:root {
  --bg: #e9ece7;
  --panel: #f4f4f4;
  --card: #ffffff;
  --ink: #181818;
  --muted: #4c4c4c;
  --line: #1e1e1e;
  --green: #62d52c;
  --green-dark: #49b421;
  --danger: #ff5d5d;
  --gold: #f7d44c;
  --purple: #bd7cff;
  --blue: #4bb8ff;
  --shadow: 0 4px 0 #1d1d1d;
}

* {
  box-sizing: border-box;
}

html, body {
  margin: 0;
  width: 100%;
  height: 100%;
  background: #25324a;
  font-family: "JetBrains Mono", monospace;
  color: var(--ink);
  overflow: hidden;
}

body {
  min-height: 100vh;
  padding: 0;
}

button {
  font: inherit;
}

.browser-window {
  max-height: none;
  background: rgba(255,255,255,0.14);
  border: 2px solid rgba(35, 35, 35, 0.18);
  border-radius: 14px 14px 10px 10px;
  overflow: hidden;
  box-shadow: 0 10px 26px rgba(0, 0, 0, 0.08);
}

.desktop {
  position: relative;
  width: 100vw;
  height: 100vh;
  overflow: hidden;
  background:
    radial-gradient(circle at 72% 12%, rgba(111, 185, 255, 0.28), transparent 34%),
    radial-gradient(circle at 18% 86%, rgba(111, 91, 205, 0.22), transparent 32%),
    linear-gradient(145deg, #18243c 0%, #2d4166 46%, #1e2945 100%);
  top: 0;
  left: 0;
}

.desktop::after {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  background: linear-gradient(120deg, transparent 0 42%, rgba(255,255,255,0.04) 50%, transparent 58%);
  opacity: 0.7;
}

.mac-menu-bar {
  position: absolute;
  z-index: 4;
  top: 0;
  right: 0;
  left: 0;
  display: flex;
  align-items: center;
  gap: 18px;
  height: 30px;
  padding: 0 16px;
  background: rgba(15, 22, 37, 0.76);
  border-bottom: 1px solid rgba(255,255,255,0.16);
  color: #f5f8ff;
  font-size: 11px;
  letter-spacing: 0.01em;
  backdrop-filter: blur(16px);
}

.mac-menu-logo {
  color: #fff;
  font-size: 13px;
}

.mac-menu-spacer {
  flex: 1;
}

.desktop-icons {
  position: absolute;
  z-index: 1;
  top: 48px;
  left: 22px;
  display: grid;
  align-content: start;
  gap: 12px;
  width: 92px;
}

.desktop:has(.browser-window.is-fullscreen:not(.is-closed)) .desktop-icons {
  display: none;
}

.desktop-icon {
  display: grid;
  justify-items: center;
  gap: 5px;
  padding: 6px 4px;
  border: 1px solid transparent;
  background: transparent;
  color: #f8fbff;
  font-size: 10px;
  line-height: 1.2;
  text-shadow: 0 1px 2px rgba(0,0,0,0.5);
  cursor: pointer;
}

.desktop-icon:hover,
.desktop-icon:focus-visible {
  border-color: rgba(255,255,255,0.5);
  background: rgba(255,255,255,0.12);
}

.desktop-icon-art {
  display: grid;
  place-items: center;
  width: 44px;
  height: 38px;
  border: 2px solid #202b42;
  border-radius: 7px;
  background: #65d538;
  color: #162019;
  font-size: 25px;
  font-weight: 900;
  box-shadow: 0 3px 0 rgba(0,0,0,0.32);
}

.folder-art {
  background: #f7d44c;
}

.quiz-art {
  background: #bd7cff;
  color: #20122f;
}

.window-stage {
  position: relative;
  z-index: 2;
  display: grid;
  place-items: center;
  width: 100%;
  height: calc(100% - 30px);
  padding: 54px 28px 76px 120px;
  pointer-events: none;
}

