Tank rectangle moved from top-aligned (top=20 in 760 frame) to vertically
centered (top=40, with 40 px top + 40 px bottom margins for the rim and
floor caption text). Header rim caption shifted to y=20, footer floor to
y=724, so both sit just outside the tank rect.
Label algorithm extended: when a label would normally go BELOW its line
but doing so would push it past the tank floor (which happens for very
small dryRunThresholdPercent — dryRunLevel sits right on outflowLevel,
both nearly at the basin floor), it falls back to stacking ABOVE the
previous label instead of extending into invisible space. This keeps
all 5 threshold labels inside the visible canvas area at the cost of a
slight visual overlap of the lowest label with its own line.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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