Move all remaining colors into CSS variables (#21903)

This should eliminate all non-variable color usage in the styles, making
gitea fully themeable via CSS variables. Also, it adds a linter to
enforce variables for colors.

.stylelintrc.yaml

 extends: stylelint-config-standard
 
+plugins:
+  - stylelint-declaration-strict-value
+
 overrides:
   - files: ["**/*.less"]
     customSyntax: postcss-less
+  - files: ["**/*.less"]
+    rules:
+      scale-unlimited/declaration-strict-value: [color, {
+        ignoreValues: /^(inherit|transparent|unset|initial)$/
+      }]
+  - files: ["**/chroma/*", "**/codemirror/*", "**/standalone/*", "**/console/*"]
+    rules:
+      scale-unlimited/declaration-strict-value: null
 
 rules:
   alpha-value-notation: null

package-lock.json

         "postcss-less": "6.0.0",
         "stylelint": "14.15.0",
         "stylelint-config-standard": "29.0.0",
+        "stylelint-declaration-strict-value": "1.9.1",
         "svgo": "3.0.2",
         "updates": "13.2.1",
         "vitest": "0.25.2"
         "node": ">= 8"
       }
     },
+    "node_modules/css-color-names": {
+      "version": "0.0.4",
+      "resolved": "https://registry.npmjs.org/css-color-names/-/css-color-names-0.0.4.tgz",
+      "integrity": "sha512-zj5D7X1U2h2zsXOAM8EyUREBnnts6H+Jm+d1M2DbiQQcUtnqgQsMrdo8JW9R80YFUmIdBZeMu5wvYM7hcgWP/Q==",
+      "dev": true,
+      "engines": {
+        "node": "*"
+      }
+    },
     "node_modules/css-functions-list": {
       "version": "3.1.0",
       "resolved": "https://registry.npmjs.org/css-functions-list/-/css-functions-list-3.1.0.tgz",
         "url": "https://github.com/sponsors/fb55"
       }
     },
+    "node_modules/css-shorthand-properties": {
+      "version": "1.1.1",
+      "resolved": "https://registry.npmjs.org/css-shorthand-properties/-/css-shorthand-properties-1.1.1.tgz",
+      "integrity": "sha512-Md+Juc7M3uOdbAFwOYlTrccIZ7oCFuzrhKYQjdeUEW/sE1hv17Jp/Bws+ReOPpGVBTYCBoYo+G17V5Qo8QQ75A==",
+      "dev": true
+    },
     "node_modules/css-tree": {
       "version": "2.2.1",
       "resolved": "https://registry.npmjs.org/css-tree/-/css-tree-2.2.1.tgz",
         "npm": ">=7.0.0"
       }
     },
+    "node_modules/css-values": {
+      "version": "0.1.0",
+      "resolved": "https://registry.npmjs.org/css-values/-/css-values-0.1.0.tgz",
+      "integrity": "sha512-hQ6JSn4t/70aOCvdlP9zTOsFFUifMSKWz3PX7rz5NZl+uEHCqTFVJJvfP07isErCGEVHYoc8Orja8wLKZRvOeg==",
+      "dev": true,
+      "dependencies": {
+        "css-color-names": "0.0.4",
+        "ends-with": "^0.2.0",
+        "postcss-value-parser": "^3.3.0"
+      }
+    },
+    "node_modules/css-values/node_modules/postcss-value-parser": {
+      "version": "3.3.1",
+      "resolved": "https://registry.npmjs.org/postcss-value-parser/-/postcss-value-parser-3.3.1.tgz",
+      "integrity": "sha512-pISE66AbVkp4fDQ7VHBwRNXzAAKJjw4Vw7nWI/+Q3vuly7SNfgYXvm6i5IgFylHGK5sP/xHAbB7N49OS4gWNyQ==",
+      "dev": true
