diff --git a/src/eval/mod.rs b/src/eval/mod.rs
index 2cff835ba..5a8b857a0 100644
--- a/src/eval/mod.rs
+++ b/src/eval/mod.rs
@@ -22,7 +22,7 @@ use fontdock::FontStyle;
 
 use crate::diag::Diag;
 use crate::diag::{Deco, Feedback, Pass};
-use crate::geom::{BoxAlign, Flow, Gen, Length, Linear, Relative, Sides, Size};
+use crate::geom::{BoxAlign, Dir, Flow, Gen, Length, Linear, Relative, Sides, Size};
 use crate::layout::{
     Document, Expansion, LayoutNode, Pad, Pages, Par, Softness, Spacing, Stack, Text,
 };
@@ -223,6 +223,23 @@ impl EvalContext {
         (group, std::mem::replace(&mut self.inner, outer))
     }
 
+    /// Updates the flow directions if the resulting main and cross directions
+    /// apply to different axes. Generates an appropriate error, otherwise.
+    pub fn set_flow(&mut self, new: Gen<Option<Spanned<Dir>>>) {
+        let flow = Gen::new(
+            new.main.map(|s| s.v).unwrap_or(self.state.flow.main),
+            new.cross.map(|s| s.v).unwrap_or(self.state.flow.cross),
+        );
+
+        if flow.main.axis() != flow.cross.axis() {
+            self.state.flow = flow;
+        } else {
+            for dir in new.main.iter().chain(new.cross.iter()) {
+                self.diag(error!(dir.span, "aligned axis"));
+            }
+        }
+    }
+
     /// Construct a text node from the given string based on the active text
     /// state.
     pub fn make_text_node(&self, text: String) -> Text {
diff --git a/src/library/align.rs b/src/library/align.rs
index a54925f07..4f4a17500 100644
--- a/src/library/align.rs
+++ b/src/library/align.rs
@@ -17,7 +17,6 @@ use std::fmt::{self, Display, Formatter};
 /// There may not be two alignment specifications for the same axis.
 pub fn align(mut args: Args, ctx: &mut EvalContext) -> Value {
     let snapshot = ctx.state.clone();
-
     let body = args.find::<SynTree>();
     let first = args.get::<_, Spanned<AlignArg>>(ctx, 0);
     let second = args.get::<_, Spanned<AlignArg>>(ctx, 1);
@@ -33,13 +32,14 @@ pub fn align(mut args: Args, ctx: &mut EvalContext) -> Value {
         .chain(ver.into_iter().map(|align| (Some(SpecAxis::Vertical), align)));
 
     let align = dedup_aligns(ctx, iter);
-    if align.main != ctx.state.align.main {
+    let ends_par = align.main != ctx.state.align.main;
+    ctx.state.align = align;
+
+    if ends_par {
         ctx.end_par_group();
         ctx.start_par_group();
     }
 
-    ctx.state.align = align;
-
     if let Some(body) = body {
         body.eval(ctx);
         ctx.state = snapshot;
diff --git a/src/library/boxed.rs b/src/library/boxed.rs
index 3d7214ae0..1ec17d880 100644
--- a/src/library/boxed.rs
+++ b/src/library/boxed.rs
@@ -9,10 +9,12 @@ use crate::prelude::*;
 /// - `height`: The height of the box (length or relative to parent's height).
 pub fn boxed(mut args: Args, ctx: &mut EvalContext) -> Value {
     let snapshot = ctx.state.clone();
-
     let body = args.find::<SynTree>().unwrap_or_default();
     let width = args.get::<_, Linear>(ctx, "width");
     let height = args.get::<_, Linear>(ctx, "height");
+    let main = args.get::<_, Spanned<Dir>>(ctx, "main");
+    let cross = args.get::<_, Spanned<Dir>>(ctx, "cross");
+    ctx.set_flow(Gen::new(main, cross));
     args.done(ctx);
 
     let flow = ctx.state.flow;
diff --git a/src/library/font.rs b/src/library/font.rs
index bb84f06be..5de0a953c 100644
--- a/src/library/font.rs
+++ b/src/library/font.rs
@@ -53,7 +53,6 @@ use crate::prelude::*;
 ///   ```
 pub fn font(mut args: Args, ctx: &mut EvalContext) -> Value {
     let snapshot = ctx.state.clone();
-
     let body = args.find::<SynTree>();
 
     if let Some(linear) = args.find::<Linear>() {
@@ -67,7 +66,6 @@ pub fn font(mut args: Args, ctx: &mut EvalContext) -> Value {
 
     let mut needs_flattening = false;
     let list: Vec<_> = args.find_all::<StringLike>().map(|s| s.to_lowercase()).collect();
-
     if !list.is_empty() {
         Rc::make_mut(&mut ctx.state.font.families).list = list;
         needs_flattening = true;
diff --git a/src/library/page.rs b/src/library/page.rs
index efb40f100..057098650 100644
--- a/src/library/page.rs
+++ b/src/library/page.rs
@@ -17,6 +17,9 @@ use crate::prelude::*;
 /// - `bottom`: The bottom margin (length or relative to height).
 /// - `flip`: Flips custom or paper-defined width and height (boolean).
 pub fn page(mut args: Args, ctx: &mut EvalContext) -> Value {
+    let snapshot = ctx.state.clone();
+    let body = args.find::<SynTree>();
+
     if let Some(paper) = args.find::<Paper>() {
         ctx.state.page.class = paper.class;
         ctx.state.page.size = paper.size();
@@ -57,8 +60,19 @@ pub fn page(mut args: Args, ctx: &mut EvalContext) -> Value {
         std::mem::swap(&mut size.width, &mut size.height);
     }
 
+    let main = args.get::<_, Spanned<Dir>>(ctx, "main");
+    let cross = args.get::<_, Spanned<Dir>>(ctx, "cross");
+    ctx.set_flow(Gen::new(main, cross));
+
     args.done(ctx);
 
+    if let Some(body) = body {
+        ctx.end_page_group();
+        ctx.start_page_group(true);
+        body.eval(ctx);
+        ctx.state = snapshot;
+    }
+
     ctx.end_page_group();
     ctx.start_page_group(false);