:root {
  color-scheme: dark;
  --background: #07111f;
  --surface: #0c192b;
  --surface-raised: #12233a;
  --surface-soft: #172b45;
  --border: #263c58;
  --text: #f4f7fb;
  --muted: #9aadc4;
  --accent: #73e2c2;
  --accent-strong: #2fc49d;
  --accent-soft: rgba(115, 226, 194, 0.13);
  --blue: #80aef8;
  --warning: #f4c76a;
  --content-width: 1180px;
  font-family:
    Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI",
    sans-serif;
  font-synthesis: none;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  scroll-padding-top: 148px;
}

body {
  min-width: 320px;
  margin: 0;
  color: var(--text);
  background:
    radial-gradient(circle at 70% -10%, rgba(49, 105, 166, 0.2), transparent 38rem),
    var(--background);
  line-height: 1.65;
}

button,
input {
  font: inherit;
}

button,
a,
label {
  -webkit-tap-highlight-color: transparent;
}

a {
  color: var(--accent);
  text-underline-offset: 0.2em;
}

a:hover {
  color: #a0f4dd;
}

.topbar {
  position: sticky;
  z-index: 20;
  top: 0;
  width: 100%;
  border-bottom: 1px solid var(--border);
  background: rgba(8, 19, 33, 0.97);
  backdrop-filter: blur(18px);
}

.topbar-main {
  display: flex;
  max-width: 1480px;
  min-height: 72px;
  align-items: center;
  gap: 16px;
  margin-inline: auto;
  padding: 10px clamp(18px, 4vw, 56px) 8px;
}

.brand {
  display: flex;
  flex: 0 0 auto;
  align-items: center;
  gap: 12px;
  color: var(--text);
  text-decoration: none;
}

.brand-mark {
  display: grid;
  width: 38px;
  height: 38px;
  place-items: center;
  border: 1px solid rgba(115, 226, 194, 0.4);
  border-radius: 11px;
  color: #07151e;
  background: linear-gradient(140deg, #97f0d7, #43caa6);
  font-size: 1rem;
  font-weight: 900;
  box-shadow: 0 7px 22px rgba(47, 196, 157, 0.18);
}

.brand-copy {
  display: flex;
  flex-direction: column;
  min-width: 125px;
}

.brand strong {
  line-height: 1.2;
  letter-spacing: -0.01em;
}

.brand small {
  color: var(--muted);
  font-size: 0.68rem;
}

.overall-card {
  flex: 1 1 250px;
  max-width: 360px;
  margin-left: auto;
  padding: 8px 12px;
  border: 1px solid var(--border);
  border-radius: 12px;
  background: linear-gradient(145deg, var(--surface-raised), var(--surface));
}

.overall-card > div:first-child {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 16px;
  color: var(--muted);
  font-size: 0.66rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.08em;
}

.overall-card strong {
  color: var(--text);
  font-size: 0.95rem;
  letter-spacing: -0.04em;
}

.overall-card small {
  display: block;
  margin-top: 4px;
  color: var(--muted);
  font-size: 0.65rem;
}

.overall-progress,
.mini-progress {
  overflow: hidden;
  border-radius: 999px;
  background: #06101e;
}

.overall-progress {
  height: 4px;
  margin-top: 5px;
}

.overall-progress span,
.mini-progress span {
  display: block;
  width: 0;
  height: 100%;
  border-radius: inherit;
  background: linear-gradient(90deg, var(--accent-strong), var(--accent));
  transition: width 220ms ease;
}

.continue-button {
  display: flex;
  align-items: center;
  gap: 10px;
  border: 0;
  border-radius: 10px;
  padding: 9px 13px;
  color: #07151e;
  background: var(--accent);
  font-size: 0.78rem;
  font-weight: 800;
  white-space: nowrap;
  cursor: pointer;
}

.continue-button:hover {
  background: #92ebd2;
}

.continue-button span {
  font-size: 1rem;
}

.topbar-actions {
  display: flex;
  flex: 0 0 auto;
  align-items: center;
  gap: 7px;
}

.reset-button {
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 8px 11px;
  color: var(--muted);
  background: var(--surface);
  font-size: 0.74rem;
  cursor: pointer;
}

.reset-button:hover {
  border-color: #3c5877;
  color: var(--text);
}

.phase-navigation {
  display: flex;
  max-width: 1480px;
  gap: 6px;
  overflow-x: auto;
  margin-inline: auto;
  padding: 0 clamp(18px, 4vw, 56px) 9px;
  scrollbar-color: var(--border) transparent;
  scrollbar-width: thin;
}

.phase-link {
  position: relative;
  display: grid;
  flex: 0 0 178px;
  grid-template-columns: 1fr auto;
  gap: 0 9px;
  border: 1px solid transparent;
  border-radius: 9px;
  padding: 6px 9px;
  color: var(--muted);
  text-decoration: none;
  transition:
    color 160ms ease,
    border-color 160ms ease,
    background 160ms ease;
}

.phase-link:hover,
.phase-link.active {
  border-color: var(--border);
  color: var(--text);
  background: var(--surface);
}

