:root {
  --bg: #f6fbff;
  --card: #ffffff;
  --text: #16324a;
  --muted: #5e7487;
  --line: #d9e8f3;
  --primary: #2f80ed;
  --primary-soft: #eaf4ff;
  --green: #31a86c;
  --yellow: #ffe27a;
  --shadow: 0 10px 28px rgba(26, 59, 94, 0.08);
}

* { box-sizing: border-box; }
body {
  margin: 0;
  font-family: "Segoe UI", Arial, sans-serif;
  background: linear-gradient(180deg, #eef7ff 0%, var(--bg) 100%);
  color: var(--text);
}

.hero {
  position: relative;
  overflow: hidden;
  background: linear-gradient(135deg, #2f80ed, #31a86c);
  color: white;
  padding: 48px 18px;
}

.hero__content, .container {
  max-width: 1050px;
  margin: 0 auto;
}

.hero__inner {
  display: grid;
  grid-template-columns: 1.2fr .8fr;
  gap: 18px;
  align-items: center;
}

.hero__visual {
  position: relative;
  min-height: 150px;
}

.float-orb {
  position: absolute;
  display: grid;
  place-items: center;
  width: 78px;
  height: 78px;
  border-radius: 50%;
  background: rgba(255, 255, 255, 0.18);
  border: 1px solid rgba(255, 255, 255, 0.3);
  box-shadow: 0 10px 24px rgba(8, 32, 63, 0.15);
  font-size: 1.8rem;
  animation: floaty 5s ease-in-out infinite;
}
.orb-a { left: 18px; top: 30px; }
.orb-b { left: 112px; top: 2px; animation-delay: .8s; }
.orb-c { right: 20px; top: 58px; animation-delay: 1.6s; }

.eyebrow {
  text-transform: uppercase;
  letter-spacing: .14em;
  font-size: .78rem;
  opacity: .95;
}

h1 { font-size: clamp(2.3rem, 5vw, 3.6rem); margin: 0 0 10px; }
h2 { margin-top: 0; }
.hero__text { max-width: 690px; font-size: 1.08rem; }
.hero__actions, .quiz-actions, .step-row { display: flex; gap: 10px; flex-wrap: wrap; }

.btn {
  display: inline-block;
  padding: 11px 16px;
  border-radius: 999px;
  text-decoration: none;
  border: 0;
  cursor: pointer;
  font-weight: 700;
}
.btn--primary { background: var(--primary); color: white; }
.btn--secondary { background: white; color: var(--text); }

.container { padding: 20px 14px 42px; }
.panel {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: 20px;
  box-shadow: var(--shadow);
  padding: 18px;
  margin-bottom: 18px;
}

.focus-note {
  background: #fffbe8;
  border: 1px solid #f3df8b;
  border-radius: 16px;
  padding: 14px 16px;
  font-size: 1.05rem;
}
.focus-note p { margin-bottom: 0; }
.section-head { margin-bottom: 12px; }
.section-head p { color: var(--muted); margin-bottom: 0; }

.goal-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
  gap: 10px;
}

.goal-card {
  display: grid;
  gap: 6px;
  padding: 12px;
  border-radius: 14px;
  background: #f8fbff;
  border: 1px solid #d7e7f4;
}

.goal-card span {
  color: var(--muted);
  line-height: 1.45;
}

.builder-grid {
  display: grid;
  grid-template-columns: 1.1fr .9fr;
  gap: 16px;
  align-items: start;
}

.cell-stage {
  position: relative;
  min-height: 330px;
  border-radius: 18px;
  border: 2px dashed #c6dcec;
  background: linear-gradient(180deg, #f9fcff 0%, #eef7ff 100%);
  overflow: hidden;
}

