/* =========================================================
   ESTUDIO · FUENTES, EJERCICIOS Y ACCESOS RÁPIDOS
   ========================================================= */
.expanded-footer {
  grid-template-columns: 1.1fr 1fr 1fr 1fr;
  gap: 30px;
}
.design-three > article {
  min-width: 0;
}
.topic-sources {
  width: min(1160px, calc(100% - 48px));
  margin: 24px auto 40px;
  background: #f5f7fc;
  border: 1px solid var(--line);
  border-radius: 16px;
  padding: 26px;
}
.topic-sources h2 {
  font-size: 1.25rem;
}
.topic-sources p,
.topic-sources li {
  font-size: 0.9rem;
}
.lesson-completion {
  margin-bottom: 45px;
  padding: 24px;
  border: 1px solid #d7dff3;
  border-radius: 16px;
  background: #f0f3ff;
}
.lesson-completion label {
  font-size: 1rem;
}
.lesson-completion input {
  accent-color: var(--blue);
}
.progress-feedback {
  margin: 12px 0;
  font-size: 0.875rem;
  color: var(--muted);
}
.lesson-completion > a {
  font-size: 0.875rem;
  font-weight: 800;
}
.keyboard-demo {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 15px;
  border: 1px solid var(--line);
  border-radius: 16px;
  padding: 25px;
}
.keyboard-demo h3,
.keyboard-demo p {
  flex: 0 0 100%;
  margin: 0;
}
.keyboard-demo button,
.keyboard-demo > a {
  min-height: 48px;
  padding: 12px 18px;
  background: var(--soft);
  border: 1px solid var(--line);
  border-radius: 9px;
  color: var(--ink);
}
.form-error {
  color: #aa2431;
  font-weight: 700;
  margin: 10px 0;
}
#accessible-form {
  max-width: 650px;
}
#accessible-form input {
  width: 100%;
  padding: 12px;
  border: 1px solid var(--line);
  border-radius: 9px;
}
#accessible-form input[aria-invalid="true"] {
  border: 2px solid #aa2431;
}
dialog {
  border: 1px solid var(--line);
  border-radius: 18px;
  padding: 28px;
  color: var(--ink);
  max-width: min(560px, calc(100% - 32px));
  max-height: 85vh;
  overflow: auto;
}
dialog::backdrop {
  background: #18213a70;
}
.study-checklist {
  list-style: none;
  padding: 0;
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 12px;
}
.study-checklist li {
  padding: 14px 18px;
  border: 1px solid var(--line);
  border-radius: 10px;
  background: white;
}
.study-checklist input {
  accent-color: var(--blue);
  margin-right: 9px;
}
.responsive-stage {
  max-width: 100%;
  overflow: auto;
  border: 1px solid var(--line);
  padding: 20px;
  background: var(--soft);
  border-radius: 16px;
  margin-top: 24px;
}
#responsive-frame {
  display: block;
  width: 360px;
  height: 660px;
  border: 0;
  background: white;
}
.challenge-grid,
.source-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 24px;
  align-items: start;
}
.challenge-card,
.source-card {
  border: 1px solid var(--line);
  border-radius: 16px;
  padding: 26px;
  min-width: 0;
}
.challenge-card details {
  padding: 15px 0;
  border-top: 1px solid var(--line);
}
.challenge-card details p {
  margin-top: 12px;
}
.challenge-card button {
  margin: 18px 0;
}
.completion-label {
  display: block;
  font-size: 0.875rem;
}
.completion-label input {
  accent-color: var(--blue);
}
.error-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 28px;
  align-items: start;
}
.error-grid > article {
  min-width: 0;
}
.error-grid .quiz {
  padding: 22px;
}
#study-progress-bar {
  width: 100%;
  height: 22px;
  accent-color: var(--blue);
}
.component-demo {
  padding: 28px;
  border: 1px solid var(--line);
  border-radius: 18px;
