body {
    font-family: "Segoe UI", sans-serif;
    margin: 30px;
    background-image: url('https://media.istockphoto.com/id/1481286583/vi/anh/n%E1%BB%81n-m%E1%BB%9D-m%C3%A0u-xanh-l%C3%A1-c%C3%A2y-v%C3%A0-%C3%A1nh-s%C3%A1ng-m%E1%BA%B7t-tr%E1%BB%9Di.jpg?s=612x612&w=0&k=20&c=g7Y3481phHZ8rLvdmtrHuzlbFTl95oUBlRKsVnJglp0='); /* Đường dẫn đến ảnh nền */
    background-size: cover; /* co ảnh vừa màn hình */
    background-position: center;
    background-attachment: fixed;
}
h1 {
    color: #333;
    text-align: center;
    background: #ffffff83;
    padding: 8px;
    border-radius:8px
}

.btn {
    background: #007bff;
    color: white;
    padding: 8px 14px;
    border-radius: 5px;
    text-decoration: none;
}
.btn:hover {
    background: #0056b3;
}
input, textarea {
    font-size: medium;
}