.window-stage .browser-window {
  pointer-events: auto;
}

.taskbar {
  position: absolute;
  z-index: 3;
  right: 50%;
  bottom: 0;
  left: auto;
  display: flex;
  align-items: center;
  height: 52px;
  gap: 10px;
  padding: 7px 12px;
  border: 1px solid rgba(255,255,255,0.22);
  border-bottom: 0;
  border-radius: 18px 18px 0 0;
  background: rgba(14, 21, 37, 0.68);
  color: #edf4ff;
  transform: translateX(50%);
  box-shadow: 0 0 24px rgba(0,0,0,0.28);
  backdrop-filter: blur(18px);
}

.launcher-button,
.taskbar-app {
  height: 36px;
  border: 1px solid rgba(255,255,255,0.25);
  border-radius: 7px;
  color: #edf4ff;
  cursor: pointer;
}

.launcher-button {
  width: 38px;
  background: #65d538;
  color: #172217;
  font-weight: 900;
}

.taskbar-divider {
  width: 1px;
  height: 26px;
  background: rgba(255,255,255,0.2);
}

.taskbar-app {
  display: flex;
  align-items: center;
  gap: 9px;
  padding: 0 14px;
  background: rgba(255,255,255,0.1);
  font-size: 11px;
  font-weight: 700;
}

.taskbar-app.is-active {
  border-bottom: 3px solid #65d538;
}

.taskbar-app-icon {
  color: #65d538;
  font-size: 18px;
}

.taskbar-status {
  display: flex;
  align-items: center;
  gap: 18px;
  margin-left: auto;
  color: #b9c8dc;
  font-size: 10px;
  font-weight: 700;
}

.status-time {
  color: #f7d44c;
}

.android-nav {
  display: none;
}

.browser-window {
  position: relative;
  width: min(1120px, calc(100vw - 220px));
  height: calc(100vh - 144px);
  max-height: none;
  background: rgba(255,255,255,0.14);
  border: 2px solid rgba(35, 35, 35, 0.18);
  border-radius: 14px 14px 10px 10px;
  overflow: hidden;
  box-shadow: 0 10px 26px rgba(0, 0, 0, 0.08);
  resize: both;
  min-width: 620px;
  min-height: 440px;
}

.browser-topbar {
  display: grid;
  grid-template-columns: 1fr minmax(260px, 1.5fr) 1fr;
  align-items: center;
  height: 46px;
  background: #efefef;
  border-bottom: 2px solid rgba(0,0,0,0.22);
  padding: 0 12px;
}

.browser-left,
.browser-right {
  display: flex;
  align-items: center;
  gap: 10px;
}

.browser-right {
  justify-content: flex-end;
}

.window-controls {
  display: flex;
  align-items: center;
  gap: 3px;
  margin-left: 8px;
  padding-left: 8px;
  border-left: 1px solid rgba(0,0,0,0.18);
}

.window-control {
  display: grid;
  place-items: center;
  width: 24px;
  height: 24px;
  padding: 0;
  border: 0;
  border-radius: 5px;
  background: transparent;
  color: #222;
  font-size: 17px;
  line-height: 1;
  cursor: pointer;
}

.window-control:hover,
.window-control:focus-visible {
  background: rgba(0,0,0,0.1);
}

.window-control.close-control:hover,
.window-control.close-control:focus-visible {
  background: #ff6157;
  color: #fff;
}

.browser-window.is-dragging {
  user-select: none;
  cursor: grabbing;
}

.browser-window.is-minimized {
  height: 46px !important;
  min-height: 46px;
  resize: none;
}

.browser-window.is-minimized .lesson-shell {
  display: none;
}

.browser-window.is-closed {
  display: none;
}

.browser-window.is-fullscreen {
  position: fixed;
  z-index: 10;
  inset: 30px 0 52px;
  width: auto !important;
  height: auto !important;
  min-width: 0;
  min-height: 0;
  border-radius: 0;
  resize: none;
}

.browser-window.is-fullscreen .left-copy li {
  font-size: clamp(1.18rem, 1.8vw, 1.5rem);
  line-height: 1.16;
}

