body{
  margin:0;
  font-family:system-ui, sans-serif;
  background:#f5f7fa;
  text-align:center;
}
.header{
  padding:80px 20px;
  background:linear-gradient(135deg,#2563eb,#1e40af);
  color:#fff;
}
.btn-primary,.btn-secondary{
  display:inline-block;
  margin-top:20px;
  padding:14px 28px;
  border-radius:10px;
  text-decoration:none;
  font-weight:600;
}
.btn-primary{background:#fff;color:#1e40af}
.btn-secondary{background:#2563eb;color:#fff}

#collage{
  max-width:900px;
  margin:30px auto;
  display:grid;
  gap:10px;
}

/* layouts */
.grid{grid-template-columns:repeat(auto-fill,minmax(200px,1fr))}
.masonry{column-count:3}
.masonry img{width:100%;margin-bottom:10px}
.split{grid-template-columns:2fr 1fr}
.polaroid img{
  background:#fff;
  padding:10px 10px 30px;
  box-shadow:0 10px 20px rgba(0,0,0,.2);
}
.overlap{position:relative;height:500px}
.overlap img{position:absolute;width:220px}

button{
  padding:12px 24px;
  border:none;
  border-radius:8px;
  background:#2563eb;
  color:#fff;
  cursor:pointer;
}
footer{
  margin:40px 0;
  font-size:14px;
}