:root {
  color-scheme: dark;
  --ink: #f7f2e8;
  --muted: #aeb8ca;
  --paper: #101727;
  --paper-2: #151f33;
  --panel: #1c2940;
  --line: #33425d;
  --lime: #c9ff5b;
  --coral: #ff8066;
  --cyan: #63d9ff;
  --yellow: #ffd866;
  --shadow: 0 22px 70px rgb(0 0 0 / 28%);
  --radius: 22px;
  --max: 1240px;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  min-width: 320px;
  background:
    radial-gradient(circle at 85% 8%, rgb(99 217 255 / 10%), transparent 28rem),
    radial-gradient(circle at 10% 26%, rgb(255 128 102 / 8%), transparent 30rem),
    var(--paper);
  color: var(--ink);
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  line-height: 1.6;
}

a { color: inherit; }
button, a { -webkit-tap-highlight-color: transparent; }
button { font: inherit; }
img { display: block; max-width: 100%; }

:focus-visible {
  outline: 3px solid var(--lime);
  outline-offset: 4px;
}

.skip-link {
  position: fixed;
  z-index: 100;
  top: 12px;
  left: 12px;
  padding: 10px 14px;
  background: var(--lime);
  color: #111827;
  transform: translateY(-150%);
  transition: transform .2s ease;
}
.skip-link:focus { transform: translateY(0); }

.site-header {
  position: sticky;
  z-index: 50;
  top: 0;
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  align-items: center;
  gap: 28px;
  min-height: 76px;
  padding: 12px max(22px, calc((100vw - var(--max)) / 2));
  border-bottom: 1px solid rgb(255 255 255 / 8%);
  background: rgb(16 23 39 / 84%);
  backdrop-filter: blur(18px);
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 11px;
  width: fit-content;
  text-decoration: none;
}
.brand-mark {
  display: grid;
  width: 42px;
  height: 42px;
  place-items: center;
  border-radius: 13px 5px 13px 5px;
  background: var(--lime);
  color: #101727;
  font-weight: 950;
}
.brand strong, .brand small { display: block; line-height: 1.1; }
.brand small { margin-top: 4px; color: var(--muted); font-size: .72rem; }
.top-nav { display: flex; gap: 26px; }
.top-nav a {
  color: var(--muted);
  font-size: .92rem;
  font-weight: 700;
  text-decoration: none;
}
.top-nav a:hover { color: var(--ink); }
.progress-chip {
  display: flex;
  align-items: center;
  justify-self: end;
  gap: 10px;
  color: var(--muted);
  font-size: .8rem;
  font-weight: 800;
}
.progress-mini {
  width: 76px;
  height: 6px;
  overflow: hidden;
  border-radius: 99px;
  background: var(--line);
}
.progress-mini i, .progress-track i {
  display: block;
  width: 0;
  height: 100%;
  background: linear-gradient(90deg, var(--lime), var(--cyan));
  transition: width .35s ease;
}

.hero {
  position: relative;
  display: grid;
  grid-template-columns: 1.15fr .85fr;
  gap: 70px;
  align-items: center;
  max-width: var(--max);
  min-height: 720px;
  margin: 0 auto;
  padding: 90px 22px 110px;
}
.eyebrow {
  margin: 0 0 14px;
  color: var(--lime);
  font-size: .78rem;
  font-weight: 900;
  letter-spacing: .13em;
  text-transform: uppercase;
}
h1, h2, h3, p { margin-top: 0; }
h1 {
  max-width: 850px;
  margin-bottom: 24px;
  font-size: clamp(3.25rem, 7.3vw, 6.65rem);
  line-height: .93;
  letter-spacing: -.07em;
}
h1 em {
  color: var(--coral);
  font-family: Georgia, "Times New Roman", serif;
  font-weight: 500;
}
.hero-lead {
  max-width: 700px;
  color: var(--muted);
  font-size: clamp(1.05rem, 2vw, 1.28rem);
}
.hero-actions { display: flex; flex-wrap: wrap; gap: 12px; margin: 34px 0; }
.button {
  display: inline-flex;
  min-height: 50px;
  align-items: center;
  justify-content: center;
  padding: 0 20px;
  border: 1px solid var(--line);
  border-radius: 13px;
  font-weight: 850;
  text-decoration: none;
}
.button.primary { border-color: var(--lime); background: var(--lime); color: #101727; }
.button.secondary { background: rgb(255 255 255 / 3%); }
.button:hover { transform: translateY(-2px); }
.trust-list {
  display: flex;
  flex-wrap: wrap;
  gap: 10px 22px;
  margin: 0;
  padding: 0;
  color: var(--muted);
  font-size: .84rem;
  list-style: none;
}
.trust-list li::before { content: "✓"; margin-right: 7px; color: var(--lime); }

