diff --git a/carousel/diff-diff-v27-carousel.pdf b/carousel/diff-diff-v27-carousel.pdf
new file mode 100644
index 00000000..dd436b2a
Binary files /dev/null and b/carousel/diff-diff-v27-carousel.pdf differ
diff --git a/carousel/generate_v27_pdf.py b/carousel/generate_v27_pdf.py
new file mode 100644
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+++ b/carousel/generate_v27_pdf.py
@@ -0,0 +1,719 @@
+#!/usr/bin/env python3
+"""Generate LinkedIn carousel PDF for diff-diff v2.7 release."""
+
+import os
+import tempfile
+from pathlib import Path
+
+import matplotlib
+matplotlib.use("Agg")
+import matplotlib.pyplot as plt  # noqa: E402
+import matplotlib.patches as mpatches  # noqa: E402
+import numpy as np  # noqa: E402
+from PIL import Image as PILImage  # noqa: E402
+
+from fpdf import FPDF  # noqa: E402
+
+# Computer Modern for math
+plt.rcParams["mathtext.fontset"] = "cm"
+
+# Page dimensions (4:5 portrait)
+WIDTH = 270     # mm
+HEIGHT = 337.5  # mm
+
+# Dark theme palette
+BG = (26, 26, 46)          # #1a1a2e
+CYAN = (0, 212, 255)       # #00d4ff
+WHITE = (255, 255, 255)    # #ffffff
+GRAY = (136, 146, 176)     # #8892b0
+DARK_PANEL = (22, 33, 62)  # #16213e
+ORANGE = (255, 107, 53)    # #ff6b35
+GREEN = (80, 250, 123)     # #50fa7b
+GOLD = (241, 250, 140)     # #f1fa8c
+
+# Hex colors for matplotlib
+CYAN_HEX = "#00d4ff"
+WHITE_HEX = "#ffffff"
+GRAY_HEX = "#8892b0"
+DARK_PANEL_HEX = "#16213e"
+ORANGE_HEX = "#ff6b35"
+
+
+class CarouselV27PDF(FPDF):
+    def __init__(self):
+        super().__init__(orientation="P", unit="mm", format=(WIDTH, HEIGHT))
+        self.set_auto_page_break(False)
+        self._temp_files = []
+
+    def cleanup(self):
+        """Remove temporary image files."""
+        for f in self._temp_files:
+            try:
+                os.unlink(f)
+            except OSError:
+                pass
+
+    # ── Background & Footer ────────────────────────────────────────
+
+    def _add_dark_bg(self):
+        """Fill page with dark background."""
+        self.set_fill_color(*BG)
+        self.rect(0, 0, WIDTH, HEIGHT, "F")
+
+    def _add_footer(self):
+        """Add footer with cyan rule and version text."""
+        rule_y = HEIGHT - 28
+        self.set_draw_color(*CYAN)
+        self.set_line_width(0.5)
+        self.line(50, rule_y, WIDTH - 50, rule_y)
+
+        self.set_font("Helvetica", "B", 12)
+        dd_text = "diff-diff "
+        v_text = "v2.7"
+        dd_w = self.get_string_width(dd_text)
+        v_w = self.get_string_width(v_text)
+        start_x = (WIDTH - dd_w - v_w) / 2
+
+        self.set_xy(start_x, HEIGHT - 22)
+        self.set_text_color(*GRAY)
+        self.cell(dd_w, 10, dd_text)
+        self.set_text_color(*CYAN)
+        self.cell(v_w, 10, v_text)
+
+    # ── Text Helpers ───────────────────────────────────────────────
+
+    def _centered_text(self, y, text, size=28, bold=True, color=WHITE):
+        """Add centered text."""
+        self.set_xy(0, y)
+        self.set_font("Helvetica", "B" if bold else "", size)
+        self.set_text_color(*color)
+        self.cell(WIDTH, size * 0.5, text, align="C")
+
+    # ── Equation Rendering ─────────────────────────────────────────
+
+    def _render_equations(self, latex_lines, fontsize=28, color=CYAN_HEX):
+        """Render LaTeX equations to transparent PNG."""