.browser-window.is-fullscreen .left-copy ul {
  gap: 12px;
}

.browser-window.is-fullscreen .photo-card {
  height: min(100%, 390px);
}

.nav-icon,
.toolbar-btn {
  width: 28px;
  height: 28px;
  background: transparent;
  border: 0;
  border-radius: 8px;
  color: #222;
  font-weight: 700;
  cursor: pointer;
}

.dot-group {
  display: flex;
  align-items: center;
  gap: 8px;
  margin-left: 6px;
}

.dot {
  width: 12px;
  height: 12px;
  padding: 0;
  border-radius: 50%;
  display: inline-block;
  border: 1px solid rgba(0,0,0,0.3);
  cursor: pointer;
}

.dot.red { background: #ff6157; }
.dot.yellow { background: #ffc12f; }
.dot.green { background: #28ca42; }

.dot:hover,
.dot:focus-visible {
  filter: brightness(0.88);
  outline: 2px solid rgba(0,0,0,0.24);
  outline-offset: 2px;
}

.browser-center {
  display: flex;
  justify-content: center;
}

.address-bar {
  width: min(100%, 540px);
  height: 30px;
  background: #f9f9f9;
  border: 1.5px solid rgba(0,0,0,0.15);
  border-radius: 999px;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  font-size: 12px;
  color: #333;
}

.address-lock {
  font-size: 11px;
}

.address-text {
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.mobile-app-title {
  display: none;
}

.lesson-shell {
  height: calc(100% - 46px);
  display: flex;
  flex-direction: column;
  background: var(--bg);
  padding: 8px 14px 10px;
  overflow: hidden;
}

.app-home {
  display: none;
  flex: 1;
  flex-direction: column;
  justify-content: center;
  padding: 28px clamp(18px, 5vw, 72px);
  background: linear-gradient(135deg, #f8fbf5 0%, #e7f2df 100%);
  border: 3px solid var(--line);
  border-radius: 18px;
  box-shadow: var(--shadow);
}

.lesson-shell.is-home .app-home { display: flex; }
.lesson-shell.is-home .progress-row,
.lesson-shell.is-home #slidesContainer,
.lesson-shell.is-home .bottom-actions { display: none; }

.app-home-kicker {
  font-size: 0.75rem;
  font-weight: 900;
  letter-spacing: 0.14em;
}

.app-home h1 {
  max-width: 620px;
  margin: 10px 0 6px;
  font-size: clamp(2.2rem, 5vw, 4.8rem);
  line-height: 0.98;
  letter-spacing: -0.08em;
}

.app-home > p {
  margin: 0 0 26px;
  font-size: clamp(1rem, 1.5vw, 1.35rem);
  font-weight: 700;
}

.feature-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 14px;
  max-width: 980px;
}

.quiz-summary {
  max-width: 980px;
  margin-top: 18px;
  padding: 12px 16px;
  border: 3px solid var(--line);
  border-radius: 12px;
  background: #fff7d6;
  box-shadow: var(--shadow);
  font-size: 0.95rem;
  font-weight: 900;
}

.unit-picker {
  max-width: 980px;
  margin-top: 18px;
  padding: 14px 18px;
  border: 3px solid var(--line);
  border-radius: 14px;
  background: #fff;
  box-shadow: var(--shadow);
}

.unit-picker > span {
  display: block;
  margin-bottom: 10px;
  font-size: 0.76rem;
  font-weight: 900;
  letter-spacing: 0.12em;
  text-transform: uppercase;
}

.unit-picker-buttons {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}

.unit-option {
  min-width: 110px;
  padding: 10px 14px;
  border: 3px solid var(--line);
  border-radius: 12px;
  background: #f2f4ee;
  color: var(--ink);
  font: inherit;
  font-weight: 900;
  cursor: pointer;
}

.unit-option.is-selected {
  background: var(--green);
}

.feature-card {
  display: grid;
  justify-items: start;
  gap: 8px;
  min-height: 150px;
  padding: 18px;
  border: 3px solid var(--line);
  border-radius: 14px;
  background: #fff;
  color: var(--ink);
  text-align: left;
  box-shadow: var(--shadow);
  cursor: pointer;
}

