Various UI and arc-green fixes (#13291)

- introduce variable for border-radius value
- fix some white borders in arc-green
- add text selection and placeholder in arc-green
- tweak branch list footer
- more things I forgot

Co-authored-by: Lauris BH <lauris@nix.lv>
Co-authored-by: techknowlogick <techknowlogick@gitea.io>
Co-authored-by: zeripath <art27@cantab.net>

web_src/less/_repository.less

@@ -248,7 +248,7 @@
       padding: 0 5px;
 
       &:first-child {
-        border-radius: .28571429rem 0 0 .28571429rem;
+        border-radius: var(--border-radius) 0 0 var(--border-radius);
       }
     }
 
@@ -1948,7 +1948,7 @@
       }
 
       .clone.button:first-child {
-        border-radius: .28571429rem 0 0 .28571429rem;
+        border-radius: var(--border-radius) 0 0 var(--border-radius);
       }
 
       .ui.action.small.input {
@@ -2390,7 +2390,14 @@
 
       .item {
         width: 100%;
-        border-radius: 3px;
+
+        &:first-of-type {
+          border-radius: var(--border-radius) 0 0 var(--border-radius);
+        }
+
+        &:last-of-type {
+          border-radius: 0 var(--border-radius) var(--border-radius) 0;
+        }
 
         a {
           color: black;
@@ -2499,6 +2506,8 @@
   }
 
   .repository-summary {
+    box-shadow: none !important;
+
     .segment.language-stats-details,
     .segment.repository-summary {
       border-top: none;
@@ -2528,6 +2537,15 @@
     }
   }
 
+  .repository-menu {
+    padding: 0 !important;
+  }
+
+  .repository-menu .item {
+    padding-top: 9px !important;
+    padding-bottom: 9px !important;
+  }
+
   &.diff .committed-by {
     padding-top: .5rem;
 
@@ -3228,11 +3246,11 @@ td.blob-excerpt {
 }
 
 .diff-file-box[data-folded="true"] .diff-file-header {
-  border-radius: .28571429rem !important;
+  border-radius: var(--border-radius) !important;
 }
 
 /* prevent page shaking on language bar click */
-.repository.file .repository-summary {
+.repository-summary-language-stats {
   height: 48px;
   overflow: hidden;
 }