.preset-btns{display:flex;gap:8px;margin-bottom:15px;flex-wrap:wrap}
.paper-preview{width:100%;max-width:300px;margin:0 auto 15px;aspect-ratio:210/297;border:2px solid #333;position:relative;background:#fff}
.paper-preview .margin-area{position:absolute;background:rgba(53,146,226,0.1);border:1px dashed #3592e2}
.paper-preview .margin-label{position:absolute;font-size:10px;color:#3592e2}
.paper-preview .top-label{top:-15px;left:50%;transform:translateX(-50%)}
.paper-preview .left-label{left:-35px;top:50%;transform:translateY(-50%) rotate(-90deg)}
.paper-preview .right-label{right:-35px;top:50%;transform:translateY(-50%) rotate(90deg)}
.paper-preview .bottom-label{bottom:-15px;left:50%;transform:translateX(-50%)}