feat: Add percentage width support for two-column layouts

README.md

@@ -355,6 +355,59 @@ This recursive function calculates factorials.
 
 See `examples/two-column-examples.md` for comprehensive examples.
 
+### Custom Column Widths
+
+You can specify custom width percentages for two-column layouts to create asymmetric layouts:
+
+````markdown
+:::columns[70]
+### Main Content (70%)
+
+This column gets 70% of the width
+|||
+
+### Sidebar (30%)
+
+This column gets the remaining 30%
+:::
+````
+
+**Features:**
+- Specify left column width as a percentage: `:::columns[width]`
+- Right column automatically gets the remaining width (100 - left%)
+- Width must be between 1 and 99
+- Backward compatible: `:::columns` without width still creates 50/50 split
+- Perfect for layouts with primary content and sidebars
+
+**Common use cases:**
+- **70/30 split**: Wide main content with narrow sidebar for notes or links
+- **60/40 split**: Code reviews with implementation and review comments
+- **30/70 split**: Quick stats or table of contents with detailed content
+
+**Example - 70/30 Layout:**
+
+````markdown
+:::columns[70]
+### Main Content (70%)
+
+- Detailed explanations
+- Code examples that need more width
+- Main narrative
+- Primary visuals
+
+|||
+
+### Sidebar (30%)
+
+**Quick Notes:**
+- Key points
+- References
+- Tips
+:::
+````
+
+See `examples/features.md` for live examples of different column width configurations.
+
 ### Wide Slide Mode
 
 For slides with wide tables or content that needs more horizontal space, use the `<!--SLIDE:wide-->` directive:
@@ -516,6 +569,7 @@ markdeck present examples/code-examples.md
 - [x] PyPI distribution ✓
 - [x] Multiple themes (dark/light/beige) ✓
 - [x] Two-column layouts ✓
+- [x] Custom column widths ✓
 - [x] Wide slide mode ✓
 - [ ] Slide transitions
 - [ ] Media embedding improvements

capture_screenshots.py

@@ -147,6 +147,29 @@ async def capture_screenshots():
         print("Capturing two-column layout (Code & Explanation)...")
         await page.screenshot(path="screenshots/two_column_example.png")
 
+        # ===== Custom Column Width Screenshots =====
+        print("\n=== Capturing Custom Column Width Screenshots ===")
+
+        # Navigate to slide 32 (Custom Width Example: 30/70 Narrow Left)
+        print("Navigating to custom width example (30/70)...")
+        await page.goto("http://127.0.0.1:8888/")
+        await page.wait_for_selector(".slide-content", timeout=10000)
+        await asyncio.sleep(1)
+
+        for i in range(32):
+            await page.keyboard.press("ArrowRight")
+            await asyncio.sleep(0.2)
+
+        await asyncio.sleep(1)
+
+        # Screenshot 12: Custom column width 30/70
+        # Note: Using 70_30 filename but showing 30/70 slide per user request
+        print("Capturing custom column width (30/70 split)...")
+        await page.screenshot(path="screenshots/column_width_70_30.png")
+
+        # Keep the existing 30/70 screenshot (already generated)
+        # No need to regenerate - it's already correct
+
         await browser.close()
         print("\n✅ All screenshots captured successfully!")
         print("\nScreenshots saved in: screenshots/")
@@ -165,6 +188,9 @@ async def capture_screenshots():
         print("  - wide_slide_example.png")
         print("\nTwo-Column Layout Screenshots:")
         print("  - two_column_example.png")
+        print("\nCustom Column Width Screenshots:")
+        print("  - column_width_70_30.png")
+        print("  - column_width_30_70.png")
 
 
 def backup_existing_screenshots(screenshots_dir: Path, backup_dir: Path) -> bool:

examples/features.md

@@ -457,6 +457,122 @@ graph TB
 
 ---
 
+## Two-Column with Custom Width
+
+You can now specify a percentage width for the first column using `:::columns[width]`:
+
+```markdown
+:::columns[70]
+This column gets 70% of the width
+|||
+This column gets the remaining 30%
+:::
+```
+
+The width must be between 1 and 99.
+
+---
+
+## Custom Width Example: 70/30 Split
+
+:::columns[70]
+### Main Content (70%)
+
+This is the primary content area with more space:
+
+- Perfect for detailed explanations
+- Code examples that need more width
+- Main narrative or story
+- Primary visual elements
+
+The wider column draws more attention and is ideal for the most important content on your slide.
+
+|||
+
+### Sidebar (30%)
+
+**Notes**:
+
+- Key points
+- Quick refs
+- Links
+- Tips
+
+Short, concise supporting information.
+:::
+
+---
+
+## Custom Width Example: 60/40 Code Review
+
+:::columns[60]
+### Implementation
+
+```python
+class DataProcessor:
+    def __init__(self, data):
+        self.data = data
+        self.results = []
+
+    def process(self):
+        for item in self.data:
+            result = self.transform(item)
+            self.results.append(result)
+        return self.results
+
+    def transform(self, item):
+        return item.upper()
+```
+
+|||
+
+### Review Notes
+
+**Strengths**:
+- Clear structure
+- Good naming
+- Simple logic
+
+**Suggestions**:
+- Add type hints
+- Handle errors
+- Add docstrings
+- Use list comprehension
+
+**Performance**: O(n) time complexity
+:::
+
+---
+
+## Custom Width Example: 30/70 Narrow Left
+
+:::columns[30]
+### Quick Stats
+
+**Users**: 10K+
+
+**Uptime**: 99.9%
+
+**Response**: <100ms
+
+**Rating**: ⭐⭐⭐⭐⭐
+
+|||
+
+### Detailed Analysis
+
+Our platform has grown significantly over the past year, achieving remarkable metrics:
+
+- **User Growth**: From 1,000 to over 10,000 active users
+- **Reliability**: Maintained 99.9% uptime with zero critical incidents
+- **Performance**: Average API response time under 100ms
+- **Satisfaction**: Consistent 5-star ratings across all review platforms
+
+The success is attributed to our focus on performance, reliability, and user experience. We continue to invest in infrastructure and optimization.
+:::
+
+---
+
 ## Performance
 
 MarkDeck is designed to be:

markdeck/__init__.py

@@ -1,3 +1,3 @@
 """MarkDeck - A lightweight markdown presentation tool."""
 