+        n = len(latex_lines)
+        fig_h = max(0.7, 0.55 * n + 0.15)
+        fig = plt.figure(figsize=(10, fig_h))
+
+        for i, line in enumerate(latex_lines):
+            y_frac = 1.0 - (2 * i + 1) / (2 * n)
+            fig.text(
+                0.5, y_frac, line,
+                fontsize=fontsize, ha="center", va="center",
+                color=color,
+            )
+
+        fig.patch.set_alpha(0)
+        fd, path = tempfile.mkstemp(suffix=".png")
+        os.close(fd)
+        fig.savefig(path, dpi=250, bbox_inches="tight", pad_inches=0.06,
+                    transparent=True)
+        plt.close(fig)
+
+        with PILImage.open(path) as img:
+            pw, ph = img.size
+
+        self._temp_files.append(path)
+        return path, pw, ph
+
+    def _place_equation_centered(self, path, pw, ph, y, max_w=200):
+        """Place equation image centered on page at given y."""
+        aspect = ph / pw
+        display_w = min(max_w, WIDTH * 0.75)
+        display_h = display_w * aspect
+        eq_x = (WIDTH - display_w) / 2
+        self.image(path, eq_x, y, display_w)
+        return display_h
+
+    # ── Diagram: Single Comparison (Slide 2) ───────────────────────
+
+    def _render_single_comparison(self):
+        """ATT(g,t) -> single arrow -> one comparison box."""
+        fig, ax = plt.subplots(figsize=(9, 2.5))
+        ax.set_xlim(0, 10)
+        ax.set_ylim(0, 2.5)
+        ax.set_aspect("equal")
+        ax.axis("off")
+        fig.patch.set_alpha(0)
+        ax.set_facecolor("none")
+
+        # ATT box (left)
+        att = mpatches.FancyBboxPatch(
+            (0.3, 0.5), 3.2, 1.5, boxstyle="round,pad=0.2",
+            facecolor="none", edgecolor=CYAN_HEX, linewidth=2.5,
+        )
+        ax.add_patch(att)
+        ax.text(1.9, 1.25, r"$ATT(g,\,t)$", color=CYAN_HEX,
+                fontsize=24, ha="center", va="center", fontweight="bold")
+
+        # Arrow
+        ax.annotate(
+            "", xy=(6.8, 1.25), xytext=(3.8, 1.25),
+            arrowprops=dict(arrowstyle="->", color=GRAY_HEX, lw=2.5,
+                            mutation_scale=20),
+        )
+
+        # Comparison box (right)
+        comp = mpatches.FancyBboxPatch(
+            (6.5, 0.5), 3.2, 1.5, boxstyle="round,pad=0.2",
+            facecolor="none", edgecolor=GRAY_HEX, linewidth=2,
+        )
+        ax.add_patch(comp)
+        ax.text(8.1, 1.25, r"$(g',\, t_{pre})$", color=GRAY_HEX,
+                fontsize=22, ha="center", va="center")
+
+        fd, path = tempfile.mkstemp(suffix=".png")
+        os.close(fd)
+        fig.savefig(path, dpi=200, bbox_inches="tight", pad_inches=0.1,
+                    transparent=True)
+        plt.close(fig)
+
+        with PILImage.open(path) as img:
+            pw, ph = img.size
+
+        self._temp_files.append(path)
+        return path, pw, ph
+
+    # ── Diagram: Fan of Comparisons (Slide 3) ─────────────────────
+
+    def _render_fan_comparison(self):
+        """ATT(g,t) -> fan of arrows -> multiple comparison boxes."""