.plant-stage::before {
  content: "";
  position: absolute;
  left: -20px;
  top: 10px;
  width: 180px;
  height: 280px;
  background: linear-gradient(115deg, rgba(255, 232, 120, 0), rgba(255, 247, 196, 0.8), rgba(255, 232, 120, 0));
  opacity: 0;
  transform: rotate(-8deg) translateX(-35px);
  pointer-events: none;
}

.plant-stage.photosynthesis-on::before {
  opacity: .9;
  animation: shine 4s linear infinite;
}

.plant-stage.focus-on .part-core,
.animal-stage.focus-on .animal-core {
  box-shadow: 0 0 0 10px rgba(194, 156, 255, 0.16);
}

.stage-label {
  position: absolute;
  left: 12px;
  top: 12px;
  background: rgba(255,255,255,.9);
  border: 1px solid var(--line);
  border-radius: 999px;
  padding: 6px 10px;
  font-size: .9rem;
  font-weight: 700;
  z-index: 2;
}

.cell-part {
  position: absolute;
  opacity: 0;
  transform: scale(.75);
  transition: all .25s ease;
}
.cell-part.is-visible {
  opacity: 1;
  transform: scale(1);
}

.part-wall {
  inset: 30px;
  border: 8px solid #64a96c;
  border-radius: 26px;
}
.part-membrane {
  inset: 48px;
  border: 4px solid #4c83c3;
  border-radius: 22px;
}
.part-plasma {
  inset: 54px;
  background: rgba(125, 195, 255, 0.28);
  border-radius: 18px;
}
.part-vacuole {
  left: 110px;
  right: 70px;
  top: 85px;
  bottom: 70px;
  background: rgba(179, 233, 255, 0.7);
  border: 3px solid #86cae4;
  border-radius: 40px;
}
.part-core {
  width: 74px;
  height: 74px;
  left: 85px;
  top: 130px;
  background: #c29cff;
  border: 4px solid #8d63d8;
  border-radius: 50%;
  animation: pulseCore 4s ease-in-out infinite;
}
.part-chloro {
  width: 52px;
  height: 28px;
  background: #7ada8b;
  border: 3px solid #2f9551;
  border-radius: 999px;
  animation: drift 4s ease-in-out infinite;
}
.part-chloro1 { top: 82px; right: 90px; }
.part-chloro2 { top: 140px; right: 60px; animation-delay: .8s; }
.part-chloro3 { top: 210px; right: 110px; animation-delay: 1.5s; }

.animal-membrane {
  inset: 45px;
  border: 4px solid #4c83c3;
  border-radius: 50% 46% 52% 48% / 48% 52% 46% 54%;
}
.animal-plasma {
  inset: 55px;
  background: rgba(125, 195, 255, 0.28);
  border-radius: 50% 46% 52% 48% / 48% 52% 46% 54%;
}
.animal-core {
  width: 78px;
  height: 78px;
  left: 130px;
  top: 120px;
  background: #c29cff;
  border: 4px solid #8d63d8;
  border-radius: 50%;
  animation: pulseCore 4s ease-in-out infinite;
}

.toolbox { display: grid; gap: 12px; }
.progress {
  margin: 0;
  font-weight: 700;
  color: var(--green);
}

.micro-tip {
  margin: -4px 0 0;
  font-size: .92rem;
  color: var(--muted);
}

.tool-list, .mini-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(140px, 1fr));
  gap: 10px;
}
.tool-btn, .mini-card, .step-btn {
  border: 1px solid var(--line);
  background: #f8fbff;
  border-radius: 14px;
  padding: 12px;
  font-weight: 700;
  cursor: pointer;
  text-align: left;
}
.tool-btn:hover, .mini-card:hover, .step-btn:hover { background: var(--primary-soft); }
.tool-btn.done, .step-btn.active {
  background: var(--primary);
  color: white;
  border-color: var(--primary);
}

.mini-card.active {
  background: var(--primary-soft);
  border-color: var(--primary);
}