.feature-card-primary { background: var(--green); }
.feature-card:active { transform: translateY(3px); box-shadow: 0 1px 0 #1d1d1d; }

.feature-icon {
  display: grid;
  place-items: center;
  width: 36px;
  height: 36px;
  border: 2px solid var(--line);
  border-radius: 10px;
  background: #fff;
  font-weight: 900;
}

.feature-card strong { font-size: 1.05rem; }
.feature-card small { font-size: 0.78rem; line-height: 1.35; font-weight: 700; }

#slidesContainer {
  flex: 1;
  min-height: 0;
  overflow: hidden;
  display: flex;
}

.progress-row {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 0 8px 12px;
}

.progress-track {
  flex: 1;
  height: 16px;
  background: #dfe2dd;
  border: 2px solid var(--line);
  border-radius: 999px;
  overflow: hidden;
}

.progress-fill {
  width: 12%;
  height: 100%;
  background: linear-gradient(90deg, #7ce234 0%, #57c91b 100%);
  border-radius: inherit;
}

.score-pill {
  min-width: 92px;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  padding: 8px 14px;
  background: #fff;
  border: 2px solid var(--line);
  border-bottom-width: 4px;
  border-radius: 14px;
  font-weight: 800;
  font-size: 14px;
}

.slide {
  display: none;
  width: 100%;
  height: 100%;
  animation: slide-in 0.36s ease both;
}

.slide.is-active {
  display: flex;
  flex-direction: column;
  justify-content: flex-start;
  gap: 10px;
}

.slide.is-forward {
  animation-name: slide-in-forward;
}

.slide.is-back {
  animation-name: slide-in-back;
}

@keyframes slide-in-forward {
  from { opacity: 0; transform: translateX(34px); }
  to { opacity: 1; transform: translateX(0); }
}

@keyframes slide-in-back {
  from { opacity: 0; transform: translateX(-34px); }
  to { opacity: 1; transform: translateX(0); }
}

.headline-panel {
  background: #f6f4f3;
  border: 3px solid var(--line);
  border-radius: 18px;
  min-height: 78px;
  display: flex;
  align-items: center;
  padding: 10px 16px;
  box-shadow: 0 4px 0 #1c1c1c;
}

.icon-box {
  width: 146px;
  height: 146px;
  border: 3px solid var(--line);
  border-radius: 18px;
  background: #f5d5b9;
  display: grid;
  place-items: center;
  box-shadow: 0 4px 0 #1d1d1d;
}

.icon-box svg {
  width: 82%;
  height: 82%;
}

.icon-box-blue {
  background: #c9efff;
}

.headline-copy {
  min-width: 0;
  width: 100%;
}

.unit-tag {
  display: inline-block;
  margin-bottom: 8px;
  font-size: 12px;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: #1e1e1e;
  font-weight: 900;
}

.headline-copy h1 {
  margin: 0;
  font-size: clamp(1.55rem, 2.3vw, 2.5rem) !important;
  line-height: 1.04;
  letter-spacing: -0.08em;
  font-weight: 900;
}

.headline-copy p {
  margin: 8px 0 0;
  max-width: 1000px;
  font-size: clamp(1rem, 1.25vw, 1.3rem) !important;
  line-height: 1.3;
  font-weight: 700;
  color: var(--muted);
}

.content-panel {
  margin-top: 0;
  background: rgba(255,255,255,0.1);
  border: 3px solid var(--line);
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 0;
  padding: 0;
  border-radius: 18px;
  box-shadow: 0 4px 0 #1d1d1d;
  flex: 1;
  min-height: 0;
}

.left-copy {
  min-width: 0;
  height: 100%;
  box-sizing: border-box;
  padding: 8px 12px;
  display: flex;
  flex-direction: column;
  min-height: 0;
}

