:root {
  --qt-ink: #132238;
  --qt-muted: #53657d;
  --qt-navy: #101a2b;
  --qt-blue: #236a93;
  --qt-rust: #dc4f2f;
  --qt-gold: #d79b2b;
  --qt-paper: #fbfcfe;
  --qt-panel: #f1f5f9;
  --qt-line: #dbe4ef;
}

html {
  font-size: 18px;
}

body {
  color: var(--qt-ink);
  background: var(--qt-paper);
  line-height: 1.68;
}

.navbar {
  border-bottom: 1px solid rgba(255, 255, 255, 0.12);
}

.navbar-brand,
.navbar-nav .nav-link {
  letter-spacing: 0.01em;
}

h1,
h2,
h3 {
  color: var(--qt-ink);
  font-weight: 700;
  letter-spacing: -0.02em;
}

h1 {
  max-width: 19ch;
}

h2 {
  margin-top: 2.7rem;
}

a {
  color: #155f87;
}

.institution-strip {
  display: grid;
  grid-template-columns: minmax(16rem, 20.5rem) minmax(0, 1fr);
  align-items: center;
  gap: clamp(1.4rem, 4vw, 3.5rem);
  max-width: 1120px;
  margin: 1rem auto 1.25rem;
  padding: 1.15rem clamp(1.25rem, 3vw, 2rem);
  border: 1px solid var(--qt-line);
  border-top: 4px solid #e2001a;
  border-radius: 0.55rem;
  background: #ffffff;
  box-shadow: 0 0.4rem 1.4rem rgba(25, 48, 75, 0.055);
}

.institution-logo-frame {
  position: relative;
  width: min(100%, 20.5rem);
  aspect-ratio: 1.807 / 1;
  overflow: hidden;
}

.institution-logo {
  position: absolute;
  top: -57.65%;
  left: -10.45%;
  width: 127.75%;
  max-width: none;
}

.institution-copy {
  padding-left: clamp(0rem, 2vw, 1.5rem);
  border-left: 1px solid var(--qt-line);
}

.institution-eyebrow {
  color: #e2001a;
  font-size: 0.78rem;
  font-weight: 800;
  letter-spacing: 0.12em;
  text-transform: uppercase;
}

.institution-campus {
  margin: 0.28rem 0 0.65rem;
  color: var(--qt-ink);
  font-size: clamp(1.08rem, 2vw, 1.35rem);
  font-weight: 750;
}

.institution-author {
  color: var(--qt-muted);
  font-size: 0.94rem;
}

.course-hero {
  position: relative;
  overflow: hidden;
  max-width: 1120px;
  margin: 1rem auto 2.5rem;
  padding: clamp(2rem, 5vw, 4.8rem);
  color: #f7f9fc;
  background:
    radial-gradient(circle at 88% 10%, rgba(220, 79, 47, 0.28), transparent 28%),
    linear-gradient(135deg, #101a2b 0%, #18334d 66%, #204c67 100%);
  border-radius: 0.8rem;
  box-shadow: 0 1.2rem 3rem rgba(16, 26, 43, 0.18);
}

.course-hero::after {
  content: "";
  position: absolute;
  right: -6rem;
  bottom: -7rem;
  width: 19rem;
  height: 19rem;
  border: 1px solid rgba(255, 255, 255, 0.18);
  border-radius: 50%;
  box-shadow:
    0 0 0 2.3rem rgba(255, 255, 255, 0.04),
    0 0 0 5.4rem rgba(255, 255, 255, 0.025);
}

.course-hero p {
  position: relative;
  z-index: 1;
  max-width: 68ch;
  margin: 1rem 0 1.7rem;
  font-size: clamp(1.05rem, 2vw, 1.3rem);
}

.course-kicker {
  position: relative;
  z-index: 1;
  color: #bcd8e8;
  font-size: 0.78rem;
  font-weight: 750;
  letter-spacing: 0.13em;
  text-transform: uppercase;
}

.course-hero .btn-primary {
  position: relative;
  z-index: 1;
  border-color: var(--qt-rust);
  background: var(--qt-rust);
  font-weight: 700;
}

.course-hero .btn-primary:hover,
.course-hero .btn-primary:focus {
  border-color: #f06b4c;
  background: #f06b4c;
}

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

.principle-card,
.observation-card {
  padding: 1.35rem;
  border: 1px solid var(--qt-line);
  border-radius: 0.55rem;
  background: #ffffff;
  box-shadow: 0 0.4rem 1.4rem rgba(25, 48, 75, 0.055);
}

.principle-card h3 {
  margin-top: 0;
  color: var(--qt-blue);
}

.course-path {
  max-width: 62rem;
  padding: 1.25rem 1.4rem;
  border-left: 4px solid var(--qt-gold);
  background: var(--qt-panel);
}

.course-link {
  display: inline-block;
  margin-top: 0.35rem;
  font-weight: 700;
}

.week-meta {
  margin: 0.5rem 0 1.8rem;
  color: var(--qt-muted);
  font-size: 0.92rem;
  letter-spacing: 0.015em;
}