.hero-visual {
  position: relative;
  min-height: 460px;
}
.hero-core {
  position: absolute;
  top: 50%;
  left: 50%;
  display: grid;
  width: 166px;
  height: 166px;
  place-items: center;
  border: 1px solid rgb(201 255 91 / 45%);
  border-radius: 50%;
  background: radial-gradient(circle at 35% 30%, #293b50, #121a2a);
  box-shadow: 0 0 100px rgb(99 217 255 / 18%);
  color: var(--lime);
  font-size: 1.25rem;
  font-weight: 950;
  line-height: 1.05;
  text-align: center;
  transform: translate(-50%, -50%);
}
.orbit {
  position: absolute;
  top: 50%;
  left: 50%;
  border: 1px dashed rgb(174 184 202 / 28%);
  border-radius: 50%;
  transform: translate(-50%, -50%) rotate(-12deg);
}
.orbit-one { width: 360px; height: 270px; }
.orbit-two { width: 475px; height: 390px; transform: translate(-50%, -50%) rotate(18deg); }
.hero-card {
  position: absolute;
  min-width: 190px;
  padding: 15px 17px;
  border: 1px solid var(--line);
  border-radius: 16px;
  background: rgb(28 41 64 / 92%);
  box-shadow: var(--shadow);
  font-size: .84rem;
  font-weight: 760;
}
.hero-card span { margin-right: 8px; color: var(--coral); font-weight: 950; }
.card-a { top: 8%; left: 2%; transform: rotate(-4deg); }
.card-b { top: 44%; right: -4%; transform: rotate(4deg); }
.card-c { bottom: 4%; left: 4%; transform: rotate(2deg); }

.section-shell { max-width: var(--max); margin: 0 auto; padding: 100px 22px; }
.section-heading { max-width: 760px; margin-bottom: 44px; }
.section-heading h2 {
  margin-bottom: 18px;
  font-size: clamp(2.3rem, 5vw, 4.4rem);
  line-height: 1;
  letter-spacing: -.055em;
}
.section-heading > p:last-child { color: var(--muted); }
.radar-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 15px; }
.radar-grid article {
  min-height: 210px;
  padding: 24px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: linear-gradient(145deg, rgb(255 255 255 / 4%), transparent);
}
.radar-grid b { color: var(--coral); font-size: .76rem; letter-spacing: .1em; }
.radar-grid h3 { margin: 38px 0 8px; font-size: 1.45rem; }
.radar-grid p { color: var(--muted); font-size: .9rem; }

.route-layout {
  display: grid;
  grid-template-columns: 270px minmax(0, 1fr);
  gap: 64px;
  align-items: start;
}
.sidebar-sticky { position: sticky; top: 112px; }
#route-nav { display: grid; gap: 6px; }
#route-nav a {
  display: grid;
  grid-template-columns: 31px 1fr;
  gap: 10px;
  align-items: center;
  padding: 9px 10px;
  border-radius: 10px;
  color: var(--muted);
  font-size: .83rem;
  font-weight: 750;
  line-height: 1.25;
  text-decoration: none;
}
#route-nav a span {
  display: grid;
  width: 28px;
  height: 28px;
  place-items: center;
  border: 1px solid var(--line);
  border-radius: 8px;
  font-size: .68rem;
}
#route-nav a:hover, #route-nav a.active { background: var(--panel); color: var(--ink); }
.overall-progress {
  margin-top: 28px;
  padding: 18px;
  border: 1px solid var(--line);
  border-radius: 16px;
}
.progress-label { display: flex; justify-content: space-between; font-size: .8rem; }
.progress-track { height: 8px; margin: 10px 0 8px; overflow: hidden; border-radius: 99px; background: var(--line); }
.text-button { padding: 0; border: 0; background: none; color: var(--muted); cursor: pointer; font-size: .75rem; }
.text-button:hover { color: var(--coral); }

.route-group { margin-bottom: 72px; scroll-margin-top: 110px; }
.route-intro {
  display: grid;
  grid-template-columns: auto 1fr;
  gap: 18px;
  align-items: start;
  margin-bottom: 22px;
}
.route-number {
  display: grid;
  width: 52px;
  height: 52px;
  place-items: center;
  border-radius: 16px 6px;
  background: var(--coral);
  color: #15131a;
  font-weight: 950;
}
.route-intro h3 { margin-bottom: 5px; font-size: 1.7rem; line-height: 1.15; }
.route-intro p { margin: 0; color: var(--muted); font-size: .9rem; }
.prereq {
  display: inline-flex;
  margin-top: 10px;
  color: var(--cyan);
  font-size: .74rem;
  font-weight: 800;
}

