/* === Landing Page Styles === */
/* Scoped to .landing-page to avoid affecting other pages */

/* --- Color overrides for landing page --- */
.landing-page {
  --color-bg: #F7F8FC;
  --color-card-bg: #FFFFFF;
  --color-text: #1B2A4A;
  --color-text-light: #6B7A99;
  --color-border: #D8DDE8;
  --color-accent: #E8443A;
  --color-highlight: #E8443A;
}

[data-theme="dark"] .landing-page {
  --color-bg: #0C1222;
  --color-card-bg: #162032;
  --color-text: #E2E8F0;
  --color-text-light: #8896B3;
  --color-border: #2A3650;
  --color-accent: #FB7B53;
  --color-highlight: #FB7B53;
  background-image: radial-gradient(circle, rgba(226, 232, 240, 0.07) 1px, transparent 1px);
}
[data-theme="dark"] .site-header {
  background: color-mix(in srgb, var(--color-accent) 30%, #000);
}

/* --- Background --- */
.landing-page {
  max-width: none;
  padding: 0;
  background: var(--color-bg);
  background-image: radial-gradient(circle, rgba(27, 42, 74, 0.10) 1px, transparent 1px);
  background-size: 22px 22px;
  font-family: 'Inter', sans-serif;
}

/* --- Typography --- */
.landing-page h1,
.landing-page h2,
.landing-page h3 {
  font-family: 'Inter', sans-serif;
}

/* --- Section shared --- */
.landing-page section {
  max-width: 1200px;
  margin: 0 auto;
  padding: 2.5rem 2rem;
}

.section-heading {
  font-size: 1.6rem;
  font-weight: 700;
  color: var(--color-text);
  margin-bottom: 0.5rem;
  display: flex;
  align-items: center;
  gap: 0.75rem;
}
.section-intro {
  color: var(--color-text-light);
  font-size: 1rem;
  margin-bottom: 2rem;
  max-width: 900px;
}

/* === Hero === */
.landing-page .hero {
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 2rem;
  align-items: end;
  text-align: left;
  padding: 4rem 2rem 2.5rem;
  overflow: visible;
}
.hero__left {
  min-width: 0;
}
.hero__title {
  font-family: 'Inter', sans-serif;
  font-size: clamp(2.8rem, 7vw, 5.5rem);
  font-weight: 700;
  color: var(--color-text);
  line-height: 1.0;
  letter-spacing: -0.035em;
}
.hero__typed {
  display: block;
  color: var(--color-accent);
}
.typing-cursor {
  display: inline-block;
  animation: blink 0.7s step-end infinite;
  color: var(--color-accent);
  font-weight: 300;
}
@keyframes blink {
  0%, 100% { opacity: 1; }
  50%      { opacity: 0; }
}
.hero__subtitle {
  font-size: 1.05rem;
  color: var(--color-text-light);
  margin-top: 1.25rem;
  font-weight: 400;
  max-width: 44ch;
}
.hero__right {
  text-align: right;
  flex-shrink: 0;
  padding-bottom: 0.25rem;
}
.hero__count {
  font-family: 'Inter', sans-serif;
  font-weight: 700;
  font-size: clamp(4rem, 9vw, 7rem);
  line-height: 0.9;
  letter-spacing: -0.05em;
  color: var(--color-accent);
  font-variant-numeric: tabular-nums;
  display: block;
}
.hero__count-label {
  font-size: 0.72rem;
  text-transform: uppercase;
  letter-spacing: 0.2em;
  color: var(--color-text-light);
  margin-top: 0.5rem;
}

