:root {
  --navy: #172f3c;
  --ink: #203945;
  --muted: #60717b;
  --green: #236252;
  --mint: #bdebd8;
  --line: #dde5e8;
  --paper: #f4f7f8;
  --accent: #d94e28;
}
* {
  box-sizing: border-box;
}
body {
  margin: 0;
  font-family:
    Inter,
    -apple-system,
    BlinkMacSystemFont,
    "Segoe UI",
    sans-serif;
  color: var(--ink);
  background: var(--paper);
  font-size: 16px;
  line-height: 1.55;
}
button,
a,
input {
  -webkit-tap-highlight-color: transparent;
}
button {
  font: inherit;
  cursor: pointer;
}
a {
  color: var(--green);
  text-underline-offset: 4px;
}
button:focus-visible,
a:focus-visible,
input:focus-visible {
  outline: 3px solid #df6a36;
  outline-offset: 4px;
}
button:disabled {
  cursor: not-allowed;
  opacity: 0.5;
}
.skip {
  position: fixed;
  top: -80px;
  z-index: 9;
  background: white;
  padding: 15px;
}
.skip:focus {
  top: 5px;
}
#sidebar {
  position: fixed;
  inset: 0 auto 0 0;
  width: 285px;
  background: var(--navy);
  color: white;
  display: flex;
  flex-direction: column;
  padding: 30px 22px 20px;
  z-index: 5;
}
.brand {
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  color: white;
  text-decoration: none;
  margin: 0 5px 40px;
}
.brand-logo {
  display: block;
  width: 100%;
  max-width: 225px;
  height: auto;
}
.university {
  display: block;
  font-size: 12px;
  letter-spacing: 4px;
  margin: 8px 0 0 2px;
}
.course-label,
.eyebrow {
  font-size: 12px;
  font-weight: 700;
  letter-spacing: 1.8px;
  color: #a8c4c9;
}
#sidebar h2 {
  font-size: 19px;
  margin: 8px 0 0;
}
.sidebar-sub {
  font-size: 14px;
  color: #b5c9d0;
  margin: 5px 0 20px;
}
progress {
  width: 100%;
  height: 5px;
  border: 0;
  border-radius: 8px;
  overflow: hidden;
  accent-color: var(--mint);
  background: #3b515d;
}
progress::-webkit-progress-bar {
  background: #3b515d;
}
progress::-webkit-progress-value {
  background: var(--mint);
}
.progress-label {
  display: flex;
  justify-content: space-between;
  font-size: 13px;
  color: #bdd3d8;
  margin: 6px 0 17px;
}
#lessons {
  overflow: auto;
  margin: 0 -10px;
  padding: 0 10px;
  scrollbar-width: thin;
  scrollbar-color: #57727d transparent;
  flex: 1;
}
.group-label {
  font-size: 11px;
  text-transform: uppercase;
  letter-spacing: 1.7px;
  color: #a1b9c2;
  margin: 24px 0 12px;
}
.lesson-link {
  display: flex;
  align-items: center;
  gap: 11px;
  text-decoration: none;
  color: #dce8ec;
  padding: 11px 9px;
  border-radius: 6px;
  line-height: 1.3;
  margin: 2px 0;
  font-size: 14px;
}
.lesson-link:hover {
  background: #264653;
}
.lesson-link.active {
  background: #d7eee6;
  color: #173d35;
}
.number {
  border: 1px solid #657c86;
  border-radius: 50%;
  height: 25px;
  min-width: 25px;
  display: grid;
  place-items: center;
  font-size: 12px;
}
.active .number {
  background: var(--green);
  color: white;
  border-color: var(--green);
}
.done .number {
  background: #375d52;
  color: var(--mint);
  border-color: #507d6d;
}
.sidebar-foot {
  border-top: 1px solid #3a515d;
  padding-top: 15px;
  font-size: 12px;
  color: #b9ced4;
  margin-top: 15px;
}
.text-button {
  background: none;
  border: 0;
  color: inherit;
  font-size: 13px;
  text-decoration: underline;
