#sifb-app { max-width:700px;margin:50px auto;font-family:sans-serif;}
.sifb-progress {display:flex;justify-content:space-between;margin-bottom:20px;}
.sifb-step {flex:1;text-align:center;padding:10px;border-bottom:2px solid #ccc;}
.sifb-step.active {border-color:#111;font-weight:bold;}
#sifb-content {padding:20px;background:#fafafa;border-radius:10px;box-shadow:0 5px 15px rgba(0,0,0,0.05);}
button {padding:10px 20px;margin:5px;background:#111;color:#fff;border:none;border-radius:6px;cursor:pointer;}
button:hover {background:#333;}
#sifb-3d-preview {height:300px;margin-top:20px;border:1px solid #ddd;border-radius:10px;}