.lesson-card {
  overflow: hidden;
  margin: 0 0 18px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: linear-gradient(145deg, rgb(255 255 255 / 4%), rgb(255 255 255 / 1%));
  box-shadow: 0 14px 40px rgb(0 0 0 / 12%);
}
.lesson-card.completed { border-color: rgb(201 255 91 / 55%); }
.lesson-head { padding: 24px 26px 20px; }
.lesson-kicker {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: 12px;
}
.tag {
  padding: 4px 9px;
  border: 1px solid var(--line);
  border-radius: 99px;
  color: var(--muted);
  font-size: .68rem;
  font-weight: 850;
}
.tag.exam { border-color: rgb(255 128 102 / 35%); color: #ffac9b; }
.tag.combination { border-color: rgb(99 217 255 / 38%); color: var(--cyan); }
.lesson-title-row { display: flex; gap: 16px; justify-content: space-between; align-items: start; }
.lesson-title-row h4 { margin: 0; font-size: clamp(1.25rem, 2.4vw, 1.75rem); line-height: 1.2; }
.complete-button {
  flex: 0 0 auto;
  min-height: 37px;
  padding: 0 12px;
  border: 1px solid var(--line);
  border-radius: 10px;
  background: transparent;
  color: var(--muted);
  cursor: pointer;
  font-size: .74rem;
  font-weight: 850;
}
.complete-button:hover, .lesson-card.completed .complete-button { border-color: var(--lime); color: var(--lime); }
.lesson-summary { max-width: 790px; margin: 13px 0 0; color: var(--muted); }
.lesson-body { padding: 0 26px 26px; }
.lesson-body details {
  border-top: 1px solid var(--line);
}
.lesson-body summary {
  padding: 17px 0;
  cursor: pointer;
  color: var(--ink);
  font-weight: 850;
}
.detail-content { padding: 0 0 22px; }
.detail-content > p { color: #d9deea; }
.key-grid { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 10px; margin: 16px 0; }
.key-point {
  padding: 14px;
  border: 1px solid var(--line);
  border-radius: 13px;
  background: rgb(0 0 0 / 10%);
  font-size: .88rem;
}
.formula {
  overflow-x: auto;
  margin: 14px 0;
  padding: 16px 18px;
  border-left: 4px solid var(--cyan);
  border-radius: 0 12px 12px 0;
  background: #0c1321;
  color: #f7f2e8;
  font-family: "Cambria Math", "Times New Roman", serif;
  font-size: 1.08rem;
  white-space: pre-wrap;
}
.algorithm {
  margin: 16px 0;
  padding: 0;
  counter-reset: algorithm;
  list-style: none;
}
.algorithm li {
  position: relative;
  min-height: 42px;
  margin: 0 0 10px;
  padding: 9px 12px 9px 48px;
  border: 1px solid var(--line);
  border-radius: 12px;
  background: rgb(255 255 255 / 2%);
}
.algorithm li::before {
  position: absolute;
  top: 9px;
  left: 10px;
  display: grid;
  width: 26px;
  height: 26px;
  place-items: center;
  border-radius: 8px;
  background: var(--lime);
  color: #101727;
  content: counter(algorithm);
  counter-increment: algorithm;
  font-size: .72rem;
  font-weight: 950;
}
.exam-answer, .danger-box, .definition-box {
  margin-top: 16px;
  padding: 16px 18px;
  border: 1px solid;
  border-radius: 14px;
}
.exam-answer { border-color: rgb(201 255 91 / 35%); background: rgb(201 255 91 / 5%); }
.danger-box { border-color: rgb(255 128 102 / 42%); background: rgb(255 128 102 / 6%); }
.definition-box { border-color: rgb(99 217 255 / 36%); background: rgb(99 217 255 / 5%); }
.exam-answer strong, .danger-box strong, .definition-box strong { display: block; margin-bottom: 6px; }
.danger-box ul, .exam-answer ul { margin-bottom: 0; }

