Chart Prompts

Restyle my chart in the "Tree Rings" 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 dendrochronology figure printed on dark walnut. Warm, patient and scientific: a dense comb of slim bars in the colors of cut wood, a calm cream spline, a single cool blue reserved for the years that matter, and faint growth rings in one corner.

Colors (use these exact values):
- Ground: #221812 (dark walnut).
- Wood ramp for ordinary bars, interpolated by time from oldest to newest like a trunk cross-section: #6E4326 (dark heartwood) at the start, #B07A45 (amber) in the middle, #D9B98A (pale sapwood) at the end. Interpolate in RGB.
- Highlight: #6F93B0 (cool blue), only for the flagged events (drought years), their leaders and callout years.
- Spline, title and baseline: #EFE2C8 (cream). Secondary text: #A08A70. Gridlines: #3A2B20. Corner rings: #3A2A1F.

Typography (Google Fonts):
- Vollkorn 600, 28px, cream for the title, stating the finding.
- Vollkorn 400, 16px #A08A70 for the subtitle (measure, what 1.0 means, years, smoothing).
- Vollkorn 13 to 14px #A08A70 for axis numerals, with lining figures (font-variant-numeric: lining-nums); the 1.0 baseline numeral 600 in cream.
- Vollkorn italic for notes: callout year 13.5px in blue, its value 12.5px #A08A70; key labels and footnote 12.5px.

Layout:
- 48px margins. Title baseline 64, subtitle 94, a one-line key at baseline 128 right of center: "Heartwood, oldest", a 96 x 10 stepped ramp swatch of the wood colors, "sapwood, newest", then a 10px blue square and "drought year".
- Plot area x 88 to 904, y 152 to 498. Footer at baseline 580: "Source: ..." left, a method note in italic right ("Composite of 38 cores from 21 trees").
- Corner rings: 12 to 15 concentric circles centered just off the top-right corner (about 980, -30), radii 18 to 250 px with irregular 7 to 23 px spacing and 0.6 to 1.5 px strokes, at 95% opacity. They stay behind everything and away from the title.

Axes and grid:
- Horizontal gridlines at 0.2 intervals, 0.7px #3A2B20; no vertical gridlines, no axis lines. The 1.0 baseline drawn over the bars as a 0.9px cream line at 70% opacity.
- X axis: small ticks every decade (0.6px, 3px long) and longer ticks every 50 years (1px, 7px long) with numerals centered 29px below the plot.

Marks:
- Bar chart: a diverging bar per period growing up or down from the baseline value (1.0 here), filling the band with a 0.7px gap, square ends, wood-ramp color by position in time, highlight bars in blue. Over them a 2px cream smoothing spline (20-period centered moving average drawn as a monotone curve), separated from the bars by a 5px walnut halo at 70% opacity.
- Line chart: an area chart in the wood ramp (a horizontal gradient from heartwood to sapwood at 55% opacity) above and below the baseline with a 1.2px #D9B98A edge line, the same cream spline on top, and blue dots (r 3.5) on the flagged years.

Labels and annotation:
- Each flagged year gets a 0.8px blue leader dropping from its bar tip to a two-line italic callout just below: the year and event ("1816 drought") in blue, the value ("index 0.38") in #A08A70 beneath. Keep callouts at least 120px apart horizontally.

Avoid: bright or saturated oranges, gradients inside individual bars, rounded bar ends, more than one highlight color, a boxed legend, and oldstyle figures on the axes.

When you're done, render the chart and check that the blue bars are exactly the flagged years, the title's claim holds for every flagged value, the spline reads clearly over the bars, and the corner rings never cross text.