:root {
  --calc-navy: #0B1F33;
  --calc-blue: #1E4E79;
  --calc-grey: #F4F6F8;
  --calc-text: #2B2F33;
  --calc-muted: #647384;
  --calc-orange: #F97316;
  --calc-line: #DDE5ED;
  --calc-white: #FFFFFF;
}

.steel-calc {
  background: var(--calc-white);
  border: 1px solid var(--calc-line);
  border-radius: 6px;
  padding: 26px;
  box-shadow: 0 18px 44px rgba(11, 31, 51, .08);
}

.steel-calc * { box-sizing: border-box; }

.steel-calc__head {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 190px;
  gap: 24px;
  align-items: start;
  margin-bottom: 22px;
}

.steel-calc__kicker {
  display: block;
  color: var(--calc-blue);
  font-size: 13px;
  font-weight: 900;
  letter-spacing: .04em;
  text-transform: uppercase;
  margin-bottom: 8px;
}

.steel-calc h2 {
  margin: 0;
  color: var(--calc-navy);
  font-size: 30px;
  line-height: 1.15;
}

.steel-calc p {
  margin: 10px 0 0;
  color: var(--calc-muted);
}

.steel-calc__density {
  background: var(--calc-grey);
  border: 1px solid var(--calc-line);
  border-radius: 6px;
  padding: 14px;
}

.steel-calc label {
  display: block;
  color: var(--calc-navy);
  font-size: 13px;
  font-weight: 900;
  margin-bottom: 7px;
}

.steel-calc input,
.steel-calc select {
  width: 100%;
  min-height: 44px;
  border: 1px solid #C9D6E2;
  border-radius: 4px;
  padding: 10px 11px;
  color: var(--calc-text);
  font: inherit;
  background: var(--calc-white);
}

.steel-calc__density span,
.steel-calc__unit span {
  color: var(--calc-muted);
  font-size: 13px;
  font-weight: 800;
}

.steel-calc__form {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 14px;
}

.steel-calc__unit {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 54px;
  gap: 8px;
  align-items: center;
}

.steel-calc__result {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 14px;
  margin-top: 18px;
}

.steel-calc__result div {
  background: var(--calc-grey);
  border: 1px solid var(--calc-line);
  border-radius: 6px;
  padding: 16px;
}

.steel-calc__result span {
  display: block;
  color: var(--calc-muted);
  font-size: 13px;
  font-weight: 800;
}

.steel-calc__result strong {
  display: block;
  color: var(--calc-navy);
  font-size: 26px;
  line-height: 1.15;
  margin-top: 5px;
}

.steel-calc__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 18px;
}

.steel-calc__btn,
.steel-calc__link {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 44px;
  border-radius: 4px;
  padding: 0 18px;
  border: 1px solid transparent;
  font-weight: 900;
  cursor: pointer;
  text-decoration: none;
}

.steel-calc__btn {
  background: var(--calc-orange);
  color: var(--calc-white);
}

.steel-calc__link {
  background: var(--calc-white);
  color: var(--calc-navy);
  border-color: #C9D6E2;
}

.steel-calc__note {
  font-size: 13px;
}

@media (max-width: 780px) {
  .steel-calc { padding: 18px; }
  .steel-calc__head,
  .steel-calc__form,
  .steel-calc__result {
    grid-template-columns: 1fr;
  }
  .steel-calc h2 { font-size: 24px; }
}