Dark theme color enhancements (#29822)

- Few very minor colors tweaks to dark theme. Slightly darker
background, slightly bluer secondary colors.
- Alias `--color-nav-hover-bg` in both themes.

Before:
<img width="1013" alt="Screenshot 2024-03-15 at 18 43 59"
src="https://github.com/go-gitea/gitea/assets/115237/ce4bdb0d-6e25-4fd6-88f5-dc8f9e3093cd">

After:
<img width="1016" alt="Screenshot 2024-03-15 at 19 02 04"
src="https://github.com/go-gitea/gitea/assets/115237/4a6dd5a1-a5b4-4fc2-9835-05a0c2c58c42">


Before:
<img width="1340" alt="Screenshot 2024-03-15 at 18 40 19"
src="https://github.com/go-gitea/gitea/assets/115237/4465fa9c-d529-4a05-94d7-e21080e0a153">

After:
<img width="1341" alt="Screenshot 2024-03-15 at 19 00 51"
src="https://github.com/go-gitea/gitea/assets/115237/6595afef-592b-42c4-a6cd-196968ba5881">

web_src/css/themes/theme-gitea-dark.css

@@ -30,45 +30,45 @@
   --color-primary-alpha-90: #4183c4e1;
   --color-primary-hover: var(--color-primary-light-1);
   --color-primary-active: var(--color-primary-light-2);
-  --color-secondary: #3f4346;
-  --color-secondary-dark-1: #464a4d;
-  --color-secondary-dark-2: #4f5356;
-  --color-secondary-dark-3: #5f6366;
-  --color-secondary-dark-4: #72767a;
-  --color-secondary-dark-5: #7f8488;
-  --color-secondary-dark-6: #8d9297;
-  --color-secondary-dark-7: #999ea3;
-  --color-secondary-dark-8: #a6abaf;
-  --color-secondary-dark-9: #aeb3b8;
-  --color-secondary-dark-10: #babfc4;
-  --color-secondary-dark-11: #c5cbd0;
-  --color-secondary-dark-12: #ced4da;
-  --color-secondary-dark-13: #d1d7dd;
-  --color-secondary-light-1: #313538;
-  --color-secondary-light-2: #272b2e;
-  --color-secondary-light-3: #1e2225;
-  --color-secondary-light-4: #171b1e;
-  --color-secondary-alpha-10: #3f434619;
-  --color-secondary-alpha-20: #3f434633;
-  --color-secondary-alpha-30: #3f43464b;
-  --color-secondary-alpha-40: #3f434666;
-  --color-secondary-alpha-50: #3f434680;
-  --color-secondary-alpha-60: #3f434699;
-  --color-secondary-alpha-70: #3f4346b3;
-  --color-secondary-alpha-80: #3f4346cc;
-  --color-secondary-alpha-90: #3f4346e1;
+  --color-secondary: #3b444a;
+  --color-secondary-dark-1: #424b51;
+  --color-secondary-dark-2: #4a545b;
+  --color-secondary-dark-3: #59646c;
+  --color-secondary-dark-4: #6b7681;
+  --color-secondary-dark-5: #78858f;
+  --color-secondary-dark-6: #87929d;
+  --color-secondary-dark-7: #939ea9;
+  --color-secondary-dark-8: #a1acb4;
+  --color-secondary-dark-9: #aab3bc;
+  --color-secondary-dark-10: #b6bfc8;
+  --color-secondary-dark-11: #c2cbd3;
+  --color-secondary-dark-12: #ccd4dc;
+  --color-secondary-dark-13: #cfd7df;
+  --color-secondary-light-1: #2e353b;
+  --color-secondary-light-2: #2b353e;
+  --color-secondary-light-3: #1c2227;
+  --color-secondary-light-4: #161b1f;
+  --color-secondary-alpha-10: #3b444a19;
+  --color-secondary-alpha-20: #3b444a33;
+  --color-secondary-alpha-30: #3b444a4b;
+  --color-secondary-alpha-40: #3b444a66;
+  --color-secondary-alpha-50: #3b444a80;
+  --color-secondary-alpha-60: #3b444a99;
+  --color-secondary-alpha-70: #3b444ab3;
+  --color-secondary-alpha-80: #3b444acc;
+  --color-secondary-alpha-90: #3b444ae1;
   --color-secondary-button: var(--color-secondary-dark-4);
   --color-secondary-hover: var(--color-secondary-dark-3);
   --color-secondary-active: var(--color-secondary-dark-2);
