Chart Prompts

Restyle my chart in the "Return Periods" 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 flood frequency figure from an engineering hydrology report. Calm, technical and trustworthy, on a pale gray-blue page, with a single blue ramp that deepens as events become rarer.

Colors (use these exact values):
- Page: #EFF3F6 (pale gray-blue). Ink #16273A, secondary text #5A6878, gridlines #D5DEE6.
- Bar ramp, lightest to darkest in category order: #A9CBE6, #86B4DB, #6399CB, #4A7FB8, #3767A3, #27528C, #1A3F72, #0E2C57.
- Reference rule and its label: #B4432F (brick red).

Typography (Google Fonts):
- Faustina 600 for the title, 29px, #16273A, sentence case, stating the finding.
- Sarabun for everything else: eyebrow 600, 11.5px uppercase with 2px letter-spacing, muted; subtitle 15px muted; value labels 700 15px ink; category labels 700 14px ink with a second line in 12px muted (for example the annual exceedance probability); tick labels 13px muted; the unit above the axis in 600 12px; reference label 700 13.5px in brick red; source 12px.

Layout:
- 64px left margin. Eyebrow at y 52, title at 92, subtitle at 120.
- Plot from x 116 to 900, zero baseline at y 486, top of scale at y 168.
- A small graded key ("More frequent", eight 16 x 12px swatches, "Rarer") at the bottom right on the same line as the source note.

Axes and grid:
- 1px #D5DEE6 gridlines at round values, a 1.4px ink baseline, no y axis line, tick labels right-aligned 12px left of the plot, the unit "m³/s" above the top tick.

Marks:
- Bar chart: square-cornered bars 56% of the band, each filled with the next ramp step so color deepens with rarity. Confidence whiskers are 1.3px lines with 14px caps; the part above the bar top is ink, the part inside a dark bar (ramp step 4 onward) turns #FFFFFF so it stays visible. Value labels sit 9px above the upper whisker cap on a small page-colored knockout.
- Line chart: a 2.5px #27528C line with dots at each point filled with the matching ramp step (r 5, 1.5px page-colored ring), and the confidence interval as a #6399CB band at 18% opacity instead of whiskers.
- Reference: a 1.8px dashed (7 5) #B4432F horizontal rule across the plot for the record value, labeled at its left end above the line on a page-colored knockout ("Largest recorded, 1968: 468 m³/s"). It passes behind value labels, never through them.

Avoid: multiple hues, gradients inside bars, rounded corners, shadows, legends for single-series data, truncated bars.

When you're done, render the chart and check that the ramp darkens monotonically, every whisker is visible against its bar, the reference line never strikes through a label, and the title's claim matches where the reference value falls.