update the link colors on darkmode (#4201)

## What are you changing in this pull request and why?

https://app.asana.com/0/1200099998847559/1204216689849797/f

Description of the Issue
Review pages and for any links on backgrounds with the color of #262a38
($neutral100), change the hover color of those links to #1FA4A3
($teal30) so that they have appropriate contrast per
[WebAIM](https://webaim.org/) requirements.

Links
Use the WebAIM web extension to check contrast
https://wave.webaim.org/extension/

NOTE: I limited the brightness on the links a bit since this was causing
unanticipated issues on images washing out. I updated the link color and
link hover color to #1FA4A3 on dark mode.

Preview:

https://docs-getdbt-com-git-fix-insufficient-contrast-o-3250d0-dbt-labs.vercel.app/docs/introduction

## Checklist
<!--
Uncomment if you're publishing docs for a prerelease version of dbt
(delete if not applicable):
- [ ] Add versioning components, as described in [Versioning
Docs](https://github.com/dbt-labs/docs.getdbt.com/blob/current/contributing/single-sourcing-content.md#versioning-entire-pages)
- [ ] Add a note to the prerelease version [Migration
Guide](https://github.com/dbt-labs/docs.getdbt.com/tree/current/website/docs/guides/migration/versions)
-->
- [ ] Review the [Content style
guide](https://github.com/dbt-labs/docs.getdbt.com/blob/current/contributing/content-style-guide.md)
and [About
versioning](https://github.com/dbt-labs/docs.getdbt.com/blob/current/contributing/single-sourcing-content.md#adding-a-new-version)
so my content adheres to these guidelines.
- [ ] Add a checklist item for anything that needs to happen before this
PR is merged, such as "needs technical review" or "change base branch."

Adding new pages (delete if not applicable):
- [ ] Add page to `website/sidebars.js`
- [ ] Provide a unique filename for the new page

Removing or renaming existing pages (delete if not applicable):
- [ ] Remove page from `website/sidebars.js`
- [ ] Add an entry `website/static/_redirects`
- [ ] [Ran link
testing](https://github.com/dbt-labs/docs.getdbt.com#running-the-cypress-tests-locally)
to update the links that point to the deleted page

website/src/css/custom.css

@@ -58,7 +58,7 @@
   --pagination-icon-prev: "\2190";
   --filter-brightness-low: 1.1;
   --filter-brightness-high: 1.5;
-
+  --darkmode-link-color: #1FA4A3;
   --light-dark-toggle: "data:image/svg+xml;base64,PHN2ZyB3aWR0aD0iMTYiIGhlaWdodD0iMTYiIGZpbGw9Im5vbmUiIHhtbG5zPSJodHRwOi8vd3d3LnczLm9yZy8yMDAwL3N2ZyI+PHBhdGggZD0iTTQuMzA4IDMuMzg1YzAtMS4xNzguMTczLTIuMzcuNjE1LTMuMzg1QzEuOTgzIDEuMjggMCA0LjI4MiAwIDcuNjkyQTguMzA4IDguMzA4IDAgMCAwIDguMzA4IDE2YzMuNDEgMCA2LjQxMi0xLjk4MyA3LjY5Mi00LjkyMy0xLjAxNS40NDItMi4yMDcuNjE1LTMuMzg1LjYxNWE4LjMwOCA4LjMwOCAwIDAgMS04LjMwNy04LjMwN1oiIGZpbGw9IiM5MkEwQjMiLz48L3N2Zz4=";
 
   /* search overrides */
@@ -104,10 +104,10 @@ html[data-theme="dark"] {
 
 /* Linked `code` tags visibility adjustment */
 html[data-theme=dark] a code {
-  color: var(--ifm-link-color);
+  color: var(--darkmode-link-color);
 }
 html[data-theme=dark] a code:hover {
-  color: var(--ifm-link-hover-color);;
+  color: var(--darkmode-link-color);
 }
 