+    },
     "node_modules/css-what": {
       "version": "6.1.0",
       "resolved": "https://registry.npmjs.org/css-what/-/css-what-6.1.0.tgz",
         "node": ">= 4"
       }
     },
+    "node_modules/ends-with": {
+      "version": "0.2.0",
+      "resolved": "https://registry.npmjs.org/ends-with/-/ends-with-0.2.0.tgz",
+      "integrity": "sha512-lRppY4dK3VkqBdR242sKcAJeYc8Gf/DhoX9AWvWI2RzccmLnqBQfwm2k4oSDv5MPDjUqawCauXhZkyWxkVhRsg==",
+      "dev": true,
+      "engines": {
+        "node": ">=0.10.0"
+      }
+    },
     "node_modules/enhanced-resolve": {
       "version": "5.10.0",
       "resolved": "https://registry.npmjs.org/enhanced-resolve/-/enhanced-resolve-5.10.0.tgz",
         "node": ">=8"
       }
     },
+    "node_modules/shortcss": {
+      "version": "0.1.3",
+      "resolved": "https://registry.npmjs.org/shortcss/-/shortcss-0.1.3.tgz",
+      "integrity": "sha512-MIOoTd99CIGTrAuGiMUx9VZrnrZmWzEHuKbGM/w+ia/w98cezhlN9w4aQOVSxswdoqkUnWrMw3tThOi3sevZAg==",
+      "dev": true,
+      "dependencies": {
+        "css-shorthand-properties": "^1.0.0"
+      }
+    },
     "node_modules/side-channel": {
       "version": "1.0.4",
       "resolved": "https://registry.npmjs.org/side-channel/-/side-channel-1.0.4.tgz",
         "stylelint": "^14.14.0"
       }
     },
+    "node_modules/stylelint-declaration-strict-value": {
+      "version": "1.9.1",
+      "resolved": "https://registry.npmjs.org/stylelint-declaration-strict-value/-/stylelint-declaration-strict-value-1.9.1.tgz",
+      "integrity": "sha512-iIkMh2ukIfSTtJoEDgGq5cqUyYWP8NExPk2YSGcePtFikb7KmJoSi0QYajiZRxge/PTbYspci7nIcrtArJlAsw==",
+      "dev": true,
+      "dependencies": {
+        "css-values": "^0.1.0",
+        "shortcss": "^0.1.3"
+      },
+      "peerDependencies": {
+        "stylelint": ">=7 <=14"
+      }
+    },
     "node_modules/stylelint/node_modules/balanced-match": {
       "version": "2.0.0",
       "resolved": "https://registry.npmjs.org/balanced-match/-/balanced-match-2.0.0.tgz",
         "which": "^2.0.1"
       }
     },
+    "css-color-names": {
+      "version": "0.0.4",
+      "resolved": "https://registry.npmjs.org/css-color-names/-/css-color-names-0.0.4.tgz",
+      "integrity": "sha512-zj5D7X1U2h2zsXOAM8EyUREBnnts6H+Jm+d1M2DbiQQcUtnqgQsMrdo8JW9R80YFUmIdBZeMu5wvYM7hcgWP/Q==",
+      "dev": true
+    },
     "css-functions-list": {
       "version": "3.1.0",
       "resolved": "https://registry.npmjs.org/css-functions-list/-/css-functions-list-3.1.0.tgz",
         "nth-check": "^2.0.1"
       }
     },
+    "css-shorthand-properties": {
+      "version": "1.1.1",
+      "resolved": "https://registry.npmjs.org/css-shorthand-properties/-/css-shorthand-properties-1.1.1.tgz",
+      "integrity": "sha512-Md+Juc7M3uOdbAFwOYlTrccIZ7oCFuzrhKYQjdeUEW/sE1hv17Jp/Bws+ReOPpGVBTYCBoYo+G17V5Qo8QQ75A==",
+      "dev": true
+    },
     "css-tree": {
       "version": "2.2.1",
       "resolved": "https://registry.npmjs.org/css-tree/-/css-tree-2.2.1.tgz",
