:root {
  --learn-green: #58cc02;
  --learn-green-dark: #3c9300;
  --learn-blue: #49a8ff;
  --learn-surface: #181a1f;
  --learn-line: #343741;
  font-family: 'Archivo', Arial, sans-serif;
}

.friendly-ui body {
  background: #0d0e10;
  font-family: 'Archivo', Arial, sans-serif;
  font-weight: 400;
}

.friendly-ui button,
.friendly-ui input,
.friendly-ui textarea,
.friendly-ui select {
  font-family: inherit;
}

.friendly-ui .lesson-title,
.friendly-ui .aside-card h3,
.friendly-ui .level-celebration strong {
  font-family: 'Archivo', Arial, sans-serif;
  font-weight: 800;
  letter-spacing: -.045em;
}

.friendly-ui .sidebar {
  padding: 24px 18px;
  background: #111318;
}

.friendly-ui .sidebar-title {
  margin: 4px 8px 26px;
  font-size: 15px;
  line-height: 1.35;
  letter-spacing: .8px;
}

.friendly-ui .course-label {
  margin: 0 10px 14px;
  color: #d4d5dc;
  font-size: 13px;
  letter-spacing: .7px;
  text-transform: none;
}

.friendly-ui .nav-list {
  gap: 10px;
}

.friendly-ui .nav-level {
  min-height: 68px;
  padding: 11px 12px;
  border: 2px solid transparent;
  border-bottom-width: 4px;
  border-radius: 17px;
  transition: transform .16s ease, border-color .16s ease, background .16s ease;
}

.friendly-ui .nav-level:not(:disabled):hover {
  transform: translateY(-1px);
  background: #1a1d23;
  border-color: #30343c;
}

.friendly-ui .nav-level.active {
  background: #1b2b19;
  border-color: var(--learn-green-dark);
}

.friendly-ui .nav-num {
  width: 36px;
  height: 36px;
  font-weight: 800;
}

.friendly-ui .active .nav-num {
  background: var(--learn-green);
  border-color: var(--learn-green);
  color: #102400;
}

.friendly-ui .nav-text {
  font-size: 15px;
  font-weight: 700;
}

.friendly-ui .nav-text small {
  margin-top: 2px;
  font-size: 12px;
}

.friendly-ui .progress-track {
  height: 9px;
  border-radius: 999px;
}

.friendly-ui .progress-fill {
  background: var(--learn-green);
  border-radius: inherit;
}

.friendly-ui .topbar {
  height: 72px;
  padding: 0 36px;
  background: rgba(13, 14, 16, .92);
  backdrop-filter: blur(12px);
}

.friendly-ui .main {
  max-width: 1040px;
  padding: 28px 42px 38px;
}

.friendly-mission {
  display: flex;
  align-items: center;
  gap: 15px;
  margin-bottom: 25px;
  padding: 17px 18px;
  border: 2px solid #2d6331;
  border-bottom-width: 5px;
  border-radius: 20px;
  background: #162219;
}

.mission-orb {
  display: grid;
  flex: 0 0 48px;
  width: 48px;
  height: 48px;
  place-items: center;
  border-radius: 15px;
  background: #24472a;
  font-size: 25px;
}

.mission-copy {
  display: grid;
  gap: 3px;
  min-width: 0;
}

.mission-copy small {
  color: #9fe0b7;
  font-size: 12px;
  font-weight: 800;
  letter-spacing: 1px;
  text-transform: uppercase;
}

.mission-copy strong {
  color: #f5f7f5;
  font-size: 16px;
  line-height: 1.35;
}

.xp-badge {
  margin-left: auto;
  padding: 7px 10px;
  border: 1px solid #356d3b;
  border-radius: 11px;
  color: #b8f58c;
  font-size: 12px;
  font-weight: 800;
  white-space: nowrap;
}

.friendly-ui .level-meta {
  margin-bottom: 15px;
}

.friendly-ui .lesson-title,
.friendly-ui .focus .lesson-title {
  max-width: 720px;
  font-size: clamp(39px, 4.1vw, 60px);
  line-height: 1.02;
}

