:root {
  --ink: #17242d;
  --muted: #5d6870;
  --paper: #f7f8f3;
  --surface: #ffffff;
  --line: #d8ddd7;
  --teal: #087f74;
  --teal-soft: #d9f0eb;
  --coral: #e85d4a;
  --yellow: #f3c84b;
  --navy: #173b57;
  --radius: 8px;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  color: var(--ink);
  background: var(--paper);
  font-family: "Manrope", sans-serif;
  letter-spacing: 0;
}

a {
  color: var(--teal);
  text-underline-offset: 0.18em;
}

a:hover {
  color: #045f58;
}

.skip-link {
  position: fixed;
  z-index: 2000;
  top: 0.75rem;
  left: 0.75rem;
  padding: 0.65rem 0.9rem;
  color: white;
  background: var(--ink);
  transform: translateY(-160%);
}

.skip-link:focus {
  transform: translateY(0);
}

.site-header {
  position: sticky;
  z-index: 1000;
  top: 0;
  border-bottom: 1px solid rgba(23, 36, 45, 0.14);
  background: rgba(247, 248, 243, 0.94);
  backdrop-filter: blur(14px);
}

.site-header .navbar {
  min-height: 68px;
}

.navbar-brand {
  display: flex;
  align-items: center;
  gap: 0.7rem;
  color: var(--ink);
  font-size: 0.92rem;
}

.brand-mark {
  display: grid;
  width: 36px;
  height: 36px;
  place-items: center;
  color: white;
  background: var(--teal);
  border-radius: 4px;
  font-size: 0.72rem;
  font-weight: 800;
}

.btn {
  border-radius: 5px;
  font-weight: 700;
}

.workshop-intro {
  overflow: hidden;
  padding: clamp(3.2rem, 8vw, 7rem) 0 clamp(2.6rem, 6vw, 5rem);
  background-color: #e9f0ed;
  background-image: linear-gradient(rgba(23, 59, 87, 0.06) 1px, transparent 1px), linear-gradient(90deg, rgba(23, 59, 87, 0.06) 1px, transparent 1px);
  background-size: 38px 38px;
  border-bottom: 1px solid var(--line);
}

.intro-grid {
  display: block;
}

.eyebrow {
  margin: 0 0 0.65rem;
  color: var(--teal);
  font-size: 0.74rem;
  font-weight: 800;
  letter-spacing: 0.12em;
  text-transform: uppercase;
}

.workshop-intro h1 {
  max-width: 870px;
  margin: 0;
  font-family: "Source Serif 4", serif;
  font-size: clamp(2.5rem, 5.5vw, 5.3rem);
  font-weight: 650;
  line-height: 0.98;
}

.intro-copy {
  max-width: 760px;
  margin: 1.5rem 0 0;
  color: #43515a;
  font-size: clamp(1rem, 1.5vw, 1.2rem);
  line-height: 1.75;
}

.exercise-catalog {
  padding: clamp(2.8rem, 7vw, 6rem) 0;
}

.catalog-toolbar {
  display: flex;
  gap: 2rem;
  align-items: end;
  justify-content: space-between;
  margin-bottom: 1.5rem;
}

.catalog-toolbar h2 {
  margin: 0;
  font-family: "Source Serif 4", serif;
  font-size: clamp(2rem, 4vw, 3.4rem);
}

.search-field {
  width: min(100%, 360px);
}

.search-field label {
  display: block;
  margin-bottom: 0.4rem;
  color: var(--muted);
  font-size: 0.76rem;
  font-weight: 700;
}

.form-control {
  min-height: 44px;
  border-color: #aeb7b1;
  border-radius: 5px;
  background: var(--surface);
}

.form-control:focus {
  border-color: var(--teal);
  box-shadow: 0 0 0 0.2rem rgba(8, 127, 116, 0.18);
}

.search-status {
  min-height: 1.25rem;
  margin: 0;
  color: var(--muted);
  font-size: 0.78rem;
}

.exercise-list {
  border-top: 1px solid var(--ink);
}

.exercise-row {
  display: grid;
  grid-template-columns: 80px minmax(0, 1fr) 44px;
  gap: clamp(1rem, 3vw, 2.2rem);
  align-items: center;
  padding: 1.6rem 0;
  border-bottom: 1px solid var(--line);
}

.exercise-row:hover {
  background: rgba(255, 255, 255, 0.55);
}

.exercise-number {
  align-self: start;
  color: var(--coral);
  font-family: "Source Serif 4", serif;
  font-size: 2rem;
  font-weight: 650;
}

