:root {
  color-scheme: light;
  --ink: #17202a;
  --muted: #5f6c7b;
  --line: #dde4ee;
  --paper: #fffdf8;
  --panel: #ffffff;
  --accent: #0f766e;
  --accent-2: #b45309;
  --soft: #eef7f5;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: Inter, Arial, sans-serif;
  line-height: 1.55;
}

.topbar {
  position: sticky;
  top: 0;
  z-index: 10;
  display: flex;
  align-items: center;
  gap: 24px;
  min-height: 68px;
  padding: 12px clamp(18px, 4vw, 48px);
  border-bottom: 1px solid var(--line);
  background: rgba(255, 253, 248, 0.94);
  backdrop-filter: blur(12px);
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  min-width: max-content;
  color: var(--ink);
  font-weight: 800;
  text-decoration: none;
}

.brand-mark {
  display: grid;
  place-items: center;
  width: 34px;
  height: 34px;
  border-radius: 8px;
  background: var(--accent);
  color: white;
  font-family: Georgia, serif;
}

nav {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 18px;
  margin-left: auto;
}

nav a,
.downloads a,
.lang-switch a {
  color: var(--ink);
  text-decoration: none;
}

nav a {
  font-weight: 700;
}

.lang-switch {
  display: grid;
  grid-template-columns: 1fr 1fr;
  overflow: hidden;
  border: 1px solid var(--line);
  border-radius: 8px;
}

.lang-switch a {
  padding: 7px 10px;
  font-weight: 700;
}

.lang-switch .active {
  background: var(--accent);
  color: white;
}

main {
  width: min(1180px, calc(100% - 32px));
  margin: 0 auto;
}

.hero {
  display: grid;
  grid-template-columns: minmax(0, 1.2fr) minmax(320px, 0.8fr);
  gap: clamp(24px, 5vw, 68px);
  align-items: center;
  min-height: min(760px, calc(100vh - 96px));
  padding: clamp(38px, 6vw, 72px) 0 28px;
}

.eyebrow,
.problem-id,
.module-panel > p {
  color: var(--accent-2);
  font-weight: 800;
  letter-spacing: 0;
  text-transform: uppercase;
}

h1 {
  max-width: 760px;
  margin: 0;
  font-family: Georgia, serif;
  font-size: clamp(3rem, 7vw, 6.2rem);
  line-height: 0.95;
  letter-spacing: 0;
}

.lead {
  max-width: 720px;
  margin: 24px 0 0;
  color: var(--muted);
  font-size: 1.3rem;
}

.note {
  max-width: 680px;
  color: var(--ink);
}

.module-panel {
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--panel);
  padding: 28px;
  box-shadow: 0 24px 70px rgba(23, 32, 42, 0.08);
}

.module-panel h2 {
  margin: 0 0 20px;
  font-size: 2rem;
  line-height: 1.12;
}

.module-grid {
  display: grid;
  gap: 10px;
}

.module-grid span {
  padding: 12px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--soft);
  font-weight: 700;
}

.content-section {
  padding: clamp(34px, 6vw, 72px) 0;
  border-top: 1px solid var(--line);
}

.section-heading {
  display: grid;
  gap: 10px;
  max-width: 780px;
  margin-bottom: 24px;
}

.section-heading h2 {
  margin: 0;
  font-size: clamp(2rem, 4vw, 3.2rem);
  line-height: 1.05;
}

.section-heading p {
  margin: 0;
  color: var(--muted);
  font-size: 1.08rem;
}

.section-heading .eyebrow {
  color: var(--accent-2);
}

.section-heading.compact {
  margin-bottom: 12px;
}

.course-grid {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 14px;
}

.course-card,
.roadmap-part {
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--panel);
  padding: 18px;
}

.course-card.active {
  border-color: rgba(15, 118, 110, 0.45);
  background: var(--soft);
}

.course-card-head {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 12px;
}

.course-card h3,
.roadmap-part h3 {
  margin: 0;
  font-size: 1.12rem;
  line-height: 1.18;
}