.friendly-ui .lead {
  display: none;
}

.friendly-ui .lesson-tabs {
  margin: 24px 0 24px;
}

.friendly-ui .lesson-grid {
  grid-template-columns: minmax(0, 800px);
  justify-content: start;
  gap: 14px;
}

.friendly-ui .lesson-panel {
  padding: 25px 27px;
  border: 2px solid var(--learn-line);
  border-bottom-width: 5px;
  border-radius: 20px;
  background: var(--learn-surface);
}

.friendly-ui .lesson-panel h2 {
  margin: 12px 0 10px;
  font-size: 24px;
}

.friendly-ui .lesson-panel .intro {
  color: #d0d1d7;
  font-size: 16px;
  line-height: 1.6;
}

.intro-summary {
  display: block;
}

.intro-details {
  margin-top: 10px;
}

.intro-details summary,
.example-disclosure > summary {
  width: fit-content;
  color: var(--learn-blue);
  font-size: 14px;
  font-weight: 800;
  cursor: pointer;
}

.intro-full {
  margin-top: 11px;
  padding-left: 14px;
  border-left: 3px solid #3d81b9;
  color: #bfc3cb;
}

.friendly-ui .concept-label {
  margin: 22px 0 12px;
  color: #d6d7dc;
  font-weight: 800;
  letter-spacing: .5px;
  text-transform: none;
}

.friendly-ui .reveal-list {
  gap: 12px;
}

.friendly-ui .reveal {
  border: 2px solid #3a3e48;
  border-bottom-width: 4px;
  border-radius: 16px;
  background: #202228;
}

.friendly-ui .reveal button {
  min-height: 58px;
  padding: 14px 17px;
  font-size: 15px;
  font-weight: 750;
}

.friendly-ui .reveal.open {
  border-color: #527b38;
  background: #1c281c;
}

.friendly-ui .reveal.open:not(.friendly-active) .reveal-body {
  display: none;
}

.friendly-ui .reveal-body {
  padding: 0 17px 17px;
  color: #e0e2e5;
  font-size: 15px;
  line-height: 1.55;
}

.example-disclosure {
  max-width: 800px;
  padding: 4px 2px;
}

.example-disclosure > summary {
  padding: 12px 14px;
  border: 2px solid #3a3e48;
  border-bottom-width: 4px;
  border-radius: 14px;
  color: #f1c75b;
  background: #1b1d22;
  list-style: none;
}

.example-disclosure > summary::-webkit-details-marker {
  display: none;
}

.example-disclosure[open] > summary {
  margin-bottom: 12px;
}

.friendly-ui .aside-card {
  border-radius: 18px;
  background: #1c181a;
}

.friendly-ui .checkpoint {
  margin-top: 24px;
  padding: 22px;
  border: 2px solid #343b49;
  border-bottom-width: 5px;
  border-radius: 18px;
  background: #181c23;
}

.friendly-ui .checkpoint .option,
.friendly-ui .question .option {
  min-height: 56px;
  border: 2px solid #3a3e48;
  border-bottom-width: 4px;
  border-radius: 15px;
  background: #202228;
  font-weight: 650;
}

.friendly-ui .option.correct {
  border-color: var(--learn-green-dark);
  background: #172b17;
}

.friendly-ui .option.incorrect {
  border-color: #b84b55;
  background: #321b20;
}

.friendly-ui .step-footer {
  max-width: 800px;
  margin-top: 22px;
}

.friendly-ui .primary {
  padding: 13px 23px;
  border: 0;
  border-bottom: 5px solid var(--learn-green-dark);
  border-radius: 15px;
  background: var(--learn-green);
  color: #122600;
  font-weight: 850;
}

.friendly-ui .primary:hover:not(:disabled) {
  background: #65df08;
}

.friendly-ui .primary:active:not(:disabled) {
  transform: translateY(2px);
  border-bottom-width: 3px;
}

