body {
  height: 100vh; 
  margin: 0;
  display: flex;
  flex-direction: column; 
  justify-content: center; 
  align-items: center; 
  background: #f4f4f4;
  font-family: Arial, sans-serif; 
  gap: 20px;
}

:root {
  --bg-img: none;
}

.quadro {
  width: 400px;
  height: 300px;
  background-image: var(--bg-img);
  background-size: cover;
  background-position: center;
  border-radius: 10px;
  box-shadow: 0 4px 8px rgba(0,0,0,0.2);
  margin-bottom: 20px;
}

.background {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-size: cover;
    background-position: center;
    z-index: -1;
}