+        fig, ax = plt.subplots(figsize=(9, 5))
+        ax.set_xlim(0, 10)
+        ax.set_ylim(-0.2, 5.2)
+        ax.set_aspect("equal")
+        ax.axis("off")
+        fig.patch.set_alpha(0)
+        ax.set_facecolor("none")
+
+        # ATT box (left, vertically centered)
+        att = mpatches.FancyBboxPatch(
+            (0.2, 1.75), 3.2, 1.5, boxstyle="round,pad=0.2",
+            facecolor="none", edgecolor=CYAN_HEX, linewidth=2.5,
+        )
+        ax.add_patch(att)
+        ax.text(1.8, 2.5, r"$ATT(g,\,t)$", color=CYAN_HEX,
+                fontsize=24, ha="center", va="center", fontweight="bold")
+
+        # Fan of comparison boxes
+        labels = [
+            r"$(g_1,\, t_1)$",
+            r"$(g_2,\, t_2)$",
+            r"$(g_3,\, t_3)$",
+            r"$(g_4,\, t_4)$",
+            r"$(g_5,\, t_5)$",
+        ]
+        y_positions = np.linspace(4.5, 0.5, len(labels))
+
+        for label, yp in zip(labels, y_positions):
+            ax.annotate(
+                "", xy=(6.5, yp), xytext=(3.6, 2.5),
+                arrowprops=dict(arrowstyle="->", color=CYAN_HEX, lw=1.8,
+                                alpha=0.7, mutation_scale=15),
+            )
+            box = mpatches.FancyBboxPatch(
+                (6.3, yp - 0.4), 3.4, 0.8, boxstyle="round,pad=0.1",
+                facecolor="none", edgecolor=GRAY_HEX, linewidth=1.5,
+            )
+            ax.add_patch(box)
+            ax.text(8.0, yp, label, color=GRAY_HEX,
+                    fontsize=15, ha="center", va="center")
+
+        fd, path = tempfile.mkstemp(suffix=".png")
+        os.close(fd)
+        fig.savefig(path, dpi=200, bbox_inches="tight", pad_inches=0.1,
+                    transparent=True)
+        plt.close(fig)
+
+        with PILImage.open(path) as img:
+            pw, ph = img.size
+
+        self._temp_files.append(path)
+        return path, pw, ph
+
+    # ── CI Comparison (Slide 4) ────────────────────────────────────
+
+    def _render_ci_comparison(self):
+        """Two horizontal CI bars: CS (wider, orange) vs EDiD (narrower, cyan)."""
+        fig, ax = plt.subplots(figsize=(8, 3.5))
+        ax.set_xlim(-4, 5)
+        ax.set_ylim(-0.5, 3)
+        ax.axis("off")
+        fig.patch.set_alpha(0)
+        ax.set_facecolor("none")
+
+        point_est = 0.8
+
+        # CS bar (wider, orange)
+        cs_lo, cs_hi = -1.5, 3.1
+        cs_y = 2.0
+        ax.plot([cs_lo, cs_hi], [cs_y, cs_y], color=ORANGE_HEX, linewidth=7,
+                solid_capstyle="round")
+        ax.plot(point_est, cs_y, "o", color=ORANGE_HEX, markersize=14,
+                zorder=5)
+        ax.text(-3.8, cs_y, "Callaway-\nSant'Anna", color=ORANGE_HEX,
+                fontsize=14, ha="left", va="center", fontweight="bold")
+
+        # EDiD bar (narrower, cyan)
+        edid_lo, edid_hi = 0.0, 1.6
+        edid_y = 0.7
+        ax.plot([edid_lo, edid_hi], [edid_y, edid_y], color=CYAN_HEX,
+                linewidth=7, solid_capstyle="round")
+        ax.plot(point_est, edid_y, "o", color=CYAN_HEX, markersize=14,
+                zorder=5)
+        ax.text(-3.8, edid_y, "EfficientDiD", color=CYAN_HEX,
+                fontsize=14, ha="left", va="center", fontweight="bold")
+
+        # Reference line at point estimate
+        ax.axvline(point_est, color=GRAY_HEX, linewidth=1.2, linestyle="--",
+                   alpha=0.6)
+
+        fd, path = tempfile.mkstemp(suffix=".png")
+        os.close(fd)
+        fig.savefig(path, dpi=200, bbox_inches="tight", pad_inches=0.15,
+                    transparent=True)
+        plt.close(fig)
+
+        with PILImage.open(path) as img:
+            pw, ph = img.size
+
+        self._temp_files.append(path)
+        return path, pw, ph
+
+    # ── Code Block (Slide 5) ───────────────────────────────────────
+
+    def _add_code_block(self, x, y, w, token_lines, font_size=13,
+                        line_height=12):
+        """Render syntax-highlighted code on a dark panel.