.friendly-ui .secondary,
.friendly-ui .icon-btn {
  border: 2px solid #3a3e48;
  border-bottom-width: 4px;
  border-radius: 13px;
}

.friendly-ui .bottom-caption {
  display: none;
}

@media (max-width: 760px) {
  .friendly-ui .main {
    padding: 20px 16px 30px;
  }

  .friendly-mission {
    align-items: flex-start;
    padding: 14px;
  }

  .mission-orb {
    flex-basis: 42px;
    width: 42px;
    height: 42px;
  }

  .xp-badge {
    display: none;
  }

  .friendly-ui .lesson-title,
  .friendly-ui .focus .lesson-title {
    font-size: 42px;
  }

  .friendly-ui .lesson-panel {
    padding: 21px 18px;
  }
}

/* Calm motion system: levitating icons, slow module light, and staged session entry. */
@keyframes icon-levitate {
  0%, 100% { transform: translate3d(0, 0, 0) rotate(-1deg); }
  50% { transform: translate3d(0, -5px, 0) rotate(1deg); }
}

@keyframes module-light-drift {
  0%, 100% { background-position: 0% 50%; }
  50% { background-position: 100% 50%; }
}

@keyframes session-rise {
  from { opacity: 0; transform: translate3d(0, 18px, 0) scale(.992); }
  to { opacity: 1; transform: translate3d(0, 0, 0) scale(1); }
}

@keyframes title-reveal {
  from { opacity: 0; transform: translate3d(0, 22px, 0); letter-spacing: -.065em; }
  to { opacity: 1; transform: translate3d(0, 0, 0); letter-spacing: -.045em; }
}

.friendly-ui .mission-orb,
.friendly-ui .main .topic-icon,
.friendly-ui .complete-icon {
  animation: icon-levitate 5.8s ease-in-out infinite;
  will-change: transform;
}

.friendly-ui .main .reveal:nth-child(2n) .topic-icon {
  animation-delay: -1.9s;
}

.friendly-ui .main .reveal:nth-child(3n) .topic-icon {
  animation-delay: -3.7s;
}

.friendly-ui .reveal,
.friendly-ui .checkpoint .option,
.friendly-ui .question .option,
.friendly-ui .example-disclosure > summary {
  background-image: linear-gradient(115deg, #202228 0%, #272a31 38%, #202228 72%, #25272d 100%);
  background-size: 240% 240%;
  animation: module-light-drift 18s ease-in-out infinite;
}

.friendly-ui .reveal.open {
  background-image: linear-gradient(115deg, #1b231d 0%, #242a27 40%, #1c211e 74%, #25282a 100%);
}

.friendly-ui .reveal:nth-child(2n),
.friendly-ui .question .option:nth-child(2n) {
  animation-delay: -6s;
}

.friendly-ui .reveal:nth-child(3n),
.friendly-ui .question .option:nth-child(3n) {
  animation-delay: -12s;
}

.friendly-ui .nav-level.active .nav-num {
  border-color: var(--red);
  background: var(--red);
  color: #fff;
  box-shadow: 0 0 0 5px rgba(10, 11, 13, .95), 0 0 18px rgba(255, 52, 59, .28);
}

.friendly-ui .nav-level.done .nav-num {
  border-color: #a62e34;
  background: #35171a;
  color: #ff6f74;
}

.friendly-ui .nav-level.done.active .nav-num {
  border-color: var(--red);
  background: var(--red);
  color: #fff;
}

.friendly-ui .sidebar {
  height: 100px;
  padding-top: 21px;
  border-top: 0;
  background: linear-gradient(to top, rgba(7, 8, 10, .98) 0%, rgba(8, 9, 11, .88) 66%, rgba(8, 9, 11, 0) 100%);
  backdrop-filter: none;
}

.friendly-ui .nav-list::before {
  background: linear-gradient(90deg, rgba(255, 52, 59, .18), #3b3d44 24%, #3b3d44 76%, rgba(255, 52, 59, .18));
}

