feat(styles): update primary color variables and enhance button text visibility

Author: phodal

src/css/custom.css

@@ -9,7 +9,7 @@
   --ifm-color-primary: #2e8555;
   --ifm-color-primary-dark: #29784c;
   --ifm-color-primary-darker: #277148;
-  --ifm-color-primary-darkest: #205d3b;
+  --ifm-color-primary-darkest: #48A178;
   --ifm-color-primary-light: #33925d;
   --ifm-color-primary-lighter: #359962;
   --ifm-color-primary-lightest: #3cad6e;

src/pages/index.tsx

@@ -21,7 +21,7 @@ function HomepageHeader() {
           <Link className="button button--secondary button--lg" to="/intro">
             快速开始
           </Link>
-          <Link className="button button--outline button--lg button--secondary" to="/features">
+          <Link className="button button--outline button--lg button--secondary font-white" to="/features">
             探索能力
           </Link>
         </div>