         "source-map-js": "^1.0.1"
       }
     },
+    "css-values": {
+      "version": "0.1.0",
+      "resolved": "https://registry.npmjs.org/css-values/-/css-values-0.1.0.tgz",
+      "integrity": "sha512-hQ6JSn4t/70aOCvdlP9zTOsFFUifMSKWz3PX7rz5NZl+uEHCqTFVJJvfP07isErCGEVHYoc8Orja8wLKZRvOeg==",
+      "dev": true,
+      "requires": {
+        "css-color-names": "0.0.4",
+        "ends-with": "^0.2.0",
+        "postcss-value-parser": "^3.3.0"
+      },
+      "dependencies": {
+        "postcss-value-parser": {
+          "version": "3.3.1",
+          "resolved": "https://registry.npmjs.org/postcss-value-parser/-/postcss-value-parser-3.3.1.tgz",
+          "integrity": "sha512-pISE66AbVkp4fDQ7VHBwRNXzAAKJjw4Vw7nWI/+Q3vuly7SNfgYXvm6i5IgFylHGK5sP/xHAbB7N49OS4gWNyQ==",
+          "dev": true
+        }
+      }
+    },
     "css-what": {
       "version": "6.1.0",
       "resolved": "https://registry.npmjs.org/css-what/-/css-what-6.1.0.tgz",
       "resolved": "https://registry.npmjs.org/emojis-list/-/emojis-list-3.0.0.tgz",
       "integrity": "sha512-/kyM18EfinwXZbno9FyUGeFh87KC8HRQBQGildHZbEuRyWFOmv1U10o9BBp8XVZDVNNuQKyIGIu5ZYAAXJ0V2Q=="
     },
+    "ends-with": {
+      "version": "0.2.0",
+      "resolved": "https://registry.npmjs.org/ends-with/-/ends-with-0.2.0.tgz",
+      "integrity": "sha512-lRppY4dK3VkqBdR242sKcAJeYc8Gf/DhoX9AWvWI2RzccmLnqBQfwm2k4oSDv5MPDjUqawCauXhZkyWxkVhRsg==",
+      "dev": true
+    },
     "enhanced-resolve": {
       "version": "5.10.0",
       "resolved": "https://registry.npmjs.org/enhanced-resolve/-/enhanced-resolve-5.10.0.tgz",
       "resolved": "https://registry.npmjs.org/shebang-regex/-/shebang-regex-3.0.0.tgz",
       "integrity": "sha512-7++dFhtcx3353uBaq8DDR4NuxBetBzC7ZQOhmTQInHEd6bSrXdiEyzCvG07Z44UYdLShWUyXt5M/yhz8ekcb1A=="
     },
+    "shortcss": {
+      "version": "0.1.3",
+      "resolved": "https://registry.npmjs.org/shortcss/-/shortcss-0.1.3.tgz",
+      "integrity": "sha512-MIOoTd99CIGTrAuGiMUx9VZrnrZmWzEHuKbGM/w+ia/w98cezhlN9w4aQOVSxswdoqkUnWrMw3tThOi3sevZAg==",
+      "dev": true,
+      "requires": {
+        "css-shorthand-properties": "^1.0.0"
+      }
+    },
     "side-channel": {
       "version": "1.0.4",
       "resolved": "https://registry.npmjs.org/side-channel/-/side-channel-1.0.4.tgz",
         "stylelint-config-recommended": "^9.0.0"
       }
     },
+    "stylelint-declaration-strict-value": {
+      "version": "1.9.1",
+      "resolved": "https://registry.npmjs.org/stylelint-declaration-strict-value/-/stylelint-declaration-strict-value-1.9.1.tgz",
+      "integrity": "sha512-iIkMh2ukIfSTtJoEDgGq5cqUyYWP8NExPk2YSGcePtFikb7KmJoSi0QYajiZRxge/PTbYspci7nIcrtArJlAsw==",
+      "dev": true,
+      "requires": {
+        "css-values": "^0.1.0",
+        "shortcss": "^0.1.3"
+      }
+    },
     "stylis": {
       "version": "4.1.3",
       "resolved": "https://registry.npmjs.org/stylis/-/stylis-4.1.3.tgz",