+
+        token_lines: list of lists of (text, color_tuple) pairs per line.
+        """
+        n_lines = len(token_lines)
+        total_h = n_lines * line_height + 24
+
+        # Dark panel
+        self.set_fill_color(*DARK_PANEL)
+        self.rect(x, y, w, total_h, "F")
+
+        self.set_font("Courier", "", font_size)
+        char_w = self.get_string_width("M")
+
+        pad_x = 15
+        pad_y = 12
+
+        for i, tokens in enumerate(token_lines):
+            cx = x + pad_x
+            cy = y + pad_y + i * line_height
+
+            for text, color in tokens:
+                if not text:
+                    continue
+                self.set_xy(cx, cy)
+                self.set_text_color(*color)
+                self.cell(char_w * len(text), 10, text)
+                cx += char_w * len(text)
+
+        return total_h
+
+    # ════════════════════════════════════════════════════════════════
+    # SLIDES
+    # ════════════════════════════════════════════════════════════════
+
+    def slide_01_hook(self):
+        """Slide 1: Hook — First open-source implementation."""
+        self.add_page()
+        self._add_dark_bg()
+
+        # Hero — method name dominates the page
+        self._centered_text(55, "Efficient DiD", size=52, color=CYAN)
+
+        # Positioning statement
+        self._centered_text(118, "First Open-Source", size=30, color=WHITE)
+        self._centered_text(150, "Implementation", size=30, color=WHITE)
+
+        # Badge
+        badge_w = 170
+        badge_h = 34
+        badge_x = (WIDTH - badge_w) / 2
+        badge_y = 195
+        self.set_draw_color(*CYAN)
+        self.set_line_width(1.5)
+        self.rect(badge_x, badge_y, badge_w, badge_h, "D")
+
+        self.set_xy(badge_x, badge_y + 8)
+        self.set_font("Helvetica", "B", 20)
+        self.set_text_color(*CYAN)
+        self.cell(badge_w, 16, "diff-diff v2.7", align="C")
+
+        # Citation
+        self.set_xy(0, 247)
+        self.set_font("Helvetica", "I", 17)
+        self.set_text_color(*GRAY)
+        self.cell(WIDTH, 10, "Chen, Sant'Anna & Xie (2025)", align="C")
+
+        # Tagline
+        self._centered_text(278, "Semiparametric efficiency bound",
+                            size=17, bold=False, color=GRAY)
+        self._centered_text(295, "for staggered DiD",
+                            size=17, bold=False, color=GRAY)
+
+        self._add_footer()
+
+    def slide_02_problem(self):
+        """Slide 2: The Problem — single comparison per target."""
+        self.add_page()
+        self._add_dark_bg()
+
+        self._centered_text(30, "The Problem", size=38, color=WHITE)
+
+        # Body text
+        self._centered_text(80, "Standard staggered DiD uses one", size=18,
+                            bold=False, color=GRAY)
+        self._centered_text(100, "comparison per target effect --", size=18,
+                            bold=False, color=GRAY)
+        self._centered_text(120, "leaving valid information unused.", size=18,
+                            bold=False, color=GRAY)
+
+        # Diagram
+        diag_path, dpw, dph = self._render_single_comparison()
+        diag_w = WIDTH * 0.82
+        diag_aspect = dph / dpw
+        diag_h = diag_w * diag_aspect
+        diag_x = (WIDTH - diag_w) / 2
+        diag_y = 155
+        self.image(diag_path, diag_x, diag_y, diag_w)
+
+        # Label
+        self._centered_text(diag_y + diag_h + 10,
+                            "Single 2x2 comparison (CS default)",
+                            size=16, bold=False, color=GRAY)
+
+        self._add_footer()
+
+    def slide_03_insight(self):
+        """Slide 3: The Insight — multiple valid comparisons, GLS weights."""