   /* console colors - used for actions console and console files */
   --color-console-fg: #f8f8f9;
   --color-console-fg-subtle: #bec4c8;
-  --color-console-bg: #181b1d;
-  --color-console-border: #313538;
-  --color-console-hover-bg: #ffffff16;
-  --color-console-active-bg: #313538;
-  --color-console-menu-bg: #272b2e;
-  --color-console-menu-border: #464a4d;
+  --color-console-bg: #171b1e;
+  --color-console-border: #2e353b;
+  --color-console-hover-bg: #e8e8ff16;
+  --color-console-active-bg: #2e353b;
+  --color-console-menu-bg: #252b30;
+  --color-console-menu-border: #424b51;
   /* named colors */
   --color-red: #cc4848;
   --color-orange: #cc580c;
@@ -81,7 +81,7 @@
   --color-purple: #b259d0;
   --color-pink: #d22e8b;
   --color-brown: #a47252;
-  --color-black: #1f2326;
+  --color-black: #1d2328;
   /* light variants - produced via Sass scale-color(color, $lightness: +10%) */
   --color-red-light: #d15a5a;
   --color-orange-light: #f6a066;
@@ -94,7 +94,7 @@
   --color-purple-light: #ba6ad5;
   --color-pink-light: #d74397;
   --color-brown-light: #b08061;
-  --color-black-light: #46494d;
+  --color-black-light: #424851;
   /* dark 1 variants - produced via Sass scale-color(color, $lightness: -10%) */
   --color-red-dark-1: #c23636;
   --color-orange-dark-1: #f38236;
@@ -107,7 +107,7 @@
   --color-purple-dark-1: #a742c9;
   --color-pink-dark-1: #be297d;
   --color-brown-dark-1: #94674a;
-  --color-black-dark-1: #2c2f35;
+  --color-black-dark-1: #292e38;
   /* dark 2 variants - produced via Sass scale-color(color, $lightness: -20%) */
   --color-red-dark-2: #ad3030;
   --color-orange-dark-2: #f16e17;
@@ -120,9 +120,9 @@
   --color-purple-dark-2: #9834b9;
   --color-pink-dark-2: #a9246f;
   --color-brown-dark-2: #835b42;
-  --color-black-dark-2: #292a2e;
+  --color-black-dark-2: #272930;
   /* ansi colors used for actions console and console files */
-  --color-ansi-black: #1f2326;
+  --color-ansi-black: #1d2328;
   --color-ansi-red: #cc4848;
   --color-ansi-green: #87ab63;
   --color-ansi-yellow: #cc9903;
@@ -130,7 +130,7 @@
   --color-ansi-magenta: #d22e8b;
   --color-ansi-cyan: #00918a;
   --color-ansi-white: var(--color-console-fg-subtle);
-  --color-ansi-bright-black: #46494d;
+  --color-ansi-bright-black: #424851;
   --color-ansi-bright-red: #d15a5a;
   --color-ansi-bright-green: #93b373;
   --color-ansi-bright-yellow: #eaaf03;
@@ -139,8 +139,8 @@
   --color-ansi-bright-cyan: #00b6ad;
   --color-ansi-bright-white: var(--color-console-fg);
   /* other colors */
-  --color-grey: #3c4043;
-  --color-grey-light: #898e92;
+  --color-grey: #384147;
+  --color-grey-light: #828f99;
   --color-gold: #b1983b;
   --color-white: #ffffff;
   --color-diff-removed-word-bg: #6f3333;
@@ -151,7 +151,7 @@
   --color-diff-removed-row-border: #634343;
   --color-diff-moved-row-border: #bcca6f;
   --color-diff-added-row-border: #314a37;
-  --color-diff-inactive: #24282b;
+  --color-diff-inactive: #22282d;
   --color-error-border: #a04141;
   --color-error-bg: #522;
   --color-error-bg-active: #744;
@@ -180,10 +180,10 @@
   --color-orange-badge-hover-bg: #f2711c4d;
   --color-git: #f05133;
   /* target-based colors */
-  --color-body: #1f2326;
-  --color-box-header: #202427;
-  --color-box-body: #191d20;
-  --color-box-body-highlight: #1d2124;
+  --color-body: #1e2224;
+  --color-box-header: #1a1d1f;