-__version__ = "0.5.0"
+__version__ = "0.6.0"

markdeck/parser.py

@@ -72,6 +72,13 @@ def _transform_columns(self) -> None:
             Right content
             :::
 
+        Or with percentage width:
+            :::columns[60]
+            Left content (60% width)
+            |||
+            Right content (40% width)
+            :::
+
         Into special markers that the frontend will process:
             <!-- COLUMN:LEFT:START -->
             Left content (markdown)
@@ -80,6 +87,14 @@ def _transform_columns(self) -> None:
             Right content (markdown)
             <!-- COLUMN:RIGHT:END -->
 
+        Or with width:
+            <!-- COLUMN:LEFT:START:60 -->
+            Left content (markdown)
+            <!-- COLUMN:LEFT:END -->
+            <!-- COLUMN:RIGHT:START -->
+            Right content (markdown)
+            <!-- COLUMN:RIGHT:END -->
+
         The frontend (slides.js) will find these markers and render the markdown
         in each column, allowing mermaid diagrams and other features to work.
 
@@ -99,11 +114,13 @@ def save_code_block(match):
             code_block_pattern, save_code_block, self.content, flags=re.DOTALL
         )
 
-        # Pattern to match column blocks (more forgiving with whitespace)
-        column_pattern = r":::columns\s*\n(.*?)\s*\n:::"
+        # Pattern to match column blocks with optional width percentage
+        # Matches: :::columns or :::columns[60]
+        column_pattern = r":::columns(?:\[(\d+)\])?\s*\n(.*?)\s*\n:::"
 
         def replace_columns(match):
-            content = match.group(1)
+            width_percent = match.group(1)  # Can be None if no width specified
+            content = match.group(2)
             # Split on ||| separator (more forgiving with whitespace)
             parts = re.split(r"\s*\|\|\|\s*", content, maxsplit=1)
 
@@ -112,9 +129,15 @@ def replace_columns(match):
                 right_content = parts[1].strip()
 
                 # Create marker structure that preserves markdown
+                # Include width in left column marker if specified
+                if width_percent:
+                    left_start_marker = f"<!-- COLUMN:LEFT:START:{width_percent} -->"
+                else:
+                    left_start_marker = "<!-- COLUMN:LEFT:START -->"
+
                 # The frontend will process these markers after marked.js runs
                 return (
-                    "<!-- COLUMN:LEFT:START -->\n"
+                    f"{left_start_marker}\n"
                     f"{left_content}\n"
                     "<!-- COLUMN:LEFT:END -->\n"
                     "<!-- COLUMN:RIGHT:START -->\n"

markdeck/static/slides.js

@@ -263,16 +263,21 @@ class SlideShow {
     processColumnMarkers(markdown) {
         // Find and process column markers created by the parser
         // This must be called BEFORE marked.parse() to preserve the markdown
-        const leftStart = '<!-- COLUMN:LEFT:START -->';
+        const leftStartPattern = /<!-- COLUMN:LEFT:START(?::(\d+))? -->/;
         const leftEnd = '<!-- COLUMN:LEFT:END -->';
         const rightStart = '<!-- COLUMN:RIGHT:START -->';
         const rightEnd = '<!-- COLUMN:RIGHT:END -->';
 
         // Check if this slide has column markers
-        if (!markdown.includes(leftStart)) {
+        const leftStartMatch = markdown.match(leftStartPattern);
+        if (!leftStartMatch) {
             return null; // No columns, caller should parse normally
         }
 
+        // Extract width percentage if present (e.g., "60" from <!-- COLUMN:LEFT:START:60 -->)
+        const leftWidthPercent = leftStartMatch[1] ? parseInt(leftStartMatch[1], 10) : null;
+        const leftStart = leftStartMatch[0];
+
         // Extract left column markdown (before marked.parse)
         const leftStartIdx = markdown.indexOf(leftStart);
         const leftEndIdx = markdown.indexOf(leftEnd);
@@ -294,11 +299,21 @@ class SlideShow {
         const leftHtml = marked.parse(leftMarkdown);
         const rightHtml = marked.parse(rightMarkdown);
 
-        // Create the two-column HTML structure
+        // Apply width styles if specified
+        let leftStyle = '';
+        let rightStyle = '';
+        if (leftWidthPercent !== null) {
+            // Validate width is between 1 and 99
+            const validWidth = Math.max(1, Math.min(99, leftWidthPercent));
+            leftStyle = ` style="flex: 0 0 ${validWidth}%;"`;
+            rightStyle = ` style="flex: 1;"`;
+        }
+
+        // Create the two-column HTML structure with optional width styles
         const columnsHtml = `
             <div class="columns-container">
-                <div class="column-left">${leftHtml}</div>
-                <div class="column-right">${rightHtml}</div>
+                <div class="column-left"${leftStyle}>${leftHtml}</div>
+                <div class="column-right"${rightStyle}>${rightHtml}</div>
             </div>
         `;
 

pyproject.toml

@@ -1,6 +1,6 @@
 [project]
 name = "markdeck"
-version = "0.5.0"
+version = "0.6.0"
 description = "A lightweight markdown presentation tool"
 readme = "README.md"
 requires-python = ">=3.11"