+        self.add_page()
+        self._add_dark_bg()
+
+        self._centered_text(25, "The Insight", size=38, color=WHITE)
+
+        # Body text
+        self._centered_text(68, "Under PT-All, multiple valid comparisons",
+                            size=17, bold=False, color=GRAY)
+        self._centered_text(86, "exist. EDiD finds the optimal combination.",
+                            size=17, bold=False, color=GRAY)
+
+        # Fan diagram
+        fan_path, fpw, fph = self._render_fan_comparison()
+        fan_w = WIDTH * 0.78
+        fan_aspect = fph / fpw
+        fan_h = fan_w * fan_aspect
+        fan_x = (WIDTH - fan_w) / 2
+        fan_y = 105
+        self.image(fan_path, fan_x, fan_y, fan_w)
+
+        # Equation
+        eq_path, epw, eph = self._render_equations(
+            [r"$w^* = \frac{\mathbf{1}' (\Omega^*)^{-1}"
+             r"}{\mathbf{1}' (\Omega^*)^{-1} \mathbf{1}}$"],
+            fontsize=34,
+        )
+        eq_y = fan_y + fan_h + 8
+        eq_h = self._place_equation_centered(eq_path, epw, eph, eq_y,
+                                             max_w=180)
+
+        # Label
+        self._centered_text(eq_y + eq_h + 8, "GLS optimal weighting",
+                            size=16, bold=True, color=CYAN)
+
+        self._add_footer()
+
+    def slide_04_assumption(self):
+        """Slide 4: The Assumption — what PT-All means and when it holds."""
+        self.add_page()
+        self._add_dark_bg()
+
+        self._centered_text(25, "The Assumption", size=38, color=WHITE)
+        self._centered_text(58, "Parallel Trends for All Groups", size=22,
+                            bold=True, color=CYAN)
+
+        # Definition (single line)
+        self._centered_text(92, "All cohorts share common outcome trends,",
+                            size=17, bold=False, color=GRAY)
+        self._centered_text(110, "treated or not.", size=17, bold=False,
+                            color=GRAY)
+
+        # Two comparison panels
+        margin = 28
+        gap = 12
+        panel_w = (WIDTH - margin * 2 - gap) / 2
+        panel_h = 65
+        panel_y = 132
+
+        panels = [
+            {
+                "x": margin,
+                "label": "PT-Post",
+                "label_color": ORANGE,
+                "line1": "Trends hold between treated",
+                "line2": "cohort and comparison group",
+                "result": "= CS post-treatment ATT",
+            },
+            {
+                "x": margin + panel_w + gap,
+                "label": "PT-All",
+                "label_color": CYAN,
+                "line1": "Trends hold across all",
+                "line2": "cohorts, treated or not",
+                "result": "= EfficientDiD",
+            },
+        ]
+
+        for panel in panels:
+            px = panel["x"]
+
+            # Panel background
+            self.set_fill_color(*DARK_PANEL)
+            self.set_draw_color(*panel["label_color"])
+            self.set_line_width(1.2)
+            self.rect(px, panel_y, panel_w, panel_h, "DF")
+
+            # Label badge centered at top edge
+            badge_w = 70
+            badge_h = 18
+            badge_x = px + (panel_w - badge_w) / 2
+            badge_y = panel_y - badge_h / 2
+            self.set_fill_color(*panel["label_color"])
+            self.rect(badge_x, badge_y, badge_w, badge_h, "F")
+            self.set_xy(badge_x, badge_y + 3)
+            self.set_font("Helvetica", "B", 11)
+            self.set_text_color(*BG)
+            self.cell(badge_w, 12, panel["label"], align="C")
+
+            # Description lines
+            self.set_font("Helvetica", "", 15)
+            self.set_text_color(*WHITE)
+            self.set_xy(px + 10, panel_y + 14)
+            self.cell(panel_w - 20, 10, panel["line1"])
+            self.set_xy(px + 10, panel_y + 28)
+            self.cell(panel_w - 20, 10, panel["line2"])
+
+            # Result
+            self.set_xy(px + 10, panel_y + 46)
+            self.set_font("Helvetica", "B", 14)
+            self.set_text_color(*panel["label_color"])
+            self.cell(panel_w - 20, 10, panel["result"])
+
+        # "When does PT-All hold?"
