* { margin: 0; padding: 0; box-sizing: border-box; }

:root {
  --bg: #F7F8F5;
  --panel: #FFFFFF;
  --ink: #1A241F;
  --muted: #5C6B62;
  --accent: #14624F;
  --accent-soft: #E3EFE9;
  --line: #D8DCD6;
  --warn: #A5432E;
  --inset: 10px;
  --gap: 22px;
  --sect: 64px;
}

html { scroll-behavior: smooth; }

body {
  font-family: 'IBM Plex Sans', sans-serif;
  font-size: 16px;
  line-height: 1.55;
  background: var(--bg);
  color: var(--ink);
}

::selection { background: var(--accent); color: #fff; }

a { color: var(--accent); }
a:focus-visible, button:focus-visible, input:focus-visible, select:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }

.wrap { max-width: 1040px; margin: 0 auto; padding-left: 24px; padding-right: 24px; }

h1, h2, h3 { font-weight: 700; line-height: 1.2; letter-spacing: -0.4px; }

h2 {
  font-size: 26px;
  text-transform: uppercase;
  letter-spacing: 1px;
  margin-bottom: 26px;
  padding-left: 14px;
  border-left: 5px solid var(--accent);
}

.lead { font-size: 18px; color: var(--muted); max-width: 620px; }

.top { background: var(--bg); border-bottom: 1px solid var(--line); position: sticky; top: 0; z-index: 10; }

.top-in { display: flex; align-items: center; gap: 30px; padding-top: 14px; padding-bottom: 14px; }

.brand {
  font-weight: 700;
  font-size: 19px;
  color: var(--ink);
  text-decoration: none;
  text-transform: uppercase;
  letter-spacing: 0.8px;
}
.brand::after { content: "®"; font-size: 11px; vertical-align: super; color: var(--muted); }

.top-nav { display: flex; gap: 22px; margin-left: auto; }
.top-nav a {
  color: var(--muted);
  text-decoration: none;
  font-size: 14px;
  text-transform: uppercase;
  letter-spacing: 0.6px;
}
.top-nav a:hover { color: var(--accent); }

.top-phone {
  font-family: 'IBM Plex Mono', monospace;
  font-weight: 600;
  text-decoration: none;
  white-space: nowrap;
}

.burger { display: none; background: none; border: 1px solid var(--ink); padding: 7px 9px; cursor: pointer; }
.burger span { display: block; width: 20px; height: 2px; background: var(--ink); margin: 4px 0; }

.intro { padding-top: 56px; padding-bottom: 36px; }
.intro h1 { font-size: 40px; max-width: 700px; margin-bottom: 16px; }

.calc {
  display: grid;
  grid-template-columns: 1.1fr 1fr;
  gap: 0;
  background: var(--panel);
  border: 1px solid var(--line);
  margin-bottom: 72px;
}

.calc-form { padding: 32px; border-right: 1px solid var(--line); display: flex; flex-direction: column; gap: 24px; }

.field label, .zones legend {
  display: block;
  font-size: 12px;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 1.2px;
  color: var(--muted);
  margin-bottom: 8px;
}
.field .hint { color: var(--accent); text-transform: none; letter-spacing: 0; font-weight: 400; }

.field > input, .field > select {
  width: 100%;
  font: inherit;
  font-size: 17px;
  padding: 11px 13px;
  border: 1px solid var(--line);
  background: var(--bg);
  color: var(--ink);
}
.field > input:focus, .field > select:focus { outline: none; border-color: var(--accent); }
.field input.error { border-color: var(--warn); }
.field input.error:focus { outline: none; }

#vol { font-family: 'IBM Plex Mono', monospace; font-weight: 600; }

.field-msg { font-size: 13px; color: var(--warn); margin-top: 7px; min-height: 0; }

.zones { border: none; }
.zones label {
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: 15px;
  text-transform: none;
  letter-spacing: 0;
  color: var(--ink);
  font-weight: 400;
  padding: 9px 12px;
  margin-bottom: 6px;
  border: 1px solid var(--line);
  cursor: pointer;
  background: var(--bg);
}
.zones label:has(input:checked) { border-color: var(--accent); background: var(--accent-soft); }
.zones input { accent-color: var(--accent); }

