:root {
  color-scheme: dark;
  --bg: #081018;
  --bg-2: #0f1d29;
  --panel: rgba(8, 17, 27, 0.82);
  --panel-strong: rgba(11, 22, 35, 0.94);
  --panel-soft: rgba(20, 34, 51, 0.66);
  --line: rgba(151, 188, 214, 0.18);
  --line-strong: rgba(151, 188, 214, 0.34);
  --text: #ecf4fb;
  --muted: #99aec2;
  --accent: #8dd7ff;
  --accent-2: #9cf0c1;
  --accent-3: #ffd37c;
  --danger: #ff9f9f;
  --shadow: 0 24px 80px rgba(0, 0, 0, 0.34);
  --radius-xl: 28px;
  --radius-lg: 20px;
  --radius-md: 14px;
  --radius-sm: 10px;
  --max: 1180px;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  min-height: 100vh;
  background:
    radial-gradient(circle at top left, rgba(141, 215, 255, 0.18), transparent 26rem),
    radial-gradient(circle at 85% 18%, rgba(156, 240, 193, 0.14), transparent 24rem),
    radial-gradient(circle at 50% 120%, rgba(255, 211, 124, 0.08), transparent 26rem),
    linear-gradient(180deg, var(--bg) 0%, #0b1520 52%, var(--bg-2) 100%);
  color: var(--text);
  font: 16px/1.6 "IBM Plex Sans", "Segoe UI", sans-serif;
}

a {
  color: inherit;
}

img {
  max-width: 100%;
}

.shell {
  width: min(var(--max), calc(100% - 32px));
  margin: 0 auto;
}

.page {
  padding: 32px 0 80px;
}

.topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  margin-bottom: 28px;
}

.brand {
  display: flex;
  align-items: center;
  gap: 12px;
  text-decoration: none;
}

.brand-mark {
  width: 44px;
  height: 44px;
  display: grid;
  place-items: center;
  border-radius: 14px;
  background: linear-gradient(145deg, rgba(141, 215, 255, 0.2), rgba(156, 240, 193, 0.16));
  border: 1px solid rgba(141, 215, 255, 0.22);
  box-shadow: inset 0 1px 0 rgba(255, 255, 255, 0.08);
  font-weight: 700;
}

.brand-copy strong,
.brand-copy span {
  display: block;
}

.brand-copy strong {
  font-size: 0.95rem;
}

.brand-copy span {
  color: var(--muted);
  font-size: 0.86rem;
}

.nav {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}

.nav-link,
.button,
.ghost-button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
  min-height: 44px;
  padding: 0 16px;
  border-radius: 999px;
  text-decoration: none;
  font-weight: 600;
  transition: transform 150ms ease, border-color 150ms ease, background 150ms ease, color 150ms ease;
}

.nav-link,
.ghost-button {
  border: 1px solid var(--line);
  background: rgba(255, 255, 255, 0.03);
  color: var(--text);
}

.button {
  border: 1px solid rgba(141, 215, 255, 0.3);
  background: linear-gradient(135deg, rgba(141, 215, 255, 0.2), rgba(156, 240, 193, 0.16));
  color: var(--text);
}

.nav-link:hover,
.button:hover,
.ghost-button:hover,
.summary-card:hover,
.study-card:hover {
  transform: translateY(-1px);
}

.hero {
  position: relative;
  overflow: hidden;
  padding: 44px;
  border: 1px solid var(--line);
  border-radius: var(--radius-xl);
  background:
    linear-gradient(135deg, rgba(9, 18, 29, 0.95), rgba(15, 28, 42, 0.86)),
    rgba(8, 17, 27, 0.82);
  box-shadow: var(--shadow);
}

.hero::after {
  content: "";
  position: absolute;
  inset: auto -12% -38% auto;
  width: 340px;
  height: 340px;
  border-radius: 50%;
  background: radial-gradient(circle, rgba(141, 215, 255, 0.16), transparent 70%);
  pointer-events: none;
}

