Chart Prompts

Restyle my chart in the "Debt Maturity" style described below. Keep my data, chart type, title meaning and units; change only the presentation. Use the charting library this project already uses (plain SVG if there is none). If the library can't express a detail, draw it in a custom layer instead of dropping it. Measurements assume a 960 x 600 chart; scale them proportionally.

Mood: a sovereign debt office's investor presentation. Deep navy, a gold hairline frame like an engraved certificate, a centered classical serif headline and restrained gold highlights.

Colors (use these exact values):
- Page: #0B1530 (deep navy).
- Gold #D4AF37 for the frame, header small caps, the primary line and its axis, window labels and the peak annotation.
- Coupon blue #93C5FD for the companion series, its strip title and its strip labels.
- Ivory #EDE6D3 for the title and legend text; muted #8C93A8 for the subtitle, year labels and ticks; gridlines #1E2A4A.

Typography (Google Fonts), lining figures throughout (font-variant-numeric: lining-nums):
- Cormorant Garamond 600, 36px, ivory, centered, for the title stating the finding; Cormorant Garamond 600 italic 17px gold for the peak annotation ("$12.9bn in 2030") and italic 14px muted for the source.
- Raleway for everything else: header 600, 11px, uppercase, 3.2px letter-spacing, gold, centered; subtitle 400, 13px, muted, centered; axis ticks 600, 12px (gold for the main plot, blue for the coupon strip); axis titles, window labels, the threshold label and the strip title 700, 9.5px, uppercase, 1.5px letter-spacing; year labels 500, 12px; legend 600, 12px ivory.

Layout:
- Frame: a 0.8px gold rectangle inset 20px from every edge, and a second 0.4px gold rectangle at 60% opacity inset 25px.
- Centered header block: small caps line, a short gold ornament under it (two 52px hairlines with a small gold diamond between), the title, then the subtitle naming both measures and units and saying the companion measure is in the strip below.
- Main plot from x 104 to 856, y 196 to 392, one left axis for the primary measure. Never put the rate on a right-hand axis.
- Companion strip below it with 44px of clear space between: a blue uppercase title ("AVERAGE COUPON, %") 14px above, then a strip from y 436 to 484 on a faint #93C5FD panel at 5% opacity with its own small scale (1%, 3%, 5%) labeled at the left in blue. Year labels sit once, under the strip; both panels get the year ticks.
- Legend and source on one line near the bottom, source right-aligned.

Axes and grid:
- Horizontal gridlines 0.8px #1E2A4A (1.2px at zero), no vertical gridlines, no axis lines. Main-plot ticks in gold with the axis title "$BN" above them; strip ticks in coupon blue with a % sign.
- Year ticks 6px on labeled years (every third), 3px otherwise, muted.
- A threshold as a 0.6px gold dotted line (2 4) at 80% opacity, always labeled at its right end in gold small caps ("REFINANCING THRESHOLD, $9.5BN").

Marks:
- Line chart: primary series as a 2.6px gold line with straight segments and round joins, a navy-filled circle marker (r 3, 1.5px gold stroke) at every point, and a faint gold wash below it (vertical gradient from 16% to 0% opacity). Companion series as a 1.6px coupon blue line dashed 5 3 in its own strip, with its first and last values labeled in 700 12px blue. Highlight windows (periods above the threshold) as full-height gold columns at 7% opacity with 0.6px gold edges at 35% opacity and a 1px gold cap line labeled above in gold small caps ("REFINANCING 2029–31").
- Bar chart: slim gold columns (about 45% of the band, square corners) for the primary series, the companion series as the same dashed blue line in its strip below, and the same shaded gold windows behind.

Avoid: a secondary y axis, unlabeled reference lines, bright fills, heavy gridlines, drop shadows, more than two data colors, and sans-serif titles.

When you're done, render the chart and check that the frame is unbroken, the main plot has a single $ scale, the coupon strip is clearly separate, the threshold is labeled, the windows cover exactly the periods above the threshold, and the title percentage is computed from the data.