@import url("https://fonts.googleapis.com/css2?family=Inter:wght@400;500;600;700;800;900&display=swap");

:root {
  color-scheme: dark;
  --bg: #07100f;
  --bg-2: #0b1518;
  --panel: rgba(16, 27, 30, 0.82);
  --panel-2: rgba(19, 34, 37, 0.94);
  --text: #f4fbf8;
  --muted: #9db2ad;
  --line: rgba(255, 255, 255, 0.13);
  --teal: #32e6c5;
  --blue: #5ca8ff;
  --amber: #ffc857;
  --red: #ff6b6b;
  --green: #86efac;
  --shadow: 0 28px 88px rgba(0, 0, 0, 0.45);
  font-family: Inter, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  background:
    linear-gradient(120deg, rgba(50, 230, 197, 0.08), transparent 34%),
    radial-gradient(circle at 84% 8%, rgba(92, 168, 255, 0.18), transparent 26rem),
    linear-gradient(180deg, var(--bg), #050908 58%, #081112);
  color: var(--text);
  line-height: 1.5;
  letter-spacing: 0;
}

body::before {
  position: fixed;
  inset: 0;
  z-index: -1;
  content: "";
  background:
    linear-gradient(rgba(255, 255, 255, 0.035) 1px, transparent 1px),
    linear-gradient(90deg, rgba(255, 255, 255, 0.028) 1px, transparent 1px);
  background-size: 42px 42px;
  mask-image: linear-gradient(180deg, #000 0%, transparent 82%);
}

a { color: inherit; text-decoration: none; }
img { display: block; max-width: 100%; }
button, input, textarea { font: inherit; }

button:focus-visible,
a:focus-visible,
input:focus-visible,
textarea:focus-visible {
  outline: 3px solid var(--amber);
  outline-offset: 3px;
}

.topbar {
  position: sticky;
  top: 0;
  z-index: 50;
  display: grid;
  grid-template-columns: auto 1fr auto;
  gap: 22px;
  align-items: center;
  min-height: 66px;
  padding: 12px clamp(16px, 4vw, 54px);
  border-bottom: 1px solid var(--line);
  background: rgba(7, 16, 15, 0.82);
  backdrop-filter: blur(18px);
}

.brand, .nav, .hero-actions, .tabs, .chips, .footer {
  display: flex;
  align-items: center;
}

.brand {
  gap: 10px;
  font-weight: 900;
  letter-spacing: 0;
}

.brand-mark {
  display: grid;
  width: 38px;
  height: 38px;
  place-items: center;
  border: 1px solid rgba(50, 230, 197, 0.55);
  border-radius: 8px;
  background: #0d2220;
  color: var(--teal);
  box-shadow: inset 0 0 20px rgba(50, 230, 197, 0.18);
}

.nav {
  justify-content: center;
  gap: 6px;
}

.nav a,
.ghost-button,
.button,
.tab,
.lesson-button,
.chip {
  min-height: 38px;
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 9px 13px;
  background: rgba(255, 255, 255, 0.04);
  color: var(--text);
  font-weight: 800;
  cursor: pointer;
}

.nav a {
  color: var(--muted);
  border-color: transparent;
}

.nav a:hover,
.ghost-button:hover,
.tab:hover,
.lesson-button:hover,
.chip:hover {
  border-color: rgba(50, 230, 197, 0.48);
  color: var(--teal);
}

.ghost-button {
  color: var(--muted);
}

.hero {
  position: relative;
  display: grid;
  grid-template-columns: minmax(0, 0.78fr) minmax(430px, 1.22fr);
  gap: clamp(28px, 5vw, 70px);
  align-items: center;
  width: min(1260px, calc(100% - 36px));
  min-height: calc(100svh - 66px);
  margin: 0 auto;
  padding: clamp(44px, 7vh, 86px) 0 68px;
}

.hero-copy {
  position: relative;
  z-index: 2;
}

.eyebrow {
  width: fit-content;
  margin: 0 0 14px;
  padding: 6px 9px;
  border: 1px solid rgba(50, 230, 197, 0.42);
  border-radius: 8px;
  background: rgba(50, 230, 197, 0.08);
  color: var(--teal);
  font-size: 12px;
  font-weight: 900;
  line-height: 1;
  text-transform: uppercase;
}

h1, h2, h3, p { margin-top: 0; }

h1 {
  margin-bottom: 18px;
  font-size: clamp(54px, 8vw, 118px);
  line-height: 0.9;
  letter-spacing: 0;
}

h2 {
  margin-bottom: 16px;
  font-size: clamp(30px, 4.5vw, 58px);
  line-height: 1;
  letter-spacing: 0;
}

h3 {
  margin-bottom: 8px;
  font-size: 20px;
}

p {
  color: var(--muted);
}

.hero-lead {
  max-width: 650px;
  margin-bottom: 26px;
  color: #c5d8d3;
  font-size: clamp(18px, 2vw, 23px);
}

