:root {
  --bg: #0e1320;
  --bg-alt: #141b2d;
  --card: #1b2336;
  --line: #2a3248;
  --text: #e8ecf5;
  --muted: #98a2bb;
  --accent: #4f7cff;
  --accent-2: #2ee6a8;
  --radius: 14px;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

h1, h2, h3 { line-height: 1.25; margin: 0 0 12px; }
a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }

.container { width: 100%; max-width: 1140px; margin: 0 auto; padding: 0 20px; }

/* header */
.header {
  position: sticky;
  top: 0;
  z-index: 10;
  background: rgba(14, 19, 32, .9);
  backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--line);
}
.header__inner { display: flex; align-items: center; gap: 24px; height: 64px; }
.logo { display: flex; align-items: center; gap: 10px; color: var(--text); font-weight: 700; font-size: 18px; }
.logo:hover { text-decoration: none; }
.logo__mark {
  display: grid; place-items: center;
  width: 30px; height: 30px; border-radius: 9px;
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  color: #0b1020; font-weight: 800;
}
.nav { display: flex; gap: 22px; margin-left: auto; }
.nav a { color: var(--muted); font-size: 15px; }
.nav a:hover { color: var(--text); text-decoration: none; }

/* buttons */
.btn {
  display: inline-block;
  padding: 13px 24px;
  border: 0;
  border-radius: 10px;
  background: var(--accent);
  color: #fff;
  font: inherit;
  font-weight: 600;
  cursor: pointer;
  transition: filter .15s, transform .15s;
}
.btn:hover { filter: brightness(1.1); text-decoration: none; }
.btn:active { transform: translateY(1px); }
.btn:disabled { opacity: .55; cursor: not-allowed; }
.btn--small { padding: 9px 16px; font-size: 14px; }
.btn--ghost { background: transparent; border: 1px solid var(--line); color: var(--text); }
.btn--block { display: block; width: 100%; }

/* hero */
.hero { padding: 84px 0 64px; background: radial-gradient(900px 400px at 15% -10%, rgba(79,124,255,.28), transparent), var(--bg); }
.hero h1 { font-size: clamp(28px, 4.6vw, 46px); max-width: 780px; }
.hero__lead { color: var(--muted); font-size: 18px; max-width: 640px; }
.hero__actions { display: flex; flex-wrap: wrap; gap: 12px; margin: 28px 0 44px; }
.hero__facts { display: flex; flex-wrap: wrap; gap: 40px; list-style: none; margin: 0; padding: 0; }
.hero__facts li { display: flex; flex-direction: column; }
.hero__facts strong { font-size: 24px; }
.hero__facts span { color: var(--muted); font-size: 14px; }

/* sections */
.section { padding: 72px 0; }
.section--alt { background: var(--bg-alt); }
.section__title { font-size: clamp(24px, 3vw, 32px); }
.section__lead { color: var(--muted); margin: 0 0 36px; }

/* tariffs */
.tariffs { display: grid; grid-template-columns: repeat(auto-fit, minmax(250px, 1fr)); gap: 20px; }
.tariff {
  position: relative;
  display: flex; flex-direction: column;
  padding: 26px 22px;
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: var(--radius);
}
.tariff--popular { border-color: var(--accent); }
.tariff__badge {
  position: absolute; top: -11px; left: 22px;
  padding: 2px 10px; border-radius: 999px;
  background: var(--accent); color: #fff; font-size: 12px; font-weight: 600;
}
.tariff__name { font-size: 20px; margin: 0; }
.tariff__subtitle { color: var(--muted); font-size: 14px; margin: 4px 0 18px; }
.tariff__price { font-size: 30px; font-weight: 700; }
.tariff__price small { font-size: 14px; font-weight: 400; color: var(--muted); }
.tariff__specs { list-style: none; margin: 18px 0; padding: 0; font-size: 15px; }
.tariff__specs li { display: flex; justify-content: space-between; padding: 6px 0; border-bottom: 1px dashed var(--line); }
.tariff__specs span { color: var(--muted); }
.tariff__features { list-style: none; margin: 0 0 22px; padding: 0; font-size: 14px; color: var(--muted); }
.tariff__features li { padding-left: 20px; position: relative; }
.tariff__features li::before { content: '✓'; position: absolute; left: 0; color: var(--accent-2); }
.tariff .btn { margin-top: auto; }

/* calculator */
.calc { display: grid; grid-template-columns: 1.4fr 1fr; gap: 28px; align-items: start; }
.calc__controls { display: grid; gap: 26px; padding: 28px; background: var(--card); border: 1px solid var(--line); border-radius: var(--radius); }
.slider label { display: flex; justify-content: space-between; align-items: baseline; gap: 12px; font-size: 15px; color: var(--muted); }
.slider output { color: var(--text); font-size: 18px; font-weight: 700; }
.slider input[type=range] { width: 100%; margin: 12px 0 4px; accent-color: var(--accent); height: 22px; }
.slider__scale { display: flex; justify-content: space-between; font-size: 12px; color: var(--muted); }

.calc__summary { padding: 28px; background: var(--card); border: 1px solid var(--accent); border-radius: var(--radius); }
.calc__price { font-size: 38px; font-weight: 700; }
.calc__price small { font-size: 15px; font-weight: 400; color: var(--muted); }
.calc__list { list-style: none; margin: 18px 0 22px; padding: 0; font-size: 15px; }
.calc__list li { display: flex; justify-content: space-between; padding: 6px 0; border-bottom: 1px dashed var(--line); }
.calc__list span { color: var(--muted); }
.calc__note { color: var(--muted); font-size: 13px; margin: 12px 0 0; }

/* features */
.features { display: grid; grid-template-columns: repeat(auto-fit, minmax(280px, 1fr)); gap: 20px; }
.features article { padding: 22px; background: var(--card); border: 1px solid var(--line); border-radius: var(--radius); }
.features h3 { font-size: 17px; }
.features p { color: var(--muted); margin: 0; font-size: 15px; }

/* form */
.form-wrap { display: grid; grid-template-columns: 1fr 1fr; gap: 40px; align-items: start; }
.form-intro p { color: var(--muted); }
.form-intro__contacts { margin-top: 24px; font-size: 17px; }
.form { padding: 28px; background: var(--card); border: 1px solid var(--line); border-radius: var(--radius); }
.field { margin-bottom: 18px; }
.field label { display: block; margin-bottom: 6px; font-size: 14px; color: var(--muted); }
.req { color: #ff6b6b; }
.field input, .field select, .field textarea {
  width: 100%;
  padding: 12px 14px;
  background: #121828;
  border: 1px solid var(--line);
  border-radius: 10px;
  color: var(--text);
  font: inherit;
  resize: vertical;
}
.field input:focus, .field select:focus, .field textarea:focus { outline: none; border-color: var(--accent); }
.field--error input, .field--error textarea { border-color: #ff6b6b; }
.field__hint { display: block; margin-top: 6px; font-size: 12px; color: var(--muted); text-align: right; }
.field__error { display: block; margin-top: 6px; font-size: 13px; color: #ff6b6b; }
.form__status { margin: 14px 0 0; font-size: 15px; min-height: 22px; }
.form__status--ok { color: var(--accent-2); }
.form__status--error { color: #ff6b6b; }

/* footer */
.footer { padding: 28px 0; border-top: 1px solid var(--line); color: var(--muted); font-size: 14px; }
.footer__inner { display: flex; flex-wrap: wrap; justify-content: space-between; gap: 12px; }

@media (max-width: 900px) {
  .calc, .form-wrap { grid-template-columns: 1fr; }
  .nav { display: none; }
}