.form-grid {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 1rem;
    }
.fg { display: flex; flex-direction: column; gap: .375rem; }
.fg.full { grid-column: 1 / -1; }
label {
      font-size: .7rem; font-weight: 700;
      text-transform: uppercase; letter-spacing: .05em;
      color: var(--text-muted);
    }
.iw { position: relative; display: flex; align-items: center; }
.pfx, .sfx {
      position: absolute;
      font-size: .875rem; color: var(--text-muted); font-weight: 500;
      pointer-events: none;
    }
.pfx { left: .75rem; }
.sfx { right: .75rem; }
input[type="number"], select {
      width: 100%;
      padding: .6875rem .75rem;
      border: 1.5px solid var(--border-strong);
      border-radius: var(--radius);
      font-size: .9375rem; color: var(--text);
      background: var(--bg);
      transition: border-color .15s, box-shadow .15s;
      -webkit-appearance: none; appearance: none;
      font-family: var(--font);
    }
.has-sfx input[type="number"] { padding-right: 2.25rem; }
input[type="number"]:focus, select:focus {
      outline: none;
      border-color: var(--blue);
      box-shadow: 0 0 0 3px rgba(37,99,235,.12);
    }
select {
      cursor: pointer;
      background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='8' viewBox='0 0 12 8'%3E%3Cpath d='M1 1l5 5 5-5' stroke='%236b7280' stroke-width='1.5' fill='none' stroke-linecap='round'/%3E%3C/svg%3E");
      background-repeat: no-repeat;
      background-position: right .75rem center;
      padding-right: 2.25rem;
    }
.calc-btn {
      display: block; width: 100%;
      padding: .875rem;
      margin-top: 1.25rem;
      background: var(--blue);
      color: white;
      border: none; border-radius: var(--radius);
      font-size: 1rem; font-weight: 700;
      cursor: pointer; letter-spacing: .01em;
      transition: background .15s, transform .1s;
      font-family: var(--font);
    }
.cost-label-row {
      font-size: .7rem; font-weight: 700;
      text-transform: uppercase; letter-spacing: .07em;
      color: var(--text-muted); margin-bottom: .625rem;
    }
.cost-grid {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: .75rem;
    }
.c-tile {
      background: var(--bg);
      border: 1px solid var(--border);
      border-radius: var(--radius);
      padding: .875rem;
    }
.c-tile .ct-label {
      font-size: .65rem; font-weight: 700;
      text-transform: uppercase; letter-spacing: .04em;
      color: var(--text-muted); margin-bottom: .25rem;
    }
.c-tile .ct-value {
      font-size: 1.1875rem; font-weight: 700;
      color: var(--text);
    }
.c-tile .ct-sub {
      font-size: .7rem; color: var(--text-muted); margin-top: .2rem;
    }
.c-tile.best {
      border-color: var(--green-border);
      background: var(--green-light);
    }
.c-tile.best .ct-value { color: var(--green); }
.best-tag {
      display: inline-block;
      font-size: .6rem; font-weight: 700;
      background: var(--green);
      color: white;
      padding: .1rem .375rem;
      border-radius: 100px;
      margin-left: .375rem;
      vertical-align: middle;
      text-transform: uppercase;
    }
.retention-tip {
      font-size: .78rem;
      color: var(--text-muted);
      text-align: center;
      padding: .375rem 0 .75rem;
    }
#result-area { display: none; }
@media (max-width: 580px) {
      .wrap { padding: 1.5rem 1rem 3.5rem; }
      .page-header h1 { font-size: 1.5rem; }
      .form-grid { grid-template-columns: 1fr; }
      .fg.full { grid-column: 1; }
      .secondary-results { grid-template-columns: 1fr 1fr; }
      .r-tile:last-child { grid-column: 1 / -1; }
      .cost-grid { grid-template-columns: 1fr; }
      .related-grid { grid-template-columns: 1fr; }
      nav { gap: 1rem; }
      .nav-links { gap: 1rem; }
    }