.exercise-row h3 {
  margin: 0.25rem 0 0.45rem;
  font-size: clamp(1.15rem, 2vw, 1.5rem);
}

.exercise-row h3 a {
  color: var(--ink);
  text-decoration: none;
}

.exercise-row h3 a::after {
  content: "";
  position: absolute;
  inset: 0;
}

.exercise-row {
  position: relative;
}

.exercise-row p {
  max-width: 860px;
  margin: 0;
  color: var(--muted);
  font-size: 0.88rem;
  line-height: 1.65;
}

.source-link svg,
.rail-toggle svg,
.rail-close svg,
.all-exercises-link svg {
  width: 16px;
  height: 16px;
}

.exercise-open {
  display: grid;
  width: 40px;
  height: 40px;
  place-items: center;
  color: var(--ink);
  border: 1px solid var(--line);
  border-radius: 50%;
}

.exercise-open svg {
  width: 18px;
}

.empty-state {
  padding: 4rem 1rem;
  text-align: center;
}

.site-footer {
  padding: 1.5rem 0;
  color: #dce6e8;
  background: var(--ink);
  font-size: 0.78rem;
}

.exercise-shell {
  display: grid;
  min-height: calc(100vh - 68px);
  grid-template-columns: 290px minmax(0, 1fr);
}

.course-rail {
  border-right: 1px solid var(--line);
  background: #edf1ed;
}

.course-rail-inner {
  position: sticky;
  top: 68px;
  max-height: calc(100vh - 68px);
  overflow-y: auto;
  padding: 2rem 1rem 2rem 1.5rem;
}

.rail-heading {
  padding: 0 0.65rem 1rem;
  border-bottom: 1px solid var(--line);
}

.rail-heading p {
  margin-bottom: 0.25rem;
  font-size: 0.78rem;
}

.course-navigation-list {
  margin: 0;
  padding: 0.75rem 0;
  list-style: none;
}

.course-navigation-list a {
  display: block;
  padding: 0.65rem;
  color: #43515a;
  border-radius: 5px;
  font-size: 0.76rem;
  line-height: 1.35;
  text-decoration: none;
}

.course-navigation-list a:hover,
.course-navigation-list a.active {
  color: var(--ink);
  background: var(--surface);
}

.course-navigation-list a.active {
  box-shadow: inset 3px 0 var(--coral);
  font-weight: 700;
}

.course-navigation-list small {
  display: block;
  margin-bottom: 0.1rem;
  color: var(--teal);
  font-size: 0.62rem;
  font-weight: 800;
  text-transform: uppercase;
}

.exercise-main {
  min-width: 0;
  padding: 0 clamp(1.25rem, 5vw, 5rem) 4rem;
}

.exercise-topbar {
  display: flex;
  min-height: 62px;
  align-items: center;
  justify-content: flex-end;
  border-bottom: 1px solid var(--line);
}

.rail-toggle {
  display: none;
  gap: 0.4rem;
  align-items: center;
}

.rail-close {
  display: none;
}

.source-link {
  display: inline-flex;
  gap: 0.4rem;
  align-items: center;
  color: var(--muted);
  font-size: 0.75rem;
  font-weight: 700;
}

.exercise-layout {
  display: grid;
  grid-template-columns: minmax(0, 780px) 190px;
  gap: clamp(2rem, 6vw, 5rem);
  justify-content: center;
}

.exercise-article {
  padding: clamp(2.8rem, 7vw, 6rem) 0 3rem;
  line-height: 1.78;
}

.exercise-article > h1 {
  margin: 0 0 2.5rem;
  padding-bottom: 1.8rem;
  border-bottom: 4px solid var(--coral);
  font-family: "Source Serif 4", serif;
  font-size: clamp(2.35rem, 5vw, 4.6rem);
  font-weight: 650;
  line-height: 1.04;
}

.exercise-article h2 {
  margin: 3.8rem 0 1.2rem;
  font-family: "Source Serif 4", serif;
  font-size: clamp(1.65rem, 3vw, 2.35rem);
  font-weight: 650;
  scroll-margin-top: 90px;
}

.exercise-article h3 {
  margin: 2.2rem 0 0.8rem;
  font-size: 1.1rem;
  scroll-margin-top: 90px;
}

.exercise-article p,
.exercise-article li {
  color: #35434c;
}

.exercise-article li + li {
  margin-top: 0.45rem;
}

.exercise-article blockquote {
  margin: 1.8rem 0;
  padding: 1.3rem 1.5rem;
  border-left: 5px solid var(--yellow);
  background: #fff9df;
  font-family: "Source Serif 4", serif;
  font-size: 1.08rem;
}

