/* ============================================
   LalaWord Layout System
   Mobile-first SPA layout
   ============================================ */

/* === App Shell === */
#app {
  display: flex;
  flex-direction: column;
  min-height: 100vh;
  max-width: var(--content-max-width);
  margin: 0 auto;
  position: relative;
  background: var(--color-white);
}

/* === Header === */
.app-header {
  position: fixed;
  top: 0;
  left: 50%;
  transform: translateX(-50%);
  width: 100%;
  max-width: var(--content-max-width);
  height: var(--header-height);
  background: var(--color-white);
  border-bottom: 1px solid var(--color-border-light);
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 var(--space-md);
  z-index: var(--z-sticky);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
}

.app-header.transparent {
  background: transparent;
  border-bottom: none;
}

.header-title {
  font-family: var(--font-en);
  font-size: var(--text-lg);
  font-weight: var(--weight-bold);
  color: var(--color-text-primary);
  flex: 1;
  text-align: center;
}

.header-left,
.header-right {
  width: 40px;
  height: 40px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius-full);
  transition: background var(--transition-fast);
}

.header-left:active,
.header-right:active {
  background: var(--color-bg);
}

/* === Page Content === */
.page {
  flex: 1;
  padding-top: var(--header-height);
  padding-bottom: calc(var(--tab-bar-height) + var(--safe-area-bottom) + var(--space-md));
  min-height: 100vh;
  display: none;
}

.page.active {
  display: block;
}

.page-content {
  padding: var(--space-md);
}

.page-content.no-pad {
  padding: 0;
}

/* === Tab Bar === */
.tab-bar {
  position: fixed;
  bottom: 0;
  left: 50%;
  transform: translateX(-50%);
  width: 100%;
  max-width: var(--content-max-width);
  height: calc(var(--tab-bar-height) + var(--safe-area-bottom));
  padding-bottom: var(--safe-area-bottom);
  background: var(--color-white);
  border-top: 1px solid var(--color-border-light);
  display: flex;
  align-items: center;
  justify-content: space-around;
  z-index: var(--z-fixed);
  box-shadow: 0 -2px 12px rgba(0, 0, 0, 0.04);
}

.tab-item {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 2px;
  padding: var(--space-xs) var(--space-sm);
  border-radius: var(--radius-md);
  transition: all var(--transition-fast);
  position: relative;
  min-width: 56px;
}

.tab-item .tab-icon {
  font-size: 22px;
  line-height: 1;
  transition: transform var(--transition-spring);
}

.tab-item .tab-label {
  font-size: var(--text-xs);
  font-weight: var(--weight-medium);
  color: var(--color-text-muted);
  transition: color var(--transition-fast);
}

.tab-item.active .tab-icon {
  transform: scale(1.1);
}

.tab-item.active .tab-label {
  color: var(--color-coral);
  font-weight: var(--weight-semibold);
}

.tab-item:active {
  transform: scale(0.92);
}

/* === Fullscreen pages (camera, splash, login) === */
.page.fullscreen {
  padding-top: 0;
  padding-bottom: 0;
}

/* === Section within page === */
.section-title {
  font-size: var(--text-lg);
  font-weight: var(--weight-bold);
  color: var(--color-text-primary);
  margin-bottom: var(--space-sm);
}

.section-subtitle {
  font-size: var(--text-sm);
  color: var(--color-text-muted);
  margin-bottom: var(--space-md);
}

/* === Grid === */
.grid-2 {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--space-sm);
}

.grid-3 {
  display: grid;
  grid-template-columns: 1fr 1fr 1fr;
  gap: var(--space-sm);
}

/* === Flex helpers === */
.flex-row {
  display: flex;
  align-items: center;
}

.flex-col {
  display: flex;
  flex-direction: column;
}

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

.flex-center {
  display: flex;
  align-items: center;
  justify-content: center;
}

.gap-xs { gap: var(--space-xs); }
.gap-sm { gap: var(--space-sm); }
.gap-md { gap: var(--space-md); }
.gap-lg { gap: var(--space-lg); }

/* === Spacing === */
.mt-xs { margin-top: var(--space-xs); }
.mt-sm { margin-top: var(--space-sm); }
.mt-md { margin-top: var(--space-md); }
.mt-lg { margin-top: var(--space-lg); }
.mt-xl { margin-top: var(--space-xl); }
.mt-2xl { margin-top: var(--space-2xl); }

.mb-xs { margin-bottom: var(--space-xs); }
.mb-sm { margin-bottom: var(--space-sm); }
.mb-md { margin-bottom: var(--space-md); }
.mb-lg { margin-bottom: var(--space-lg); }
.mb-xl { margin-bottom: var(--space-xl); }

.px-md { padding-left: var(--space-md); padding-right: var(--space-md); }

/* === Divider === */
.divider {
  height: 1px;
  background: var(--color-border-light);
  margin: var(--space-md) 0;
}

.divider-thick {
  height: 8px;
  background: var(--color-bg);
  margin: var(--space-lg) calc(-1 * var(--space-md));
}