breadgreet: bring the login UI up to the lock screen's polish

breadgreet's stylesheet was a crude subset of what `design/sketch.html`
specifies for `.greetoverlay`. Ported it faithfully so the greeter and
the lock screen read as one visual identity:

- Card: proper elevation (`box-shadow: 0 6px 28px`), a hairline
  `alpha(@overlay, 0.09)` border, 10px radius, 300px min-width.
- Entry: recessed `shade(@surface, 1.5)` fill, and an accent focus ring
  (`border-color: @accent` + `box-shadow: 0 0 0 2px alpha(@accent, .28)`)
  matching the sketch's `.gentry:focus`.
- Clock/date over the wallpaper get a soft text-shadow for legibility on
  any background; sizes match the sketch (46 / 14).
- Session picker styled as a surface pill (button + popover), not a bare
  GtkDropDown.
- A CSS-animated ring shown while a greetd request is in flight
  (`sync_busy`, driven from the single `update` exit point).
- Shake on a failed attempt (`flash_error`), matching the lock screen's
  wrong-password motion — fired from both `AppInput::Error` and a PAM
  `AuthPrompt::Error`.

Uses the shared `@define-color` palette (`@surface`, `@overlay`,
`@accent`, `@red`) so it recolours with the theme, same as breadbar.

`cargo test --workspace --all-targets` (157) / `clippy --all-targets -D
warnings` / `fmt --check` all clean. Visual pass still wanted — the CSS
is a direct translation of the mockup, not screenshot-verified.

breadgreet/src/main.rs

@@ -46,6 +46,8 @@ struct App {
     date_lbl: gtk4::Label,
     status_lbl: gtk4::Label,
     entry: gtk4::Entry,
+    card: gtk4::Box,
+    spinner: gtk4::Box,
     stage: Stage,
     username: String,
     sessions: Vec<sessions::Session>,
@@ -168,10 +170,18 @@ impl SimpleComponent for App {
             dropdown.upcast()
         };
 
-        let card = gtk4::Box::new(gtk4::Orientation::Vertical, 8);
+        // A CSS-animated ring (not GtkSpinner) so it matches the design
+        // sketch exactly: 2px track, accent top, shown only while a greetd
+        // request is in flight (see `set_busy`).
+        let spinner = gtk4::Box::new(gtk4::Orientation::Horizontal, 0);
+        spinner.add_css_class("login-spinner");
+        spinner.set_halign(gtk4::Align::Center);
+
+        let card = gtk4::Box::new(gtk4::Orientation::Vertical, 0);
         card.add_css_class("login-card");
         card.append(&entry);
         card.append(&status_lbl);
+        card.append(&spinner);
         card.append(&session_widget);
 
         let widgets = view_output!();
@@ -243,6 +253,8 @@ impl SimpleComponent for App {
             date_lbl,
             status_lbl,
             entry,
+            card,
+            spinner,
             stage: Stage::Username,
             username: String::new(),
             sessions,
@@ -289,10 +301,38 @@ impl SimpleComponent for App {
             }
             AppInput::Cancel => self.cancel_auth(),
         }
+        self.sync_busy();
     }
 }
 
