feat: 新增样式文件

src/static/scss/flex.scss

@@ -0,0 +1,20 @@
+// 弹性布局
+.flex {
+  display: flex;
+}
+
+.flex-items-center {
+  align-items: center;
+}
+
+.flex-justify-center {
+  justify-content: center;
+}
+
+.flex-col {
+  flex-direction: column;
+}
+
+.flex-wrap {
+  flex-wrap: wrap;
+}