.image-gallery {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 12px;
  margin: 18px 0;
}
.course-figure {
  display: flex;
  min-height: 210px;
  flex-direction: column;
  margin: 0;
  overflow: hidden;
  border: 1px solid var(--line);
  border-radius: 16px;
  background: #f8f8f5;
}
.course-figure img {
  width: 100%;
  min-height: 160px;
  flex: 1;
  object-fit: contain;
}
.course-figure figcaption {
  padding: 10px 12px;
  background: #162034;
  color: var(--muted);
  font-size: .72rem;
}
.sources-list {
  display: flex;
  flex-wrap: wrap;
  gap: 7px;
  margin-top: 20px;
  padding-top: 16px;
  border-top: 1px dashed var(--line);
}
.source-pill {
  padding: 6px 9px;
  border-radius: 8px;
  background: #0d1422;
  color: var(--yellow);
  font-size: .7rem;
  font-weight: 800;
}

.simulations { scroll-margin-top: 80px; }
.simulation-note {
  display: grid;
  grid-template-columns: auto 1fr;
  gap: 12px;
  margin-bottom: 20px;
  padding: 16px 18px;
  border: 1px solid rgb(255 216 102 / 36%);
  border-radius: 14px;
  background: rgb(255 216 102 / 5%);
  color: var(--muted);
  font-size: .84rem;
}
.simulation-note strong { color: var(--yellow); }
.simulation-list { display: grid; gap: 18px; }
.simulation-card {
  overflow: hidden;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: linear-gradient(145deg, rgb(255 255 255 / 4%), rgb(255 255 255 / 1%));
}
.simulation-head {
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto;
  gap: 30px;
  align-items: center;
  padding: 24px 26px;
}
.simulation-head h3 { margin: 8px 0; font-size: clamp(1.45rem, 3vw, 2rem); }
.simulation-head p { margin: 0; color: var(--muted); }
.exam-stats {
  display: grid;
  grid-template-columns: repeat(3, auto);
  gap: 8px;
}
.exam-stats span {
  min-width: 82px;
  padding: 10px;
  border: 1px solid var(--line);
  border-radius: 12px;
  color: var(--muted);
  font-size: .68rem;
  text-align: center;
}
.exam-stats b { display: block; color: var(--lime); font-size: .88rem; }
.simulation-paper {
  border-top: 1px solid var(--line);
}
.simulation-paper > summary {
  padding: 17px 26px;
  cursor: pointer;
  color: var(--cyan);
  font-weight: 900;
}
.simulation-questions {
  display: grid;
  gap: 14px;
  padding: 0 26px 26px;
}
.exam-question {
  overflow: hidden;
  border: 1px solid var(--line);
  border-radius: 17px;
  background: #111a2b;
}
.question-head {
  display: flex;
  gap: 20px;
  justify-content: space-between;
  padding: 20px 20px 16px;
}
.question-head h4 { margin: 4px 0 0; font-size: 1.2rem; }
.question-type {
  color: var(--coral);
  font-size: .66rem;
  font-weight: 900;
  letter-spacing: .1em;
  text-transform: uppercase;
}
.points {
  display: grid;
  min-width: 50px;
  height: 38px;
  place-items: center;
  border-radius: 11px;
  background: var(--lime);
  color: #101727;
  font-size: .8rem;
}
.question-prompt {
  padding: 0 20px 18px;
  color: #d9deea;
}
.question-prompt > strong { display: block; margin-bottom: 8px; color: var(--yellow); }
.question-prompt p { margin: 7px 0; }
.question-figures {
  padding: 0 20px 18px;
}
.question-figures > strong {
  display: block;
  margin-bottom: 9px;
  color: var(--cyan);
  font-size: .72rem;
  letter-spacing: .04em;
  text-transform: uppercase;
}
.question-figures > div {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 10px;
}
.question-figures figure {
  margin: 0;
  overflow: hidden;
  border: 1px solid var(--line);
  border-radius: 13px;
  background: #f8f8f5;
}
.question-figures img {
  width: 100%;
  max-height: 180px;
  object-fit: contain;
}
.question-figures figcaption {
  padding: 8px 10px;
  background: #162034;
  color: var(--muted);
  font-size: .68rem;
}
.exam-question > details { border-top: 1px solid var(--line); }
.exam-question > details > summary {
  padding: 14px 20px;
  cursor: pointer;
  font-size: .86rem;
  font-weight: 850;
}
.solution-panel { padding: 0 20px 20px; }
.definition-answers, .solution-steps { margin: 0; padding-left: 23px; }
.definition-answers li, .solution-steps li { margin: 0 0 10px; color: #d9deea; }
.final-result {
  margin: 14px 0 0;
  padding: 13px 15px;
  border: 1px solid rgb(201 255 91 / 40%);
  border-radius: 12px;
  background: rgb(201 255 91 / 6%);
  color: var(--lime);
}
.rubric-grid, .deduction-list {
  display: grid;
  gap: 8px;
  padding: 0 20px 20px;
}
.rubric-grid div, .deduction-list div {
  display: grid;
  grid-template-columns: 58px 1fr auto;
  gap: 10px;
  align-items: start;
  padding: 11px 12px;
  border: 1px solid var(--line);
  border-radius: 11px;
  color: var(--muted);
  font-size: .8rem;
}
.rubric-grid strong { color: var(--lime); }
.deduction-list strong { color: var(--coral); }
.deduction-list small {
  padding: 2px 6px;
  border-radius: 6px;
  background: rgb(255 255 255 / 5%);
  color: var(--yellow);
  white-space: nowrap;
}
.question-sources {
  display: flex;
  flex-wrap: wrap;
  gap: 7px;
  padding: 16px 20px 20px;
  border-top: 1px dashed var(--line);
}
.question-sources > strong {
  width: 100%;
  color: var(--yellow);
  font-size: .72rem;
  letter-spacing: .05em;
  text-transform: uppercase;
}
.question-sources span {
  padding: 7px 9px;
  border-radius: 9px;
  background: #0b1220;
  color: var(--ink);
  font-size: .68rem;
}
.question-sources small { display: block; color: var(--muted); }
.source-panel {
  display: grid;
  grid-template-columns: 1.35fr .65fr;
  gap: 50px;
  padding: clamp(28px, 6vw, 62px);
  border: 1px solid rgb(201 255 91 / 30%);
  border-radius: 28px;
  background: linear-gradient(135deg, rgb(201 255 91 / 7%), rgb(99 217 255 / 5%));
}
.source-panel h2 { font-size: clamp(2rem, 4vw, 3.6rem); line-height: 1; letter-spacing: -.045em; }
.source-panel p, .source-panel li { color: var(--muted); }
.source-panel ul { margin: 0; padding: 0; list-style: none; }
.source-panel li { padding: 12px 0; border-bottom: 1px solid var(--line); }
footer {
  display: flex;
  justify-content: space-between;
  max-width: var(--max);
  margin: 0 auto;
  padding: 32px 22px 55px;
  border-top: 1px solid var(--line);
  color: var(--muted);
  font-size: .82rem;
}
footer p { margin: 0; }
footer a { color: var(--lime); text-decoration: none; }
.loading { color: var(--muted); }
.error-state { padding: 20px; border: 1px solid var(--coral); border-radius: 14px; color: #ffc1b4; }