 impl App {
+    /// Spinner runs exactly while a greetd request is in flight. Driven from
+    /// one place (the end of `update`) so every path — submit, prompt,
+    /// cancel, error — stays in sync with `self.stage`.
+    fn sync_busy(&self) {
+        let busy = matches!(self.stage, Stage::Working | Stage::Starting);
+        if busy {
+            self.spinner.add_css_class("spinning");
+        } else {
+            self.spinner.remove_css_class("spinning");
+        }
+    }
+
+    /// One-shot shake on the card, matching the lock screen's wrong-password
+    /// motion. Re-armed each call by dropping the class first (a running
+    /// animation won't restart just from re-adding it).
+    fn flash_error(&self) {
+        self.card.remove_css_class("shake");
+        let card = self.card.clone();
+        gtk4::glib::timeout_add_local_once(std::time::Duration::from_millis(10), move || {
+            card.add_css_class("shake");
+            let card2 = card.clone();
+            gtk4::glib::timeout_add_local_once(std::time::Duration::from_millis(420), move || {
+                card2.remove_css_class("shake");
+            });
+        });
+    }
+
     fn handle_submit(&mut self) {
         if matches!(self.stage, Stage::Working | Stage::Starting) {
             return;
@@ -338,6 +378,7 @@ impl App {
             AuthPrompt::Error(message) => {
                 self.status_lbl.add_css_class("error");
                 self.status_lbl.set_label(&message);
+                self.flash_error();
                 self.pam_status_held = true;
                 self.dispatch(greetd::Command::Respond(None));
             }
@@ -403,6 +444,7 @@ impl App {
             self.status_lbl.remove_css_class("error");
         } else {
             self.status_lbl.add_css_class("error");
+            self.flash_error();
         }
         self.reset_to_username();
     }

breadgreet/src/theme.rs

@@ -1,4 +1,14 @@
-use bread_theme::{gtk as bgtk, ink_on, load_palette};
+//! breadgreet's app stylesheet.
+//!
+//! Layered on top of `bread_theme`'s shared `@define-color` palette
+//! (`@surface`, `@overlay`, `@accent`, `@red`, …) via `apply_shared()` +
+//! `apply_app_css()`. The visual target is `design/sketch.html`'s
+//! `.greetoverlay` section — the same design language as the lock screen:
+//! a floating surface card over a cover-fit / Ken-Burns wallpaper, an
+//! accent focus ring on the entry, a spinner while a request is in flight,
+//! and a shake on a failed attempt.
+
+use bread_theme::gtk as bgtk;
 use gtk4::CssProvider;
 use std::cell::RefCell;
 
