style: 更新全局样式和主题变量

- 添加新的 CSS 变量
- 优化暗色主题样式

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

web/src/assets/styles/base/variables.css

@@ -44,7 +44,7 @@
   --spacing-2xl: 32px;
 
   /* 字体-family: -apple */
-  --font-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
+  --font-system: BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
   --font-size-xs: 12px;
   --font-size-sm: 14px;
   --font-size-md: 16px;

web/src/assets/styles/index.css

@@ -1,4 +1,15 @@
 /* Main Entry - 全局样式入口 */
+/* Base styles - @import must be first */
+@import './base/variables.css';
+@import './base/reset.css';
+
+/* Component styles */
+@import './components/button.css';
+@import './components/form.css';
+@import './components/modal.css';
+@import './components/table.css';
+
+/* Tailwind directives */
 @tailwind base;
 @tailwind components;
 @tailwind utilities;
@@ -15,16 +26,6 @@ body {
   color: #f3f4f6;
 }
 
-/* Base styles */
-@import './base/variables.css';
-@import './base/reset.css';
-
-/* Component styles */
-@import './components/button.css';
-@import './components/form.css';
-@import './components/modal.css';
-@import './components/table.css';
-
 /* Animations */
 @keyframes bar-grow {
   from {

web/src/style.css

@@ -120,7 +120,15 @@ html.dark .el-select .el-select__wrapper .el-select__selected-item {
 }
 
 html.dark .el-select .el-input__inner::placeholder {
-  color: #6b7280;
+  color: #6b7280 !important;
+}
+
+html.dark .el-select .el-select__placeholder {
+  color: #6b7280 !important;
+}
+
+html.dark .el-input__inner::placeholder {
+  color: #6b7280 !important;
 }
 
 /* 下拉箭头 */