feat: 添加水印颜色变量并在主题中应用

Signed-off-by: wangsimiao1 <wangsimiao1@xiaomi.com>

Author: WangSimiao2000

_sass/base/_base.scss

@@ -462,6 +462,25 @@ mjx-container {
 
 #main-wrapper {
   position: relative;
+  overflow: hidden;
+
+  &::after {
+    content: 'MickeyMiao\'s Blog';
+    position: fixed;
+    top: 50%;
+    left: 50%;
+    transform: translate(-50%, -50%) rotate(-18deg);
+    font-size: clamp(6rem, 12vw, 14rem);
+    font-family: 'Lato', 'Source Sans Pro', sans-serif;
+    font-weight: 900;
+    font-style: italic;
+    letter-spacing: 0.04em;
+    white-space: nowrap;
+    color: var(--watermark-color, rgba(0, 0, 0, 0.03));
+    pointer-events: none;
+    user-select: none;
+    z-index: 0;
+  }
 
   @include mx.pl-pr(0);
 

_sass/themes/_dark.scss

@@ -48,6 +48,9 @@
   --topbar-text-color: var(--text-color);
   --search-border-color: #3A3632;
   --search-icon-color: #6A6560;
+
+  /* Watermark */
+  --watermark-color: rgba(255, 255, 255, 0.03);
   --input-focus-border-color: #C4956E;
 
   /* Home page */

_sass/themes/_light.scss

@@ -47,6 +47,9 @@
   --search-icon-color: #B8B0A8;
   --input-focus-border-color: #B07D62;
 
+  /* Watermark */
+  --watermark-color: rgba(0, 0, 0, 0.03);
+
   /* Home page */
   --post-list-text-color: #6B6B6B;
   --btn-patinator-text-color: #5A5A5A;