.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 6px 12px;
  border-radius: 999px;
  border: 1px solid rgba(141, 215, 255, 0.2);
  background: rgba(141, 215, 255, 0.08);
  color: var(--accent);
  font-size: 0.78rem;
  font-weight: 700;
  letter-spacing: 0.06em;
  text-transform: uppercase;
}

.hero h1,
.page-heading h1 {
  margin: 18px 0 14px;
  font-size: clamp(2.4rem, 5vw, 4.9rem);
  line-height: 0.94;
  letter-spacing: -0.06em;
}

.hero p,
.page-heading p,
.lead {
  max-width: 760px;
  color: var(--muted);
  font-size: 1.02rem;
}

.hero-actions,
.stack-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 28px;
}

.grid {
  display: grid;
  gap: 18px;
}

.grid-2 {
  grid-template-columns: repeat(2, minmax(0, 1fr));
}

.grid-3 {
  grid-template-columns: repeat(3, minmax(0, 1fr));
}

.section {
  margin-top: 26px;
}

.section-title {
  margin: 0 0 14px;
  font-size: 1rem;
  letter-spacing: 0.02em;
  text-transform: uppercase;
  color: var(--accent);
}

.summary-card,
.study-card,
.info-card,
.panel {
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  background: var(--panel);
  box-shadow: var(--shadow);
}

.summary-card,
.info-card,
.panel {
  padding: 22px;
}

.summary-card h2,
.study-card h2,
.info-card h2,
.panel h2,
.panel h3 {
  margin: 0 0 10px;
  letter-spacing: -0.03em;
}

.summary-card p,
.info-card p,
.panel p,
.study-card p,
.study-card li,
.meta-list li {
  color: var(--muted);
}

.summary-meta,
.meta-list,
.pill-row {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}

.pill,
.chip {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 7px 11px;
  border-radius: 999px;
  border: 1px solid var(--line);
  background: rgba(255, 255, 255, 0.03);
  color: var(--text);
  font-size: 0.84rem;
}

.chip.warm {
  border-color: rgba(255, 211, 124, 0.26);
  color: var(--accent-3);
}

.chip.good {
  border-color: rgba(156, 240, 193, 0.26);
  color: var(--accent-2);
}

.progress-line {
  position: relative;
  height: 10px;
  overflow: hidden;
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.06);
}

.progress-line > span {
  position: absolute;
  inset: 0 auto 0 0;
  width: 0;
  border-radius: inherit;
  background: linear-gradient(90deg, var(--accent), var(--accent-2));
}

.stat-row {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 12px;
  margin-top: 16px;
}

.stat {
  padding: 14px;
  border-radius: var(--radius-md);
  border: 1px solid var(--line);
  background: rgba(255, 255, 255, 0.025);
}

.stat strong,
.stat span {
  display: block;
}

.stat strong {
  font-size: 1.1rem;
}

.stat span {
  color: var(--muted);
  font-size: 0.84rem;
}

.study-card {
  overflow: hidden;
}

.study-head {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 16px;
  width: 100%;
  padding: 22px;
  border: 0;
  background: transparent;
  color: inherit;
  text-align: left;
  cursor: pointer;
}

.study-head:hover {
  background: rgba(255, 255, 255, 0.02);
}

.study-title {
  flex: 1;
}

.study-title h2 {
  margin-bottom: 8px;
  font-size: 1.45rem;
}

.study-subtitle {
  display: block;
  color: var(--muted);
  font-size: 0.92rem;
}

.toggle {
  flex: 0 0 auto;
  min-width: 42px;
  height: 42px;
  display: grid;
  place-items: center;
  border-radius: 12px;
  border: 1px solid var(--line);
  background: rgba(255, 255, 255, 0.03);
  font-size: 1.2rem;
}

.study-body {
  display: none;
  padding: 0 22px 22px;
  border-top: 1px solid rgba(255, 255, 255, 0.05);
}