@media (max-width: 1040px) {
  .hero { grid-template-columns: 1fr; min-height: auto; }
  .hero-visual { display: none; }
  .radar-grid { grid-template-columns: repeat(2, 1fr); }
  .route-layout { grid-template-columns: 220px minmax(0, 1fr); gap: 34px; }
  .simulation-head { grid-template-columns: 1fr; }
  .exam-stats { justify-content: start; }
}

@media (max-width: 760px) {
  .site-header { grid-template-columns: 1fr auto; min-height: 64px; padding: 9px 16px; }
  .top-nav { display: none; }
  .progress-chip { grid-column: 2; }
  .hero { padding: 70px 18px 80px; }
  h1 { font-size: clamp(3rem, 15vw, 4.6rem); }
  .section-shell { padding: 76px 18px; }
  .radar-grid { grid-template-columns: 1fr; }
  .radar-grid article { min-height: 160px; }
  .route-layout { display: block; }
  .route-sidebar { margin-bottom: 48px; }
  .sidebar-sticky { position: static; }
  #route-nav { grid-template-columns: repeat(2, 1fr); }
  .lesson-head, .lesson-body { padding-right: 18px; padding-left: 18px; }
  .lesson-title-row { display: block; }
  .complete-button { margin-top: 15px; }
  .key-grid, .image-gallery, .source-panel { grid-template-columns: 1fr; }
  .simulation-note { grid-template-columns: 1fr; }
  .simulation-head, .simulation-paper > summary { padding-right: 18px; padding-left: 18px; }
  .simulation-questions { padding-right: 12px; padding-left: 12px; }
  .exam-stats { grid-template-columns: 1fr; width: 100%; }
  .exam-stats span { display: flex; justify-content: space-between; }
  .exam-stats b { display: inline; }
  .rubric-grid div, .deduction-list div { grid-template-columns: 52px 1fr; }
  .rubric-grid small, .deduction-list small { grid-column: 2; width: fit-content; }
  .question-figures > div { grid-template-columns: 1fr; }
  footer { display: grid; gap: 12px; }
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    scroll-behavior: auto !important;
    transition-duration: .01ms !important;
    animation-duration: .01ms !important;
  }
}