.exercise-article blockquote p {
  margin: 0;
  color: var(--ink);
}

.exercise-article code {
  color: #9f2f35;
  font-size: 0.86em;
}

.exercise-article pre {
  overflow-x: auto;
  padding: 1.25rem;
  color: #edf4f2;
  background: var(--navy);
  border-radius: var(--radius);
}

.exercise-article pre code {
  color: inherit;
}

.exercise-article .table-responsive {
  margin: 1.5rem 0;
  border: 1px solid var(--line);
  border-radius: var(--radius);
}

.exercise-article .table {
  margin: 0;
  font-size: 0.86rem;
}

.exercise-article .table th {
  color: white;
  background: var(--navy);
}

.section-rail {
  position: sticky;
  top: 100px;
  align-self: start;
  max-height: calc(100vh - 130px);
  overflow-y: auto;
  margin-top: 4rem;
  padding-left: 1rem;
  border-left: 1px solid var(--line);
}

.section-rail-title {
  margin-bottom: 0.65rem;
  font-size: 0.7rem;
  font-weight: 800;
  text-transform: uppercase;
}

.section-rail ol {
  margin: 0;
  padding: 0;
  list-style: none;
}

.section-rail a {
  display: block;
  padding: 0.36rem 0;
  color: var(--muted);
  font-size: 0.72rem;
  line-height: 1.4;
  text-decoration: none;
}

.section-rail a:hover {
  color: var(--teal);
}

.exercise-actions {
  max-width: 1040px;
  margin: 0 auto;
  padding-top: 2rem;
  border-top: 1px solid var(--line);
}

.previous-next {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1rem;
  margin-top: 2.5rem;
}

.next-link {
  display: grid;
  padding: 1.25rem;
  color: var(--ink);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--surface);
  text-decoration: none;
}

.next-link.next {
  grid-column: 2;
  text-align: right;
}

.next-link small {
  margin-bottom: 0.3rem;
  color: var(--teal);
  font-size: 0.65rem;
  font-weight: 800;
  text-transform: uppercase;
}

.next-link span {
  font-size: 0.82rem;
  font-weight: 700;
}

@media (max-width: 1100px) {
  .exercise-shell {
    grid-template-columns: 240px minmax(0, 1fr);
  }

  .section-rail {
    display: none;
  }

  .exercise-layout {
    display: block;
  }
}

@media (max-width: 767px) {
  .catalog-toolbar {
    align-items: stretch;
    flex-direction: column;
  }

  .search-field {
    width: 100%;
  }

  .exercise-row {
    grid-template-columns: 50px minmax(0, 1fr) 34px;
    gap: 0.75rem;
  }

  .exercise-number {
    font-size: 1.4rem;
  }

  .exercise-open {
    width: 32px;
    height: 32px;
  }

  .exercise-shell {
    display: block;
  }

  .course-rail {
    position: fixed;
    z-index: 900;
    top: 68px;
    bottom: 0;
    left: 0;
    width: min(86vw, 320px);
    box-shadow: 12px 0 30px rgba(23, 36, 45, 0.15);
    transform: translateX(-110%);
    transition: transform 180ms ease;
  }

  .course-rail.is-open {
    transform: translateX(0);
  }

  .course-rail-inner {
    top: 0;
    max-height: 100%;
    padding-top: 1rem;
  }

  .rail-close {
    display: grid;
    width: 36px;
    height: 36px;
    margin: 0 0 1rem auto;
    place-items: center;
  }

  .exercise-main {
    padding: 0 1.1rem 3rem;
  }

  .exercise-topbar {
    justify-content: space-between;
  }

  .rail-toggle {
    display: inline-flex;
  }

  .exercise-article > h1 {
    overflow-wrap: anywhere;
  }

  .previous-next {
    grid-template-columns: 1fr;
  }

  .next-link.next {
    grid-column: 1;
    text-align: left;
  }
}

@media (max-width: 480px) {
  .site-header .navbar {
    flex-wrap: nowrap;
  }

  .site-header .navbar-brand {
    font-size: 0.8rem;
  }

  .all-exercises-link {
    display: grid;
    flex: 0 0 auto;
    width: 38px;
    height: 38px;
    place-items: center;
  }

  .all-exercises-link span {
    display: none;
  }
}

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

  .course-rail {
    transition: none;
  }
}