package.json

     "postcss-less": "6.0.0",
     "stylelint": "14.15.0",
     "stylelint-config-standard": "29.0.0",
+    "stylelint-declaration-strict-value": "1.9.1",
     "svgo": "3.0.2",
     "updates": "13.2.1",
     "vitest": "0.25.2"

web_src/less/_base.less

   --color-info-border: #a9d5de;
   --color-info-bg: #f8ffff;
   --color-info-text: #276f86;
+  --color-red-badge: #db2828;
+  --color-red-badge-bg: #db28281a;
+  --color-red-badge-hover-bg: #db28284d;
+  --color-green-badge: #21ba45;
+  --color-green-badge-bg: #21ba451a;
+  --color-green-badge-hover-bg: #21ba454d;
+  --color-yellow-badge: #fbbd08;
+  --color-yellow-badge-bg: #fbbd081a;
+  --color-yellow-badge-hover-bg: #fbbd084d;
+  --color-orange-badge: #f2711c;
+  --color-orange-badge-bg: #f2711c1a;
+  --color-orange-badge-hover-bg: #f2711c4d;
+  --color-git: #f05133;
+  /* target-based colors */
   --color-body: #ffffff;
   --color-text-dark: #080808;
   --color-text: #212121;
   }
 
   .searchbox {
-    background-color: #f4f4f4 !important;
-
-    &:focus {
-      background-color: #e9e9e9 !important;
-    }
+    background-color: var(--color-input-background) !important;
   }
 
   .text .svg {
 }
 
 .archived-icon {
-  color: lighten(#000000, 70%) !important;
+  color: var(--color-secondary-dark-2) !important;
 }
 
 .oauth2-authorize-application-box {
 .lines-commit {
   &:extend(.unselectable);
   vertical-align: top;
-  color: #999999;
+  color: var(--color-grey);
   padding: 0 !important;
   background: var(--color-code-sidebar-bg);
   width: 1%;
   color: var(--color-text);
 }
 
+.ui.active.button,
 .ui.button:active,
 .ui.active.button:active,
 .ui.active.button:hover {
 }
 
 .migrate .svg.gitea-git {
-  color: #f05133; /* from https://upload.wikimedia.org/wikipedia/commons/e/e0/Git-logo.svg */
+  color: var(--color-git);
 }
 
 .color-icon {

web_src/less/_dashboard.less

     }
 
     #privateFilterCheckbox .svg {
-      color: #888888;
+      color: var(--color-grey);
       margin-right: .25rem;
     }
 

web_src/less/_install.less

     .reinstall-message {
       width: 70%;
       margin: 20px auto;
-      color: red;
+      color: var(--color-red);
       text-align: left;
       font-weight: bold;
     }

web_src/less/_repository.less

             position: absolute;
             top: 9px;
             left: 10px;
-            color: #b0c4ce;
+            color: var(--color-grey);
           }
         }
       }
                 border: 1px solid var(--color-light-border);
 
                 &.isSigned.isWarning {
-                  border: 1px solid #db2828;
-                  background: fade(#db2828, 10%);
+                  border: 1px solid var(--color-red-badge);
+                  background: var(--color-red-badge-bg);
 
                   .shortsha {
                     display: inline-block;
                   }
 
                   &:hover {
-                    background: fade(#db2828, 30%) !important;
+                    background: var(--color-red-badge-hover-bg) !important;
                   }
                 }
 
                 &.isSigned.isVerified {
-                  border: 1px solid #21ba45;
-                  background: fade(#21ba45, 10%);
+                  border: 1px solid var(--color-green-badge);
+                  background: var(--color-green-badge-bg);
 
                   .shortsha {
                     display: inline-block;
                   }
 
                   &:hover {
-                    background: fade(#21ba45, 30%) !important;
+                    background: var(--color-green-badge-hover-bg) !important;
                   }
                 }
 
                 &.isSigned.isVerifiedUntrusted {
-                  border: 1px solid #fbbd08;
-                  background: fade(#fbbd08, 10%);
+                  border: 1px solid var(--color-yellow-badge);
+                  background: var(--color-yellow-badge-bg);
 
                   .shortsha {
                     display: inline-block;
                   }
 
                   &:hover {
-                    background: fade(#fbbd08, 30%) !important;
+                    background: var(--color-yellow-badge-hover-bg) !important;
                   }
                 }
 