  margin-bottom: 24px;
}
.component-demo [role="tablist"] {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin: 20px 0;
}
.component-demo [role="tab"] {
  border: 1px solid var(--line);
  background: white;
  padding: 12px 20px;
  border-radius: 8px;
  color: var(--ink);
  font-weight: 800;
}
.component-demo [role="tab"][aria-selected="true"] {
  background: var(--blue);
  color: white;
  border-color: var(--blue);
}
.component-demo [role="tabpanel"] {
  padding: 22px;
  background: var(--soft);
  border-radius: 12px;
}
.component-demo [role="tabpanel"] h4 {
  margin-top: 0;
}
.component-demo details {
  border-top: 1px solid var(--line);
  padding: 16px 0;
}
.component-demo details p {
  margin-top: 16px;
}
.comparison-table {
  border-collapse: collapse;
  width: 100%;
  font-size: 0.95rem;
}
.comparison-table caption {
  text-align: left;
  margin-bottom: 15px;
  color: var(--muted);
}
.comparison-table th,
.comparison-table td {
  padding: 14px;
  text-align: left;
  border: 1px solid var(--line);
}
.comparison-table th {
  background: var(--soft);
}
.project-stages {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  list-style: none;
  padding: 0;
  gap: 22px;
}
.project-stages li {
  border: 1px solid var(--line);
  border-radius: 16px;
  padding: 24px;
}
.glossary-entry {
  padding: 24px;
}
.glossary-entry > span {
  font-size: 0.75rem;
  color: var(--blue);
  font-weight: 800;
}
.glossary-entry p {
  margin-top: 16px;
  font-size: 0.9rem;
}
.glossary-entry > a {
  font-size: 0.85rem;
}
.source-card > span {
  display: inline-block;
  background: var(--soft);
  color: var(--muted);
  padding: 5px 10px;
  border-radius: 6px;
  font-size: 0.75rem;
  margin-bottom: 18px;
}
.source-card h3 {
  font-size: 1.2rem;
}
.source-card p {
  font-size: 0.9rem;
}
.source-card nav {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  font-size: 0.85rem;
  font-weight: 800;
}
@media (max-width: 1100px) {
  .nav-practice {
    display: none;
  }
  .nav-inner {
    gap: 18px;
  }
  #main-nav {
    gap: 18px;
  }
}
@media (max-width: 940px) {
  .design-nav nav::before { display: none; }
  .nav-inner {
    min-height: 72px;
    display: grid;
    grid-template-columns: 1fr auto;
    padding: 12px 0;
  }
  .menu-button {
    display: grid;
    place-items: center;
    width: 44px;
    height: 44px;
    background: white;
    border: 1px solid var(--line);
    border-radius: 9px;
  }
  #main-nav {
    display: none;
    grid-column: 1/-1;
    width: 100%;
    margin: 0;
    padding-top: 12px;
    gap: 8px;
  }
  #main-nav.is-open {
    display: grid;
  }
  #main-nav a {
    padding: 10px;
  }
  .design-nav {
    width: 100%;
  }
  .design-nav summary {
    padding: 10px;
  }
  .design-nav nav {
    position: static;
    box-shadow: none;
    margin-top: 8px;
    width: 100%;
  }
  .expanded-footer {
    grid-template-columns: 1fr 1fr;
  }
}
@media (max-width: 650px) {
  .challenge-grid,
  .source-grid,
  .error-grid,
  .project-stages,
  .study-checklist {
    grid-template-columns: 1fr;
  }
  .topic-sources {
    width: calc(100% - 32px);
    padding: 22px;
  }
  .component-demo,
  .challenge-card,
  .source-card {
    padding: 22px;
  }
  .responsive-stage {
    padding: 12px;
  }
}
@media (max-width: 400px) {
  .expanded-footer {
    grid-template-columns: 1fr;
  }
  .comparison-table th,
  .comparison-table td {
    padding: 8px;
  }
}