/* ===== Reset ===== */
* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

/* ===== Base layout ===== */
body {
  font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  background-color: #252525;
  color: #ffffff;
  display: flex;
  flex-direction: column;
  min-height: 100vh;
}

/* ===== Top band ===== */
.topbar {
  width: 100%;
  background: #252525;
  color: #ffffff;
  padding: 1rem;
  text-align: center;
  font-size: 1.5rem;
  font-weight: 600;
  box-shadow: 0 1px 4px rgba(0, 0, 0, 0.08);
}

/* ===== Navigation band ===== */
.navbar {
  width: 100%;
  display: flex;
  justify-content: center;
  gap: 0.5rem;
  background: #303030;
  padding: 0.5rem;
}

.nav-item {
  background: transparent;
  border: none;
  padding: 0.5rem 0.9rem;
  font-size: 0.9rem;
  color: #ffffff;
  cursor: pointer;
  border-radius: 8px;
}

.nav-item.active {
  background: #252525;
  font-weight: 600;
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.15);
}

/* ===== Main ===== */
main {
  width: 100%;
  max-width: 900px;
  margin: 0 auto;
  padding: 1rem;
}

/* ===== Sections ===== */
.section {
  display: none;
}

.section.active {
  display: block;
}

/* ===== Alphabet subsections ===== */
.alphabet-subsection {
  margin-bottom: 2rem;
  padding: 1rem;
  background: #303030;
  border-radius: 12px;
  box-shadow: 0 2px 6px rgba(0,0,0,0.05);
}

.subsection-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 0.5rem;
}

.toggle-btn {
  background: transparent;
  color: #ffffff;
  border: none;
  cursor: pointer;
  font-size: 1rem;
  transform: rotate(0deg);
  transition: transform 0.2s ease;
}

.toggle-btn.folded {
  transform: rotate(-90deg); /* arrow points right when folded */
}

.alphabet-subsection h2 {
  font-size: 1.2rem;
  border-bottom: 1px solid #ddd;
  padding-bottom: 0.3rem;
  margin: 0;
}

/* ===== Grid ===== */
.grid {
  display: grid;
  grid-template-columns: repeat(var(--columns, 10), 1fr);
  gap: 1rem;
  justify-items: center;
}

/* ===== Cards ===== */
.card {
  background-color: #252525;
  border-radius: 12px;
  padding: 1rem 0.5rem;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  box-shadow: 0 2px 6px rgba(0, 0, 0, 0.08);
  transition: transform 0.12s ease, box-shadow 0.12s ease;
}

.card:hover {
  transform: translateY(-2px);
  box-shadow: 0 4px 10px rgba(0, 0, 0, 0.12);
}

.card:active {
  transform: translateY(0);
  box-shadow: 0 2px 6px rgba(0, 0, 0, 0.1);
}

/* ===== Character ===== */
.char {
  font-size: 2.5rem;
  line-height: 1;
  margin-bottom: 0.4rem;
}

.label {
  font-size: 1rem;
  opacity: 0.85;
}

/* ===== Footer ===== */
footer {
  margin-top: auto;
  padding: 0.75rem;
  font-size: 0.75rem;
  opacity: 0.6;
  text-align: center;
}

/* ===== Responsive ===== */
@media (max-width: 480px) {
  .grid {
    grid-template-columns: repeat(auto-fit, minmax(50px, 1fr));
    gap: 0.75rem;
  }

  .char {
    font-size: 2.2rem;
  }

  .label {
    font-size: 0.9rem;
  }

  .alphabet-subsection h2 {
    font-size: 1rem;
  }
}