docs(sb): disable forced-color-adjust & update styles (SAP#6555)

This PR also styles the search input to look more like a Horizon input
and improves some general styles.

Related to SAP/ui5-webcomponents#9917

Author: Lukas742

.storybook/manager-head.html

@@ -1,11 +1,41 @@
 <style>
   @import url('@ui5/webcomponents-base/dist/css/FontFace.css');
 
+  html {
+    forced-color-adjust: none;
+  }
   body {
-    font-family: '72', Arial, Helvetica, sans-serif;
+    font-family: var(--sapFontFamily);
   }
   #storybook-explorer-searchfield {
-    background: transparent !important;
+    font-size: var(--sapFontSize);
+    box-sizing: border-box;
+    border: 0;
+    white-space: nowrap;
+    text-overflow: ellipsis;
+    height: var(--sapElement_Height);
+    min-height: var(--sapElement_Height);
+    border-radius: var(--sapField_BorderCornerRadius);
+    padding-inline-end: 0.625rem;
+    box-shadow: var(--sapField_Shadow);
+    color: var(--sapField_TextColor);
+    background: var(--sapField_BackgroundStyle, var(--sapField_BackgroundStyle));
+    background-color: var(--sapField_Background, var(--sapField_Background));
+    border: var(--sapField_BorderWidth) var(--sapField_BorderStyle) var(--sapField_BorderColor);
+  }
+
+  #storybook-explorer-searchfield:hover {
+    background: var(--sapField_Hover_BackgroundStyle, var(--sapField_Hover_BackgroundStyle));
+    background-color: var(--sapField_Hover_Background, var(--sapField_Hover_Background));
+    border-color: var(--sapField_Hover_BorderColor);
+    box-shadow: var(--sapField_Hover_Shadow);
+  }
+
+  #storybook-explorer-searchfield:focus {
+    background: var(--sapField_Focus_Background, var(--sapField_Focus_Background));
+    outline: var(--sapField_Active_BorderColor) var(--sapContent_FocusStyle) var(--sapContent_FocusWidth);
+    outline-offset: -0.125rem;
+    box-shadow: none;
   }
 
   .docblock-argstable-body label[title] {

.storybook/preview-head.html

@@ -1,6 +1,13 @@
 <style>
+  html[data-sap-theme]:not([data-sap-theme*='hc']),
+  /*fallback*/
+  html:not([data-sap-theme]) {
+    forced-color-adjust: none;
+  }
+
   body {
     font-family: var(--sapFontFamily);
+    color: var(--sapTextColor);
     background-color: var(--sapBackgroundColor);
   }
 
@@ -69,7 +76,7 @@
   }
 
   .dynamicPageStickyContent::part(fit-content) {
-      position: static;
+    position: static;
   }
 
   /* TODO remove this workaround as soon as https://github.com/storybookjs/storybook/issues/20497 is fixed */