/* === CTA + Course Cards === */
.landing-page .cta-courses {
  display: grid;
  grid-template-columns: 5fr 7fr;
  gap: 1rem;
  align-items: start;
  padding-top: 0;
}
.cta-primary-card {
  background: #0f172a;
  color: #f8fafc;
  text-decoration: none;
  border-radius: 18px;
  padding: 1.75rem 2rem;
  display: flex;
  flex-direction: row;
  align-items: stretch;
  gap: 1.5rem;
  min-height: 280px;
  transition: transform 0.2s ease, box-shadow 0.2s ease;
}
[data-theme="light"] .cta-primary-card {
  background: #1e293b;
  color: #f8fafc;
}
[data-theme="dark"] .cta-primary-card {
  background: #1e2d45;
}
.cta-primary-card:hover {
  transform: translateY(-3px);
  box-shadow: 0 0 40px 8px color-mix(in srgb, var(--color-accent) 35%, transparent);
}
.cta-primary-card__left {
  flex: 1;
  display: flex;
  flex-direction: column;
  min-width: 0;
}
.cta-primary-card__icon {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 64px;
  height: 64px;
  border-radius: 10px;
  background: var(--color-accent);
  color: #fff;
  flex-shrink: 0;
  align-self: center;
}
.cta-primary-card__body {
  margin-top: 1.75rem;
}
.cta-primary-card__title {
  font-size: 2.2rem;
  font-weight: 700;
  letter-spacing: -0.03em;
  line-height: 1.0;
  font-family: 'Inter', sans-serif;
}
.cta-primary-card__title em {
  color: var(--color-accent);
  font-style: normal;
}
.cta-primary-card__desc {
  opacity: 0.7;
  font-size: 0.92rem;
  margin-top: 0.5rem;
  line-height: 1.55;
  max-width: 30ch;
}
.cta-primary-card__btn {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  background: var(--color-accent);
  color: #fff;
  padding: 0.6rem 1.1rem;
  border-radius: 999px;
  font-size: 0.88rem;
  font-weight: 600;
  margin-top: 1.4rem;
  margin-bottom: 1rem;
  align-self: flex-start;
  transition: transform 0.2s ease;
}
.cta-primary-card:hover .cta-primary-card__btn {
  transform: translateX(4px);
}

/* === How It Works === */
.steps {
  display: flex;
  align-items: flex-start;
  justify-content: center;
  gap: 0;
}
.step {
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  flex: 0 1 200px;
}
.step__number {
  width: 40px;
  height: 40px;
  border-radius: 50%;
  background: var(--color-accent);
  color: #fff;
  display: flex;
  align-items: center;
  justify-content: center;
  font-family:  'Inter', sans-serif;
  font-weight: 700;
  font-size: 1rem;
  margin-bottom: 0.75rem;
}
.step__icon {
  margin-bottom: 0.5rem;
  color: var(--color-text-light);
}
.step__icon svg {
  width: 32px;
  height: 32px;
}
.step__title {
  font-size: 1.05rem;
  font-weight: 600;
  margin-bottom: 0.25rem;
  color: var(--color-text);
}
.step__desc {
  font-size: 0.85rem;
  color: var(--color-text-light);
  line-height: 1.5;
  max-width: 180px;
}
.step__connector {
  display: flex;
  align-items: center;
  padding-top: 18px;
  color: var(--color-text-light);
  opacity: 0.4;
}
.step__connector svg {
  width: 40px;
  height: 20px;
}

/* === Annotated Question Preview === */
.question-preview {
  padding-bottom: 3rem;
}
.preview-wrapper {
  position: relative;
  padding: 90px 100px 0;
  max-width: 1200px;
  margin: 0 auto;
}

/* Annotations */
.annotation {
  position: absolute;
  display: flex;
  align-items: center;
  gap: 0.5rem;
  white-space: nowrap;
}
.annotation__label {
  display: flex;
  flex-direction: column;
  font-size: 0.78rem;
  line-height: 1.3;
}
.annotation__label strong {
  color: var(--color-text);
  font-weight: 600;
}
.annotation__label span {
  color: var(--color-text-light);
  font-size: 0.7rem;
}
.annotation__line {
  height: 1px;
  background: var(--color-text-light);
  opacity: 0.35;
  flex-shrink: 0;
}
.annotation__dot {
  width: 5px;
  height: 5px;
  border-radius: 50%;
  background: var(--color-text-light);
  opacity: 0.5;
  flex-shrink: 0;
}

/* Top annotations: source, course, difficulty point down to card row 1 */
.annotations-top {
  position: absolute;
  top: 0;
  left: 100px;
  right: 100px;
  height: 90px;
  display: flex;
  justify-content: space-between;
  align-items: flex-end;
}
.annotations-top__left {
  display: flex;
  gap: 3rem;
  align-items: flex-end;
}
.annotation--top {
  position: relative !important;
  flex-direction: column;
  align-items: center;
  gap: 0;
}
.annotation--top .annotation__label {
  align-items: center;
  text-align: center;
  margin-bottom: 0.2rem;
}
.annotation--top .annotation__line {
  width: 1px !important;
  height: 28px;
}

