* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: "Nunito", "Avenir", "Segoe UI", sans-serif;
  background: #f4f8f7;
  color: #1e3d3a;
}

.page-layout {
  display: flex;
  min-height: 100vh;
}

.sidebar {
  width: 260px;
  background: #2d4357;
  color: white;
  padding: 24px 22px;
  flex-shrink: 0;
}

.sidebar h2 {
  font-size: 1.2rem;
  color: white;
  margin-bottom: 16px;
  padding-bottom: 14px;
  border-bottom: 1px solid rgba(255,255,255,0.18);
}

.sidebar ul {
  list-style: none;
  padding: 0;
  margin: 0;
}

.sidebar li {
  margin: 14px 0;
}

.sidebar a {
  color: white;
  text-decoration: none;
  cursor: pointer;
  font-size: 1rem;
  display: block;
  padding: 8px 10px;
  border-radius: 8px;
}

.sidebar a:hover,
.sidebar a.active-stage {
  background: rgba(255,255,255,0.16);
}

.prototype-area {
  flex: 1;
  padding: 24px;
  display: flex;
  justify-content: center;
  background: linear-gradient(135deg, #e7f6ef, #dceef8);
}

.app {
  width: 100%;
  max-width: 430px;
  min-height: 100vh;
  background: #f9fffc;
  box-shadow: 0 0 30px rgba(0, 60, 80, 0.12);
}

header {
  height: 70px;
  padding: 0 18px;
  background: linear-gradient(135deg, #4fa987, #3b93b7);
  color: white;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

header h1 {
  font-size: 1.1rem;
  margin: 0;
}

header button,
.menu-btn {
  background: transparent;
  border: none;
  color: white;
  font-size: 1.4rem;
  cursor: pointer;
}

.screen {
  display: none;
  padding: 22px;
  animation: fadeIn 0.35s ease;
}

.screen.active {
  display: block;
}

h2 {
  margin-top: 8px;
  font-size: 1.7rem;
  color: #17423f;
}

h3 {
  margin-bottom: 8px;
}

.subtitle {
  color: #5c7772;
  margin-top: -6px;
  line-height: 1.5;
}

.choice-card,
.practice,
.insight-card,
.graph-card,
.list-item {
  background: white;
  border-radius: 22px;
  padding: 18px;
  margin: 16px 0;
  box-shadow: 0 10px 25px rgba(34, 80, 78, 0.08);
}

.choice-card {
  display: flex;
  gap: 16px;
  align-items: center;
  cursor: pointer;
  border: 1px solid #d7eee7;
  transition: transform 0.25s ease, box-shadow 0.25s ease;
}

.choice-card:hover,
.practice:hover {
  transform: translateY(-3px);
  box-shadow: 0 14px 28px rgba(34, 80, 78, 0.14);
}

.choice-card.green {
  background: linear-gradient(135deg, #f0fff7, #ffffff);
}

.choice-card.blue {
  background: linear-gradient(135deg, #eef8ff, #ffffff);
}

.icon {
  font-size: 2.4rem;
}

label {
  display: block;
  margin-top: 16px;
  margin-bottom: 6px;
  font-weight: 700;
  color: #315b56;
}

input,
textarea,
select {
  width: 100%;
  padding: 13px;
  border-radius: 14px;
  border: 1px solid #cde3df;
  font-family: inherit;
  font-size: 1rem;
  background: white;
}

textarea {
  min-height: 90px;
  resize: vertical;
}

.toggle-row {
  display: flex;
  gap: 10px;
}

.toggle-row button {
  flex: 1;
  padding: 14px;
  border-radius: 16px;
  border: 1px solid #cde3df;
  background: white;
  font-weight: 700;
  cursor: pointer;
}

.toggle-row button.selected {
  background: #4fa987;
  color: white;
}

.primary,
.secondary,
.back {
  width: 100%;
  margin-top: 16px;
  padding: 14px;
  border-radius: 16px;
  border: none;
  font-weight: 800;
  font-size: 1rem;
  cursor: pointer;
}

