/wikipedia/commons/9/92/Isotoxal_octagon_rhombic_dissection.jpg);
background-size: cover;
width: 100%;
padding-top: 100%;
position: relative;
}
.q2 {
background-image: url(https://upload.wikimedia.org/wikipedia/commons/e/ea/CSIRO_ScienceImage_2212_CSIRO_Parkes_Telescope_This_photo_taken_in_1969_shows_the_telescope_as_it_was_around_the_time_of_the_first_manned_Moon_landing.jpg);
background-size: cover;
width: 100%;
padding-top: 100%;
position: relative;
}