:root {
  --bg: #f8fafc;
  --panel: #ffffff;
  --border: #e2e8f0;
  --text: #111827;
  --muted: #64748b;
  --blue: #3358d4;
  --green: #11845b;
  --shadow: 0 18px 45px rgba(15, 23, 42, .08);
  --font-ui: "Space Grotesk", system-ui, sans-serif;
  --font-mono: "JetBrains Mono", ui-monospace, monospace;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-height: 100vh;
  background: var(--bg);
  color: var(--text);
  font-family: var(--font-ui);
  -webkit-font-smoothing: antialiased;
}

.shell {
  width: min(1120px, calc(100% - 40px));
  margin: 0 auto;
  padding: 56px 0;
}

.hero {
  display: flex;
  align-items: end;
  justify-content: space-between;
  gap: 28px;
  padding-bottom: 28px;
  border-bottom: 1px solid var(--border);
}

.eyebrow {
  margin: 0 0 10px;
  color: var(--green);
  font: 700 12px/1 var(--font-mono);
  letter-spacing: .08em;
  text-transform: uppercase;
}

h1 {
  margin: 0;
  font-size: clamp(38px, 6vw, 78px);
  line-height: .92;
  letter-spacing: 0;
}

.intro {
  width: min(420px, 100%);
  margin: 0 0 7px;
  color: var(--muted);
  font-size: 18px;
  line-height: 1.45;
}

.concept-list {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 16px;
  padding-top: 28px;
}

.concept-card {
  display: grid;
  gap: 10px;
  min-height: 184px;
  padding: 22px;
  border: 1px solid var(--border);
  border-radius: 8px;
  background: var(--panel);
  color: inherit;
  text-decoration: none;
  box-shadow: var(--shadow);
  transition: border-color .16s ease, transform .16s ease, box-shadow .16s ease;
}

.concept-card:hover {
  border-color: rgba(51, 88, 212, .45);
  transform: translateY(-2px);
  box-shadow: 0 22px 55px rgba(15, 23, 42, .12);
}

.concept-card:focus-visible {
  outline: 2px solid var(--blue);
  outline-offset: 3px;
}

.concept-kicker {
  color: var(--blue);
  font: 700 11px/1 var(--font-mono);
  letter-spacing: .08em;
  text-transform: uppercase;
}

.concept-title {
  font-size: 25px;
  font-weight: 700;
  line-height: 1.05;
}

.concept-copy {
  max-width: 34rem;
  color: var(--muted);
  font-size: 15px;
  line-height: 1.5;
}

@media (max-width: 720px) {
  .shell {
    width: min(100% - 28px, 1120px);
    padding: 36px 0;
  }

  .hero {
    display: block;
  }

  .intro {
    margin-top: 18px;
    font-size: 16px;
  }
}