.info-card {
  background: #f4f9ff;
  border: 1px solid #cfe2f4;
  border-radius: 16px;
  padding: 14px;
}
.info-card h3 { margin-top: 0; }
.info-card.is-pop { animation: popIn .35s ease; }
.hint-list { display: grid; gap: 8px; }
.hint {
  background: #fffbe8;
  border: 1px solid #f1df97;
  border-radius: 12px;
  padding: 10px 12px;
  font-weight: 600;
}

.division-wrap {
  position: relative;
  min-height: 230px;
  margin: 14px 0;
  border: 1px solid #e3dca5;
  border-radius: 18px;
  background: linear-gradient(180deg, #f7f4d3 0%, #f2efc2 100%);
  overflow: hidden;
}

.division-scene {
  display: none;
  min-height: 230px;
  align-items: center;
  justify-content: center;
  padding: 14px;
}

.division-scene.is-active { display: flex; }

.cell-graphic {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 18px;
  width: 100%;
}

.plant-division {
  flex-direction: column;
  gap: 10px;
}

.plant-division--image {
  gap: 8px;
}

.division-reference-image {
  display: block;
  width: min(104px, 100%);
  height: auto;
  image-rendering: auto;
  filter: drop-shadow(0 4px 8px rgba(98, 70, 13, 0.14));
}

.scene-label {
  margin: 0;
  font-size: .95rem;
  font-weight: 700;
  color: #6f5c1f;
  text-align: center;
}

.division-plant-shell,
.division-mini-plant {
  position: relative;
  background: linear-gradient(180deg, #fff8b8 0%, #ffe98a 56%, #ffdf71 100%);
  border: 3px solid #a86b1c;
  box-shadow: inset 0 0 0 3px #f3c95a, 0 6px 12px rgba(98, 70, 13, 0.14);
}

.division-plant-shell::after,
.division-mini-plant::after {
  content: "";
  position: absolute;
  inset: 4px;
  border: 1.5px solid rgba(123, 81, 20, 0.45);
  border-radius: inherit;
  pointer-events: none;
}

.division-plant-shell {
  width: 100px;
  height: 148px;
  border-radius: 14px 14px 18px 18px / 10px 10px 18px 18px;
}

.division-scene.is-active .division-plant-shell,
.division-scene.is-active .division-mini-plant {
  animation: bob 3s ease-in-out infinite;
}

.nucleus-dot {
  position: absolute;
  border-radius: 50%;
  background: radial-gradient(circle at 35% 35%, #ecc88f 0%, #c98c3e 62%, #a86920 100%);
  border: 2px solid #9a611c;
}

.division-nucleus {
  width: 24px;
  height: 24px;
  left: 50%;
  top: 50%;
  transform: translate(-50%, -50%);
}

.stretch-nucleus {
  position: absolute;
  left: 50%;
  top: 36px;
  width: 28px;
  height: 72px;
  transform: translateX(-50%);
  border-radius: 999px;
  background: linear-gradient(180deg, #deb57b 0%, #c98531 50%, #deb57b 100%);
  border: 2px solid #9a611c;
  z-index: 1;
  animation: stretchBeat 2.3s ease-in-out infinite;
}

.constricting-shell,
.closing-shell {
  overflow: hidden;
}

.constricting-shell::before,
.constricting-shell::after,
.closing-shell::before,
.closing-shell::after {
  content: "";
  position: absolute;
  top: 55px;
  width: 30px;
  height: 38px;
  background: linear-gradient(180deg, #f7f4d3 0%, #f2efc2 100%);
  border: 3px solid #a86b1c;
  z-index: 2;
}

.constricting-shell::before,
.closing-shell::before {
  left: -7px;
  border-right: 0;
  border-radius: 0 18px 18px 0;
}

.constricting-shell::after,
.closing-shell::after {
  right: -7px;
  border-left: 0;
  border-radius: 18px 0 0 18px;
}

.constricting-shell::before {
  animation: pinchInLeft 2.4s ease-in-out infinite;
}

