diff --git a/.readthedocs.yml b/.readthedocs.yml
index 7ac1f46..b98090c 100644
--- a/.readthedocs.yml
+++ b/.readthedocs.yml
@@ -10,6 +10,8 @@ build:
     python: "3"
 
   commands:
+    # TEMPORARY: build the Persian (fa) translation to preview RTL support.
     - git clone --depth=1 https://github.com/python/cpython
-    - make html CPYTHON_PATH=cpython
+    - git clone --depth=1 https://github.com/python/python-docs-fa cpython/Doc/locales/fa/LC_MESSAGES
+    - make html CPYTHON_PATH=cpython SPHINXERRORHANDLING= SPHINXOPTS="-D language=fa -D html_theme_options.is_rtl=true"
     - mv cpython/Doc/build _readthedocs
diff --git a/python_docs_theme/layout.html b/python_docs_theme/layout.html
index 1903fad..2bd2274 100644
--- a/python_docs_theme/layout.html
+++ b/python_docs_theme/layout.html
@@ -6,7 +6,7 @@
       <h3>{{ _('Navigation') }}</h3>
       <ul>
           {%- for rellink in rellinks %}
-          <li class="right" {% if loop.first %}style="margin-right: 10px"{% endif %}>
+          <li class="right" {% if loop.first %}style="margin-inline-end: 10px"{% endif %}>
               <a href="{{ pathto(rellink[0])|e }}" title="{{ rellink[1]|striptags|e }}"
                  {{ accesskey(rellink[2]) }}>{{ rellink[3] }}
               </a>
@@ -89,7 +89,7 @@ <h3>{{ _('Navigation') }}</h3>
 {%- endblock -%}
 
 {%- block body_tag %}
-{{ super() }}
+<body{% if theme_is_rtl|tobool %} dir="rtl"{% endif %}>
 {%- if builder != 'htmlhelp' %}
 <div class="mobile-nav">
     <input type="checkbox" id="menuToggler" class="toggler__input" aria-controls="navigation"
diff --git a/python_docs_theme/static/pydoctheme.css b/python_docs_theme/static/pydoctheme.css
index aa9622d..9f67649 100644
--- a/python_docs_theme/static/pydoctheme.css
+++ b/python_docs_theme/static/pydoctheme.css
@@ -108,7 +108,7 @@ div.related a:hover {
 }
 
 .switchers > div {
-    margin-right: 5px;
+    margin-inline-end: 5px;
 }
 
 div.related ul::after {
@@ -117,6 +117,17 @@ div.related ul::after {
     display: block;
 }
 
+div.related ul {
+    padding: 0;
+    padding-inline-start: 10px;
+}
+
+html[dir='rtl'] div.related ul li.right {
+    float: left;
+    margin-right: 0;
+    margin-left: 5px;
+}
+
 .inline-search,
 form.inline-search input {
     display: inline;
@@ -142,6 +153,9 @@ span.pre {
 div.sphinxsidebar {
     display: flex;
     width: min(25vw, 350px);
+    flex-shrink: 0;
+    margin: 0;
+    order: 0;
     float: none;
     position: sticky;
     top: 0;
@@ -158,8 +172,14 @@ div.sphinxsidebar h4 {
     margin-top: 1.5em;
 }
 
-div.bodywrapper {
-    margin-left: min(25vw, 350px);
+div.document div.bodywrapper {
+    margin: 0;
+}
+
+div.documentwrapper {
+    flex: 1;
+    min-width: 0;
+    order: 1;
 }
 
 div.sphinxsidebarwrapper {
@@ -179,6 +199,11 @@ div.sphinxsidebarwrapper > ul > li > ul > li {
     margin-bottom: 0.4em;
 }
 