.course-card-head span {
  flex: 0 0 auto;
  border-radius: 999px;
  background: #f8ead7;
  color: #7c2d12;
  padding: 4px 8px;
  font-size: 0.78rem;
  font-weight: 800;
}

.course-card.active .course-card-head span {
  background: var(--accent);
  color: white;
}

.course-card p {
  margin: 12px 0 0;
  color: var(--muted);
}

.roadmap-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 14px;
}

.roadmap-part ol {
  display: grid;
  gap: 8px;
  margin: 14px 0 0;
  padding-left: 22px;
}

.roadmap-part li {
  padding-left: 4px;
}

.practice-section {
  padding-bottom: 0;
}

.toolbar {
  display: grid;
  grid-template-columns: minmax(240px, 1fr) 220px;
  gap: 16px;
  align-items: end;
  padding: 22px 0;
}

label span {
  display: block;
  margin-bottom: 6px;
  color: var(--muted);
  font-size: 0.92rem;
  font-weight: 700;
}

input,
select,
button {
  width: 100%;
  min-height: 44px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: white;
  color: var(--ink);
  font: inherit;
}

input,
select {
  padding: 0 12px;
}

button {
  padding: 0 14px;
  cursor: pointer;
  font-weight: 800;
}

.problem-list {
  display: grid;
  gap: 16px;
  padding-bottom: 42px;
}

.problem-card {
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--panel);
  padding: clamp(18px, 3vw, 28px);
}

.problem-head {
  display: flex;
  gap: 18px;
  justify-content: space-between;
}

.problem-card h2 {
  margin: 0;
  font-size: 1.45rem;
}

.badge {
  align-self: flex-start;
  min-width: 94px;
  border-radius: 999px;
  background: #f8ead7;
  color: #7c2d12;
  padding: 6px 10px;
  text-align: center;
  font-weight: 800;
}

.subtopic {
  color: var(--muted);
  font-weight: 700;
}

.statement {
  font-size: 1.08rem;
}

.actions {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-top: 16px;
}

.actions button {
  width: auto;
  background: var(--accent);
  color: white;
  border-color: var(--accent);
}

.reveal {
  display: none;
  margin-top: 14px;
  padding: 16px;
  border-left: 4px solid var(--accent);
  background: var(--soft);
}

.reveal.open {
  display: block;
}

.reveal h3 {
  margin: 0 0 8px;
}

.downloads {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  align-items: center;
  padding: 28px 0 56px;
  border-top: 1px solid var(--line);
}

.downloads h2 {
  width: 100%;
}

.downloads a {
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 10px 14px;
  background: white;
  font-weight: 800;
}

.empty {
  padding: 28px;
  color: var(--muted);
  text-align: center;
}

.account-pill {
  border: 1px solid var(--line);
  border-radius: 999px;
  padding: 6px 10px;
  background: white;
  color: var(--muted);
  font-weight: 800;
}

.form-error {
  border: 1px solid #fecaca;
  border-radius: 8px;
  background: #fff1f2;
  color: #991b1b;
  padding: 10px 12px;
  font-weight: 700;
}

.auth-panel {
  width: min(520px, 100%);
}

.admin-page {
  display: grid;
  min-height: 100vh;
  place-items: center;
  padding: 32px 0;
}

.admin-page h1 {
  font-size: 2.4rem;
  line-height: 1.05;
}

.admin-page form {
  display: grid;
  gap: 12px;
  margin: 18px 0;
}

@media (max-width: 1050px) {
  .course-grid,
  .roadmap-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

@media (max-width: 820px) {
  .topbar {
    flex-wrap: wrap;
    gap: 12px;
    padding: 10px 16px;
  }

  nav {
    order: 3;
    width: 100%;
    margin-left: 0;
    gap: 12px;
  }

  .hero,
  .toolbar,
  .roadmap-grid,
  .course-grid {
    grid-template-columns: 1fr;
  }

  h1 {
    font-size: 3rem;
  }

  .lead {
    font-size: 1.08rem;
  }

  .problem-head,
  .course-card-head {
    display: grid;
  }

  .badge,
  .course-card-head span {
    justify-self: start;
  }
}