/* Left-side annotations */
.annotation--left {
  right: calc(100% - 90px);
  flex-direction: row;
  text-align: right;
}
.annotation--left .annotation__label {
  align-items: flex-end;
  order: 1;
}
.annotation--left .annotation__line {
  order: 2;
  width: 30px;
}
.annotation--left .annotation__dot {
  order: 3;
}

/* Right-side annotations */
.annotation--right {
  left: calc(100% - 90px);
  flex-direction: row;
}
.annotation--right .annotation__dot {
  order: 1;
}
.annotation--right .annotation__line {
  order: 2;
  width: 30px;
}
.annotation--right .annotation__label {
  order: 3;
  align-items: flex-start;
}

/* Side annotation vertical positions are set dynamically by positionAnnotations() in index.html */

/* Anatomy card — scoped spacing overrides (don't affect main app) */
.question-preview .question-card__summary {
  padding: 0.75rem 1rem;
}
.question-preview .question-card__rows {
  gap: 0.4rem;
}
.question-preview .question-card__body {
  padding: 1.25rem 1.25rem 1rem;
  font-size: 1rem;
  line-height: 1.9;
}
.question-preview .question-card__solution,
.question-preview .question-card__criteria {
  margin: 0 1rem;
}
.question-preview .question-card__solution summary,
.question-preview .question-card__criteria summary {
  padding-top: 0.65rem;
  padding-bottom: 0.65rem;
}
.question-preview .question-card__solution-content {
  padding-top: 0.65rem;
  padding-bottom: 1rem;
  font-size: 0.95rem;
  line-height: 2.5;
}
.question-preview .question-card__solution-content img {
  max-height: 180px;
  width: auto;
  display: block;
  margin: 0.75rem auto 0;
}

/* === Filter Showcase === */
.filter-showcase {
  padding-top: 1.5rem;
}
.showcase-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 2rem;
}
.showcase-item {
  background: var(--color-card-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  overflow: hidden;
  box-shadow: var(--shadow);
  display: flex;
  flex-direction: column;
}
.showcase-item__visual {
  flex: 1;
  padding: 1.25rem;
  border-bottom: 1px solid var(--color-border);
  background: var(--color-card-bg);
}
.showcase-item__text {
  padding: 1rem 1.25rem;
}
.showcase-item__text h3 {
  font-size: 1rem;
  font-weight: 600;
  color: var(--color-text);
  margin-bottom: 0.25rem;
}
.showcase-item__text p {
  font-size: 0.85rem;
  color: var(--color-text-light);
  line-height: 1.5;
}
.showcase-chips {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
}
.showcase-chips .chip {
  cursor: pointer;
}
.showcase-context-menu {
  margin-top: 0.75rem;
  background: var(--color-card-bg);
  border: 1px solid var(--color-border);
  border-radius: 6px;
  padding: 0.3rem 0;
  box-shadow: 0 4px 16px rgba(0,0,0,0.12);
  display: inline-block;
}
.showcase-context-menu__item {
  padding: 0.35rem 0.75rem;
  font-size: 0.78rem;
  color: var(--color-text);
}
.showcase-btn-dark {
  display: inline-flex;
  align-items: center;
  padding: 0.4rem 0.85rem;
  border-radius: var(--radius);
  background: var(--color-dark);
  color: #fff;
  font-size: 0.8rem;
  font-weight: 600;
  pointer-events: none;
  flex-shrink: 0;
}

.showcase-search {
  display: flex;
  gap: 0.5rem;
  align-items: center;
}
.showcase-search__input {
  flex: 1;
  padding: 0.5rem 0.75rem;
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  background: var(--color-card-bg);
  color: var(--color-text);
  font-size: 0.85rem;
  font-family: inherit;
}
.showcase-groups {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}
.showcase-group {
  display: flex;
  flex-direction: column;
}
.showcase-subtopic-demo .subtopic-group {
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  background: var(--color-card-bg);
}
.showcase-subtopic-demo .subtopic-group__summary {
  padding: 0.5rem 0.75rem;
  cursor: default;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}
.showcase-subtopic-demo .filter-row--subtopic {
  padding: 0.5rem 0.75rem;
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
}