.left-copy h2 {
  margin: 0 0 12px;
  font-size: clamp(1.8rem, 2.6vw, 2.6rem) !important;
  letter-spacing: -0.07em;
  font-weight: 900;
}

.left-copy ul {
  margin: 0;
  padding-left: 22px;
  list-style: disc;
  display: flex;
  flex-direction: column;
  flex: 1;
  justify-content: flex-start;
  gap: 12px;
}

.left-copy li {
  font-size: clamp(1.25rem, 1.8vw, 1.6rem) !important;
  line-height: 1.15;
  font-weight: 700;
  color: var(--ink);
  overflow-wrap: anywhere;
  word-break: break-word;
}

.slide.is-dense .left-copy ul {
  gap: 6px;
}

.slide.is-dense .left-copy li {
  font-size: clamp(1.08rem, 1.7vw, 1.45rem);
  line-height: 1.16;
}

.slide.is-very-dense .left-copy ul {
  gap: 4px;
}

.slide.is-very-dense .left-copy li {
  font-size: clamp(0.96rem, 1.45vw, 1.25rem);
  line-height: 1.12;
}

.right-art {
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 100%;
  background: transparent;
  border-left: 3px solid var(--line);
  border-radius: 0;
  overflow: visible;
  padding: 8px 0 8px 0;
}

.photo-card {
  width: min(100%, 360px);
  height: min(100%, 420px);
  border: none;
  border-radius: 0;
  overflow: visible;
  background: transparent;
  box-shadow: none;
  display: flex;
  flex-direction: row;
  align-items: center;
  justify-content: center;
  gap: 12px;
  padding: 0;
  flex-wrap: wrap;
}

.slide-image {
  display: block;
  flex: 1 1 calc(50% - 6px);
  width: calc(50% - 6px);
  height: auto;
  max-height: 220px;
  object-fit: contain;
  object-position: center;
  background: transparent;
}

.art-blue {
  min-height: 260px;
  border: 3px solid var(--line);
  border-radius: 16px;
  background: #e7f7ff;
}

.quiz-panel {
  flex: 1;
  min-height: 0;
  border: 3px solid var(--line);
  border-radius: 18px;
  box-shadow: 0 4px 0 #1d1d1d;
  padding: 20px 32px 16px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: rgba(255,255,255,0.12);
}

.quiz-copy {
  width: min(100%, 820px);
}

.quiz-copy h2 {
  margin: 0 0 12px;
  font-size: clamp(1.8rem, 2.7vw, 2.7rem);
  font-weight: 900;
}

.quiz-question {
  margin: 0 0 18px;
  font-size: clamp(1.1rem, 1.7vw, 1.6rem);
  line-height: 1.3;
  font-weight: 800;
}

.quiz-options {
  display: grid;
  gap: 10px;
}

.quiz-identification-label {
  display: block;
  margin-bottom: 8px;
  font-weight: 800;
}

.quiz-identification {
  display: flex;
  gap: 10px;
  align-items: stretch;
}

.quiz-answer {
  flex: 1;
  min-width: 0;
  min-height: 52px;
  padding: 14px 18px;
  border: 3px solid var(--line);
  border-radius: 12px;
  background: #fff;
  color: var(--ink);
  font: inherit;
  font-size: clamp(1rem, 1.3vw, 1.25rem);
  font-weight: 700;
  text-transform: uppercase;
}

.quiz-submit {
  min-width: 170px;
  padding: 12px 16px;
  border: 3px solid var(--line);
  border-radius: 12px;
  background: var(--green);
  color: var(--ink);
  font: inherit;
  font-weight: 900;
  cursor: pointer;
}

.quiz-submit:disabled {
  cursor: default;
  opacity: 0.7;
}

.quiz-option {
  width: 100%;
  padding: 14px 18px;
  border: 3px solid var(--line);
  border-radius: 12px;
  background: #fff;
  color: var(--ink);
  text-align: left;
  font-size: clamp(0.95rem, 1.2vw, 1.2rem);
  line-height: 1.25;
  font-weight: 700;
  cursor: pointer;
}

