Replace fomantic divider module with our own (#25539)

Should look exactly like before for normal dividers. "Horizontal" ones
look better because they no longer use image backgrounds.

<img width="917" alt="Screenshot 2023-06-27 at 19 07 56"
src="https://github.com/go-gitea/gitea/assets/115237/d97d8dec-6859-44a8-85ba-e4549b4dd9df">

<img width="914" alt="Screenshot 2023-06-27 at 19 05 58"
src="https://github.com/go-gitea/gitea/assets/115237/8bf98544-2d82-4ebf-ac68-d6dc237bd6b2">

<img width="1246" alt="Screenshot 2023-06-27 at 19 00 42"
src="https://github.com/go-gitea/gitea/assets/115237/36a6bb21-6029-4f53-8bee-535f55c66fed">

<img width="344" alt="Screenshot 2023-06-27 at 18 58 15"
src="https://github.com/go-gitea/gitea/assets/115237/a9e70aee-8e6b-4ea1-9e93-19c9f96aec6e">
<img width="823" alt="Screenshot 2023-06-27 at 18 56 22"
src="https://github.com/go-gitea/gitea/assets/115237/e7a497cd-f262-4683-8872-23c3c8cce32f">

<img width="330" alt="Screenshot 2023-06-27 at 19 21 11"
src="https://github.com/go-gitea/gitea/assets/115237/42f24149-a655-4c7e-bd26-8ab52db6446b">

6 files changed, 43 insertions, 24 deletions

diff --git a/web_src/css/admin.css b/web_src/css/admin.css
index 58e0527350..07c0190f52 100644
--- a/web_src/css/admin.css
+++ b/web_src/css/admin.css
@@ -15,11 +15,6 @@
   flex-wrap: wrap;
 }
 
-/* divider needs explicit width because the parent container is "display: flex" */
-.admin dl.admin-dl-horizontal .ui.divider {
-  width: 100%;
-}
-
 .admin dl.admin-dl-horizontal dt,
 .admin dl.admin-dl-horizontal dd {
   line-height: 1;
diff --git a/web_src/css/base.css b/web_src/css/base.css
index 016c263e43..8b8d376c57 100644
--- a/web_src/css/base.css
+++ b/web_src/css/base.css
@@ -465,15 +465,6 @@ a.label,
   background-color: var(--color-markup-code-block);
 }
 
-.ui.divider {
-  color: var(--color-text);
-}
-
-.ui.divider:not(.vertical,.horizontal) {
-  border-top-color: var(--color-secondary) !important;
-  border-bottom: none !important;
-}
-
 .ui.dividing.header {
   border-bottom-color: var(--color-secondary);
 }
@@ -2083,11 +2074,6 @@ table th[data-sortt-desc] .svg {
   border-radius: 0 0 var(--border-radius) var(--border-radius);
 }
 
-.ui.dropdown .menu > .divider {
-  border-top: 1px solid var(--color-secondary);
-  margin: 4px 0;
-}
-
 .ui.multiple.dropdown > .label {
   box-shadow: 0 0 0 1px var(--color-secondary) inset;
 }
diff --git a/web_src/css/helpers.css b/web_src/css/helpers.css
index 520a199682..68d4a1b021 100644
--- a/web_src/css/helpers.css
+++ b/web_src/css/helpers.css
@@ -76,6 +76,7 @@ Gitea's private styles use `g-` prefix.
 .gt-self-end { align-self: flex-end !important; }
 .gt-no-underline { text-decoration-line: none !important; }
 .gt-w-auto { width: auto !important; }
+.gt-normal-case { text-transform: none !important; }
 
 .gt-overflow-x-auto { overflow-x: auto !important; }
 .gt-overflow-x-scroll { overflow-x: scroll !important; }
diff --git a/web_src/css/index.css b/web_src/css/index.css
index d7ac9f453d..6a3e7d0dd5 100644
--- a/web_src/css/index.css
+++ b/web_src/css/index.css
@@ -9,6 +9,7 @@
 @import "./modules/comment.css";
 @import "./modules/navbar.css";
 @import "./modules/toast.css";
+@import "./modules/divider.css";
 
 @import "./shared/issuelist.css";
 @import "./shared/milestone.css";
diff --git a/web_src/css/modules/divider.css b/web_src/css/modules/divider.css
new file mode 100644
index 0000000000..8c9649d6ba
--- /dev/null
+++ b/web_src/css/modules/divider.css
@@ -0,0 +1,39 @@
+.divider {
+  margin: 1rem 0;
+  height: 0;
+  font-weight: var(--font-weight-medium);
+  text-transform: uppercase;
+  color: var(--color-text);
+  font-size: 1rem;
+  width: 100%;
+}
+
+.divider:not(.divider-text) {
+  border-top: 1px solid var(--color-secondary);
+}
+
+.divider.divider-text {
+  display: flex;
+  align-items: center;
+  padding: 7px 0;
+}
+
+.divider.divider-text::before,
+.divider.divider-text::after {
+  content: "";
+  flex: 1;
+  border-top: 1px solid var(--color-secondary);
+}
+
+.divider.divider-text::before {
+  margin-right: .75em;
+}
+
+.divider.divider-text::after {
+  margin-left: .75em;
+}
+
+.ui.dropdown .menu > .divider {
+  border-top: 1px solid var(--color-secondary);
+  margin: 4px 0;
+}
diff --git a/web_src/css/repo.css b/web_src/css/repo.css
index 0122e79aae..e20355dbc3 100644
--- a/web_src/css/repo.css
+++ b/web_src/css/repo.css
@@ -138,10 +138,6 @@
   background-color: var(--color-header-wrapper);
 }
 
-.repository .header-wrapper .ui.tabs.divider {
-  border-bottom: 0;
-}
-
 .repository .header-wrapper .ui.tabular .svg {
   margin-right: 5px;
 }
@@ -591,6 +587,7 @@
 
 .repository.options .danger .ui.divider {
   margin: 0;
+  border-color: var(--color-error-border);
 }
 
 .repository.new.issue .comment.form .comment .avatar {
@@ -1012,7 +1009,7 @@
 
 .repository.view.issue .comment-list .comment .merge-section .divider {
   margin-left: -1rem;
-  margin-right: -1rem;
+  width: calc(100% + 2rem);
 }
 
 .repository.view.issue .comment-list .comment .merge-section.no-header::before,