/* Keep it simple and responsive */
* { box-sizing: border-box; }
html, body { height: 100%; margin: 0; }

.center {
  min-height: 100vh;           /* fill screen height */
  display: grid;               /* easy centering */
  place-items: center;         /* center horizontally + vertically */
  padding: 16px;               /* breathing room on small screens */
}

.banner {
  display: block;
  width: min(100%, 900px);     /* cap the banner width on large screens */
}

.banner img {
  display: block;
  width: 100%;
  height: auto;                /* maintain aspect ratio */
  border-radius: 8px;          /* optional: small rounded corners */
}