.quiz-option.is-correct {
  background: #c9f2b9;
}

.quiz-option.is-incorrect {
  background: #ffd1d1;
}

.quiz-option:disabled {
  cursor: default;
}

.quiz-feedback {
  min-height: 1.4em;
  margin: 14px 0 0;
  font-weight: 800;
}

.quiz-answer-reveal {
  display: none;
  margin: 12px 0 0;
  padding: 12px 14px;
  border: 2px solid var(--line);
  border-radius: 10px;
  background: #fff;
  line-height: 1.35;
  font-weight: 700;
}

.quiz-answer-reveal.is-visible {
  display: block;
}

.quiz-answer-reveal.is-correct {
  background: #c9f2b9;
}

.quiz-answer-reveal.is-incorrect {
  background: #ffd1d1;
}

.movement-figure {
  width: 190px;
  height: 210px;
  position: relative;
}

.figure-head {
  position: absolute;
  top: 8px;
  left: 73px;
  width: 44px;
  height: 44px;
  border: 3px solid var(--line);
  border-radius: 50%;
  background: #fff;
}

.figure-body,
.figure-arm,
.figure-leg {
  position: absolute;
  display: block;
  width: 6px;
  border-radius: 99px;
  background: var(--line);
  transform-origin: top center;
}

.figure-body {
  top: 51px;
  left: 92px;
  height: 82px;
}

.figure-arm {
  top: 64px;
  height: 62px;
}

.figure-arm.left {
  left: 94px;
  transform: rotate(48deg);
}

.figure-arm.right {
  left: 94px;
  transform: rotate(-48deg);
}

.figure-leg {
  top: 125px;
  height: 78px;
}

.figure-leg.left {
  left: 94px;
  transform: rotate(28deg);
}

.figure-leg.right {
  left: 94px;
  transform: rotate(-28deg);
}

.screen-frame {
  width: min(100%, 390px);
  height: 220px;
  border-radius: 18px;
  background: #313131;
  border: 3px solid var(--line);
  box-shadow: 0 4px 0 #1d1d1d;
  padding: 12px 12px 18px;
}

.screen-header {
  display: flex;
  align-items: center;
  gap: 8px;
  height: 36px;
  padding: 0 8px;
  border-radius: 12px 12px 0 0;
  background: #f5f5f5;
  border: 2px solid var(--line);
}

.mini-dot {
  width: 12px;
  height: 12px;
  border-radius: 50%;
  display: inline-block;
  border: 1.5px solid rgba(0,0,0,0.28);
}

.mini-dot.red { background: #ff6157; }
.mini-dot.yellow { background: #ffc12f; }
.mini-dot.green { background: #28ca42; }

.screen-body {
  height: calc(100% - 36px);
  display: grid;
  place-items: center;
}

.sensor-pair {
  width: 190px;
  height: 110px;
  background: rgba(255,255,255,0.08);
  border-radius: 18px;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 28px;
  position: relative;
}

.sensor {
  width: 54px;
  height: 54px;
  border-radius: 50%;
  border: 3px solid var(--line);
  display: inline-block;
}

.sensor.purple { background: #b06af3; }
.sensor.blue { background: #41b7ff; }

.bottom-actions {
  display: flex;
  align-items: center;
  justify-content: flex-end;
  gap: 12px;
  flex-shrink: 0;
  margin-top: 8px;
  padding: 0 6px 0;
}

.actions-divider {
  width: 2px;
  height: 34px;
  background: var(--line);
  margin: 0 2px;
}

.secondary-btn,
.primary-btn {
  min-width: 152px;
  height: 58px;
  border: 3px solid var(--line);
  border-bottom-width: 5px;
  border-radius: 16px;
  font-size: 0.8rem;
  letter-spacing: 0.12em;
  font-weight: 800;
  cursor: pointer;
  transition: transform 0.12s ease;
}

.secondary-btn:disabled {
  color: #9d9d9d;
  background: #e3e3e3;
  cursor: not-allowed;
}