.calc-result { padding: 32px; background: var(--accent-soft); }

.res-table { width: 100%; border-collapse: collapse; font-size: 15px; }
.res-table th {
  text-align: left;
  font-weight: 400;
  color: var(--muted);
  padding: 9px 0;
  border-bottom: 1px solid #C4D2C9;
  width: 55%;
}
.res-table td {
  text-align: right;
  font-family: 'IBM Plex Mono', monospace;
  font-weight: 600;
  padding: 9px 0;
  border-bottom: 1px solid #C4D2C9;
  white-space: nowrap;
}
.res-disc { color: var(--accent); }
.res-disc td { color: var(--accent); }
#r-mat { white-space: normal; }
.res-total th, .res-total td {
  font-size: 19px;
  border-bottom: 2px solid var(--ink);
  color: var(--ink);
}
.res-disc[hidden] { display: none; }

.calc-note { font-size: 13px; color: var(--muted); margin-top: 14px; }

.order { display: flex; gap: 10px; margin-top: 22px; }
.order input {
  flex: 1;
  min-width: 0;
  font-family: 'IBM Plex Mono', monospace;
  font-size: 15px;
  padding: 11px 13px;
  border: 1px solid var(--line);
  background: var(--panel);
}
.order input:focus { outline: none; border-color: var(--accent); }
.order input.error { border-color: var(--warn); }

.order-msg { font-size: 13px; color: var(--muted); margin-top: 12px; }
.order-msg.ok { color: var(--accent); font-weight: 600; }
.order-msg.err { color: var(--warn); }

.btn {
  background: var(--accent);
  color: #fff;
  border: none;
  padding: 12px 22px;
  font: inherit;
  font-size: 15px;
  font-weight: 600;
  cursor: pointer;
  text-transform: uppercase;
  letter-spacing: 0.6px;
}
.btn:hover { background: #0E5140; }
.btn:active { transform: translateY(1px); background: #0A3D31; }
.btn:disabled { background: #9FB3AA; cursor: not-allowed; transform: none; }

.faq { padding-top: var(--sect); padding-bottom: 56px; border-top: 1px solid var(--line); }

.faq-list { list-style: none; }
.faq-list li { padding: 20px 0; border-bottom: 1px solid var(--line); }
.faq-list li:first-child { padding-top: 0; }
.faq-list h3 { font-size: 17px; margin-bottom: 7px; }
.faq-list p { color: var(--muted); max-width: 640px; }

.contacts { padding-top: var(--sect); padding-bottom: 64px; border-top: 1px solid var(--line); }

.cont-list dt {
  font-size: 12px;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 1.2px;
  color: var(--muted);
  margin-top: 20px;
}
.cont-list dt:first-child { margin-top: 0; }
.cont-list dd { font-size: 16px; margin-top: 3px; }
.cont-list dd a { text-decoration: none; font-weight: 600; }

.foot { border-top: 1px solid var(--line); padding-top: 24px; padding-bottom: 24px; }
.foot-in { display: flex; justify-content: space-between; gap: 24px; font-size: 13px; color: var(--muted); }
.foot-note { text-align: right; }
.demo-tag { color: #97A19A; }

@media (max-width: 900px) {
  .top-nav {
    display: none;
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background: var(--bg);
    border-bottom: 1px solid var(--line);
    flex-direction: column;
    padding: 16px 24px;
    gap: 14px;
  }
  .top-nav.open { display: flex; }
  .burger { display: block; margin-left: auto; }
  .top-phone { display: none; }

  .calc { grid-template-columns: 1fr; }
  .calc-form { border-right: none; border-bottom: 1px solid var(--line); }
  .intro h1 { font-size: 30px; }
}

@media (max-width: 480px) {
  .wrap { padding-left: 20px; padding-right: 20px; }
  .intro { padding-top: 36px; }
  .intro h1 { font-size: 26px; }
  .calc-form, .calc-result { padding: 22px; }
  .order { flex-direction: column; }
  .order .btn { width: 100%; }
  h2 { font-size: 21px; }
  .res-table th { width: 45%; }
}