@charset "utf-8";
body {
	margin-right: auto;
	margin-left: auto;
}
.ppt-gallery {
    max-width: 900px;
    margin: 0 auto;
    display: flex;
    flex-direction: column;
    gap: 20px;
}
.ppt-gallery img {
    width: 100%;
    border-radius: 12px;
    box-shadow: 0 2px 12px rgba(0,0,0,0.08);
}
.btn-back {
    display: inline-block;
    color: #4a90e2;
    text-decoration: none;
    font-weight: 500;
    padding: 10px 24px;
    border: 1px solid #4a90e2;
    border-radius: 30px;
    transition: all 0.3s;
    margin-top: 10px;
}
.btn-back:hover {
    background: #4a90e2;
    color: #fff;
}