body{font-family:Arial, sans-serif; padding:20px;}
header{display:flex; justify-content:space-between; align-items:center;}
.center-box{max-width:360px;margin:40px auto;padding:20px;border:1px solid #ddd;border-radius:8px;}
input,select{padding:8px;margin:6px 0;width:95%;}
button{padding:10px 14px;border:none;border-radius:6px;background:#2b7;cursor:pointer;}
.error{color:red;}
.cards{display:flex;gap:20px;margin-top:30px;}
.card{display:block;padding:20px;border:1px solid #ddd;border-radius:8px;text-decoration:none;color:#333;}
.flat-btn{padding:10px 12px;margin:6px;border-radius:6px;border:none;color:white;cursor:pointer;}
.available{background:green;}
.sold{background:red;}
.hold{background:orange;}
#popup{display:none;position:fixed;left:50%;top:50%;transform:translate(-50%,-50%);background:#fff;padding:15px;border:1px solid #333;z-index:1000;}
#overlay{display:none;position:fixed;left:0;top:0;width:100%;height:100%;background:rgba(0,0,0,0.4);z-index:900;}
.flat-row{padding:6px 0;}