帮我写个css用于缩小以下html占屏幕中间并且上下留空div class=modal-contentx div class=modal-content div class=modal-header h5 class=modal-title id=orderde

.modal-contentx { width: 50%; /* 缩小至屏幕宽度的一半 / margin: auto; / 居中 / padding: 20px; / 上下留空 */ }

.modal-content { background-color: #fff; border-radius: 10px; box-shadow: 0px 0px 10px rgba(0, 0, 0, 0.5); }

.modal-header { border-bottom: 1px solid #ccc; padding: 10px; text-align: center; }

.modal-title { font-size: 18px; font-weight: 600; margin: 0; }

.modal-body { padding: 10px; }

.table-responsive { overflow-x: auto; }

.table { margin-bottom: 0; }

.table th { font-weight: 600; text-align: center; }

.table td { text-align: center; }

.btn-close { position: absolute; top: 10px; right: 10px;