.scientist-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1.2rem;
  margin: 1.5rem 0 2rem;
}

.scientist-card {
  display: grid;
  grid-template-columns: minmax(10rem, 0.82fr) minmax(0, 1.18fr);
  overflow: hidden;
  border: 1px solid var(--qt-line);
  border-radius: 0.65rem;
  background: #ffffff;
  box-shadow: 0 0.7rem 2rem rgba(25, 48, 75, 0.08);
}

.scientist-visual {
  display: flex;
  flex-direction: column;
  min-width: 0;
  background: var(--qt-navy);
}

.scientist-visual p {
  margin: 0;
}

.scientist-portrait {
  display: block;
  width: 100%;
  height: 100%;
  min-height: 19rem;
  aspect-ratio: 4 / 5;
  object-fit: cover;
  filter: contrast(1.03);
}

.scientist-card:first-child .scientist-portrait {
  object-position: 50% 24%;
}

.scientist-card:nth-child(2) .scientist-portrait {
  object-position: 50% 18%;
}

.image-credit {
  display: block;
  padding: 0.55rem 0.7rem 0.65rem;
  color: #c7d7e4;
  font-size: 0.68rem;
  line-height: 1.35;
}

.image-credit:hover,
.image-credit:focus {
  color: #ffffff;
}

.scientist-copy {
  padding: 1.25rem 1.3rem 1.35rem;
}

.scientist-copy h3 {
  margin: 0.2rem 0 0.75rem;
  font-size: 1.35rem;
}

.scientist-copy p:last-child {
  margin-bottom: 0;
}

.scientist-year,
.history-year {
  color: var(--qt-rust);
  font-size: 0.76rem;
  font-weight: 800;
  letter-spacing: 0.09em;
  text-transform: uppercase;
}

.history-track {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 0;
  margin: 1.7rem 0 2.3rem;
  border-top: 2px solid var(--qt-blue);
}

.history-step {
  position: relative;
  padding: 1.2rem 1rem 0;
  color: var(--qt-muted);
  font-size: 0.86rem;
}

.history-step::before {
  content: "";
  position: absolute;
  top: -0.42rem;
  left: 1rem;
  width: 0.72rem;
  height: 0.72rem;
  border: 2px solid var(--qt-paper);
  border-radius: 50%;
  background: var(--qt-blue);
  box-shadow: 0 0 0 1px var(--qt-blue);
}

.history-step p {
  margin: 0.35rem 0 0;
}

.derivation-check {
  margin: 1.2rem 0;
  padding: 1rem 1.15rem;
  border-left: 4px solid var(--qt-gold);
  background: #fff8e8;
}

.concept-solution {
  margin: 1.2rem 0;
  padding: 0.85rem 1rem;
  border: 1px solid var(--qt-line);
  border-radius: 0.45rem;
  background: #ffffff;
}

.concept-solution summary {
  color: var(--qt-blue);
  font-weight: 700;
  cursor: pointer;
}

.concept-solution[open] summary {
  margin-bottom: 0.8rem;
}

.simulation-shell {
  overflow: hidden;
  margin: 1.4rem 0 1.8rem;
  border: 1px solid #cbd6e2;
  border-radius: 0.65rem;
  background: #ffffff;
  box-shadow: 0 0.8rem 2.4rem rgba(25, 48, 75, 0.1);
}

.simulation-label {
  padding: 0.72rem 1rem;
  color: #dbe9f2;
  background: var(--qt-navy);
  font-size: 0.72rem;
  font-weight: 750;
  letter-spacing: 0.11em;
}

.simulation-frame {
  display: block;
  width: 100%;
  min-height: 900px;
  border: 0;
  background: var(--qt-paper);
}

.observation-card {
  font-size: 0.92rem;
}

.observation-card strong {
  color: var(--qt-rust);
  letter-spacing: 0.02em;
}

.callout {
  border-radius: 0.45rem;
}

.page-footer {
  color: var(--qt-muted);
  border-top: 1px solid var(--qt-line);
}

@media (max-width: 900px) {
  html {
    font-size: 16px;
  }

  .institution-strip {
    grid-template-columns: 1fr;
  }

  .institution-logo-frame {
    width: min(100%, 19rem);
  }

  .institution-copy {
    padding-top: 1rem;
    padding-left: 0;
    border-top: 1px solid var(--qt-line);
    border-left: 0;
  }

  .course-principles,
  .observation-grid,
  .scientist-grid {
    grid-template-columns: 1fr;
  }

  .history-track {
    grid-template-columns: 1fr;
    gap: 0.9rem;
    border-top: 0;
    border-left: 2px solid var(--qt-blue);
  }

  .history-step {
    padding: 0 0 0 1.3rem;
  }

  .history-step::before {
    top: 0.15rem;
    left: -0.42rem;
  }

  .simulation-frame {
    min-height: 980px;
  }
}

@media (max-width: 560px) {
  .scientist-card {
    grid-template-columns: 1fr;
  }

  .scientist-portrait {
    min-height: 0;
    max-height: 26rem;
  }
}

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