+div.sphinxsidebar ul ul {
+    margin-left: 0;
+    margin-inline-start: 20px;
+}
+
 div.sphinxsidebar a:hover {
     color: #0095c4;
 }
@@ -211,11 +236,16 @@ div.sphinxsidebar input[type='text'] {
 }
 
 div.body {
-    padding: 0 0 0 1.2em;
+    padding: 0;
+    padding-inline-start: 1.2em;
+}
+
+html[dir='rtl'] div.body {
+    direction: rtl;
 }
 
 div.body p, div.body dd, div.body li, div.body blockquote {
-    text-align: left;
+    text-align: start;
     line-height: 1.6;
 }
 div.body h1, div.body h2, div.body h3, div.body h4, div.body h5, div.body h6 {
@@ -225,6 +255,10 @@ div.body h1, div.body h2, div.body h3, div.body h4, div.body h5, div.body h6 {
 }
 div.body dl.field-list > dt {
     line-height: 1.6;
+    padding-left: 0;
+    padding-right: 0;
+    padding-inline-start: 0.5em;
+    padding-inline-end: 5px;
 }
 
 div.body hr {
@@ -233,6 +267,21 @@ div.body hr {
     height: 1px;
 }
 
+dl > dt span ~ em,
+.sig {
+    font-family: Menlo, Consolas, Monaco, Liberation Mono, Lucida Console, monospace;
+}
+
+pre,
+code,
+div.highlight,
+dl > dt span ~ em,
+.sig,
+.sig-param {
+    direction: ltr;
+    unicode-bidi: isolate;
+}
+
 div.body pre {
     border-radius: 3px;
     border: 1px solid #ac9;
@@ -258,12 +307,10 @@ div.code-block-caption {
     padding: 0.3em 0.6em;
     font-size: 90%;
     color: #333;
-
     & + div pre {
         border-top-left-radius: 0 !important;
         border-top-right-radius: 0 !important;
     }
-
     & + div .copybutton {
         border-top-right-radius: 0 !important;
     }
@@ -402,7 +449,7 @@ table.docutils th {
 
 table p,
 table li {
-    text-align: left !important;
+    text-align: start !important;
 }
 
 table.docutils th {
@@ -416,9 +463,9 @@ table.footnote td {
 
 div.footer {
     line-height: 150%;
-    text-align: right;
+    text-align: end;
     width: auto;
-    margin-right: 10px;
+    margin-inline-end: 10px;
 }
 
 div.footer a {
@@ -477,17 +524,12 @@ div.footer a:hover {
 }
 
 
-dl > dt span ~ em,
-.sig {
-    font-family: Menlo, Consolas, Monaco, Liberation Mono, Lucida Console, monospace;
-}
-
 .toctree-wrapper ul {
-    padding-left: 20px;
+    padding-inline-start: 20px;
 }
 
 .theme-selector {
-    margin-left: .5em;
+    margin-inline-start: .5em;
 }
 
 div.genindex-jumpbox,
@@ -506,17 +548,17 @@ div.genindex-jumpbox a {
     cursor: pointer;
     position: absolute;
     top: 0;
-    right: 0;
+    right: 0; /* physical right; always, even in RTL, since code is LTR */
     font-family: Menlo, Consolas, Monaco, Liberation Mono, Lucida Console, monospace;
     font-size: 80%;
     padding-left: .5em;
     padding-right: .5em;
     height: 100%;
     max-height: min(100%, 2.4em);
-    border-radius: 0 3px 0 0;
+    border-radius: 0 3px 0 0; /* physical — top-right corner, always */
     color: #000;
     background-color: #fff;
-    border: 1px solid #ac9; /* follows div.body pre */
+    border: 1px solid #ac9;
     display: none;
 }
 