/* === Course Grid (right column of cta-courses) === */
.course-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(170px, 1fr));
  gap: 0.75rem;
  align-content: start;
}
.course-card {
  background: var(--color-card-bg);
  border: 1px solid var(--color-border);
  border-radius: 14px;
  padding: 1.25rem 1.5rem;
  box-shadow: var(--shadow);
  transition: box-shadow 0.15s ease, transform 0.15s ease;
}
.course-card:hover {
  box-shadow: var(--shadow-hover);
  transform: translateY(-1px);
}
.course-card__header {
  display: flex;
  flex-direction: column;
  gap: 0.25rem;
}
.course-card__title {
  font-size: 1rem;
  font-weight: 600;
  color: var(--color-text);
}
.course-card__count {
  font-family: 'Inter', sans-serif;
  font-size: 1rem;
  font-weight: 700;
  color: var(--color-accent);
  white-space: nowrap;
}
.course-card__topics {
  display: flex;
  flex-wrap: wrap;
  gap: 0.3rem;
}

/* Skeleton loading */
.course-grid--loading .course-card {
  min-height: 70px;
}
.course-grid--loading .course-card__header,
.course-grid--loading .course-card__topics {
  visibility: hidden;
}
.course-grid--loading .course-card::after {
  content: '';
  display: block;
  height: 60px;
  background: linear-gradient(90deg, var(--color-border) 25%, var(--color-bg) 50%, var(--color-border) 75%);
  background-size: 200% 100%;
  border-radius: 4px;
  animation: shimmer 1.5s infinite;
}
@keyframes shimmer {
  0%   { background-position: 200% 0; }
  100% { background-position: -200% 0; }
}

/* === Other Sites Footer === */
.other-sites {
  padding: 1.5rem 2rem 2.5rem;
  max-width: 1200px;
  margin: 0 auto;
}
.other-sites__inner {
  display: flex;
  align-items: center;
  gap: 1.5rem;
  padding: 1rem 1.5rem;
  background: var(--color-card-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
}
.other-sites__label {
  font-size: 0.75rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--color-text-light);
  white-space: nowrap;
}
.other-sites__links {
  display: flex;
  gap: 1rem;
  flex-wrap: wrap;
}
.other-site {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  text-decoration: none;
  color: var(--color-text);
  padding: 0.4rem 0.8rem;
  border-radius: 100px;
  border: 1px solid var(--color-border);
  font-size: 0.85rem;
  font-weight: 500;
  transition: border-color 0.2s ease, box-shadow 0.2s ease;
}
.other-site:hover {
  border-color: var(--color-accent);
  box-shadow: 0 2px 8px rgba(0,0,0,0.06);
}
.other-site__icon {
  font-size: 1rem;
  display: flex;
  align-items: center;
}
.other-site__icon img {
  width: 18px;
  height: 18px;
}
.other-site__arrow {
  color: var(--color-text-light);
  font-size: 0.9rem;
  transition: transform 0.2s ease;
}
.other-site:hover .other-site__arrow {
  transform: translateX(2px);
}

/* === Scroll Reveal === */
.reveal-on-scroll {
  opacity: 0;
  transform: translateY(30px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}
.reveal-on-scroll.revealed {
  opacity: 1;
  transform: translateY(0);
}
.step:nth-child(1) { transition-delay: 0s; }
.step:nth-child(3) { transition-delay: 0.15s; }
.step:nth-child(5) { transition-delay: 0.3s; }

/* === Responsive === */
@media (max-width: 1024px) {
  .preview-wrapper {
    padding: 80px 100px 0;
  }
  .annotations-top {
    left: 100px;
    right: 100px;
  }
  .annotation__label {
    font-size: 0.72rem;
  }
}

@media (max-width: 768px) {
  .landing-page .hero {
    grid-template-columns: 1fr;
    padding: 2.5rem 1.25rem 1.5rem;
    gap: 1rem;
  }
  .hero__right {
    text-align: left;
  }
  .hero__count {
    font-size: clamp(3rem, 15vw, 5rem);
  }
  .hero__title {
    font-size: clamp(2.2rem, 9vw, 3.5rem);
    letter-spacing: -0.025em;
  }
  .landing-page .cta-courses {
    grid-template-columns: 1fr;
  }
  .course-grid {
    grid-template-columns: repeat(auto-fill, minmax(150px, 1fr));
  }
  .landing-page section {
    padding: 1.5rem 1rem;
  }