.constricting-shell::after {
  animation: pinchInRight 2.4s ease-in-out infinite;
}

.closing-shell::before {
  transform: translateX(18px);
}

.closing-shell::after {
  transform: translateX(-18px);
}

.dot-top {
  left: 50%;
  top: 26px;
  transform: translateX(-50%);
}

.dot-bottom {
  left: 50%;
  top: auto;
  bottom: 26px;
  transform: translateX(-50%);
}

.membrane-in {
  gap: 12px;
}

.division-caption {
  margin: 0;
  max-width: 430px;
  font-size: .92rem;
  text-align: center;
  color: #665826;
}

.membrane-arm {
  position: absolute;
  top: 69px;
  height: 6px;
  border-radius: 999px;
  z-index: 3;
}

.membrane-arm--left {
  left: 22px;
  background: linear-gradient(90deg, #a86b1c, rgba(168, 107, 28, 0.12));
  transform-origin: left center;
  animation: growPlateLeft 2.4s ease-in-out infinite;
}

.membrane-arm--right {
  right: 22px;
  background: linear-gradient(270deg, #a86b1c, rgba(168, 107, 28, 0.12));
  transform-origin: right center;
  animation: growPlateRight 2.4s ease-in-out infinite;
}

.closing-seam {
  position: absolute;
  left: 50%;
  top: 50%;
  width: 5px;
  height: 62px;
  transform: translate(-50%, -50%) scaleY(.15);
  transform-origin: center;
  border-radius: 999px;
  background: rgba(168, 107, 28, 0.45);
  opacity: 0;
  z-index: 3;
  animation: seamJoin 2.4s ease-in-out infinite;
}

.growth-stage {
  gap: 14px;
}

.daughter-column,
.grown-column {
  display: grid;
  gap: 12px;
  align-items: center;
}

.division-mini-plant {
  width: 88px;
  height: 54px;
  border-radius: 14px;
}

.division-mini-plant--grown {
  width: 118px;
  height: 70px;
}

.mini-division-dot {
  width: 16px;
  height: 16px;
  left: 50%;
  top: 50%;
  transform: translate(-50%, -50%);
}

.grown-division-dot {
  width: 18px;
  height: 18px;
}

.growth-arrow {
  font-size: 1.5rem;
  color: #7b6322;
  font-weight: 700;
}

.division-facts {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 12px;
  margin-top: 12px;
}

.fact-list {
  margin: 10px 0 0 18px;
  padding: 0;
}

.fact-list li {
  margin-bottom: 8px;
}

.compare-grid {
  display: grid;
  gap: 10px;
}

.compare-card {
  border-radius: 12px;
  padding: 10px 12px;
  border: 1px solid var(--line);
}

.compare-card p {
  margin: 6px 0 0;
}

.compare-card--blue {
  background: #eef6ff;
}

.compare-card--green {
  background: #effcf5;
}

.quiz-score-bar {
  display: flex;
  align-items: center;
  gap: 14px;
  background: #f4f9ff;
  border: 1px solid var(--line);
  border-radius: 14px;
  padding: 10px 14px;
  margin-bottom: 14px;
}

.quiz-score-bar[hidden] { display: none; }

#quiz-score-text {
  font-weight: 700;
  white-space: nowrap;
  min-width: 100px;
}

.quiz-score-track {
  flex: 1;
  height: 10px;
  background: #dde8f4;
  border-radius: 999px;
  overflow: hidden;
}

.quiz-score-fill {
  height: 100%;
  width: 0%;
  background: var(--green);
  border-radius: 999px;
  transition: width .4s ease;
}

.quiz {
  display: grid;
  gap: 12px;
  margin-bottom: 12px;
}

.quiz-grid {
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
}

.quiz-question {
  border: 1px solid var(--line);
  border-radius: 14px;
  padding: 14px;
  background: #fbfdff;
  transition: border-color .2s;
}

