:root {
  color: #111827;
  background: #f2eee6;
  font-family:
    Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI",
    sans-serif;
  font-size: 16px;
  line-height: 1.5;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-width: 320px;
  background:
    linear-gradient(120deg, rgba(37, 99, 235, 0.12), transparent 34%),
    linear-gradient(240deg, rgba(15, 118, 110, 0.16), transparent 30%),
    #f2eee6;
}

button,
input {
  font: inherit;
}

.course-shell {
  width: min(1180px, calc(100% - 32px));
  margin: 0 auto;
  padding: 28px 0 48px;
}

.course-header {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(320px, 0.78fr);
  gap: 28px;
  align-items: stretch;
  min-height: 360px;
  padding: clamp(22px, 4vw, 40px);
  border: 1px solid rgba(17, 24, 39, 0.12);
  border-radius: 8px;
  background: rgba(255, 253, 252, 0.88);
}

.trace-section {
  background: rgba(255, 253, 252, 0.88);
  border: 1px solid rgba(17, 24, 39, 0.12);
}

.course-copy {
  display: flex;
  flex-direction: column;
  justify-content: center;
}

.eyebrow {
  margin: 0 0 10px;
  color: #0f766e;
  font-size: 0.78rem;
  font-weight: 800;
  letter-spacing: 0;
  text-transform: uppercase;
}

h1,
h2,
h3,
p {
  overflow-wrap: anywhere;
}

h1 {
  max-width: 760px;
  margin: 0;
  font-size: 5.8rem;
  line-height: 0.95;
  letter-spacing: 0;
}

.lede {
  max-width: 680px;
  margin: 24px 0 0;
  color: #334155;
  font-size: 1.28rem;
}

.loop-panel {
  display: grid;
  place-items: center;
  min-height: 320px;
  padding: 24px;
  border-radius: 8px;
}

.loop-panel img {
  display: block;
  width: min(100%, 520px);
  height: auto;
}

.progress-strip {
  display: grid;
  grid-template-columns: auto minmax(140px, 1fr);
  gap: 18px;
  align-items: center;
  margin-top: 36px;
}

.metric {
  display: block;
  color: #111827;
  font-size: 2.2rem;
  font-weight: 850;
  line-height: 1;
}

.metric-label {
  color: #64748b;
  font-size: 0.9rem;
  font-weight: 700;
}

.progress-track {
  height: 12px;
  overflow: hidden;
  border-radius: 999px;
  background: #d7dce3;
}

.progress-fill {
  height: 100%;
  border-radius: inherit;
  background: linear-gradient(90deg, #2563eb, #0f766e);
  transition: width 180ms ease;
}

.workspace {
  display: grid;
  grid-template-columns: 330px minmax(0, 1fr);
  gap: 22px;
  margin-top: 22px;
}

.lesson-list {
  display: grid;
  gap: 10px;
  align-content: start;
}

.lesson-tab {
  width: 100%;
  min-height: 108px;
  padding: 18px;
  border: 1px solid rgba(17, 24, 39, 0.14);
  border-radius: 8px;
  background: rgba(255, 255, 255, 0.7);
  color: #111827;
  text-align: left;
  cursor: pointer;
  transition:
    transform 140ms ease,
    border-color 140ms ease,
    background 140ms ease;
}

.lesson-tab:hover,
.lesson-tab:focus-visible,
.lesson-tab.active {
  border-color: #2563eb;
  background: #ffffff;
  outline: none;
  transform: translateY(-1px);
}

.lesson-tab.complete {
  border-color: rgba(15, 118, 110, 0.58);
}

.lesson-number,
.lesson-title,
.lesson-meta {
  display: block;
}

.lesson-number {
  color: #f59e0b;
  font-size: 0.78rem;
  font-weight: 850;
}

.lesson-title {
  margin-top: 6px;
  font-size: 1.05rem;
  font-weight: 820;
  line-height: 1.2;
}

.lesson-meta {
  margin-top: 8px;
  color: #64748b;
  font-size: 0.88rem;
  font-weight: 700;
}

.lesson-detail {
  min-height: 430px;
  padding: clamp(24px, 4vw, 42px);
}

.detail-heading {
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto;
  gap: 12px;
  align-items: start;
}

.detail-heading .eyebrow {
  grid-column: 1 / -1;
}

.detail-heading h2 {
  margin: 0;
  font-size: 3.7rem;
  line-height: 1;
  letter-spacing: 0;
}

.detail-heading span {
  display: inline-flex;
  align-items: center;
  min-height: 34px;
  padding: 5px 10px;
  border: 1px solid rgba(17, 24, 39, 0.18);
  border-radius: 999px;
  color: #334155;
  font-size: 0.9rem;
  font-weight: 800;
  white-space: nowrap;
}

.summary {
  max-width: 780px;
  margin: 20px 0 0;
  color: #334155;
  font-size: 1.14rem;
}

.detail-grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(260px, 0.7fr);
  gap: 18px;
  margin-top: 30px;
}

.outcome-block,
.lab-block {
  min-height: 210px;
  padding: 22px;
  border: 1px solid rgba(17, 24, 39, 0.12);
  border-radius: 8px;
  background: #ffffff;
}

.outcome-block h3,
.lab-block h3 {
  margin: 0 0 14px;
  font-size: 1rem;
  letter-spacing: 0;
  text-transform: uppercase;
}

.outcome-block ul {
  display: grid;
  gap: 12px;
  margin: 0;
  padding-left: 20px;
  color: #334155;
}

.lab-block p {
  margin: 0;
  color: #334155;
}

.complete-toggle {
  display: inline-flex;
  gap: 10px;
  align-items: center;
  margin-top: 24px;
  color: #111827;
  font-weight: 800;
}

.complete-toggle input {
  width: 20px;
  height: 20px;
  accent-color: #0f766e;
}

.trace-section {
  display: grid;
  grid-template-columns: minmax(240px, 0.45fr) minmax(0, 1fr);
  gap: 24px;
  margin-top: 22px;
  padding: clamp(24px, 4vw, 42px);
  border-radius: 8px;
}

.trace-section h2 {
  margin: 0;
  font-size: 2.8rem;
  line-height: 1;
}

.trace {
  display: grid;
  gap: 12px;
  margin: 0;
  padding: 0;
  list-style: none;
  counter-reset: trace;
}

.trace li {
  display: grid;
  grid-template-columns: 78px minmax(0, 160px) minmax(0, 1fr);
  gap: 12px;
  align-items: start;
  padding: 14px;
  border: 1px solid rgba(17, 24, 39, 0.12);
  border-radius: 8px;
  background: #ffffff;
}

.trace p {
  margin: 0;
  color: #475569;
}

.timestamp {
  color: #2563eb;
  font-size: 0.86rem;
  font-weight: 850;
}

@media (max-width: 900px) {
  .course-header,
  .workspace,
  .detail-grid,
  .trace-section {
    grid-template-columns: 1fr;
  }

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

  h1 {
    font-size: 4.5rem;
  }

  .detail-heading h2 {
    font-size: 3rem;
  }
}

@media (max-width: 620px) {
  .course-shell {
    width: min(100% - 20px, 1180px);
    padding-top: 10px;
  }

  h1 {
    font-size: 3.1rem;
  }

  .lede {
    font-size: 1.05rem;
  }

  .detail-heading h2,
  .trace-section h2 {
    font-size: 2.15rem;
  }

  .progress-strip,
  .lesson-list,
  .trace li {
    grid-template-columns: 1fr;
  }

  .detail-heading {
    grid-template-columns: 1fr;
  }

  .detail-heading span {
    width: fit-content;
  }
}