@@ -583,7 +625,7 @@ div.genindex-jumpbox a {
         width: 100%;
         position: fixed;
         top: 0;
-        left: 0;
+        inset-inline-start: 0;
         box-shadow: rgba(0, 0, 0, 0.25) 0 0 2px 0;
         z-index: 1;
     }
@@ -605,7 +647,7 @@ div.genindex-jumpbox a {
         align-items: stretch;
     }
     .nav-logo {
-        margin-right: 1rem;
+        margin-inline-end: 1rem;
         flex-shrink: 0;
         align-self: center;
     }
@@ -614,7 +656,7 @@ div.genindex-jumpbox a {
         width: 20px;
     }
     .version_switcher_placeholder {
-        margin-right: 1rem;
+        margin-inline-end: 1rem;
     }
     .version_switcher_placeholder > select {
         height: 100%;
@@ -627,7 +669,7 @@ div.genindex-jumpbox a {
     }
     .nav-content .search input[type=search] {
         border: 0;
-        padding-left: 24px;
+        padding-inline-start: 24px;
         width: 100%;
         flex: 1;
     }
@@ -635,14 +677,14 @@ div.genindex-jumpbox a {
         height: 100%;
         box-shadow: none;
         border: 0;
-        border-left: 1px solid #a9a9a9;
+        border-inline-start: 1px solid #a9a9a9;
         cursor: pointer;
-        margin-right: 0;
+        margin-inline-end: 0;
     }
     .nav-content .search svg {
         position: absolute;
         align-self: center;
-        padding-left: 4px;
+        inset-inline-start: 4px;
     }
     .toggler__input {
         display: none;
@@ -674,7 +716,7 @@ div.genindex-jumpbox a {
         width: 100%;
         background: inherit;
         position: absolute;
-        left: 0;
+        inset-inline-start: 0;
         top: -8px;
     }
     .toggler__label > span::after {
@@ -695,7 +737,7 @@ div.genindex-jumpbox a {
     }
     .toggler__input:checked ~ .menu-wrapper {
         visibility: visible;
-        left: 0;
+        transform: translateX(0);
     }
 
     /* Sliding side menu */
@@ -703,8 +745,9 @@ div.genindex-jumpbox a {
         display: block;
         position: fixed;
         top: 0;
-        transition: left 400ms ease;
-        left: -310px;
+        inset-inline-start: 0;
+        transition: transform 400ms ease;
+        transform: translateX(-100%);
         width: 300px;
         height: 100%;
         background-color: #eee;
@@ -712,12 +755,18 @@ div.genindex-jumpbox a {
         box-shadow: 0 0 10px rgba(0, 0, 0, 0.2);
         overflow-y: auto;
     }
+    html[dir='rtl'] .menu-wrapper {
+        transform: translateX(100%);
+    }
     .menu-wrapper.open {
         visibility: visible;
-        left: 0;
+        transform: translateX(0);
     }
     .menu {
-        padding: 40px 10px 30px 20px;
+        padding-block-start: 40px;
+        padding-inline-end: 10px;
+        padding-block-end: 30px;
+        padding-inline-start: 20px;
     }
     .menu-wrapper h3,
     .menu-wrapper h4 {
@@ -742,10 +791,10 @@ div.genindex-jumpbox a {
         list-style: none;
         line-height: 1.4;
         overflow-wrap: break-word;
-        padding-left: 0;
+        padding-inline-start: 0;
     }
     .menu ul ul {
-        margin-left: 20px;
+        margin-inline-start: 20px;
         list-style: square;
     }
     .menu ul li {
@@ -801,26 +850,26 @@ div.versionadded,
 div.versionchanged,
 div.deprecated,
 div.deprecated-removed {
-    border-left: 3px solid;
+    border-inline-start: 3px solid;
     padding: 0 1rem;
 }
 
 div.versionadded {
-    border-left-color: var(--versionadded-border);
+    border-inline-start-color: var(--versionadded-border);
 }
 
 div.versionchanged {
-    border-left-color: var(--versionchanged-border);
+    border-inline-start-color: var(--versionchanged-border);
 }
 
 div.deprecated,
 div.deprecated-removed,
 div.versionremoved {
-    border-left-color: var(--deprecated-border);
+    border-inline-start-color: var(--deprecated-border);
 }
 
 div.soft-deprecated {
-    border-left-color: var(--soft-deprecated-border);
+    border-inline-start-color: var(--soft-deprecated-border);
 }
 
 div.versionadded .versionmodified {
diff --git a/python_docs_theme/theme.toml b/python_docs_theme/theme.toml
index 1d3cdbd..c0f9c79 100644
--- a/python_docs_theme/theme.toml
+++ b/python_docs_theme/theme.toml
@@ -27,6 +27,7 @@ headbgcolor = "white"
 headlinkcolor = "#aaaaaa"
 codebgcolor = "#eeffcc"
 codetextcolor = "#333333"
+is_rtl = "false"
 
 hosted_on = ""
 issues_url = ""