.study-card[data-open="true"] .study-body {
  display: block;
}

.study-card[data-open="true"] .toggle {
  background: rgba(141, 215, 255, 0.1);
  border-color: rgba(141, 215, 255, 0.24);
}

.two-col {
  display: grid;
  grid-template-columns: minmax(0, 1.2fr) minmax(280px, 0.8fr);
  gap: 18px;
  margin-top: 18px;
}

.callout {
  padding: 16px;
  border-radius: var(--radius-md);
  border: 1px solid var(--line);
  background: rgba(255, 255, 255, 0.03);
}

.callout strong,
.small-title {
  display: block;
  margin-bottom: 8px;
  font-size: 0.82rem;
  font-weight: 700;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  color: var(--accent);
}

.checklist {
  display: grid;
  gap: 10px;
  margin-top: 16px;
}

.task {
  display: flex;
  align-items: flex-start;
  gap: 12px;
  padding: 12px 14px;
  border-radius: var(--radius-md);
  border: 1px solid var(--line);
  background: rgba(255, 255, 255, 0.025);
}

.task input {
  margin-top: 3px;
  width: 18px;
  height: 18px;
  accent-color: #7ed8ff;
}

.task-body strong,
.task-body span {
  display: block;
}

.task-body strong {
  font-size: 0.96rem;
}

.task-body span {
  color: var(--muted);
  font-size: 0.87rem;
}

.resource-list,
.note-list {
  display: grid;
  gap: 10px;
  margin: 14px 0 0;
  padding: 0;
  list-style: none;
}

.resource-list a {
  color: var(--accent);
  text-decoration: none;
}

.resource-list a:hover {
  text-decoration: underline;
}

.resource-list li,
.note-list li {
  padding: 12px 14px;
  border-radius: var(--radius-md);
  border: 1px solid var(--line);
  background: rgba(255, 255, 255, 0.025);
}

.page-heading {
  margin-bottom: 20px;
}

.footer {
  margin-top: 32px;
  color: var(--muted);
  font-size: 0.9rem;
}

.footer a {
  color: var(--accent);
}

.page-lock {
  position: fixed;
  inset: 0;
  z-index: 30;
  display: none;
  align-items: center;
  justify-content: center;
  padding: 24px;
  background: rgba(3, 7, 12, 0.84);
  backdrop-filter: blur(12px);
}

.page-lock[data-visible="true"] {
  display: flex;
}

.lock-card {
  width: min(460px, 100%);
  padding: 28px;
  border-radius: 24px;
  border: 1px solid var(--line-strong);
  background: var(--panel-strong);
  box-shadow: var(--shadow);
}

.lock-card h2 {
  margin: 0 0 10px;
  font-size: 1.8rem;
}

.lock-card p {
  color: var(--muted);
}

.lock-form {
  display: grid;
  gap: 12px;
  margin-top: 18px;
}

.lock-form input {
  width: 100%;
  min-height: 50px;
  padding: 0 16px;
  border-radius: 14px;
  border: 1px solid var(--line);
  background: rgba(255, 255, 255, 0.04);
  color: var(--text);
  font: inherit;
}

.error {
  color: var(--danger);
  min-height: 1.25em;
  font-size: 0.88rem;
}

.hidden {
  display: none !important;
}

@media (max-width: 920px) {
  .grid-2,
  .grid-3,
  .two-col,
  .stat-row {
    grid-template-columns: 1fr;
  }

  .hero,
  .summary-card,
  .info-card,
  .panel,
  .study-head,
  .study-body,
  .lock-card {
    padding-left: 20px;
    padding-right: 20px;
  }
}

@media (max-width: 640px) {
  .page {
    padding-top: 20px;
  }

  .topbar {
    flex-direction: column;
    align-items: stretch;
  }

  .nav {
    justify-content: flex-start;
  }

  .hero h1,
  .page-heading h1 {
    font-size: clamp(2.1rem, 12vw, 3.5rem);
  }
}