.phase-link.active::before {
  position: absolute;
  inset: auto 9px -2px;
  height: 3px;
  border-radius: 999px;
  background: var(--accent);
  content: "";
}

.phase-link-number {
  color: var(--accent);
  font-size: 0.57rem;
  font-weight: 800;
  text-transform: uppercase;
  letter-spacing: 0.09em;
}

.phase-link-title {
  overflow: hidden;
  grid-column: 1;
  font-size: 0.68rem;
  font-weight: 650;
  line-height: 1.35;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.phase-link-progress {
  grid-column: 2;
  grid-row: 1 / span 2;
  align-self: center;
  color: var(--muted);
  font-size: 0.62rem;
  font-variant-numeric: tabular-nums;
}

.phase-link.complete .phase-link-progress {
  color: var(--accent);
}

main {
  width: 100%;
  padding: 30px clamp(18px, 4vw, 64px) 120px;
}

.hero,
.lesson {
  width: min(100%, var(--content-width));
  margin-inline: auto;
}

.hero {
  padding: 28px 0 48px;
}

.hero h1 {
  max-width: 760px;
  margin: 10px 0 16px;
  font-size: clamp(2.5rem, 6vw, 5.2rem);
  line-height: 0.99;
  letter-spacing: -0.065em;
}

.hero p {
  max-width: 670px;
  margin: 0;
  color: var(--muted);
  font-size: 1.05rem;
}

.eyebrow {
  color: var(--accent);
  font-size: 0.72rem;
  font-weight: 850;
  text-transform: uppercase;
  letter-spacing: 0.13em;
}

.flow {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
  margin-top: 32px;
}

.flow span {
  border: 1px solid var(--border);
  border-radius: 999px;
  padding: 7px 12px;
  color: #c8d5e5;
  background: var(--surface);
  font-size: 0.75rem;
  font-weight: 700;
}

.flow b {
  color: var(--accent);
  font-size: 0.8rem;
}

.lesson {
  margin-bottom: 70px;
  scroll-margin-top: 145px;
  border: 1px solid var(--border);
  border-radius: 24px;
  background: rgba(12, 25, 43, 0.88);
  box-shadow: 0 24px 70px rgba(0, 0, 0, 0.18);
}

.lesson-header {
  padding: clamp(24px, 5vw, 46px);
  border-bottom: 1px solid var(--border);
  background:
    radial-gradient(circle at 90% 0, rgba(115, 226, 194, 0.1), transparent 45%),
    var(--surface);
  border-radius: 24px 24px 0 0;
}

.lesson-header h1 {
  max-width: 760px;
  margin: 8px 0 16px;
  font-size: clamp(1.7rem, 4vw, 2.8rem);
  line-height: 1.08;
  letter-spacing: -0.045em;
}

.tags {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
}

.tag {
  border: 1px solid rgba(128, 174, 248, 0.2);
  border-radius: 999px;
  padding: 3px 8px;
  color: #aac7f3;
  background: rgba(128, 174, 248, 0.07);
  font-size: 0.65rem;
}

.lesson-progress-row {
  display: grid;
  grid-template-columns: auto minmax(100px, 210px);
  align-items: center;
  justify-content: start;
  gap: 12px;
  margin-top: 20px;
  color: var(--muted);
  font-size: 0.74rem;
}

.mini-progress {
  height: 5px;
}

.lesson-content {
  padding: clamp(24px, 5vw, 48px);
}

.lesson-content h2,
.lesson-content h3,
.lesson-content h4 {
  line-height: 1.2;
  letter-spacing: -0.025em;
}

.lesson-content h2 {
  margin: 2.4em 0 0.8em;
  font-size: 1.55rem;
}

.lesson-content h2:first-child {
  margin-top: 0;
}

.lesson-content h3 {
  margin: 2em 0 0.65em;
  font-size: 1.2rem;
}

.lesson-content p,
.lesson-content li {
  color: #c8d5e5;
}

.lesson-content p {
  margin: 0.9em 0;
}

.lesson-content ul,
.lesson-content ol {
  padding-left: 1.4rem;
}

.lesson-content li {
  margin: 0.45em 0;
}

.lesson-content strong {
  color: var(--text);
}

.lesson-content :not(pre) > code {
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 0.12em 0.35em;
  color: #b8d8ff;
  background: #081422;
  font-family: "SFMono-Regular", Consolas, "Liberation Mono", monospace;
  font-size: 0.84em;
}

.task-item {
  position: relative;
  display: grid;
  grid-template-columns: 25px 1fr;
  gap: 12px;
  align-items: start;
  margin: 16px 0 10px;
  border: 1px solid var(--border);
  border-radius: 14px;
  padding: 15px 16px;
  background: var(--surface-raised);
  cursor: pointer;
  transition:
    border-color 160ms ease,
    background 160ms ease,
    transform 160ms ease;
}

.task-item:hover {
  border-color: #3c5877;
  background: var(--surface-soft);
  transform: translateY(-1px);
}

