refactor: move individual css into global css for sharing use

frontend/public/index.scss

@@ -1,3 +1,40 @@
 // 导入 Bulma
 @charset "utf-8";
 @import "bulma/bulma.sass";
+
+// coconut-leaf 全局样式
+
+// 卡片样式（作用于集合列表，Todo列表项等）
+div.paperbox-item {
+  display: flex;
+  flex-flow: row;
+  align-items: flex-start;
+
+  padding: 1.25rem;
+  margin-bottom: 1.25rem;
+}
+
+div.paperbox-item-words {
+  flex-grow: 1;
+  flex-basis: 0;
+
+  word-break: break-all;
+}
+
+div.paperbox-item-icon {
+  margin-left: 0.75rem;
+}
+
+// 按钮列表样式
+
+div.button-list {
+  display: flex;
+  flex-flow: row;
+  flex-wrap: wrap;
+}
+
+div.button-list>* {
+  margin-right: 0.75rem;
+  margin-bottom: 0.75rem;
+  margin-left: 0 !important;
+}