+  --color-box-body: #14171a;
+  --color-box-body-highlight: #121517;
   --color-text-dark: #f8f8f9;
   --color-text: #ced2d5;
   --color-text-light: #bec4c8;
@@ -191,46 +191,46 @@
   --color-text-light-2: #8d969c;
   --color-text-light-3: #747f87;
   --color-footer: var(--color-nav-bg);
-  --color-timeline: #383c3f;
+  --color-timeline: #353c42;
   --color-input-text: var(--color-text-dark);
-  --color-input-background: #161a1d;
-  --color-input-toggle-background: #313538;
+  --color-input-background: #151a1e;
+  --color-input-toggle-background: #2e353b;
   --color-input-border: var(--color-secondary);
   --color-input-border-hover: var(--color-secondary-dark-1);
-  --color-header-wrapper: #191d20;
-  --color-light: #00000028;
+  --color-header-wrapper: #181c20;
+  --color-light: #00001728;
   --color-light-mimic-enabled: rgba(0, 0, 0, calc(40 / 255 * 222 / 255 / var(--opacity-disabled)));
-  --color-light-border: #ffffff28;
-  --color-hover: #ffffff19;
-  --color-active: #ffffff24;
-  --color-menu: #161a1d;
-  --color-card: #161a1d;
-  --color-markup-table-row: #ffffff06;
-  --color-markup-code-block: #ffffff16;
-  --color-button: #161a1d;
+  --color-light-border: #e8e8ff28;
+  --color-hover: #e8e8ff19;
+  --color-active: #e8e8ff24;
+  --color-menu: #151a1e;
+  --color-card: #151a1e;
+  --color-markup-table-row: #e8e8ff06;
+  --color-markup-code-block: #e8e8ff16;
+  --color-button: #151a1e;
   --color-code-bg: #191d20;
   --color-code-sidebar-bg: #1b1f22;
-  --color-shadow: #00000058;
+  --color-shadow: #00001758;
   --color-secondary-bg: #2f3135;
   --color-expand-button: #414348;
   --color-placeholder-text: var(--color-text-light-3);
   --color-editor-line-highlight: var(--color-primary-light-5);
   --color-project-board-bg: var(--color-secondary-light-2);
-  --color-project-board-dark-label: #111111;
-  --color-project-board-light-label: #eeeeee;
+  --color-project-board-dark-label: #0e1011;
+  --color-project-board-light-label: #dde0e2;
   --color-caret: var(--color-text); /* should ideally be --color-text-dark, see #15651 */
-  --color-reaction-bg: #ffffff12;
+  --color-reaction-bg: #e8e8ff12;
   --color-reaction-hover-bg: var(--color-primary-light-4);
   --color-reaction-active-bg: var(--color-primary-light-5);
-  --color-tooltip-text: #ffffff;
-  --color-tooltip-bg: #000000f0;
-  --color-nav-bg: #1b1f22;
-  --color-nav-hover-bg: #272b2e;
+  --color-tooltip-text: #fafafb;
+  --color-tooltip-bg: #000017f0;
+  --color-nav-bg: #16191c;
+  --color-nav-hover-bg: var(--color-secondary-light-1);
   --color-nav-text: var(--color-text);
   --color-label-text: var(--color-text);
-  --color-label-bg: #7a7f834b;
-  --color-label-hover-bg: #7a7f83a0;
-  --color-label-active-bg: #7a7f83ff;
+  --color-label-bg: #73828e4b;
+  --color-label-hover-bg: #73828ea0;
+  --color-label-active-bg: #73828eff;
   --color-accent: var(--color-primary-light-1);
   --color-small-accent: var(--color-primary-light-5);
   --color-active-line: #534d1b;

web_src/css/themes/theme-gitea-light.css

@@ -225,7 +225,7 @@
   --color-tooltip-text: #ffffff;
   --color-tooltip-bg: #000000f0;
   --color-nav-bg: #ffffff;
-  --color-nav-hover-bg: #ebebeb;
+  --color-nav-hover-bg: var(--color-secondary-light-1);
   --color-nav-text: var(--color-text);
   --color-label-text: var(--color-text);
   --color-label-bg: #9d9d9d4b;