style: remove active tab underline

docs/editing.md

@@ -218,7 +218,7 @@ Use `:tab.new` to open the current buffer in a new, focused tab with one pane. E
 | `:tab.close` | `config.core.tab.close` | Close the current tab and all its panes, protecting unsaved changes |
 | `:tab.force_close` | `config.core.tab.force_close` | Explicitly discard exclusively displayed edits and close the tab |
 
-Multiple tabs show a single top row with padded numbered filenames, subtle separators, and dirty markers. The active tab uses bold, underlined accent text; the row keeps the terminal's background instead of painting a full-width band. Narrow terminals keep the active tab visible. New/close actions have no default keybinding; for example, `config.bind "leader t", config.core.tab.new`.
+Multiple tabs show a single top row with padded numbered filenames, subtle separators, and dirty markers. The active tab uses bold accent text; the row keeps the terminal's background instead of painting a full-width band. Narrow terminals keep the active tab visible. New/close actions have no default keybinding; for example, `config.bind "leader t", config.core.tab.new`.
 
 Closing a tab refuses dirty buffers whose final displayed owner would disappear, including a comparison's working and return buffers. Buffers displayed in another tab remain open with their edits, even on force-close. Other hidden buffers remain loaded. Closing the last tab quits only if every open buffer is clean; force-close quits without saving.
 

src/tui.rs

@@ -1061,7 +1061,7 @@ fn draw_tab_bar(frame: &mut Frame, editor: &Editor, area: Rect) -> Rect {
         let style = if index == active {
             Style::default()
                 .fg(Color::Cyan)
-                .add_modifier(Modifier::BOLD | Modifier::UNDERLINED)
+                .add_modifier(Modifier::BOLD)
         } else {
             inactive
         };