.hero-actions {
  flex-wrap: wrap;
  gap: 12px;
}

.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 48px;
  padding: 13px 18px;
}

.primary {
  border-color: rgba(50, 230, 197, 0.62);
  background: linear-gradient(135deg, #32e6c5, #5ca8ff);
  color: #03100f;
  box-shadow: 0 18px 48px rgba(50, 230, 197, 0.2);
}

.secondary {
  background: rgba(255, 255, 255, 0.05);
  color: var(--text);
}

.hero-visual {
  position: relative;
}

.hero-visual img {
  width: 100%;
  border: 1px solid var(--line);
  border-radius: 8px;
  box-shadow: var(--shadow);
}

.status-card {
  position: absolute;
  width: 190px;
  padding: 14px;
  border: 1px solid rgba(255, 255, 255, 0.17);
  border-radius: 8px;
  background: rgba(7, 16, 15, 0.86);
  backdrop-filter: blur(14px);
  box-shadow: 0 20px 54px rgba(0, 0, 0, 0.32);
}

.status-card span {
  display: block;
  margin-bottom: 5px;
  color: var(--muted);
  font-size: 12px;
  font-weight: 800;
  text-transform: uppercase;
}

.status-card strong {
  color: var(--teal);
}

.card-a { left: -16px; bottom: 42px; }
.card-b { right: 18px; top: 26px; }

.metrics,
.section,
.learning-shell {
  width: min(1260px, calc(100% - 36px));
  margin: 0 auto;
}

.metrics {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 12px;
  padding: 0 0 48px;
}

.metrics article,
.course-summary,
.mechanics-grid article,
.knowledge-card,
.progress-box,
.lesson-panel,
.sidebar {
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--panel);
  box-shadow: 0 18px 52px rgba(0, 0, 0, 0.22);
}

.metrics article {
  padding: 18px;
}

.metrics strong {
  display: block;
  margin-bottom: 4px;
  color: var(--amber);
  font-size: 34px;
  line-height: 1;
}

.metrics span {
  color: var(--muted);
  font-weight: 800;
}

.section {
  padding: 72px 0;
}

.split {
  display: grid;
  grid-template-columns: minmax(0, 0.95fr) minmax(320px, 0.65fr);
  gap: 26px;
  align-items: start;
}

.course-summary {
  padding: 22px;
}

.course-summary div + div {
  margin-top: 18px;
  padding-top: 18px;
  border-top: 1px solid var(--line);
}

.course-summary span {
  display: block;
  margin-bottom: 5px;
  color: var(--muted);
  font-size: 12px;
  font-weight: 900;
  text-transform: uppercase;
}

.course-summary strong {
  font-size: 18px;
}

.learning-shell {
  display: grid;
  grid-template-columns: 360px minmax(0, 1fr);
  gap: 18px;
  align-items: start;
  padding: 12px 0 70px;
}

.sidebar {
  position: sticky;
  top: 84px;
  max-height: calc(100svh - 100px);
  overflow: auto;
  padding: 14px;
}

.progress-box {
  margin-bottom: 12px;
  padding: 16px;
  background: var(--panel-2);
}

.progress-box span {
  color: var(--muted);
  font-size: 12px;
  font-weight: 900;
  text-transform: uppercase;
}

.progress-box strong {
  display: block;
  margin: 8px 0;
  font-size: 28px;
}

.progress-track {
  height: 9px;
  overflow: hidden;
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.09);
}

.progress-track i {
  display: block;
  width: 0%;
  height: 100%;
  border-radius: inherit;
  background: linear-gradient(90deg, var(--teal), var(--amber));
}

.module {
  margin-bottom: 10px;
  border: 1px solid var(--line);
  border-radius: 8px;
  overflow: hidden;
  background: rgba(255, 255, 255, 0.035);
}

.module-title {
  padding: 12px;
  border-bottom: 1px solid var(--line);
  color: var(--text);
  font-weight: 900;
}

.lesson-button {
  display: grid;
  grid-template-columns: 22px 1fr auto;
  gap: 8px;
  align-items: center;
  width: 100%;
  min-height: 48px;
  border: 0;
  border-radius: 0;
  border-bottom: 1px solid rgba(255, 255, 255, 0.08);
  background: transparent;
  color: var(--muted);
  text-align: left;
}

.lesson-button:last-child { border-bottom: 0; }
.lesson-button.active { background: rgba(50, 230, 197, 0.09); color: var(--text); }
.lesson-button.locked { opacity: 0.52; cursor: not-allowed; }
.lesson-button.done .dot { background: var(--green); }

.dot {
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background: var(--line);
}

