+ 新功能提示框(白/黑)

+ fix: 暗黑模式 一些小问题
+ 一些 scss 通用方法

(cherry picked from commit 8c149b6fa82dde3d2c03c236c699939154c65508)

src/scss/_variables.scss

@@ -8,6 +8,8 @@ $text-main : #2C3E50;
 $color-link: $blue;
 
 $fz-main: 14px;
+$fz-mini-title: 13px;
+$fz-mini-content: 12px;
 
 $font-family: "Helvetica Neue", Helvetica, "PingFang SC",
 "Hiragino Sans GB", "Microsoft YaHei", "微软雅黑", Arial, sans-serif;
@@ -25,4 +27,8 @@ $dark-btn-bg                : lighten(black, 20%);
 $dark-btn-bg-highlight      : lighten(black, 30%);
 $dark-bg-th                 : lighten(black, 18%);
 $dark-bg-td                 : lighten(black, 13%);
-$dark-color-link            : $green;
+$dark-color-link            : $green;
+
+$dark-blue      : darken(desaturate($blue, 40%), 30%);
+$dark-red       : darken(desaturate($red, 50%), 30%);
+$dark-green     : darken(desaturate($green, 30%), 30%);