.secondary-btn {
  background: #fff;
  color: var(--ink);
}

.primary-btn {
  background: #65d538;
  color: #0f1d0c;
}

.secondary-btn:active,
.primary-btn:active {
  transform: translateY(3px);
  border-bottom-width: 3px;
}

@media (max-width: 900px) {
  .window-stage {
    padding: 8px 8px 8px 92px;
  }

  .browser-window {
    min-width: 0;
  }

  .headline-panel {
    grid-template-columns: 1fr;
    text-align: left;
  }

  .icon-box {
    width: 110px;
    height: 110px;
  }

  .content-panel {
    grid-template-columns: 1fr;
  }

  .app-home {
    padding: 22px 14px;
    border-radius: 12px;
  }

  .feature-grid { grid-template-columns: 1fr; }

  .feature-card {
    min-height: 86px;
    grid-template-columns: auto 1fr;
    align-items: center;
    column-gap: 10px;
    padding: 12px;
  }

  .feature-card strong,
  .feature-card small { grid-column: 2; }

  .feature-icon { grid-row: span 2; }

  .browser-topbar {
    grid-template-columns: 1fr;
    height: auto;
    gap: 10px;
    padding: 8px 12px;
  }

  .browser-center {
    order: 3;
  }

  .browser-left,
  .browser-right {
    justify-content: space-between;
  }
}

@media (max-width: 900px) {
  html,
  body {
    overflow: hidden;
    background: #111827;
  }

  .desktop {
    top: 0;
    left: 0;
    width: 100%;
    height: 100vh;
    min-height: 100vh;
    background: #111827;
  }



  .desktop-icons {
    display: none;
  }

  .mac-menu-bar {
    display: none;
  }

  .window-stage {
    height: calc(100% - 28px);
    padding: 0;
  }

  .browser-window,
  .browser-window.is-fullscreen {
    width: 100%;
    height: 100%;
    min-width: 0;
    min-height: 0;
    border: 0;
    border-radius: 0;
    resize: none;
  }

  .browser-topbar {
    grid-template-columns: 1fr auto;
    height: 52px;
    padding: 0 12px;
    background: #25324a;
    border-bottom: 0;
  }

  .browser-center {
    display: flex;
    order: 2;
    justify-content: flex-start;
  }

  .browser-right,
  .browser-right > .toolbar-btn,
  .dot-group,
  .window-controls,
  .address-bar {
    display: none;
  }

  .mobile-app-title {
    display: block;
    color: #f4f7fb;
    font-size: 0.85rem;
    font-weight: 800;
    letter-spacing: 0.04em;
  }

  .browser-left {
    gap: 0;
  }

  .nav-icon {
    width: 36px;
    height: 36px;
    color: #f4f7fb;
    font-size: 1.25rem;
  }

  .lesson-shell {
    height: calc(100% - 52px);
    padding: 5px 7px 6px;
    border-radius: 18px 18px 0 0;
  }

  .lesson-shell.is-home {
    overflow-y: auto;
    overscroll-behavior: contain;
  }

  .lesson-shell.is-home .app-home {
    flex: 0 0 auto;
    min-height: 100%;
    justify-content: flex-start;
    padding-top: 18px;
    padding-bottom: 20px;
  }

  .progress-row {
    gap: 5px;
    padding: 0 2px 6px;
  }

  .progress-track {
    min-width: 0;
    height: 11px;
  }

  .score-pill {
    min-width: 0;
    padding: 6px 8px;
    border-radius: 9px;
    font-size: 10px;
  }

  .score-pill.clip-counter {
    min-width: 74px;
  }

  .headline-panel {
    min-height: 74px;
    padding: 8px 10px;
    border-radius: 12px;
  }

  .unit-tag {
    margin-bottom: 4px;
    font-size: 10px;
  }

  .headline-copy h1 {
    font-size: clamp(1.85rem, 6vw, 2.6rem) !important;
    line-height: 1.05;
  }