  padding: 5px 0;
}
.workspace {
  margin-left: 285px;
}
.topbar {
  height: 78px;
  border-bottom: 1px solid var(--line);
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 40px;
  background: white;
  font-size: 14px;
  gap: 15px;
}
.topbar > a {
  text-decoration: none;
}
.slash {
  margin: 0 12px;
  color: #a0aeb4;
}
.topbar strong {
  font-weight: 500;
}
main {
  max-width: 1500px;
  margin: auto;
  padding: 36px 40px 22px;
}
.eyebrow {
  color: var(--green);
  margin: 0 0 12px;
}
h1 {
  font-size: clamp(29px, 2.6vw, 42px);
  font-weight: 550;
  line-height: 1.15;
  letter-spacing: -1.4px;
  margin: 0 0 14px;
}
h2,
h3 {
  line-height: 1.25;
}
h2 {
  font-size: 24px;
}
h3 {
  font-size: 19px;
}
.intro {
  color: var(--muted);
  margin: 0;
  max-width: 820px;
}
.lesson-head {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: 24px;
  margin-bottom: 28px;
}
.duration {
  white-space: nowrap;
  font-size: 13px;
  color: var(--green);
  background: #e5efe9;
  border-radius: 30px;
  padding: 8px 13px;
  margin-top: 6px;
}
.tabs {
  display: flex;
  gap: 30px;
  border-bottom: 1px solid var(--line);
  margin-bottom: 25px;
}
.tab {
  background: none;
  border: 0;
  border-bottom: 3px solid transparent;
  padding: 12px 0;
  color: var(--muted);
  font-size: 15px;
}
.tab.active {
  border-color: var(--green);
  color: var(--green);
  font-weight: 650;
}
.walk-layout {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 290px;
  gap: 24px;
  align-items: start;
}
.screen-card {
  border: 1px solid var(--line);
  border-radius: 12px;
  background: white;
  overflow: hidden;
}
.screen-bar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 12px 18px;
  border-bottom: 1px solid var(--line);
  font-size: 12px;
  color: var(--muted);
  gap: 12px;
}
.screen-bar strong {
  font-size: 13px;
  color: var(--ink);
}
.screen-stage {
  padding: 18px;
  background: #eaf0f2;
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 280px;
}
.screenshot {
  position: relative;
  width: 100%;
  max-width: 900px;
  line-height: 0;
}
.screenshot img {
  display: block;
  width: 100%;
  height: auto;
  max-height: 470px;
  object-fit: contain;
}
.screenshot.portrait {
  width: auto;
  max-width: 100%;
}
.screenshot.portrait img {
  width: auto;
  max-width: 100%;
  max-height: 480px;
}
.hotspot {
  position: absolute;
  border: 3px solid #ed602f;
  background: rgba(239, 105, 49, 0.13);
  border-radius: 7px;
  box-shadow: 0 0 0 4px #fff9;
  min-width: 26px;
  min-height: 26px;
}
.hotspot:hover {
  background: #f07b3340;
}
.hotspot span {
  position: absolute;
  top: -14px;
  left: -13px;
  border-radius: 50%;
  background: #c34620;
  color: white;
  width: 26px;
  height: 26px;
  display: grid;
  place-items: center;
  font-weight: 700;
  font-size: 13px;
  line-height: 1;
}
.caption {
  padding: 10px 18px;
  margin: 0;
  color: var(--muted);
  font-size: 12px;
  border-top: 1px solid var(--line);
}
.caption a {
  color: inherit;
}
.coach {
  background: white;
  border: 1px solid var(--line);
  border-radius: 12px;
  padding: 23px;
}
.step-count {
  color: var(--green);
  font-size: 12px;
  letter-spacing: 1.2px;
  font-weight: 700;
}
.coach h2 {
  font-size: 23px;
