* { box-sizing: border-box; }
body { margin: 0; font-family: Arial, sans-serif; color: #173651; line-height: 1.5; }
.banner {
  background: url("../assets/banner.svg") no-repeat center center;
  background-size: cover;
  padding: 3rem 1rem;
  text-align: center;
}
nav, .footer { padding: 1rem; background-color: #edf5f7; }
nav a, .footer a { display: inline-block; margin: 0.25rem 0.5rem; color: #175a72; }
a:focus { outline: 2px solid blue; }
.slogan { background-color: #f8f9fa; text-align: center; }
.slogan:hover { color: blue; font-style: italic; }
.row { display: flex; flex-wrap: wrap; max-width: 100%; padding: 1rem; }
.block_3 { flex: 0 0 auto; width: 33.333333%; padding: 0.75rem; }
.block_2 { flex: 0 0 auto; width: 50%; padding: 1rem; }
.content { max-width: 1000px; margin: 0 auto; }
img, video { max-width: 100%; height: auto; }
label { display: block; margin-top: 1rem; }
input, select, button { font: inherit; max-width: 100%; }
input, select { width: 18rem; padding: 0.4rem; }
button { margin: 1rem 0; padding: 0.5rem 1rem; }
@media (max-width: 600px) {
  .block_3, .block_2 { width: 100%; }
  .banner { padding: 2rem 1rem; }
}

/* Đổi thiết kế bằng các khai báo viết sau trong cùng tệp. */
body { font-family: Georgia, serif; color: #562b43; }
.banner { background-image: none; background-color: #f8eaf1; padding: 2rem 1rem; }
nav, .footer { background-color: #f8f1e5; }
.slogan { background-color: #fbf5f9; }
.content .row { flex-direction: row-reverse; }