:root {
  --background: #f4f4f5;
  --surface: #ffffff;
  --border: #e4e4e7;
  --text: #18181b;
  --muted: #52525b;
  --accent: #27272a;
  --accent-text: #ffffff;
  --selected: #f4f4f5;
  --success: #166534;
  --success-background: #dcfce7;
  --danger: #b91c1c;
  --danger-background: #fee2e2;
  --info: #3f3f46;
  --info-background: #f4f4f5;
  --code-background: #18181b;
  --code-text: #e4e4e7;
  color-scheme: light dark;
}

@media (prefers-color-scheme: dark) {
  :root {
    --background: #09090b;
    --surface: #18181b;
    --border: #3f3f46;
    --text: #fafafa;
    --muted: #a1a1aa;
    --accent: #e4e4e7;
    --accent-text: #18181b;
    --selected: #27272a;
    --success: #4ade80;
    --success-background: #052e16;
    --danger: #f87171;
    --danger-background: #450a0a;
    --info: #d4d4d8;
    --info-background: #27272a;
    --code-background: #000000;
    --code-text: #e4e4e7;
  }
}

*,
*::before,
*::after {
  box-sizing: border-box;
}

html {
  -webkit-text-size-adjust: 100%;
}

body {
  margin: 0;
  background: var(--background);
  color: var(--text);
  font: 1rem/1.5 system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

a {
  color: inherit;
  text-underline-offset: 0.15em;
}

:focus-visible {
  outline: 3px solid var(--accent);
  outline-offset: 2px;
}

.skip {
  position: absolute;
  left: 0.5rem;
  top: -3rem;
  padding: 0.5rem 0.75rem;
  background: var(--accent);
  color: var(--accent-text);
  border-radius: 0.375rem;
  z-index: 10;
}

.skip:focus {
  top: 0.5rem;
}

.top {
  background: var(--surface);
  border-bottom: 1px solid var(--border);
}

.bar {
  max-width: 56rem;
  margin: 0 auto;
  padding: 0.5rem 1rem;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.25rem 1rem;
}

.brand {
  font-weight: 600;
  text-decoration: none;
  margin-right: auto;
  padding: 0.5rem 0;
}

.bar nav ul {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-wrap: wrap;
  gap: 0.25rem;
}

.bar nav a,
.link {
  display: inline-block;
  min-height: 2.75rem;
  padding: 0.6rem 0.75rem;
  border-radius: 0.375rem;
  text-decoration: none;
}

.bar nav a[aria-current="page"] {
  background: var(--selected);
  font-weight: 600;
}

.bar form {
  margin: 0;
}

main {
  flex: 1 0 auto;
  width: 100%;
  max-width: 56rem;
  margin: 0 auto;
  padding: 1rem 1rem 3rem;
}

main:focus {
  outline: none;
}

h1 {
  font-size: 1.6rem;
  line-height: 1.25;
  margin: 0.75rem 0 0.75rem;
}

h2 {
  font-size: 1.2rem;
  margin: 0 0 0.75rem;
}

.lead {
  margin-top: 0;
}

.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 0.5rem;
  padding: 1rem;
  margin: 0 0 1rem;
}

.media {
  margin: 0 0 1rem;
}

.text {
  margin: 0 0 1.5rem;
  line-height: 1.6;
  max-width: 44rem;
}

.text img {
  display: block;
  max-width: 100%;
  height: auto;
  margin: 1rem 0;
  border-radius: 8px;
}

.text table {
  border-collapse: collapse;
  margin: 1rem 0;
}

.text th,
.text td {
  border: 1px solid var(--border);
  padding: 0.4rem 0.6rem;
  text-align: left;
}

.text pre {
  overflow-x: auto;
}

.text blockquote {
  margin: 1rem 0;
  padding-left: 1rem;
  border-left: 3px solid var(--border);
}

.media video,
.media img {
  display: block;
  width: 100%;
  height: auto;
  max-height: 80vh;
  border-radius: 0.5rem;
  background: var(--border);
}

.media audio {
  width: 100%;
}

.narrow {
  max-width: 28rem;
  margin: 1.5rem auto;
}

.muted {
  color: var(--muted);
}

.grid {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 1rem;
  grid-template-columns: repeat(auto-fill, minmax(16rem, 1fr));
}

.grid .card {
  margin: 0;
  height: 100%;
}

h3 {
  font-size: 1.05rem;
  margin: 0 0 0.5rem;
}

h2.group {
  margin: 1.5rem 0 0.75rem;
}

.grid h2 a,
.grid h3 a {
  text-decoration: none;
}

.grid h2 a:hover,
.grid h3 a:hover {
  text-decoration: underline;
}

progress {
  width: 100%;
  height: 0.75rem;
  accent-color: var(--accent);
}

.items {
  list-style: none;
  margin: 0;
  padding: 0;
}

.item {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.25rem 0.75rem;
  padding: 0.75rem 0;
  border-top: 1px solid var(--border);
}

