fix(web): restore mobile welcome support stacking

Author: pallyoung

packages/web/src/styles/components.css

@@ -12089,9 +12089,16 @@ body.is-dragging-pane .session-action-btn-drag {
   }
 
   .welcome-card--mobile .welcome-flow__steps {
+    grid-template-columns: 1fr;
     gap: var(--sp-2);
   }
 
+  .welcome-card--mobile .welcome-flow__support {
+    flex-direction: column;
+    align-items: stretch;
+    padding: var(--sp-3);
+  }
+
   .welcome-card--mobile .welcome-step-card {
     padding: var(--sp-3);
     gap: var(--sp-2);

packages/web/src/styles/components.theme.test.ts

@@ -2642,6 +2642,7 @@ describe("components.css theme-sensitive surfaces", () => {
     const welcomeContainer = getLastRuleBlock(".welcome-container--mobile");
     const mobileWelcomeLayout = getLastRuleBlock(".welcome-card--mobile .welcome-layout");
     const mobileWelcomeSteps = getLastRuleBlock(".welcome-card--mobile .welcome-flow__steps");
+    const mobileWelcomeSupport = getLastRuleBlock(".welcome-card--mobile .welcome-flow__support");
     const mobileSupportList = getLastRuleBlock(".welcome-card--mobile .welcome-support-list");
     const authScreen = getLastRuleBlock(".auth-screen--mobile");
 
@@ -2651,6 +2652,8 @@ describe("components.css theme-sensitive surfaces", () => {
     expect(welcomeContainer).toContain("overflow-y: auto");
     expect(mobileWelcomeLayout).toContain("flex-direction: column");
     expect(mobileWelcomeSteps).toContain("grid-template-columns: 1fr");
+    expect(mobileWelcomeSupport).toContain("flex-direction: column");
+    expect(mobileWelcomeSupport).toContain("align-items: stretch");
     expect(mobileSupportList).toContain("grid-template-columns: 1fr");
     expect(authScreen).toContain("padding:");
   });