  /* Steps stack */
  .steps {
    flex-direction: column;
    align-items: center;
    gap: 0.5rem;
  }
  .step {
    flex-direction: row;
    text-align: left;
    gap: 1rem;
    max-width: 320px;
    width: 100%;
  }
  .step__number {
    width: 36px;
    height: 36px;
    flex-shrink: 0;
  }
  .step__icon { display: none; }
  .step__desc { max-width: none; }
  .step__connector {
    transform: rotate(90deg);
    padding-top: 0;
  }

  /* Preview annotations → list */
  .preview-wrapper {
    padding: 0;
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
  }
  .annotations-top {
    position: static;
    height: auto;
    flex-direction: column;
    align-items: flex-start;
    gap: 0.4rem;
    padding: 0 0.5rem;
  }
  .annotations-top__left {
    flex-direction: column;
    gap: 0.4rem;
  }
  .annotations,
  .annotations-top {
    display: flex;
    flex-direction: column;
    gap: 0.4rem;
    padding: 0 0.5rem;
  }
  .annotation {
    position: static !important;
    flex-direction: row;
    gap: 0.75rem;
  }
  .annotation--top {
    flex-direction: row;
    align-items: center;
    text-align: left;
  }
  .annotation--top .annotation__label {
    align-items: flex-start;
    text-align: left;
    margin-bottom: 0;
  }
  .annotation--top .annotation__line {
    width: 12px !important;
    height: 1px;
  }
  .annotation--left,
  .annotation--right {
    right: auto;
    left: auto;
  }
  .annotation--left .annotation__label,
  .annotation--right .annotation__label {
    align-items: flex-start;
    text-align: left;
  }
  .annotation--left .annotation__label { order: 3; }
  .annotation--left .annotation__dot { order: 1; }
  .annotation--left .annotation__line { order: 2; width: 12px; }
  .annotation__line {
    width: 12px !important;
  }

  /* Showcase */
  .showcase-grid {
    grid-template-columns: 1fr;
  }

  /* Course grid */
  .course-grid {
    grid-template-columns: 1fr;
  }

  /* Other sites */
  .other-sites__inner {
    flex-direction: column;
    align-items: flex-start;
    gap: 0.75rem;
  }
}

/* === Worksheet Showcase === */
.worksheet-showcase { padding-top: 1.5rem; }

/* Item 1 — random questions */
.ws-random-demo { display: flex; flex-direction: column; gap: 0.65rem; }
.ws-random-demo__row { display: flex; align-items: center; gap: 0.5rem; flex-wrap: wrap; }

/* Item 2 — solutions toggle */
.ws-solutions-demo { display: flex; flex-direction: column; gap: 0.5rem; }
.ws-solution-toggle {
  display: inline-flex; align-items: center; gap: 0.4rem;
  padding: 0.35rem 0.8rem; border-radius: var(--radius);
  border: 1.5px solid var(--color-border);
  background: var(--color-card-bg); font-size: 0.8rem; font-weight: 600;
  color: var(--color-text); cursor: pointer; align-self: flex-start;
  transition: background 0.2s, border-color 0.2s, color 0.2s;
  user-select: none; font-family: inherit; margin-bottom: 0.25rem;
}
.ws-solution-toggle.active {
  background: var(--color-accent); border-color: var(--color-accent); color: #fff;
}
.ws-q-mock {
  background: var(--color-card-bg); border: 1px solid var(--color-border);
  border-radius: 6px; overflow: hidden;
}
.ws-q-mock__body { padding: 0.55rem 0.7rem; display: flex; flex-direction: column; gap: 0.3rem; }
.ws-q-mock__line { height: 0.45rem; border-radius: 3px; background: var(--color-border); }
.ws-q-mock__line--short { width: 60%; }
.ws-q-mock__solution { max-height: 0; overflow: hidden; transition: max-height 0.32s ease; }
.ws-q-mock__solution-inner {
  padding: 0.45rem 0.7rem; border-top: 1px solid var(--color-accent);
  background: color-mix(in srgb, var(--color-accent) 8%, transparent);
  display: flex; flex-direction: column; gap: 0.25rem;
}
.ws-q-mock__sol-line {
  height: 0.4rem; border-radius: 3px;
  background: color-mix(in srgb, var(--color-accent) 35%, var(--color-border));
}
.ws-q-mock__sol-line--short { width: 45%; }
.ws-solutions-demo.solutions-visible .ws-q-mock__solution { max-height: 60px; }

