* {
  box-sizing: border-box;
}

:root {
  --bg: #050814;
  --panel: rgba(15, 23, 42, 0.9);
  --panel-strong: rgba(17, 24, 39, 0.96);
  --soft: rgba(255, 255, 255, 0.065);
  --soft-hover: rgba(255, 255, 255, 0.095);
  --border: rgba(255, 255, 255, 0.13);
  --border-strong: rgba(91, 140, 255, 0.45);
  --text: #eef4ff;
  --muted: #9aa8bd;
  --green: #32d583;
  --blue: #5b8cff;
  --purple: #9b7cff;
}

body {
  margin: 0;
  min-height: 100vh;
  font-family: Inter, Arial, sans-serif;
  color: var(--text);
  background:
    radial-gradient(circle at 12% 14%, rgba(91, 140, 255, 0.28), transparent 32%),
    radial-gradient(circle at 86% 10%, rgba(155, 124, 255, 0.22), transparent 30%),
    radial-gradient(circle at 50% 100%, rgba(50, 213, 131, 0.14), transparent 34%),
    linear-gradient(180deg, #070b14 0%, var(--bg) 100%);
}

.page {
  width: min(1120px, 100%);
  margin: 0 auto;
  padding: 34px 22px 70px;
}

.top-actions {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 14px;
  margin-bottom: 34px;
}

.back,
.secondary-link,
.start-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 46px;
  padding: 12px 20px;
  border-radius: 999px;
  color: var(--text);
  text-decoration: none;
  background: rgba(255, 255, 255, 0.075);
  border: 1px solid var(--border);
  font-weight: 900;
  transition: 0.2s ease;
}

.back:hover,
.secondary-link:hover,
.start-btn:hover {
  transform: translateY(-2px);
  border-color: var(--border-strong);
}

.secondary-link,
.start-btn {
  background: linear-gradient(135deg, var(--blue), var(--purple));
  border: 0;
  box-shadow: 0 16px 36px rgba(91, 140, 255, 0.24);
}

.hero {
  margin-bottom: 28px;
  padding: 42px;
  border-radius: 36px;
  background:
    linear-gradient(145deg, rgba(91, 140, 255, 0.16), rgba(155, 124, 255, 0.09)),
    var(--panel);
  border: 1px solid var(--border);
  box-shadow: 0 30px 90px rgba(0, 0, 0, 0.38);
}

.eyebrow {
  margin: 0 0 14px;
  color: var(--green);
  font-size: 13px;
  font-weight: 900;
  letter-spacing: 0.14em;
  text-transform: uppercase;
}

h1 {
  max-width: 900px;
  margin: 0;
  font-size: clamp(42px, 7vw, 76px);
  line-height: 0.95;
  letter-spacing: -0.07em;
}

.hero p {
  max-width: 760px;
  margin: 20px 0 0;
  color: var(--muted);
  font-size: 18px;
  line-height: 1.7;
}

.grid {
  display: grid;
  grid-template-columns: minmax(0, 1.08fr) minmax(320px, 0.92fr);
  gap: 22px;
}

.card {
  margin-top: 22px;
  padding: 30px;
  border-radius: 30px;
  background: linear-gradient(145deg, var(--panel-strong), rgba(15, 23, 42, 0.82));
  border: 1px solid var(--border);
  box-shadow: 0 24px 70px rgba(0, 0, 0, 0.28);
}

.card h2 {
  margin: 0 0 18px;
  font-size: clamp(26px, 4vw, 34px);
  letter-spacing: -0.04em;
}

.card h3 {
  margin: 0 0 10px;
  font-size: 20px;
}

.card p,
.card li {
  color: var(--muted);
  line-height: 1.75;
  font-size: 16px;
}

.card strong {
  color: var(--text);
}

.card ul {
  margin: 20px 0 0;
  padding: 0;
  list-style: none;
  display: grid;
  gap: 12px;
}

.card li {
  padding: 14px 16px;
  border-radius: 18px;
  background: var(--soft);
  border: 1px solid var(--border);
}

.note {
  margin: 16px 0 0;
  padding: 12px 14px;
  border-radius: 14px;
  background: rgba(50, 213, 131, 0.12);
  border: 1px solid rgba(50, 213, 131, 0.28);
}

.visual-card {
  min-height: 340px;
}

.mini-cards {
  display: grid;
  gap: 14px;
}

.mini-cards div {
  padding: 16px;
  border-radius: 16px;
  background: var(--soft);
  border: 1px solid var(--border);
}

.mini-cards p {
  margin: 8px 0 0;
}

.formula-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 18px;
}

.formula {
  padding: 22px;
  border-radius: 24px;
  background: var(--soft);
  border: 1px solid var(--border);
  transition: 0.2s ease;
}

.formula:hover {
  transform: translateY(-3px);
  background: var(--soft-hover);
  border-color: var(--border-strong);
}

.formula h3 {
  color: var(--green);
}

.formula p {
  margin: 0;
  color: var(--text);
  font-size: 18px;
  font-weight: 900;
}

.steps {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 18px;
}

.steps div {
  padding: 22px;
  border-radius: 24px;
  background: var(--soft);
  border: 1px solid var(--border);
}

.steps span {
  display: inline-grid;
  place-items: center;
  width: 42px;
  height: 42px;
  margin-bottom: 14px;
  border-radius: 50%;
  background: rgba(91, 140, 255, 0.17);
  color: #b9ccff;
  font-weight: 900;
}

.calc {
  color: #b9ccff !important;
  font-weight: 900;
}

.result {
  color: var(--green) !important;
  font-size: 20px !important;
  font-weight: 900;
}

.example {
  margin-top: 16px;
  padding: 22px;
  border-radius: 24px;
  background: rgba(7, 11, 20, 0.46);
  border: 1px solid var(--border);
}

.example:first-of-type {
  margin-top: 0;
}

.example p {
  margin: 8px 0;
}

.tip-card {
  background:
    linear-gradient(145deg, rgba(91, 140, 255, 0.2), rgba(50, 213, 131, 0.12)),
    var(--panel-strong);
}

.tip-card ol {
  margin: 0;
  padding-left: 22px;
}

.tip-card li {
  margin-bottom: 8px;
  color: var(--text);
}

.start-btn {
  margin-top: 18px;
}

@media (max-width: 900px) {
  .grid,
  .formula-grid,
  .steps {
    grid-template-columns: 1fr;
  }

  .hero {
    padding: 30px;
  }
}

@media (max-width: 620px) {
  .page {
    padding: 20px 14px 50px;
  }

  .top-actions {
    flex-direction: column;
    align-items: stretch;
    margin-bottom: 22px;
  }

  .back,
  .secondary-link,
  .start-btn {
    width: 100%;
    text-align: center;
  }

  .hero,
  .card {
    padding: 22px;
    border-radius: 24px;
  }

  .card {
    margin-top: 16px;
  }

  h1 {
    font-size: clamp(38px, 13vw, 54px);
  }
}