  margin: 13px 0;
}
.coach p {
  font-size: 15px;
  color: var(--muted);
}
.hint {
  background: #f0f5f2;
  border-left: 3px solid #79a993;
  padding: 12px 14px;
  font-size: 14px;
  margin-top: 20px;
}
.hint strong {
  display: block;
  color: var(--green);
  margin-bottom: 3px;
}
.primary,
.secondary {
  border-radius: 7px;
  padding: 11px 19px;
  font-weight: 600;
  font-size: 14px;
}
.primary {
  border: 1px solid var(--green);
  background: var(--green);
  color: white;
}
.primary:hover {
  background: #164b3d;
}
.secondary {
  border: 1px solid #c7d4d8;
  color: var(--ink);
  background: white;
}
.secondary:hover {
  background: #f0f5f6;
}
.coach .primary {
  width: 100%;
  margin-top: 18px;
}
.step-nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-top: 18px;
  gap: 16px;
}
.dots {
  display: flex;
  gap: 7px;
}
.dot {
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background: #d5e1e5;
  border: 0;
  padding: 0;
}
.dot.active {
  background: var(--green);
}
.dot.checked {
  background: #75a892;
}
.below {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 24px;
  margin-top: 26px;
}
.note {
  padding: 20px 22px;
  border-top: 1px solid #cddade;
}
.note h3 {
  font-size: 15px;
  margin: 0 0 9px;
}
.note p {
  font-size: 14px;
  color: var(--muted);
  margin: 0;
}
.lesson-footer {
  border-top: 1px solid var(--line);
  margin-top: 26px;
  padding-top: 20px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
}
.lesson-footer p {
  font-size: 13px;
  color: var(--muted);
  margin: 0;
}
.page-foot {
  max-width: 1500px;
  padding: 18px 40px 25px;
  margin: auto;
  font-size: 12px;
  color: var(--muted);
  display: flex;
  justify-content: space-between;
  gap: 20px;
}
.mobile-menu {
  display: none;
}
.video-wrap {
  aspect-ratio: 16/9;
  background: var(--navy);
  border-radius: 10px;
  overflow: hidden;
  display: grid;
  place-items: center;
  max-width: 950px;
  color: white;
  text-align: center;
  padding: 25px;
}
.video-wrap iframe {
  width: 100%;
  height: 100%;
  border: 0;
}
.video-wrap.playing {
  padding: 0;
}
.video-wrap h2 {
  color: white;
}
.video-meta {
  display: flex;
  gap: 20px;
  align-items: center;
  margin-top: 20px;
  font-size: 14px;
}
.howto {
  background: white;
  border: 1px solid var(--line);
  padding: 26px;
  border-radius: 12px;
  max-width: 950px;
}
.howto li {
  padding: 9px 0 9px 8px;
  color: var(--muted);
}
.howto strong {
  color: var(--ink);
}
.howto h2 {
  margin-top: 0;
}
.question {
  border: 0;
  padding: 0;
  margin: 25px 0;
}
.question legend {
  font-size: 23px;
  font-weight: 600;
  margin-bottom: 20px;
}
.option {
  display: flex;
  gap: 13px;
  border: 1px solid var(--line);
  border-radius: 7px;
  padding: 16px;
  margin: 11px 0;
  cursor: pointer;
}
.option:has(input:checked) {
  background: #ecf6f1;
  border-color: var(--green);
}
.option input {
  accent-color: var(--green);
  width: 18px;
}
.feedback {
  padding: 15px;
  border-radius: 7px;
  background: #e5f2eb;
  margin-top: 18px;
}
.feedback.error {
  background: #fff0e6;
}
.complete {
  padding: 35px;
  background: #e2f1e9;
  border: 1px solid #b5d4c4;
  border-radius: 12px;
  max-width: 900px;
}
.complete h2 {
  font-size: 31px;
