feat: add view-body flex layout and --bg-surface variable

coordinator/tests/test_frontend_css.py

@@ -90,3 +90,48 @@ def test_css_session_pill():
 def test_css_reduced_motion():
     css = read_css()
     assert "prefers-reduced-motion" in css
+
+
+def test_css_bg_surface_variable():
+    """--bg-surface variable must exist in :root."""
+    css = read_css()
+    assert "--bg-surface: #1A1F2B" in css
+
+
+def test_css_view_body_flex_layout():
+    """`.view-body` must have flex row layout properties."""
+    css = read_css()
+    assert ".view-body" in css
+    # Extract the .view-body rule block
+    view_body_idx = css.index(".view-body")
+    block_start = css.index("{", view_body_idx)
+    block_end = css.index("}", block_start)
+    block = css[block_start:block_end]
+    assert "display: flex" in block
+    assert "flex-direction: row" in block
+    assert "flex: 1" in block
+    assert "min-height: 0" in block
+    assert "overflow: hidden" in block
+
+
+def test_css_view_body_before_terminal_container():
+    """.view-body rule must appear before .terminal-container in the file."""
+    css = read_css()
+    assert ".view-body" in css
+    assert ".terminal-container" in css
+    assert css.index(".view-body") < css.index(".terminal-container")
+
+
+def test_css_terminal_container_min_width():
+    """.terminal-container must have min-width: 0 to prevent flex overflow."""
+    css = read_css()
+    terminal_idx = css.index(".terminal-container")
+    block_start = css.index("{", terminal_idx)
+    block_end = css.index("}", block_start)
+    block = css[block_start:block_end]
+    assert "min-width: 0" in block
+    # Existing properties preserved
+    assert "flex: 1" in block
+    assert "overflow: hidden" in block
+    assert "background: #000" in block
+    assert "padding: 0 4px" in block