.grille{display:grid;grid-template-columns:repeat(3,1fr);grid-gap:10px}.h2col{font-size:1.2em;text-align:center;margin:0 auto;padding:5px}.section_3col{margin:5px auto;text-align:center;border:1px solid #ccc;border-radius:5px;width:98%}@media only screen and (max-width:500px){.grille{display:grid;grid-template-columns:repeat(1,1fr);grid-gap:10px;grid-auto-rows:minmax(100px,auto)}.section_3col{width:98%}}