+        section_y = panel_y + panel_h + 16
+        self._centered_text(section_y, "When does PT-All hold?", size=20,
+                            bold=True, color=WHITE)
+
+        examples = [
+            "Staggered policy rollouts across regions",
+            "Administrative or geographic phasing",
+            "Treatment timing unrelated to anticipated effects",
+        ]
+
+        y_cursor = section_y + 26
+        for example in examples:
+            self.set_xy(50, y_cursor)
+            self.set_font("Helvetica", "B", 14)
+            self.set_text_color(*CYAN)
+            self.cell(10, 10, "-")
+            self.set_font("Helvetica", "", 14)
+            self.set_text_color(*GRAY)
+            self.cell(WIDTH - 100, 10, example)
+            y_cursor += 18
+
+        self._add_footer()
+
+    def slide_05_payoff(self):
+        """Slide 5: The Payoff — tightest possible CIs."""
+        self.add_page()
+        self._add_dark_bg()
+
+        self._centered_text(30, "The Payoff", size=38, color=WHITE)
+
+        # Body text
+        self._centered_text(80, "Achieves the semiparametric efficiency bound",
+                            size=18, bold=False, color=GRAY)
+        self._centered_text(98, "-- tightest possible confidence intervals.",
+                            size=18, bold=False, color=GRAY)
+
+        # CI comparison
+        ci_path, cpw, cph = self._render_ci_comparison()
+        ci_w = WIDTH * 0.82
+        ci_aspect = cph / cpw
+        ci_h = ci_w * ci_aspect
+        ci_x = (WIDTH - ci_w) / 2
+        ci_y = 145
+        self.image(ci_path, ci_x, ci_y, ci_w)
+
+        # Annotation
+        ann_y = ci_y + ci_h + 15
+        self.set_xy(0, ann_y)
+        self.set_font("Helvetica", "I", 16)
+        self.set_text_color(*GRAY)
+        self.cell(WIDTH, 10,
+                  '"Often exceeding 40% gains in precision"',
+                  align="C")
+
+        self.set_xy(0, ann_y + 20)
+        self.set_font("Helvetica", "", 14)
+        self.set_text_color(*GRAY)
+        self.cell(WIDTH, 10,
+                  "-- Chen, Sant'Anna & Xie (2025)",
+                  align="C")
+
+        self._add_footer()
+
+    def slide_06_code(self):
+        """Slide 6: The Code — syntax-highlighted API example."""
+        self.add_page()
+        self._add_dark_bg()
+
+        self._centered_text(30, "The Code", size=38, color=WHITE)
+
+        margin = 28
+        code_y = 80
+
+        token_lines = [
+            [("from", CYAN), (" diff_diff ", WHITE),
+             ("import", CYAN), (" EfficientDiD", GOLD)],
+            [],  # blank line
+            [("edid", WHITE), (" = ", WHITE), ("EfficientDiD", GOLD),
+             ("(", WHITE), ("pt_assumption", WHITE), ("=", WHITE),
+             ('"all"', GREEN), (")", WHITE)],
+            [("results", WHITE), (" = edid.fit(data, ", WHITE),
+             ("outcome", WHITE), ("=", WHITE), ('"y"', GREEN),
+             (",", WHITE)],
+            [("                   ", WHITE), ("unit", WHITE),
+             ("=", WHITE), ('"id"', GREEN), (", ", WHITE),
+             ("time", WHITE), ("=", WHITE), ('"t"', GREEN),
+             (",", WHITE)],
+            [("                   ", WHITE), ("first_treat", WHITE),
+             ("=", WHITE), ('"g"', GREEN), (",", WHITE)],
+            [("                   ", WHITE), ("aggregate", WHITE),
+             ("=", WHITE), ('"all"', GREEN), (")", WHITE)],
+            [("results", WHITE), (".print_summary()", WHITE)],
+        ]
+
+        code_h = self._add_code_block(
+            margin, code_y, WIDTH - margin * 2, token_lines,
+        )
+
+        # Subtitle
+        self._centered_text(code_y + code_h + 18,
+                            "sklearn-like API", size=18, bold=False,
+                            color=GRAY)
+
+        self._add_footer()
+
+    def slide_07_safety_net(self):
+        """Slide 7: Safety Net — PT-Post post-treatment ATT matches CS."""