.friendly-ui.session-transition .friendly-mission {
  animation: session-rise .62s cubic-bezier(.2, .72, .22, 1) both;
}

.friendly-ui.session-transition .level-meta {
  animation: session-rise .62s .07s cubic-bezier(.2, .72, .22, 1) both;
}

.friendly-ui.session-transition .lesson-title {
  animation: title-reveal .72s .13s cubic-bezier(.18, .74, .2, 1) both;
}

.friendly-ui.session-transition .lesson-tabs {
  animation: session-rise .62s .21s cubic-bezier(.2, .72, .22, 1) both;
}

.friendly-ui.session-transition .lesson-grid,
.friendly-ui.session-transition .quiz,
.friendly-ui.session-transition .complete {
  animation: session-rise .68s .29s cubic-bezier(.2, .72, .22, 1) both;
}

.friendly-ui.session-transition .step-footer {
  animation: session-rise .62s .38s cubic-bezier(.2, .72, .22, 1) both;
}

.friendly-ui.session-transition .mission-copy small {
  animation: session-rise .5s .13s ease-out both;
}

.friendly-ui.session-transition .mission-copy strong,
.friendly-ui.session-transition .lesson-panel h2,
.friendly-ui.session-transition .lesson-panel .intro {
  animation: session-rise .58s .25s ease-out both;
}

.friendly-ui .reveal-body {
  animation: session-rise .42s cubic-bezier(.2, .72, .22, 1) both;
}

@media (max-width: 760px) {
  .friendly-ui .sidebar {
    height: 92px;
    padding-top: 17px;
  }
}

@media (prefers-reduced-motion: reduce) {
  .friendly-ui .mission-orb,
  .friendly-ui .main .topic-icon,
  .friendly-ui .complete-icon,
  .friendly-ui .reveal,
  .friendly-ui .checkpoint .option,
  .friendly-ui .question .option,
  .friendly-ui .example-disclosure > summary,
  .friendly-ui.session-transition .friendly-mission,
  .friendly-ui.session-transition .level-meta,
  .friendly-ui.session-transition .lesson-title,
  .friendly-ui.session-transition .lesson-tabs,
  .friendly-ui.session-transition .lesson-grid,
  .friendly-ui.session-transition .quiz,
  .friendly-ui.session-transition .complete,
  .friendly-ui.session-transition .step-footer,
  .friendly-ui.session-transition .mission-copy small,
  .friendly-ui.session-transition .mission-copy strong,
  .friendly-ui.session-transition .lesson-panel h2,
  .friendly-ui.session-transition .lesson-panel .intro,
  .friendly-ui .reveal-body {
    animation: none !important;
  }
}

@media (prefers-reduced-motion: reduce) {
  .friendly-ui .nav-level,
  .friendly-ui .primary {
    transition: none;
  }
}

/* Immersive single-window lesson with a quiet connector path in the footer. */
.friendly-ui body {
  min-height: 100vh;
  min-height: 100dvh;
  background:
    linear-gradient(135deg, #050506 0%, #121316 48%, #292b2f 100%) fixed;
}

.friendly-ui body::before {
  content: '';
  position: fixed;
  inset: 0;
  z-index: 0;
  pointer-events: none;
  opacity: .055;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='180' height='180' viewBox='0 0 180 180'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='.8' numOctaves='3' stitchTiles='stitch'/%3E%3CfeColorMatrix type='saturate' values='0'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23n)' opacity='.7'/%3E%3C/svg%3E");
  mix-blend-mode: soft-light;
}

.friendly-ui .shell {
  position: relative;
  z-index: 1;
  margin-left: 0;
  min-height: 100vh;
  min-height: 100dvh;
  background: transparent;
}

.friendly-ui .topbar {
  height: 64px;
  border-bottom-color: rgba(255, 255, 255, .08);
  background: rgba(8, 9, 11, .58);
}