 /* For /dbt-cloud/api REDOC Page */
@@ -122,11 +122,11 @@ html[data-theme="dark"] .api-content h1 {
 
 html[data-theme="dark"] .api-content button,
 html[data-theme="dark"] .api-content a {
-  filter: brightness(1.25);
+  filter: brightness(var(--filter-brightness-low));
 }
 
 html[data-theme="dark"] .api-content a:hover {
-  filter: brightness(1.25);
+  filter: brightness(var(--filter-brightness-low));
 }
 
 .redoc-wrap .api-content a,
@@ -165,8 +165,19 @@ table td {
   vertical-align: top;
 }
 
+html[data-theme=dark] main .row .col:first-of-type a:not(.button) {
+  color: var(--darkmode-link-color);
+}
+
+html[data-theme="dark"] main .row .col:first-of-type a:hover {
+  filter: brightness(var(--filter-brightness-low));
+}
+
+html[data-theme="dark"] main .row .col:first-of-type a article * {
+  color: white;
+}
+
 html[data-theme="dark"] table td {
-  filter: brightness(1.5);
   color: white;
 }
 
@@ -668,6 +679,14 @@ i.theme-doc-sidebar-item-category.theme-doc-sidebar-item-category-level-2.menu__
   color: var(--ifm-color-gray-900);
 }
 
+.alert--secondary,
+.alert--secondary a,
+.alert--secondary svg {
+  --ifm-alert-background-color: #474748;
+  color: white !important;
+  fill: white !important;
+}
+
 html[data-theme="dark"] .alert * {
   --ifm-alert-foreground-color: var(--ifm-color-gray-900);
 }
@@ -683,7 +702,7 @@ html[data-theme="dark"] .alert table {
 .alert--success a,
 .alert--danger a,
 .alert--warning a {
-  color: var(--ifm-color-gray-900);
+  color: var(--ifm-color-gray-900) !important;
 }
 
 .linkout {
@@ -842,6 +861,14 @@ div .toggle_src-components-faqs-styles-module {
   gap: 1em;
 }
 
+html[data-theme="dark"] .pagination-nav a {
+  color: var(--darkmode-link-color);
+}
+
+html[data-theme="dark"] .pagination-nav a:hover {
+  filter: brightness(var(--filter-brightness-low));
+}
+
 .pagination-nav__link {
   padding: 1rem 0;
   transition: 100ms all ease-in-out;
@@ -948,8 +975,13 @@ html[data-theme="dark"] .blog-breadcrumbs a[href="#"] {
   filter: brightness(var(--filter-brightness-low));
 }
 
-html[data-theme="dark"] .blog-breadcrumbs a:not(:last-of-type):after {
-  color: var(--ifm-link-color);
+html[data-theme="dark"] .blog-breadcrumbs a:hover {
+  filter: brightness(var(--filter-brightness-low));
+}
+
+html[data-theme="dark"] .blog-breadcrumbs a:not(:last-of-type):after,
+html[data-theme="dark"] .blog-breadcrumbs a {
+  color: var(--darkmode-link-color);
 }
 
 html[data-theme="dark"] .breadcrumbs__item--active .breadcrumbs__link {
@@ -993,6 +1025,21 @@ article[itemprop="blogPost"] h2 {
   font-size: 2rem;
 }
 
+html[data-theme="dark"] article[itemprop="blogPost"] a {
+  color: var(--darkmode-link-color);
+}
+
+html[data-theme="dark"] article[itemprop="blogPost"] a:hover {
+  filter: brightness(var(--filter-brightness-low));
+}
+
+/* Sidebar Nav */
+html[data-theme="dark"] .main-wrapper nav a:hover,
+html[data-theme="dark"] .main-wrapper nav a:active {
+  color: var(--darkmode-link-color) !important;
+  filter: brightness(var(--filter-brightness-low));
+}
+
 /* footer styles */
 .footer {
   font-weight: var(--ifm-font-weight-narrow);
@@ -1053,7 +1100,7 @@ article[itemprop="blogPost"] h2 {
 /* copyright */
 .footer__bottom {
   text-align: left;
-  color: var(--color-footer-accent);
+  color: white;
   font-size: 0.875rem;
 }