diff --git a/src/entities/experience/ui/ExperienceCard/ExperienceCard.test.tsx b/src/entities/experience/ui/ExperienceCard/ExperienceCard.test.tsx
index 8b5158d..9bdad95 100644
--- a/src/entities/experience/ui/ExperienceCard/ExperienceCard.test.tsx
+++ b/src/entities/experience/ui/ExperienceCard/ExperienceCard.test.tsx
@@ -36,25 +36,25 @@ describe('ExperienceCard', () => {
     it('period badge is inside the sidebar column', () => {
       render(<ExperienceCard {...DEFAULT_PROPS} />);
       const badge = screen.getByText('2021 – 2024');
-      expect(badge.closest('.brutal-border-sidebar')).toBeInTheDocument();
+      expect(badge.closest('[data-slot="card-sidebar"]')).toBeInTheDocument();
     });
 
     it('company name is inside the sidebar column', () => {
       render(<ExperienceCard {...DEFAULT_PROPS} />);
       const company = screen.getByText('Acme Corp');
-      expect(company.closest('.brutal-border-sidebar')).toBeInTheDocument();
+      expect(company.closest('[data-slot="card-sidebar"]')).toBeInTheDocument();
     });
 
     it('title is outside the sidebar column', () => {
       render(<ExperienceCard {...DEFAULT_PROPS} />);
       const title = screen.getByText('Senior Developer');
-      expect(title.closest('.brutal-border-sidebar')).toBeNull();
+      expect(title.closest('[data-slot="card-sidebar"]')).toBeNull();
     });
 
     it('description is outside the sidebar column', () => {
       render(<ExperienceCard {...DEFAULT_PROPS} />);
       const desc = screen.getByText('Built scalable frontend systems.');
-      expect(desc.closest('.brutal-border-sidebar')).toBeNull();
+      expect(desc.closest('[data-slot="card-sidebar"]')).toBeNull();
     });
   });
 
@@ -88,8 +88,8 @@ describe('ExperienceCard', () => {
       render(<ExperienceCard {...DEFAULT_PROPS} stack={['React', 'TypeScript']} />);
       const react = screen.getByText('React');
       const ts = screen.getByText('TypeScript');
-      expect(react.closest('.brutal-border-sidebar')).toBeInTheDocument();
-      expect(ts.closest('.brutal-border-sidebar')).toBeInTheDocument();
+      expect(react.closest('[data-slot="card-sidebar"]')).toBeInTheDocument();
+      expect(ts.closest('[data-slot="card-sidebar"]')).toBeInTheDocument();
       expect(react).toHaveClass('brutal-border', 'bg-transparent', 'px-2');
     });
 
diff --git a/src/entities/project/ui/ProjectCard/ProjectCard.test.tsx b/src/entities/project/ui/ProjectCard/ProjectCard.test.tsx
index 9d3db95..d9aff04 100644
--- a/src/entities/project/ui/ProjectCard/ProjectCard.test.tsx
+++ b/src/entities/project/ui/ProjectCard/ProjectCard.test.tsx
@@ -51,29 +51,29 @@ describe('ProjectCard', () => {
   describe('layout', () => {
     it('year is inside the sidebar column', () => {
       render(<ProjectCard {...DEFAULT_PROPS} />);
-      expect(screen.getByText('2024').closest('.brutal-border-sidebar')).toBeInTheDocument();
+      expect(screen.getByText('2024').closest('[data-slot="card-sidebar"]')).toBeInTheDocument();
     });
 
     it('tags are inside the sidebar column', () => {
       render(<ProjectCard {...DEFAULT_PROPS} />);
-      expect(screen.getByText('React').closest('.brutal-border-sidebar')).toBeInTheDocument();
-      expect(screen.getByText('Node').closest('.brutal-border-sidebar')).toBeInTheDocument();
+      expect(screen.getByText('React').closest('[data-slot="card-sidebar"]')).toBeInTheDocument();
+      expect(screen.getByText('Node').closest('[data-slot="card-sidebar"]')).toBeInTheDocument();
     });
 