  .headline-copy p {
    margin-top: 4px;
    font-size: clamp(1.05rem, 4vw, 1.3rem) !important;
    line-height: 1.3;
  }

  .content-panel {
    display: flex;
    flex-direction: column;
    gap: 6px;
    padding: 8px;
    border-radius: 12px;
    overflow-y: auto;
  }

  .left-copy {
    padding: 1px 3px 0;
    height: 100%;
    min-height: 100%;
    flex: 1 0 auto;
    overflow: visible;
  }

  .left-copy h2 {
    margin-bottom: 8px;
    font-size: clamp(2rem, 5.5vw, 2.6rem) !important;
  }

  .left-copy ul,
  .slide.is-dense .left-copy ul,
  .slide.is-very-dense .left-copy ul {
    flex: 1 0 auto;
    justify-content: space-evenly;
    gap: 10px;
  }

  .left-copy li,
  .slide.is-dense .left-copy li,
  .slide.is-very-dense .left-copy li,
  .browser-window.is-fullscreen .left-copy li {
    font-size: clamp(1.1rem, 4.5vw, 1.35rem) !important;
    line-height: 1.3;
  }

  .right-art {
    flex: 0 0 190px;
    min-height: 0;
    border-top: 2px solid var(--line);
    border-left: 0;
    padding: 5px 0 0;
  }

  .photo-card,
  .browser-window.is-fullscreen .photo-card {
    width: min(100%, 280px);
    height: 180px;
  }

  .quiz-panel {
    padding: 20px 16px;
    border-radius: 12px;
    align-items: flex-start;
    overflow-y: auto;
  }

  .quiz-copy {
    width: 100%;
    flex: 0 0 auto;
    margin-block: auto;
  }

  .quiz-copy h2 {
    margin-bottom: 12px;
    font-size: 1.6rem;
  }

  .quiz-question {
    margin-bottom: 20px;
    font-size: clamp(1.15rem, 4.5vw, 1.35rem);
    line-height: 1.4;
  }

  .quiz-options {
    gap: 10px;
  }

  .quiz-option {
    min-height: 56px;
    padding: 12px 14px;
    font-size: clamp(1.05rem, 4vw, 1.2rem);
    line-height: 1.35;
  }

  .quiz-identification {
    flex-direction: column;
    gap: 10px;
  }

  .quiz-answer {
    width: 100%;
    min-height: 56px;
    padding: 12px 14px;
    font-size: 1rem;
  }

  .quiz-submit {
    width: 100%;
    min-height: 54px;
    font-size: 0.95rem;
  }

  .quiz-feedback:empty {
    display: none;
  }

  .quiz-feedback {
    margin-top: 9px;
    font-size: 1rem;
    line-height: 1.35;
  }

  .quiz-answer-reveal {
    font-size: 0.95rem;
    line-height: 1.4;
  }

  .bottom-actions {
    gap: 6px;
    margin-top: 5px;
    padding: 0 2px;
  }

  .actions-divider {
    height: 28px;
  }

  .secondary-btn,
  .primary-btn {
    min-width: 0;
    width: 50%;
    height: 42px;
    border-radius: 11px;
    font-size: 0.78rem;
  }

  .taskbar {
    display: none;
  }

  .android-nav {
    position: absolute;
    z-index: 20;
    right: 0;
    bottom: 0;
    left: 0;
    display: flex;
    align-items: center;
    justify-content: space-around;
    height: 28px;
    background: #05070c;
  }

  .android-nav button {
    width: 33.33%;
    height: 100%;
    padding: 0;
    border: 0;
    background: transparent;
    color: #f4f7fb;
    font-family: Arial, sans-serif;
    font-size: 17px;
    line-height: 1;
  }

  .progress-row {
    padding-top: 2px;
  }

  .launcher-button {
    width: 32px;
    height: 32px;
  }

  .taskbar-app {
    height: 32px;
    padding: 0 9px;
    font-size: 9px;
  }

  .taskbar-status {
    gap: 5px;
    font-size: 8px;
  }

  .status-time {
    display: none;
  }
}