.item:first-child {
  border-top: 0;
}

.item .title {
  flex: 1 1 12rem;
  min-height: 1.5rem;
}

.item .lock {
  flex-basis: 100%;
}

.badge {
  display: inline-block;
  font-size: 0.875rem;
  padding: 0.125rem 0.5rem;
  border-radius: 999px;
  background: var(--info-background);
  color: var(--info);
  border: 1px solid var(--border);
}

.badge.completed {
  background: var(--success-background);
  color: var(--success);
}

.badge.locked {
  background: var(--danger-background);
  color: var(--danger);
}

.lock {
  margin: 0.25rem 0 0;
  color: var(--muted);
}

.notice {
  border-radius: 0.5rem;
  padding: 0.75rem 1rem;
  margin: 0 0 1rem;
  background: var(--info-background);
  color: var(--info);
  border: 1px solid var(--border);
}

.notice.error {
  background: var(--danger-background);
  color: var(--danger);
}

.notice.success {
  background: var(--success-background);
  color: var(--success);
}

label {
  display: block;
  font-weight: 600;
  margin: 0 0 0.25rem;
}

.field {
  margin: 0 0 1rem;
}

.hint {
  display: block;
  font-weight: 400;
  color: var(--muted);
  font-size: 0.9rem;
}

input[type="email"],
input[type="password"],
input[type="text"],
input[type="number"],
.question textarea {
  width: 100%;
  min-height: 2.75rem;
  padding: 0.5rem 0.75rem;
  font: inherit;
  color: var(--text);
  background: var(--surface);
  border: 1px solid var(--muted);
  border-radius: 0.375rem;
}

fieldset {
  border: 1px solid var(--border);
  border-radius: 0.375rem;
  margin: 0 0 1rem;
  padding: 0.5rem 1rem 0.75rem;
}

legend {
  font-weight: 600;
  padding: 0 0.25rem;
}

.choice {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-weight: 400;
  min-height: 2.75rem;
}

.choice input {
  width: 1.25rem;
  height: 1.25rem;
  accent-color: var(--accent);
}

details {
  margin: 0 0 1rem;
}

summary {
  cursor: pointer;
  min-height: 2.75rem;
  padding: 0.6rem 0;
}

.button,
button {
  font: inherit;
  cursor: pointer;
}

.button {
  display: inline-block;
  min-height: 2.75rem;
  padding: 0.6rem 1.1rem;
  border-radius: 0.375rem;
  border: 1px solid var(--accent);
  background: var(--accent);
  color: var(--accent-text);
  font-weight: 600;
  text-decoration: none;
}

.button.secondary {
  background: var(--surface);
  color: var(--text);
  border-color: var(--muted);
}

.link {
  background: none;
  border: 0;
  color: inherit;
  text-decoration: underline;
}

.actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  align-items: center;
  margin: 1rem 0 0;
}

.question .option {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-weight: 400;
  min-height: 2.75rem;
}

.question textarea {
  min-height: 8rem;
  resize: vertical;
}

.question .points {
  font-weight: 400;
  color: var(--muted);
}

.marks {
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 0.25rem 1rem;
}

.marks dd {
  margin: 0;
}

.feedback {
  white-space: pre-line;
}

.inline {
  display: inline;
  margin: 0;
}

.score {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0.75rem;
}

table {
  width: 100%;
  border-collapse: collapse;
}

th,
td {
  text-align: left;
  padding: 0.6rem 0.5rem;
  border-top: 1px solid var(--border);
  vertical-align: top;
}

thead th {
  border-top: 0;
}

.table {
  overflow-x: auto;
}

.qr {
  display: inline-block;
  padding: 0.75rem;
  background: #ffffff;
  border-radius: 0.375rem;
  line-height: 0;
}

.qr svg {
  width: 13rem;
  height: 13rem;
}

code,
.code {
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  background: var(--code-background);
  color: var(--code-text);
  border-radius: 0.25rem;
  padding: 0.1rem 0.35rem;
  overflow-wrap: anywhere;
}

.codes {
  list-style: none;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(11rem, 1fr));
  gap: 0.5rem;
}

.crumbs {
  margin: 0.5rem 0 0;
}

@media (min-width: 40rem) {
  main {
    padding-top: 1.5rem;
  }

  h1 {
    font-size: 2rem;
  }

  .card {
    padding: 1.25rem 1.5rem;
  }
}

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation: none !important;
    transition: none !important;
    scroll-behavior: auto !important;
  }
}

.sr {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

.foot {
  border-top: 1px solid var(--border);
  background: var(--surface);
  color: var(--text);
  font-size: 0.9rem;
}

.foot .bar {
  gap: 0.5rem 1rem;
  padding-top: 0.75rem;
  padding-bottom: 0.75rem;
}

.foot img {
  display: block;
}

.foot a {
  display: inline-block;
  padding: 0.5rem 0;
}