:root {
    --accent: #DE0101;
    --text-main: #1a1a1a;
    --text-muted: #6b6b6b;
    --bg-page: #f7f7f8;
    --card-shadow: 0 0 1em 0 #e2e2e2;
    --border: #e2e2e2;
  }
  * { box-sizing: border-box; }
  .calc-card {
    max-width: 860px;
    margin: 0 auto;
    background: #fff;
    border-radius: 0.5em;
    box-shadow: var(--card-shadow);
    padding: 28px 24px;
  }
  .subtitle { color: var(--text-muted); font-size: 14px; margin: 0 0 20px; line-height: 1.5; }
  h3 {
    font-size: 16px; font-weight: 700; margin: 30px 0 4px;
    display: flex; align-items: center; gap: 8px;
  }
  h3 .zone-badge {
    font-size: 11px; font-weight: 700; padding: 2px 10px; border-radius: 20px;
    background: #fdeaea; color: var(--accent);
  }
  .section-hint { font-size: 12px; color: var(--text-muted); margin: 0 0 14px; line-height: 1.5; }

  .field { margin-bottom: 12px; }
  .field label { display: block; font-size: 12.5px; font-weight: 600; margin-bottom: 5px; }
  input[type="number"], select {
    width: 100%; padding: 9px 10px; border: 1px solid #d9d9d9; border-radius: 3px;
    font-family: 'Montserrat', sans-serif; font-size: 13.5px; color: var(--text-main); outline: none;
    background: #fff;
  }
  input[type="number"]:focus, select:focus { border-color: var(--accent); }
  input[type="checkbox"] { width: auto; margin-right: 6px; }
  .checkbox-row { display: flex; align-items: center; font-size: 13px; font-weight: 600; margin-bottom: 14px; }

  .segment-card {
    border: 1px solid var(--border);
    border-radius: 0.5em;
    padding: 16px;
    margin-bottom: 12px;
    background: #fafafa;
    position: relative;
  }
  .segment-card .remove-btn {
    position: absolute; top: 12px; right: 12px;
    background: none; border: none; color: var(--accent);
    font-size: 18px; cursor: pointer; line-height: 1;
  }
  .segment-title {
    font-size: 13px; font-weight: 700; margin-bottom: 12px;
  }
  .grid3 { display: grid; grid-template-columns: repeat(3, 1fr); gap: 10px; }
  .grid2 { display: grid; grid-template-columns: repeat(2, 1fr); gap: 10px; }

  .pipe-row {
    border: 1px dashed #d9d9d9;
    border-radius: 0.4em;
    padding: 10px 12px;
    margin-top: 10px;
    background: #fff;
    position: relative;
  }
  .pipe-row .remove-pipe {
    position: absolute; top: 8px; right: 10px;
    background: none; border: none; color: var(--accent);
    font-size: 15px; cursor: pointer;
  }

  .add-btn, .add-pipe-btn {
    background: #fff; border: 1px dashed var(--accent); color: var(--accent);
    border-radius: 3px; padding: 8px 14px; font-family: 'Montserrat', sans-serif;
    font-weight: 600; font-size: 12.5px; cursor: pointer;
  }
  .add-btn { width: 100%; margin-bottom: 6px; }
  .add-pipe-btn { margin-top: 8px; }

  .seg-result {
    margin-top: 12px; padding-top: 10px; border-top: 1px dashed #e2e2e2;
    font-size: 12.5px; color: var(--text-muted); line-height: 1.6;
  }
  .seg-result b { color: var(--text-main); }
  .seg-warning {
    margin-top: 8px; padding: 8px 10px; border-radius: 0.4em;
    background: #ffe9e9; color: var(--accent); font-size: 12px; line-height: 1.5; display: none;
  }
  .seg-warning.show { display: block; }

  .totals {
    margin-top: 30px; padding: 20px; border-radius: 0.5em;
    background: #fafafa; border: 1px solid #ececec;
  }
  .totals h4 { font-size: 14px; margin: 0 0 12px; }
  .total-row {
    display: flex; justify-content: space-between; padding: 6px 0;
    font-size: 13px; color: var(--text-muted); border-bottom: 1px dashed #e6e6e6;
  }
  .total-row:last-child { border-bottom: none; }
  .total-row span:last-child { color: var(--text-main); font-weight: 700; }

  .board-warning {
    margin-top: 14px; padding: 12px 14px; border-radius: 0.5em;
    background: #fff4de; color: #9a6b00; font-size: 12.5px; line-height: 1.6; display: none;
  }
  .board-warning.show { display: block; }

  .install-notes {
    margin-top: 24px; padding: 16px 18px; border-radius: 0.5em;
    background: #f5f7ff; border: 1px solid #e4e8fb; font-size: 12.5px; line-height: 1.7;
  }
  .install-notes b { display: block; margin-bottom: 6px; font-size: 13px; }
  .install-notes ul { margin: 0; padding-left: 18px; }

  .cta { margin-top: 22px; text-align: center; }
  .cta a {
    display: inline-block; background: var(--accent); color: #fff; text-decoration: none;
    padding: 12px 28px; border-radius: 3px; font-weight: 600; font-size: 14px;
  }