.primary {
  background: linear-gradient(135deg, #4fa987, #287c9e);
  color: white;
}

.secondary {
  background: #eef8ff;
  color: #287c9e;
  border: 1px solid #bfddea;
}

.back {
  width: auto;
  background: transparent;
  color: #287c9e;
  padding-left: 0;
}

.practice {
  display: flex;
  justify-content: space-between;
  align-items: center;
  cursor: pointer;
}

.practice span {
  color: #5c7772;
  font-size: 0.9rem;
}

.insight-card {
  background: linear-gradient(135deg, #e9fff4, #e8f6ff);
  border: 1px solid #c6eadc;
}

.graph-card {
  text-align: center;
}

.graph {
  font-size: 3rem;
  letter-spacing: 6px;
  color: #4fa987;
}

.list-item {
  border-left: 5px solid #4fa987;
}

.list-item.draining {
  border-left-color: #d87966;
}

.list-item small {
  display: block;
  color: #6f817e;
  margin-top: 5px;
}

.list-actions {
  margin-top: 10px;
}

.list-actions button {
  margin-right: 8px;
  border: none;
  background: #eef8ff;
  color: #287c9e;
  padding: 7px 10px;
  border-radius: 10px;
  cursor: pointer;
}

.media-box {
  height: 260px;
  margin-top: 24px;
  border-radius: 26px;
  background: linear-gradient(135deg, #a8d8c2, #7bb8d8);
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  color: white;
  box-shadow: 0 12px 28px rgba(34, 80, 78, 0.16);
}

.play {
  width: 76px;
  height: 76px;
  border-radius: 50%;
  background: rgba(255,255,255,0.9);
  color: #287c9e;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 2rem;
  margin-bottom: 12px;
}

.note,
.saved-msg {
  text-align: center;
  color: #5c7772;
  margin-top: 18px;
}

.saved-msg {
  font-weight: 700;
  color: #4fa987;
}

/* Low-Fidelity Prototype appears only inside Screen 1 */
.low-fidelity-section {
  margin-top: 34px;
  padding-top: 22px;
  border-top: 1px solid #d7eee7;
}

.low-fidelity-section h3 {
  font-size: 1.15rem;
  margin-bottom: 8px;
  color: #17423f;
}

.low-fidelity-section p {
  font-size: 0.9rem;
  line-height: 1.4;
  color: #5c7772;
  margin-bottom: 14px;
}

.prototype-image-card {
  width: 100%;
  background: white;
  border-radius: 18px;
  padding: 10px;
  box-shadow: 0 8px 20px rgba(34, 80, 78, 0.08);
  border: 1px solid #d7eee7;
  overflow: hidden;
}

.prototype-image-card img {
  width: 100%;
  max-width: 100%;
  height: auto;
  display: block;
  border-radius: 12px;
  object-fit: contain;
}
.core-function-section {
  margin-top: 34px;
  padding-top: 22px;
  border-top: 1px solid #d7eee7;
}

.code-block {
  background: #243746;
  color: #d9f3ef;
  border-radius: 16px;
  padding: 18px;
  overflow-x: auto;
  margin-top: 16px;
}

.code-block pre {
  margin: 0;
  font-family: "Courier New", monospace;
  font-size: 0.9rem;
  line-height: 1.5;
}
@keyframes fadeIn {
  from {
    opacity: 0;
    transform: translateY(8px);
  }

  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@media (max-width: 760px) {
  .page-layout {
    flex-direction: column;
  }

  .sidebar {
    width: 100%;
  }

  .sidebar ul {
    display: flex;
    overflow-x: auto;
    gap: 8px;
  }

  .sidebar li {
    margin: 0;
    white-space: nowrap;
  }

  .prototype-area {
    padding: 12px;
  }

  .app {
    min-height: auto;
  }
}