diff --git a/src/css/custom.css b/src/css/custom.css
index d0ddba8..f47e05f 100644
--- a/src/css/custom.css
+++ b/src/css/custom.css
@@ -271,6 +271,14 @@ body:not(.is-scrolling) .navbar {
   padding: 2rem 0.5rem;
 }
 
+/* When there is no desktop TOC, expand the content column to full width,
+   keeping a right margin equal to the gap between article and TOC on TOC pages. */
+main .row:not(:has(.theme-doc-toc-desktop)) > .col {
+  max-width: 100% !important;
+  flex: 0 0 100% !important;
+  padding-right: calc(var(--ifm-spacing-horizontal) * 4) !important;
+}
+
 .theme-doc-sidebar-container + main > .container {
   padding-top: 0 !important;
   padding-bottom: 0 !important;