     it('View Project button is inside the sidebar column', () => {
       render(<ProjectCard {...DEFAULT_PROPS} />);
       const btn = screen.getByRole('link', { name: /view project/i });
-      expect(btn.closest('.brutal-border-sidebar')).toBeInTheDocument();
+      expect(btn.closest('[data-slot="card-sidebar"]')).toBeInTheDocument();
     });
 
     it('title is outside the sidebar column', () => {
       render(<ProjectCard {...DEFAULT_PROPS} />);
-      expect(screen.getByText('My Project').closest('.brutal-border-sidebar')).toBeNull();
+      expect(screen.getByText('My Project').closest('[data-slot="card-sidebar"]')).toBeNull();
     });
 
     it('description is outside the sidebar column', () => {
       render(<ProjectCard {...DEFAULT_PROPS} />);
-      expect(screen.getByText('A cool project description').closest('.brutal-border-sidebar')).toBeNull();
+      expect(screen.getByText('A cool project description').closest('[data-slot="card-sidebar"]')).toBeNull();
     });
   });
 
diff --git a/src/shared/styles/theme.css b/src/shared/styles/theme.css
index 09f6425..6208b3c 100644
--- a/src/shared/styles/theme.css
+++ b/src/shared/styles/theme.css
@@ -332,16 +332,6 @@
     "SOFT" var(--fraunces-soft);
 }
 
-.brutal-border-sidebar {
-  border-bottom: var(--border-width) solid var(--blue);
-}
-@media (min-width: 1024px) {
-  .brutal-border-sidebar {
-    border-bottom: none;
-    border-right: var(--border-width) solid var(--blue);
-  }
-}
-
 /* Editorial rich-text typography */
 .rich-text {
   max-width: 65ch;
diff --git a/src/shared/ui/Card/ui/Card.test.tsx b/src/shared/ui/Card/ui/Card.test.tsx
index 4f48ced..4c4bbed 100644
--- a/src/shared/ui/Card/ui/Card.test.tsx
+++ b/src/shared/ui/Card/ui/Card.test.tsx
@@ -91,10 +91,10 @@ describe('CardSidebar', () => {
       expect(container.firstChild).toHaveClass('flex');
     });
 
-    it('sidebar column has brutal-border-sidebar class', () => {
+    it('marks the sidebar column with a data-slot hook', () => {
       render(<CardSidebar sidebar={<span>Sidebar</span>}>Main</CardSidebar>);
       const sidebar = screen.getByText('Sidebar').parentElement;
-      expect(sidebar).toHaveClass('brutal-border-sidebar');
+      expect(sidebar).toHaveAttribute('data-slot', 'card-sidebar');
     });
 
     it('sidebar column has fixed width on lg', () => {
diff --git a/src/shared/ui/Card/ui/Card.tsx b/src/shared/ui/Card/ui/Card.tsx
index 8e73a82..2a2a3a2 100644
--- a/src/shared/ui/Card/ui/Card.tsx
+++ b/src/shared/ui/Card/ui/Card.tsx
@@ -109,7 +109,12 @@ interface CardSidebarProps {
 export function CardSidebar({ sidebar, children, className }: CardSidebarProps) {
   return (
     <div className={cn('flex flex-col lg:flex-row', className)}>
-      <div className="shrink-0 lg:w-64 brutal-border-sidebar pb-6 lg:pb-0 lg:pr-8 mb-6 lg:mb-0">{sidebar}</div>
+      <div
+        data-slot="card-sidebar"
+        className="shrink-0 lg:w-64 brutal-border-bottom lg:border-b-0 lg:brutal-border-right pb-6 lg:pb-0 lg:pr-8 mb-6 lg:mb-0"
+      >
+        {sidebar}
+      </div>
       <div className="flex-1 min-w-0 lg:pl-8">{children}</div>
     </div>
   );