                 &.isSigned.isVerifiedUnmatched {
-                  border: 1px solid #f2711c;
-                  background: fade(#f2711c, 10%);
+                  border: 1px solid var(--color-orange-badge);
+                  background: var(--color-orange-badge-bg);
 
                   .shortsha {
                     display: inline-block;
                   }
 
                   &:hover {
-                    background: fade(#f2711c, 30%) !important;
+                    background: var(--color-orange-badge-hover-bg) !important;
                   }
                 }
               }
     }
 
     &.isSigned.isWarning {
-      border: 1px solid #db2828;
-      background: fade(#db2828, 10%);
+      border: 1px solid var(--color-red-badge);
+      background: var(--color-red-badge-bg);
 
       .shortsha {
         display: inline-block;
       }
 
       .detail.icon {
-        border-left: 1px solid #db2828;
-        color: #db2828;
+        border-left: 1px solid var(--color-red-badge);
+        color: var(--color-red-badge);
       }
 
       &:hover {
-        background: fade(#db2828, 30%) !important;
+        background: var(--color-red-badge-hover-bg) !important;
       }
     }
 
     &.isSigned.isVerified {
-      border: 1px solid #21ba45;
-      background: fade(#21ba45, 10%);
+      border: 1px solid var(--color-green-badge);
+      background: var(--color-green-badge-bg);
 
       .shortsha {
         display: inline-block;
       }
 
       .detail.icon {
-        border-left: 1px solid #21ba45;
-        color: #21ba45;
+        border-left: 1px solid var(--color-green-badge);
+        color: var(--color-green-badge);
       }
 
       &:hover {
-        background: fade(#21ba45, 30%) !important;
+        background: var(--color-green-badge-hover-bg) !important;
       }
     }
 
     &.isSigned.isVerifiedUntrusted {
-      border: 1px solid #fbbd08;
-      background: fade(#fbbd08, 10%);
+      border: 1px solid var(--color-yellow-badge);
+      background: var(--color-yellow-badge-bg);
 
       .shortsha {
         display: inline-block;
       }
 
       .detail.icon {
-        border-left: 1px solid #fbbd08;
-        color: #fbbd08;
+        border-left: 1px solid var(--color-yellow-badge);
+        color: var(--color-yellow-badge);
       }
 
       &:hover {
-        background: fade(#fbbd08, 30%) !important;
+        background: var(--color-yellow-badge-hover-bg) !important;
       }
     }
 
     &.isSigned.isVerifiedUnmatched {
-      border: 1px solid #f2711c;
-      background: fade(#f2711c, 10%);
+      border: 1px solid var(--color-orange-badge);
+      background: var(--color-orange-badge-bg);
 
       .shortsha {
         display: inline-block;
       }
 
       .detail.icon {
-        border-left: 1px solid #f2711c;
-        color: #f2711c;
+        border-left: 1px solid var(--color-orange-badge);
+        color: var(--color-orange-badge);
       }
 
       &:hover {
-        background: fade(#f2711c, 30%) !important;
+        background: var(--color-orange-badge-hover-bg) !important;
       }
     }
   }

web_src/less/themes/theme-arc-green.less

   --color-info-border: #306090;
   --color-info-bg: #26354c;
   --color-info-text: #38a8e8;
+  --color-red-badge: #db2828;
+  --color-red-badge-bg: #db28281a;
+  --color-red-badge-hover-bg: #db28284d;
+  --color-green-badge: #21ba45;
+  --color-green-badge-bg: #21ba451a;
+  --color-green-badge-hover-bg: #21ba454d;
+  --color-yellow-badge: #fbbd08;
+  --color-yellow-badge-bg: #fbbd081a;
+  --color-yellow-badge-hover-bg: #fbbd084d;
+  --color-orange-badge: #f2711c;
+  --color-orange-badge-bg: #f2711c1a;
+  --color-orange-badge-hover-bg: #f2711c4d;
+  --color-git: #f05133;
   /* target-based colors */
   --color-body: #383c4a;
   --color-box-header: #404652;