}
.complete .primary {
  margin-top: 16px;
}
.actions {
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
}
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
}
dialog {
  border: 1px solid var(--line);
  border-radius: 12px;
  padding: 25px;
  max-width: min(95vw, 1500px);
  max-height: 95vh;
  color: var(--ink);
}
dialog::backdrop {
  background: #0e263bba;
}
#zoom img {
  display: block;
  max-width: 100%;
  max-height: 80vh;
  object-fit: contain;
  margin-top: 15px;
}
#reset-dialog {
  max-width: 460px;
}
.badge {
  display: inline-block;
  background: #e1f1e9;
  color: var(--green);
  font-size: 12px;
  border-radius: 20px;
  padding: 3px 10px;
}
.storage-warning {
  color: #8c3418;
  background: #ffebdf;
  padding: 12px;
  border-radius: 8px;
}
.source-line {
  font-size: 13px;
  color: var(--muted);
  margin-top: 20px;
}
.source-line a {
  color: inherit;
}
@media (min-width: 1500px) {
  .walk-layout {
    grid-template-columns: minmax(0, 1fr) 330px;
  }
  .screen-stage {
    min-height: 400px;
  }
}
@media (max-width: 1150px) {
  #sidebar {
    width: 245px;
    padding: 25px 17px;
  }
  .workspace {
    margin-left: 245px;
  }
  .topbar {
    padding: 0 25px;
  }
  main {
    padding: 28px 25px;
  }
  .walk-layout {
    grid-template-columns: minmax(0, 1fr);
  }
  .coach {
    display: block;
  }
  .coach .primary {
    width: auto;
  }
  .coach p {
    max-width: 850px;
  }
  .screen-stage {
    min-height: 200px;
  }
  .page-foot {
    padding: 20px 25px;
  }
}
@media (max-width: 760px) {
  #sidebar {
    display: none;
    top: 65px;
    width: 290px;
  }
  body.menu-open #sidebar {
    display: flex;
    box-shadow: 10px 0 30px #172f3c40;
  }
  .workspace {
    margin-left: 0;
  }
  .mobile-menu {
    display: block;
  }
  .topbar {
    height: 65px;
    padding: 0 16px;
  }
  .topbar > span {
    display: none;
  }
  .topbar a {
    font-size: 13px;
  }
  main {
    padding: 27px 18px;
  }
  .lesson-head {
    gap: 10px;
  }
  .duration {
    display: none;
  }
  h1 {
    font-size: 30px;
  }
  .tabs {
    gap: 20px;
    overflow: auto;
    white-space: nowrap;
  }
  .tab {
    font-size: 14px;
  }
  .below {
    grid-template-columns: 1fr;
    gap: 0;
  }
  .screen-stage {
    padding: 10px;
    min-height: 100px;
  }
  .screen-bar {
    padding: 10px;
  }
  .screen-bar > span {
    display: none;
  }
  .lesson-footer {
    align-items: flex-start;
  }
  .lesson-footer .primary {
    max-width: 180px;
  }
  .page-foot {
    display: block;
    padding: 20px 18px;
  }
  .page-foot span {
    display: block;
    margin-top: 5px;
  }
  .coach {
    padding: 20px;
  }
  .video-meta {
    align-items: flex-start;
    flex-direction: column;
  }
  .screenshot.portrait img {
    max-height: 420px;
  }
}
@media (prefers-reduced-motion: no-preference) {
  button,
  a {
    transition:
      background 0.15s,
      color 0.15s;
  }
}
.screenshot img {
  max-height: none;
}
.hotspot {
  min-width: 0;
  min-height: 0;
}
main:focus {
  outline: none;
}
@media (max-width: 480px) {
  .tabs {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 0 20px;
    overflow: visible;
  }
  .tab {
    text-align: left;
    padding: 10px 0;
  }
}