/* Item 3 — answer space slider */
.spacing-demo { display: flex; flex-direction: column; gap: 0.5rem; }
.spacing-demo__q {
  background: var(--color-card-bg); border: 1px solid var(--color-border);
  border-radius: 6px; padding: 0.55rem 0.75rem;
  display: flex; flex-direction: column; gap: 0.28rem;
}
.spacing-demo__q-line { height: 0.45rem; border-radius: 3px; background: var(--color-border); }
.spacing-demo__q-line--short { width: 55%; }
.spacing-demo__space {
  position: relative;
  border: 1.5px dashed var(--color-accent);
  border-radius: 6px;
  background: color-mix(in srgb, var(--color-accent) 5%, transparent);
  display: flex; align-items: flex-start; justify-content: center;
  padding-top: 0.4rem;
}
.spacing-demo__space-label {
  font-size: 0.7rem; color: var(--color-accent); opacity: 0.7;
  font-weight: 500; letter-spacing: 0.03em;
}
.spacing-demo__handle {
  position: absolute;
  bottom: 0; left: 0; right: 0;
  height: 14px;
  cursor: ns-resize;
  display: flex; align-items: center; justify-content: center;
}
.spacing-demo__handle::after {
  content: '';
  width: 36px; height: 4px;
  border-top: 1.5px solid var(--color-accent);
  border-bottom: 1.5px solid var(--color-accent);
  opacity: 0.5;
}

/* Items 4 & 5 — shared mock question card */
.add-question-demo,
.remove-question-demo {
  display: flex;
  flex-direction: column;
  justify-content: center;
  height: 100%;
}
.demo-card {
  background: var(--color-card-bg);
  border: 1px solid var(--color-border);
  border-left: 3px solid transparent;
  border-radius: 6px;
  overflow: hidden;
  transition: border-left-color 0.2s ease, background 0.25s ease,
              opacity 0.35s ease, transform 0.35s ease;
}
.demo-card__summary {
  display: flex;
  align-items: center;
  gap: 0.65rem;
  padding: 0.5rem 0.7rem;
  position: relative;
}
.demo-card__rows {
  flex: 1;
  display: flex;
  flex-direction: column;
  gap: 0.28rem;
  min-width: 0;
}
.demo-card__line {
  height: 0.42rem;
  border-radius: 3px;
  background: var(--color-border);
}
.demo-card__line--short { width: 58%; }
.demo-card__checkbox {
  flex-shrink: 0;
  width: 1.4rem;
  height: 1.4rem;
  display: flex;
  align-items: center;
  justify-content: center;
}
.demo-card__checkbox-box {
  width: 1.4rem;
  height: 1.4rem;
  border-radius: 3px;
  border: 2px solid var(--color-border);
  background: var(--color-card-bg);
  transition: border-color 0.15s ease, background 0.15s ease;
  position: relative;
}
.demo-card__checkbox--checked .demo-card__checkbox-box {
  border-color: var(--color-accent);
  background: var(--color-accent);
}
.demo-card__checkbox--checked .demo-card__checkbox-box::after {
  content: '';
  position: absolute;
  top: 2px;
  left: 5px;
  width: 5px;
  height: 9px;
  border: 2px solid #fff;
  border-top: none;
  border-left: none;
  transform: rotate(45deg);
}
@keyframes demo-checkbox-pop {
  0%   { transform: scale(1); }
  40%  { transform: scale(1.35); }
  70%  { transform: scale(0.9); }
  100% { transform: scale(1); }
}
.demo-card__checkbox--popping .demo-card__checkbox-box {
  animation: demo-checkbox-pop 0.22s ease-out;
}
.demo-card--selected {
  border-left-color: var(--color-accent);
  background: color-mix(in srgb, var(--color-accent) 8%, transparent);
}
.demo-card--removing {
  opacity: 0;
  transform: translateX(-18px);
}
.demo-card__remove-btn {
  position: absolute;
  top: 0.3rem;
  right: 0.4rem;
  width: 1.4rem;
  height: 1.4rem;
  display: flex;
  align-items: center;
  justify-content: center;
  border: none;
  border-radius: 4px;
  background: transparent;
  color: var(--color-text-light);
  font-size: 0.75rem;
  font-family: inherit;
  cursor: pointer;
  padding: 0;
  pointer-events: none;
  transition: background 0.15s ease, color 0.15s ease;
}
.demo-card__remove-btn--hover {
  background: color-mix(in srgb, var(--color-accent) 15%, transparent);
  color: var(--color-accent);
}