.quiz-question.q-correct {
  border-color: var(--green);
  background: #f0fdf6;
}

.quiz-question.q-wrong {
  border-color: #e05555;
  background: #fff5f5;
}

.quiz-question p { margin-top: 0; font-weight: 700; }

.quiz-option {
  display: flex;
  align-items: center;
  gap: 8px;
  margin: 6px 0;
  padding: 8px 10px;
  border-radius: 10px;
  border: 1px solid transparent;
  cursor: pointer;
  transition: background .15s, border-color .15s;
}

.quiz-option:hover {
  background: var(--primary-soft);
  border-color: var(--primary);
}

.quiz-option input[type="radio"] {
  accent-color: var(--primary);
}

.quiz-option.opt-correct {
  background: #e6f9ee;
  border-color: var(--green);
  font-weight: 700;
}

.quiz-option.opt-wrong {
  background: #fdeaea;
  border-color: #e05555;
  text-decoration: line-through;
  opacity: .8;
}

.quiz-feedback {
  margin-top: 10px;
  font-size: .88rem;
  border-radius: 10px;
  padding: 8px 10px;
  display: none;
}

.quiz-feedback.fb-correct {
  display: block;
  background: #e6f9ee;
  color: #1a6e3c;
  border: 1px solid #a8e6c4;
}

.quiz-feedback.fb-wrong {
  display: block;
  background: #fdeaea;
  color: #952c2c;
  border: 1px solid #f5a7a7;
}
.footer {
  text-align: center;
  color: var(--muted);
  padding: 20px;
}

.support-note {
  position: fixed;
  left: 8px;
  bottom: 6px;
  margin: 0;
  font-size: .62rem;
  color: #6f8090;
  opacity: .9;
  letter-spacing: .02em;
  z-index: 20;
}

@keyframes floaty {
  0%, 100% { transform: translateY(0); }
  50% { transform: translateY(-10px); }
}

@keyframes drift {
  0%, 100% { transform: translateY(0) rotate(0deg); }
  50% { transform: translateY(-6px) rotate(4deg); }
}

@keyframes pulseCore {
  0%, 100% { transform: scale(1); }
  50% { transform: scale(1.04); }
}

@keyframes bob {
  0%, 100% { transform: translateY(0); }
  50% { transform: translateY(-8px); }
}

@keyframes shine {
  0% { transform: rotate(-8deg) translateX(-40px); }
  100% { transform: rotate(-8deg) translateX(220px); }
}

@keyframes popIn {
  0% { transform: scale(.98); }
  100% { transform: scale(1); }
}

@keyframes stretchBeat {
  0%, 100% { transform: translateX(-50%) scaleY(.96); }
  50% { transform: translateX(-50%) scaleY(1.05); }
}

@keyframes pinchInLeft {
  0%, 15% { transform: translateX(0); }
  55%, 100% { transform: translateX(22px); }
}

@keyframes pinchInRight {
  0%, 15% { transform: translateX(0); }
  55%, 100% { transform: translateX(-22px); }
}

@keyframes growPlateLeft {
  0%, 12% { width: 0; opacity: 0; }
  45% { width: 22px; opacity: .95; }
  78%, 100% { width: 28px; opacity: 1; }
}

@keyframes growPlateRight {
  0%, 12% { width: 0; opacity: 0; }
  45% { width: 22px; opacity: .95; }
  78%, 100% { width: 28px; opacity: 1; }
}

@keyframes seamJoin {
  0%, 60% {
    opacity: 0;
    transform: translate(-50%, -50%) scaleY(.15);
  }
  82%, 100% {
    opacity: 1;
    transform: translate(-50%, -50%) scaleY(1);
  }
}

@media (max-width: 800px) {
  .hero__inner,
  .builder-grid { grid-template-columns: 1fr; }

  .hero__visual {
    min-height: 95px;
  }
}