Light theme color enhancements (#29830)

Same as https://github.com/go-gitea/gitea/pull/29822 but for light
theme. Slight shift towards blue and made the themes match more, like on
header and footer background.

Before
<img width="1342" alt="Screenshot 2024-03-16 at 00 43 03"
src="https://github.com/go-gitea/gitea/assets/115237/b46021a1-241c-446a-b220-ca25cc90f3bf">


After
<img width="1343" alt="Screenshot 2024-03-16 at 00 45 21"
src="https://github.com/go-gitea/gitea/assets/115237/1c898875-a6bb-4bd3-b059-f82e1a145c99">


Before
<img width="1018" alt="Screenshot 2024-03-16 at 00 43 13"
src="https://github.com/go-gitea/gitea/assets/115237/d237ee7d-b4cc-4688-a074-1e96515ac475">

After
<img width="1022" alt="Screenshot 2024-03-16 at 00 43 50"
src="https://github.com/go-gitea/gitea/assets/115237/89b1da77-6bc9-4b38-9688-546e794aadfa">

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

@@ -30,33 +30,33 @@
   --color-primary-alpha-90: #4183c4e1;
   --color-primary-hover: var(--color-primary-dark-1);
   --color-primary-active: var(--color-primary-dark-2);
-  --color-secondary: #dedede;
-  --color-secondary-dark-1: #cecece;
-  --color-secondary-dark-2: #bfbfbf;
-  --color-secondary-dark-3: #a0a0a0;
-  --color-secondary-dark-4: #909090;
-  --color-secondary-dark-5: #818181;
-  --color-secondary-dark-6: #717171;
-  --color-secondary-dark-7: #626262;
-  --color-secondary-dark-8: #525252;
-  --color-secondary-dark-9: #434343;
-  --color-secondary-dark-10: #333333;
-  --color-secondary-dark-11: #242424;
-  --color-secondary-dark-12: #141414;
-  --color-secondary-dark-13: #040404;
-  --color-secondary-light-1: #e5e5e5;
-  --color-secondary-light-2: #ebebeb;
-  --color-secondary-light-3: #f2f2f2;
-  --color-secondary-light-4: #f8f8f8;
-  --color-secondary-alpha-10: #dedede19;
-  --color-secondary-alpha-20: #dedede33;
-  --color-secondary-alpha-30: #dedede4b;
-  --color-secondary-alpha-40: #dedede66;
-  --color-secondary-alpha-50: #dedede80;
-  --color-secondary-alpha-60: #dedede99;
-  --color-secondary-alpha-70: #dededeb3;
-  --color-secondary-alpha-80: #dededecc;
-  --color-secondary-alpha-90: #dededee1;
+  --color-secondary: #d0d7de;
+  --color-secondary-dark-1: #c7ced5;
+  --color-secondary-dark-2: #b9c0c7;
+  --color-secondary-dark-3: #99a0a7;
+  --color-secondary-dark-4: #899097;
+  --color-secondary-dark-5: #7a8188;
+  --color-secondary-dark-6: #6a7178;
+  --color-secondary-dark-7: #5b6269;
+  --color-secondary-dark-8: #4b5259;
+  --color-secondary-dark-9: #3c434a;
+  --color-secondary-dark-10: #2c333a;
+  --color-secondary-dark-11: #1d242b;
+  --color-secondary-dark-12: #0d141b;
+  --color-secondary-dark-13: #00040b;
+  --color-secondary-light-1: #dee5ec;
+  --color-secondary-light-2: #e4ebf2;
+  --color-secondary-light-3: #ebf2f9;
+  --color-secondary-light-4: #f1f8ff;
+  --color-secondary-alpha-10: #d0d7de19;
+  --color-secondary-alpha-20: #d0d7de33;
+  --color-secondary-alpha-30: #d0d7de4b;
+  --color-secondary-alpha-40: #d0d7de66;
+  --color-secondary-alpha-50: #d0d7de80;
+  --color-secondary-alpha-60: #d0d7de99;
+  --color-secondary-alpha-70: #d0d7deb3;
+  --color-secondary-alpha-80: #d0d7decc;
+  --color-secondary-alpha-90: #d0d7dee1;
   --color-secondary-button: var(--color-secondary-dark-4);
   --color-secondary-hover: var(--color-secondary-dark-5);
   --color-secondary-active: var(--color-secondary-dark-6);
@@ -81,7 +81,7 @@
   --color-purple: #a333c8;
   --color-pink: #e03997;
   --color-brown: #a5673f;
-  --color-black: #1b1c1d;
+  --color-black: #191c1d;
   /* light variants - produced via Sass scale-color(color, $lightness: +25%) */
   --color-red-light: #e45e5e;
   --color-orange-light: #f59555;
@@ -107,7 +107,7 @@
   --color-purple-dark-1: #932eb4;
   --color-pink-dark-1: #db228a;
   --color-brown-dark-1: #955d39;
-  --color-black-dark-1: #18191a;
+  --color-black-dark-1: #16191c;
   /* dark 2 variants - produced via Sass scale-color(color, $lightness: -20%) */
   --color-red-dark-2: #b11e1e;
   --color-orange-dark-2: #cc580c;
@@ -120,7 +120,7 @@
   --color-purple-dark-2: #8229a0;
   --color-pink-dark-2: #c21e7b;
   --color-brown-dark-2: #845232;