+        self.add_page()
+        self._add_dark_bg()
+
+        self._centered_text(30, "Safety Net", size=38, color=WHITE)
+
+        # Body text — scoped to post-treatment ATT
+        self._centered_text(78, "Under PT-Post, post-treatment ATT(g,t)",
+                            size=18, bold=False, color=GRAY)
+        self._centered_text(100, "matches Callaway-Sant'Anna exactly",
+                            size=22, bold=True, color=CYAN)
+
+        # Prominent equivalence badge
+        badge_w = 200
+        badge_h = 36
+        badge_x = (WIDTH - badge_w) / 2
+        badge_y = 150
+        self.set_draw_color(*CYAN)
+        self.set_line_width(1.5)
+        self.rect(badge_x, badge_y, badge_w, badge_h, "D")
+        self.set_xy(badge_x, badge_y + 8)
+        self.set_font("Helvetica", "B", 18)
+        self.set_text_color(*CYAN)
+        self.cell(badge_w, 18, "ATT point estimates identical",
+                  align="C")
+
+        # Corollary citation
+        self.set_xy(0, badge_y + badge_h + 25)
+        self.set_font("Helvetica", "I", 14)
+        self.set_text_color(*GRAY)
+        self.cell(WIDTH, 10,
+                  "Corollary 3.2, Chen, Sant'Anna & Xie (2025)",
+                  align="C")
+
+        self._add_footer()
+
+    def slide_08_cta(self):
+        """Slide 8: CTA — Get Started."""
+        self.add_page()
+        self._add_dark_bg()
+
+        self._centered_text(55, "Get Started", size=42, color=WHITE)
+
+        # pip install badge
+        badge_w = 210
+        badge_h = 36
+        badge_x = (WIDTH - badge_w) / 2
+        badge_y = 115
+        self.set_fill_color(*CYAN)
+        self.rect(badge_x, badge_y, badge_w, badge_h, "F")
+
+        self.set_xy(badge_x, badge_y + 9)
+        self.set_font("Courier", "B", 16)
+        self.set_text_color(*BG)
+        self.cell(badge_w, 16, "pip install diff-diff", align="C")
+
+        # Links
+        self._centered_text(178, "github.com/igerber/diff-diff",
+                            size=18, color=CYAN)
+        self._centered_text(205, "arXiv:2506.17729",
+                            size=18, color=CYAN)
+
+        # Wordmark
+        self.set_font("Helvetica", "B", 36)
+        dd_text = "diff-diff "
+        v_text = "v2.7"
+        dd_w = self.get_string_width(dd_text)
+        v_w = self.get_string_width(v_text)
+        start_x = (WIDTH - dd_w - v_w) / 2
+
+        self.set_xy(start_x, 255)
+        self.set_text_color(*WHITE)
+        self.cell(dd_w, 20, dd_text)
+        self.set_text_color(*CYAN)
+        self.cell(v_w, 20, v_text)
+
+        # Subtitle
+        self._centered_text(288, "Difference-in-Differences for Python",
+                            size=15, bold=False, color=GRAY)
+
+        self._add_footer()
+
+
+def main():
+    pdf = CarouselV27PDF()
+
+    pdf.slide_01_hook()
+    pdf.slide_02_problem()
+    pdf.slide_03_insight()
+    pdf.slide_04_assumption()
+    pdf.slide_05_payoff()
+    pdf.slide_06_code()
+    pdf.slide_07_safety_net()
+    pdf.slide_08_cta()
+
+    output_path = Path(__file__).parent / "diff-diff-v27-carousel.pdf"
+    pdf.output(str(output_path))
+    print(f"PDF saved to: {output_path}")
+
+    pdf.cleanup()
+
+
+if __name__ == "__main__":
+    main()