.lesson-button.active .dot { background: var(--teal); }

.lock {
  color: var(--amber);
  font-size: 12px;
  font-weight: 900;
}

.lesson-panel {
  min-height: 780px;
  padding: clamp(18px, 3vw, 30px);
  background: rgba(10, 20, 22, 0.9);
}

.lesson-head {
  display: flex;
  justify-content: space-between;
  gap: 18px;
  align-items: flex-start;
  margin-bottom: 18px;
}

.lesson-state {
  flex: 0 0 auto;
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 8px 10px;
  color: var(--muted);
  font-size: 12px;
  font-weight: 900;
  text-transform: uppercase;
}

.lesson-state.open { color: var(--teal); border-color: rgba(50, 230, 197, 0.45); }
.lesson-state.done { color: var(--green); border-color: rgba(134, 239, 172, 0.45); }

.tabs {
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: 20px;
}

.tab.active {
  border-color: rgba(50, 230, 197, 0.55);
  background: rgba(50, 230, 197, 0.12);
  color: var(--teal);
}

.lesson-content { display: none; }
.lesson-content.active { display: block; }

.lesson-content h3 {
  margin-top: 22px;
}

.lesson-content ul,
.lesson-content ol {
  padding-left: 20px;
  color: #c8d8d4;
}

.lesson-content li + li {
  margin-top: 8px;
}

.video-slot,
.note-box,
.review-box,
.workbook-card {
  margin: 16px 0;
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 16px;
  background: rgba(255, 255, 255, 0.04);
}

.video-slot {
  display: grid;
  min-height: 170px;
  place-items: center;
  color: var(--muted);
  font-weight: 900;
}

textarea {
  width: 100%;
  min-height: 230px;
  resize: vertical;
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 14px;
  background: rgba(0, 0, 0, 0.25);
  color: var(--text);
}

.review-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-top: 12px;
}

.review-result {
  margin-top: 16px;
  border-left: 4px solid var(--amber);
  padding: 14px;
  background: rgba(255, 200, 87, 0.08);
}

.review-result.pass {
  border-color: var(--green);
  background: rgba(134, 239, 172, 0.08);
}

.review-result.fail {
  border-color: var(--red);
  background: rgba(255, 107, 107, 0.08);
}

.mechanics .section-heading,
.knowledge .section-heading {
  max-width: 760px;
}

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

.mechanics-grid article,
.knowledge-card {
  padding: 18px;
}

.mechanics-grid span {
  display: inline-grid;
  width: 36px;
  height: 36px;
  place-items: center;
  margin-bottom: 18px;
  border-radius: 8px;
  background: rgba(50, 230, 197, 0.12);
  color: var(--teal);
  font-weight: 900;
}

.knowledge-tools {
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto;
  gap: 12px;
  margin-bottom: 18px;
}

.knowledge-tools input {
  min-height: 48px;
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 0 14px;
  background: rgba(255, 255, 255, 0.05);
  color: var(--text);
}

.chips {
  flex-wrap: wrap;
  gap: 8px;
}

.chip.active {
  border-color: rgba(255, 200, 87, 0.58);
  color: var(--amber);
}

.knowledge-card {
  min-height: 210px;
}

.knowledge-card b {
  display: block;
  margin-bottom: 8px;
  color: var(--amber);
  font-size: 12px;
  text-transform: uppercase;
}

.knowledge-card h3 {
  font-size: 18px;
}

.footer {
  justify-content: space-between;
  gap: 20px;
  padding: 26px clamp(18px, 4vw, 54px);
  border-top: 1px solid var(--line);
  color: var(--muted);
  font-weight: 800;
}

@media (max-width: 1080px) {
  .topbar { grid-template-columns: 1fr auto; }
  .nav { order: 3; grid-column: 1 / -1; justify-content: flex-start; overflow-x: auto; }
  .hero { grid-template-columns: 1fr; min-height: auto; }
  .hero-visual { max-width: 820px; }
  .learning-shell { grid-template-columns: 1fr; }
  .sidebar { position: static; max-height: none; }
  .mechanics-grid, .knowledge-grid { grid-template-columns: repeat(2, 1fr); }
}

@media (max-width: 720px) {
  .topbar { grid-template-columns: 1fr; }
  .ghost-button { width: 100%; }
  .hero { width: min(100% - 28px, 1260px); padding-top: 34px; }
  .metrics, .split, .mechanics-grid, .knowledge-grid, .knowledge-tools { grid-template-columns: 1fr; }
  .metrics, .section, .learning-shell { width: min(100% - 28px, 1260px); }
  .status-card { position: static; width: auto; margin-top: 10px; }
  .lesson-head { display: block; }
  .lesson-state { width: fit-content; margin-top: 10px; }
  .footer { display: block; }
  .footer span { display: block; margin-top: 8px; }
}