-  --color-black-dark-2: #161617;
+  --color-black-dark-2: #131619;
   /* ansi colors used for actions console and console files */
   --color-ansi-black: #1f2326;
   --color-ansi-red: #cc4848;
@@ -139,8 +139,8 @@
   --color-ansi-bright-cyan: #00b6ad;
   --color-ansi-bright-white: var(--color-console-fg);
   /* other colors */
-  --color-grey: #707070;
-  --color-grey-light: #838383;
+  --color-grey: #697077;
+  --color-grey-light: #7c838a;
   --color-gold: #a1882b;
   --color-white: #ffffff;
   --color-diff-removed-word-bg: #fdb8c0;
@@ -151,7 +151,7 @@
   --color-diff-removed-row-border: #f1c0c0;
   --color-diff-moved-row-border: #d0e27f;
   --color-diff-added-row-border: #e6ffed;
-  --color-diff-inactive: #f2f2f2;
+  --color-diff-inactive: #f0f2f4;
   --color-error-border: #e0b4b4;
   --color-error-bg: #fff6f6;
   --color-error-bg-active: #fbb;
@@ -181,56 +181,56 @@
   --color-git: #f05133;
   /* target-based colors */
   --color-body: #ffffff;
-  --color-box-header: #f7f7f7;
+  --color-box-header: #f1f3f5;
   --color-box-body: #ffffff;
-  --color-box-body-highlight: #fafafa;
-  --color-text-dark: #080808;
-  --color-text: #212121;
-  --color-text-light: #555555;
-  --color-text-light-1: #6a6a6a;
-  --color-text-light-2: #808080;
-  --color-text-light-3: #a0a0a0;
+  --color-box-body-highlight: #f4faff;
+  --color-text-dark: #03080d;
+  --color-text: #1c2126;
+  --color-text-light: #3c434a;
+  --color-text-light-1: #4b5259;
+  --color-text-light-2: #6a7178;
+  --color-text-light-3: #899097;
   --color-footer: var(--color-nav-bg);
-  --color-timeline: #ececec;
+  --color-timeline: #d0d7de;
   --color-input-text: var(--color-text-dark);
-  --color-input-background: #fafafa;
-  --color-input-toggle-background: #dedede;
+  --color-input-background: #f8f9fb;
+  --color-input-toggle-background: #d0d7de;
   --color-input-border: var(--color-secondary);
   --color-input-border-hover: var(--color-secondary-dark-1);
-  --color-header-wrapper: transparent;
-  --color-light: #00000006;
+  --color-header-wrapper: #fafbfc;
+  --color-light: #00001706;
   --color-light-mimic-enabled: rgba(0, 0, 0, calc(6 / 255 * 222 / 255 / var(--opacity-disabled)));
-  --color-light-border: #0000001d;
-  --color-hover: #00000014;
-  --color-active: #0000001b;
-  --color-menu: #fafafa;
-  --color-card: #fafafa;
-  --color-markup-table-row: #00000008;
-  --color-markup-code-block: #00000010;
-  --color-button: #fafafa;
-  --color-code-bg: #ffffff;
-  --color-code-sidebar-bg: #f5f5f5;
-  --color-shadow: #00000026;
-  --color-secondary-bg: #f4f4f4;
+  --color-light-border: #0000171d;
+  --color-hover: #00001708;
+  --color-active: #00001714;
+  --color-menu: #f8f9fb;
+  --color-card: #f8f9fb;
+  --color-markup-table-row: #00001708;
+  --color-markup-code-block: #00001710;
+  --color-button: #f8f9fb;
+  --color-code-bg: #fafdff;
+  --color-code-sidebar-bg: #f2f5f8;
+  --color-shadow: #00001726;
+  --color-secondary-bg: #f2f5f8;
   --color-expand-button: #d8efff;
   --color-placeholder-text: var(--color-text-light-3);
   --color-editor-line-highlight: var(--color-primary-light-6);
   --color-project-board-bg: var(--color-secondary-light-4);
-  --color-project-board-dark-label: #111111;
-  --color-project-board-light-label: #eeeeee;
+  --color-project-board-dark-label: #0e1114;
+  --color-project-board-light-label: #eaeef2;
   --color-caret: var(--color-text-dark);
-  --color-reaction-bg: #0000000a;
+  --color-reaction-bg: #0000170a;
   --color-reaction-hover-bg: var(--color-primary-light-5);
   --color-reaction-active-bg: var(--color-primary-light-6);
-  --color-tooltip-text: #ffffff;
-  --color-tooltip-bg: #000000f0;
-  --color-nav-bg: #ffffff;
+  --color-tooltip-text: #fbfdff;
+  --color-tooltip-bg: #000017f0;
+  --color-nav-bg: #f8f9fb;
   --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;
-  --color-label-hover-bg: #9d9d9da0;
-  --color-label-active-bg: #9d9d9dff;
+  --color-label-bg: #949da64b;
+  --color-label-hover-bg: #949da6a0;
+  --color-label-active-bg: #949da6ff;
   --color-accent: var(--color-primary-light-1);
   --color-small-accent: var(--color-primary-light-6);
   --color-active-line: #fffbdd;