Map colors to meaning. The inline .casca-legend sits under any
chart; the grid-based .casca-legend-row adds a truncating label
and a right-aligned chip rail, and can be a <button> or
<a> when a row should filter or link. Color is always paired
with a text label.
<div class="casca-legend">
<div class="casca-legend-item">
<span class="casca-legend-swatch" style="--_color: var(--casca-color-1)"></span>
Revenue
</div>
</div>
<div class="casca-legend-row">
<span class="casca-legend-swatch" style="--_color: var(--casca-color-1)"></span>
<span class="casca-legend-row-label">Products</span>
<div class="casca-legend-row-rail">
<span class="casca-chip">$45k</span>
<span class="casca-chip" data-variant="success">↑ 12%</span>
</div>
</div>
<!-- interactive: swap the wrapper for a <button> or <a> -->
<a href="#category" class="casca-legend-row"> … </a>