.friendly-ui .mobile-menu,
.friendly-ui [data-source],
.friendly-ui #source {
  display: none !important;
}

.friendly-ui .main {
  width: min(100%, 1120px);
  min-height: calc(100vh - 64px);
  min-height: calc(100dvh - 64px);
  margin: 0 auto;
  padding: 34px 48px 128px;
}

.friendly-ui .friendly-mission,
.friendly-ui .level-meta,
.friendly-ui .lesson-title,
.friendly-ui .lesson-tabs,
.friendly-ui .lesson-grid,
.friendly-ui .step-footer,
.friendly-ui .quiz,
.friendly-ui .complete {
  margin-right: auto;
  margin-left: auto;
}

.friendly-ui .friendly-mission,
.friendly-ui .level-meta,
.friendly-ui .lesson-title,
.friendly-ui .lesson-tabs,
.friendly-ui .lesson-grid,
.friendly-ui .step-footer {
  width: min(100%, 860px);
}

.friendly-ui .quiz,
.friendly-ui .complete {
  width: min(100%, 780px);
}

.friendly-ui .lesson-title {
  max-width: 860px;
}

.friendly-ui .sidebar {
  inset: auto 0 0 0;
  z-index: 30;
  display: block;
  width: 100%;
  height: 88px;
  padding: 9px 22px 7px;
  overflow-x: auto;
  overflow-y: hidden;
  border-top: 1px solid rgba(255, 255, 255, .1);
  border-right: 0;
  background: rgba(10, 11, 13, .9);
  backdrop-filter: blur(18px);
  transform: none;
}

.friendly-ui .sidebar-title,
.friendly-ui .course-label,
.friendly-ui .sidebar-bottom {
  display: none;
}

.friendly-ui .nav-list {
  position: relative;
  display: grid;
  grid-template-columns: repeat(8, minmax(82px, 1fr));
  gap: 2px;
  width: min(100%, 920px);
  min-width: 720px;
  margin: 0 auto;
}

.friendly-ui .nav-list::before {
  content: '';
  position: absolute;
  top: 15px;
  right: 5%;
  left: 5%;
  z-index: 0;
  height: 2px;
  background: #353840;
}

.friendly-ui .nav-level,
.friendly-ui .nav-level:hover,
.friendly-ui .nav-level.active {
  position: relative;
  z-index: 1;
  display: flex;
  flex-direction: column;
  gap: 4px;
  min-height: 68px;
  padding: 0 4px;
  border: 0;
  background: transparent;
  transform: none;
}

.friendly-ui .nav-num {
  width: 30px;
  height: 30px;
  border: 2px solid #4a4e57;
  background: #15171b;
  box-shadow: 0 0 0 5px rgba(10, 11, 13, .95);
  font-size: 10px;
}

.friendly-ui .active .nav-num {
  border-color: var(--learn-green);
  background: var(--learn-green);
  box-shadow: 0 0 0 5px rgba(10, 11, 13, .95), 0 0 18px rgba(88, 204, 2, .22);
}

.friendly-ui .nav-text {
  max-width: 92px;
  color: #a9abb3;
  font-size: 10px;
  font-weight: 650;
  line-height: 1.15;
  text-align: center;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.friendly-ui .nav-level.active .nav-text {
  color: #e8e9ec;
}

.friendly-ui .nav-text .topic-icon {
  margin-right: 3px;
}

.friendly-ui .nav-text small,
.friendly-ui .lock {
  display: none;
}

@media (max-width: 760px) {
  .friendly-ui .topbar {
    height: 58px;
  }

  .friendly-ui .main {
    min-height: calc(100dvh - 58px);
    padding: 22px 16px 112px;
  }

  .friendly-ui .sidebar {
    height: 80px;
    padding: 7px 10px 5px;
  }

  .friendly-ui .nav-list {
    min-width: 650px;
  }

  .friendly-ui .nav-level {
    min-height: 62px;
  }

  .friendly-ui .nav-text {
    font-size: 9px;
  }
}