Phone 320px: list grids with a 290-420px minimum column use minmax(min(N, 100%), 1fr), so a single column fits a 320px screen (#75)

ddiff --git a/public/css/housing.css b/public/css/housing.css
iindex 1ab51d2..d8ac319 100644
---- a/public/css/housing.css
++++ b/public/css/housing.css
@@@ -16,7 +16,7 @@
  .housing-group { margin-top: 26px; }
  .housing-group h3 { margin: 0 0 2px; font-size: 1.15rem; }
  .housing-explain { margin: 0 0 10px; color: var(--text-secondary, #96a7c2); font-size: .92rem; max-width: 760px; }
--.housing-list { list-style: none; padding: 0; margin: 0; display: grid; gap: 10px; grid-template-columns: repeat(auto-fill, minmax(290px, 1fr)); }
++.housing-list { list-style: none; padding: 0; margin: 0; display: grid; gap: 10px; grid-template-columns: repeat(auto-fill, minmax(min(290px, 100%), 1fr)); }
  .housing-card { display: flex; flex-direction: column; gap: 4px; padding: 12px 14px; border-radius: 12px; border: 1px solid var(--border, #1f2d47); background: var(--bg-card, #131c2e); }
  .housing-card p { margin: 0; }
  .housing-card-head { display: flex; justify-content: space-between; align-items: baseline; gap: 10px; }