.task-item input {
  position: absolute;
  width: 1px;
  height: 1px;
  opacity: 0;
}

.task-check {
  position: relative;
  display: block;
  width: 23px;
  height: 23px;
  margin-top: 1px;
  border: 2px solid #58708d;
  border-radius: 7px;
  background: #091526;
}

.task-item input:focus-visible + .task-check {
  outline: 3px solid rgba(128, 174, 248, 0.55);
  outline-offset: 3px;
}

.task-item input:checked + .task-check {
  border-color: var(--accent-strong);
  background: var(--accent-strong);
}

.task-item input:checked + .task-check::after {
  position: absolute;
  top: 3px;
  left: 7px;
  width: 5px;
  height: 10px;
  border: solid #062018;
  border-width: 0 2px 2px 0;
  content: "";
  transform: rotate(45deg);
}

.task-item.is-complete {
  border-color: rgba(47, 196, 157, 0.3);
  background: var(--accent-soft);
}

.task-item.is-complete .task-text {
  color: #91a69f;
  text-decoration: line-through;
  text-decoration-color: rgba(145, 166, 159, 0.55);
}

.task-text {
  color: var(--text);
  font-size: 0.94rem;
  font-weight: 650;
  line-height: 1.5;
}

.code-block {
  overflow: hidden;
  margin: 10px 0 24px;
  border: 1px solid var(--border);
  border-radius: 14px;
  background: #050d18;
}

.code-toolbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  min-height: 42px;
  padding: 0 9px 0 15px;
  border-bottom: 1px solid #1d3049;
  color: var(--muted);
  background: #0b1727;
  font-size: 0.66rem;
  font-weight: 800;
  text-transform: uppercase;
  letter-spacing: 0.1em;
}

.copy-button {
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 5px 10px;
  color: #c8d5e5;
  background: var(--surface-raised);
  font-size: 0.68rem;
  font-weight: 700;
  text-transform: none;
  letter-spacing: 0;
  cursor: pointer;
}

.copy-button:hover {
  border-color: var(--accent-strong);
  color: var(--accent);
}

pre {
  overflow-x: auto;
  margin: 0;
  padding: 20px;
  color: #d8e5f5;
  font-family: "SFMono-Regular", Consolas, "Liberation Mono", monospace;
  font-size: 0.78rem;
  line-height: 1.65;
  tab-size: 2;
}

.toast {
  position: fixed;
  z-index: 50;
  right: 24px;
  bottom: 24px;
  pointer-events: none;
  border: 1px solid rgba(115, 226, 194, 0.35);
  border-radius: 12px;
  padding: 10px 14px;
  color: var(--text);
  background: #10243a;
  box-shadow: 0 12px 40px rgba(0, 0, 0, 0.35);
  font-size: 0.8rem;
  opacity: 0;
  transform: translateY(8px);
  transition:
    opacity 160ms ease,
    transform 160ms ease;
}

.toast.visible {
  opacity: 1;
  transform: translateY(0);
}

@media (max-width: 900px) {
  .topbar-main {
    gap: 10px;
  }

  .overall-card {
    max-width: 300px;
  }

  main {
    padding: 24px 20px 90px;
  }

  .hero {
    padding-top: 24px;
  }
}

@media (max-width: 700px) {
  html {
    scroll-padding-top: 178px;
  }

  .topbar-main {
    flex-wrap: wrap;
    padding: 8px 12px 7px;
  }

  .brand {
    margin-right: auto;
  }

  .overall-card {
    display: grid;
    flex: 1 0 100%;
    grid-template-columns: auto minmax(90px, 1fr) auto;
    align-items: center;
    gap: 9px;
    max-width: none;
    margin-left: 0;
  }

  .overall-card > div:first-child {
    gap: 8px;
  }

  .overall-progress,
  .overall-card small {
    margin-top: 0;
  }

  .phase-navigation {
    padding: 0 12px 8px;
  }

  .phase-link {
    flex-basis: 150px;
  }

  .lesson {
    scroll-margin-top: 175px;
  }

  main {
    padding-inline: 12px;
  }

  .hero {
    padding-inline: 8px;
  }

  .hero h1 {
    font-size: 2.8rem;
  }

  .flow {
    gap: 6px;
  }

  .flow b {
    display: none;
  }

  .lesson {
    border-radius: 18px;
  }

  .lesson-header {
    border-radius: 18px 18px 0 0;
  }

  .lesson-progress-row {
    grid-template-columns: 1fr;
  }

  .task-item {
    padding: 13px;
  }

  pre {
    padding: 16px;
    font-size: 0.72rem;
  }
}

@media (max-width: 440px) {
  .brand-copy {
    min-width: auto;
  }

  .brand-copy small {
    display: none;
  }

  .continue-button {
    padding-inline: 11px;
  }

  .overall-card > div:first-child > span {
    display: none;
  }

  .hero h1 {
    font-size: 2.4rem;
  }
}

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    scroll-behavior: auto !important;
    transition-duration: 0.01ms !important;
  }
}