:root {
  --ink: #152331;
  --muted-ink: #52616f;
  --paper: #f7f8f8;
  --panel: #ffffff;
  --line: #d8dee3;
  --accent: #235d73;
  --accent-dark: #174454;
  --soft: #eaf0f2;
  --max-width: 1120px;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  line-height: 1.65;
}

a {
  color: var(--accent-dark);
}

a:hover,
a:focus-visible {
  color: var(--accent);
}

.skip-link {
  position: absolute;
  left: -999px;
  top: 0;
  z-index: 100;
  padding: 0.75rem 1rem;
  background: var(--ink);
  color: #fff;
}

.skip-link:focus {
  left: 1rem;
  top: 1rem;
}

.container {
  width: min(calc(100% - 2rem), var(--max-width));
  margin-inline: auto;
}

.narrow {
  max-width: 820px;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 20;
  border-bottom: 1px solid rgba(216, 222, 227, 0.9);
  background: rgba(247, 248, 248, 0.94);
  backdrop-filter: blur(10px);
}

.nav-wrap {
  display: flex;
  align-items: center;
  justify-content: space-between;
  min-height: 68px;
  gap: 1rem;
}

.site-name {
  color: var(--ink);
  font-size: 1.05rem;
  font-weight: 750;
  text-decoration: none;
}

nav {
  display: flex;
  flex-wrap: wrap;
  gap: 1.25rem;
}

nav a {
  color: var(--muted-ink);
  font-size: 0.94rem;
  font-weight: 650;
  text-decoration: none;
}

.hero {
  padding: 6.5rem 0 5.5rem;
  background:
    radial-gradient(circle at 90% 10%, rgba(35, 93, 115, 0.13), transparent 30%),
    linear-gradient(180deg, #ffffff, var(--paper));
}

.hero-grid {
  display: grid;
  grid-template-columns: minmax(0, 1.45fr) minmax(280px, 0.75fr);
  gap: 4rem;
  align-items: center;
}

.eyebrow {
  margin: 0 0 0.7rem;
  color: var(--accent);
  font-size: 0.82rem;
  font-weight: 800;
  letter-spacing: 0.12em;
  text-transform: uppercase;
}

h1,
h2,
h3 {
  line-height: 1.16;
  letter-spacing: -0.025em;
}

h1 {
  max-width: 760px;
  margin: 0;
  font-size: clamp(2.7rem, 6vw, 5.3rem);
  font-weight: 780;
}

h2 {
  max-width: 820px;
  margin: 0 0 1.25rem;
  font-size: clamp(2rem, 4vw, 3.2rem);
}

h3 {
  margin: 0 0 0.65rem;
  font-size: 1.22rem;
}

.lead {
  max-width: 760px;
  margin: 1.5rem 0 0;
  color: var(--muted-ink);
  font-size: clamp(1.12rem, 2vw, 1.42rem);
}

.actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.8rem;
  margin-top: 2rem;
}

.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 46px;
  padding: 0.75rem 1.05rem;
  border: 1px solid var(--accent);
  border-radius: 7px;
  font-weight: 750;
  text-decoration: none;
}

.button.primary {
  background: var(--accent);
  color: #fff;
}

.button.primary:hover,
.button.primary:focus-visible {
  background: var(--accent-dark);
  color: #fff;
}

.button.secondary {
  background: transparent;
  color: var(--accent-dark);
}

.credential-card {
  padding: 1.6rem;
  border: 1px solid var(--line);
  border-radius: 12px;
  background: rgba(255, 255, 255, 0.88);
  box-shadow: 0 18px 45px rgba(21, 35, 49, 0.07);
}

.credential-card p {
  margin: 0 0 1.15rem;
}

.credential-card p:last-child {
  margin-bottom: 0;
}

.credential-title {
  color: var(--accent);
  font-weight: 800;
  letter-spacing: 0.03em;
  text-transform: uppercase;
}

.section {
  padding: 5rem 0;
}

.section.muted {
  border-block: 1px solid var(--line);
  background: var(--soft);
}

.section-intro {
  max-width: 840px;
  margin: 0 0 2.4rem;
  color: var(--muted-ink);
  font-size: 1.12rem;
}

.topic-grid,
.background-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 1rem;
}

.topic-grid article,
.background-grid article {
  padding: 1.35rem;
  border: 1px solid var(--line);
  border-radius: 9px;
  background: var(--panel);
}

.topic-grid p,
.background-grid p {
  margin: 0;
  color: var(--muted-ink);
}

.question-intro {
  margin-bottom: 1.7rem;
}

.question-list {
  display: grid;
  gap: 0.9rem;
}

.question-list details {
  overflow: hidden;
  border: 1px solid var(--line);
  border-left: 3px solid var(--accent);
  border-radius: 8px;
  background: rgba(255, 255, 255, 0.78);
}

.question-list summary {
  position: relative;
  padding: 1.1rem 3.3rem 1.1rem 1.15rem;
  color: var(--ink);
  font-size: 1.06rem;
  font-weight: 720;
  line-height: 1.45;
  cursor: pointer;
  list-style: none;
}

.question-list summary::-webkit-details-marker {
  display: none;
}

.question-list summary::after {
  position: absolute;
  top: 50%;
  right: 1.15rem;
  width: 1.6rem;
  height: 1.6rem;
  border: 1px solid var(--line);
  border-radius: 50%;
  content: "+";
  color: var(--accent-dark);
  font-size: 1.2rem;
  font-weight: 700;
  line-height: 1.35rem;
  text-align: center;
  transform: translateY(-50%);
}

.question-list details[open] summary {
  border-bottom: 1px solid var(--line);
  background: rgba(255, 255, 255, 0.92);
}

.question-list details[open] summary::after {
  content: "−";
}

.question-list summary:hover,
.question-list summary:focus-visible {
  background: #fff;
  color: var(--accent-dark);
}

.question-list summary:focus-visible {
  outline: 3px solid rgba(35, 93, 115, 0.22);
  outline-offset: -3px;
}

.question-answer {
  padding: 1.2rem 1.25rem 1.3rem;
  color: var(--muted-ink);
  font-size: 1.02rem;
}

.question-answer p {
  max-width: 74ch;
  margin: 0;
}

.contact {
  background: var(--ink);
  color: #fff;
}

.contact .eyebrow,
.contact a {
  color: #b8dae5;
}

.contact p {
  max-width: 720px;
  color: #dce5ea;
}

.contact .button.primary {
  border-color: #b8dae5;
  background: #b8dae5;
  color: var(--ink);
}

.contact .button.secondary {
  border-color: #87afbd;
  color: #dcebf0;
}

.site-footer {
  padding: 1.5rem 0;
  background: #0f1a24;
  color: #aebbc4;
  font-size: 0.9rem;
}

.site-footer p {
  margin: 0;
}

@media (max-width: 820px) {
  .hero {
    padding-top: 4.5rem;
  }

  .hero-grid,
  .topic-grid,
  .background-grid {
    grid-template-columns: 1fr;
  }

  .hero-grid {
    gap: 2.4rem;
  }

  nav {
    display: none;
  }
}

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }
}