@@ -15,25 +25,99 @@ fn css_font_family(family: &str) -> String {
 }
 
 fn load_css(font_family: &str) -> String {
-    let p = load_palette();
     let font = css_font_family(font_family);
     format!(
-        "window.breadgreet {{ background-color: {bg}; color: {on_bg}; {font} }}\
+        // ---- window + wallpaper ----------------------------------------
-         .login-card {{ background: {surface}; color: {on_surface}; border-radius: 8px;\
+        "window.breadgreet {{ background-color: @bg; color: @on-bg; {font} }}\
-             padding: 20px; min-width: 320px; }}\
+         .login-veil {{\
-         .login-clock {{ font-size: 48px; font-weight: bold; }}\
+             background-image: linear-gradient(to bottom,\
-         .login-date {{ font-size: 18px; font-weight: 500; opacity: 0.8; }}\
+                 alpha(black, 0.42) 0%, alpha(black, 0.20) 45%, alpha(black, 0.34) 100%);\
-         .login-entry {{ font-size: 14px; }}\
+         }}\
-         .login-status {{ font-size: 12px; opacity: 0.75; margin-top: 8px; }}\
+         \
-         .login-status.error {{ color: {red}; opacity: 1; }}\
+         /* ---- clock cluster (over the wallpaper) --------------------- */\
-         .login-session {{ font-size: 12px; opacity: 0.85; margin-top: 12px; }}\
+         .login-clock {{\
-         dropdown.login-session {{ min-height: 32px; }}\
+             font-size: 46px; font-weight: 700; color: white;\
-         .login-veil {{ background-image: linear-gradient(to bottom, rgba(0,0,0,0.34) 0%, rgba(0,0,0,0.16) 100%); }}",
+             text-shadow: 0 2px 12px alpha(black, 0.55);\
-        bg = p.background,
+         }}\
-        surface = p.color0,
+         .login-date {{\
-        red = p.color1,
+             font-size: 14px; font-weight: 500; color: alpha(white, 0.82);\
-        on_bg = ink_on(&p.background),
+             text-shadow: 0 1px 8px alpha(black, 0.5);\
-        on_surface = ink_on(&p.color0),
+         }}\
+         \
+         /* ---- the card --------------------------------------------- */\
+         .login-card {{\
+             background: @surface; color: @on-surface;\
+             border: 1px solid alpha(@overlay, 0.09);\
+             border-radius: 10px; padding: 22px;\
+             min-width: 300px;\
+             box-shadow: 0 6px 28px alpha(black, 0.5);\
+         }}\
+         .login-card.shake {{ animation: breadgreet-shake 380ms cubic-bezier(0.36, 0.07, 0.19, 0.97); }}\
+         \
+         /* ---- entry ----------------------------------------------- */\
+         .login-entry {{\
+             background: shade(@surface, 1.5); color: @on-surface;\
+             border: 1px solid alpha(@overlay, 0.14);\
+             border-radius: 7px; padding: 11px 14px; font-size: 14px;\
+             caret-color: @accent;\
+             transition: border-color 180ms ease, box-shadow 180ms ease;\
+         }}\
+         .login-entry:disabled {{ opacity: 0.55; }}\
+         .login-entry > text {{ background: transparent; }}\
+         .login-entry:focus-within {{\
+             border-color: @accent;\
+             box-shadow: 0 0 0 2px alpha(@accent, 0.28);\
+             outline: none;\
+         }}\
+         \
+         /* ---- status line --------------------------------------- */\
+         .login-status {{\
+             font-size: 12px; color: alpha(@on-surface, 0.72);\
+             margin-top: 10px; min-height: 1em;\
+             transition: color 160ms ease;\
+         }}\
+         .login-status.error {{ color: @red; opacity: 1; font-weight: 700; }}\
+         \
+         /* ---- spinner (shown while a request is in flight) ------ */\
+         .login-spinner {{\
+             min-width: 16px; min-height: 16px;\
+             margin-top: 12px;\
+             border: 2px solid alpha(@overlay, 0.15);\
+             border-top: 2px solid @accent;\
+             border-radius: 999px;\
+             opacity: 0;\
+         }}\
+         .login-spinner.spinning {{ opacity: 1; animation: breadgreet-spin 800ms linear infinite; }}\
+         \
+         /* ---- session picker (styled as a surface pill) -------- */\
+         .login-session {{\
+             margin-top: 14px; font-size: 12px;\
+         }}\
+         .login-session > button {{\
+             background: shade(@surface, 1.5); color: alpha(@on-surface, 0.9);\
+             border: 1px solid alpha(@overlay, 0.14);\
+             border-radius: 7px; padding: 9px 12px; min-height: 20px;\
+         }}\
+         .login-session > button:hover {{ border-color: alpha(@accent, 0.5); }}\
+         .login-session > button:focus-within {{\
+             border-color: @accent; box-shadow: 0 0 0 2px alpha(@accent, 0.28); outline: none;\
+         }}\
+         .login-session arrow {{ color: alpha(@on-surface, 0.6); min-height: 16px; min-width: 16px; }}\
+         .login-session popover > contents {{\
+             background: @surface; border: 1px solid alpha(@overlay, 0.12);\
+             border-radius: 8px; padding: 4px;\
+         }}\
+         .login-session popover row {{ border-radius: 6px; padding: 6px 10px; }}\
+         .login-session popover row:selected {{ background: alpha(@accent, 0.22); color: @on-surface; }}\
+         \
+         /* ---- keyframes --------------------------------------- */\
+         @keyframes breadgreet-spin {{ to {{ transform: rotate(360deg); }} }}\
+         @keyframes breadgreet-shake {{\
+             10%, 90% {{ transform: translateX(-2px); }}\
+             20%, 80% {{ transform: translateX(4px); }}\
+             30%, 50%, 70% {{ transform: translateX(-7px); }}\
+             40%, 60% {{ transform: translateX(7px); }}\
+         }}",
         font = font,
     )
 }