/* ==========================================================================
   Base Styles & Reset
   ========================================================================== */

*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
  -webkit-tap-highlight-color: transparent;
}

html {
  font-size: 16px;
  line-height: 1.5;
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
  -webkit-overflow-scrolling: touch;
}

body {
  font-family: var(--font-family-base);
  font-size: var(--font-size-base);
  color: var(--color-text-primary);
  background-color: var(--color-background);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  transition: background-color var(--transition-normal), color var(--transition-normal);
  overflow-x: hidden;
  padding-bottom: env(safe-area-inset-bottom);
  text-rendering: optimizeLegibility;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

a {
  color: var(--color-primary);
  text-decoration: none;
  transition: color var(--transition-fast);
}

a:hover {
  color: var(--color-primary-hover);
}

button {
  font-family: inherit;
  cursor: pointer;
  border: none;
  background: none;
  outline: none;
  touch-action: manipulation;
}

input, textarea {
  font-family: inherit;
  font-size: inherit;
  color: inherit;
  outline: none;
  border: none;
}

img, svg {
  display: block;
  max-width: 100%;
  height: auto;
  user-select: none;
}

/* ==========================================================================
   Header & App Bar
   ========================================================================== */

.app-header {
  position: sticky;
  top: 0;
  z-index: var(--z-header);
  background-color: var(--color-surface);
  border-bottom: 1px solid var(--color-border-subtle);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  transition: background-color var(--transition-normal), border-color var(--transition-normal);
}

.header-container {
  max-width: var(--max-width-content);
  margin: 0 auto;
  height: var(--header-height);
  padding: 0 var(--space-md);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-md);
}

.brand-link {
  display: flex;
  align-items: center;
  gap: var(--space-xs);
  color: var(--color-text-primary);
  font-weight: var(--font-weight-bold);
  font-size: var(--font-size-md);
  letter-spacing: -0.2px;
}

.brand-icon {
  width: 32px;
  height: 32px;
  border-radius: var(--radius-xs);
  flex-shrink: 0;
}

.brand-name {
  display: flex;
  align-items: center;
  gap: 4px;
}

.brand-badge {
  font-size: var(--font-size-xs);
  font-weight: var(--font-weight-medium);
  background: var(--color-primary-subtle);
  color: var(--color-primary-subtle-text);
  padding: 2px 8px;
  border-radius: var(--radius-full);
}

.header-actions {
  display: flex;
  align-items: center;
  gap: var(--space-xs);
}

.header-nav {
  display: none;
  align-items: center;
  gap: var(--space-xs);
  margin-right: var(--space-sm);
}

@media (min-width: 768px) {
  .header-nav {
    display: flex;
  }
}

.nav-link {
  font-size: var(--font-size-sm);
  font-weight: var(--font-weight-medium);
  color: var(--color-text-secondary);
  padding: var(--space-xs) var(--space-sm);
  border-radius: var(--radius-full);
  transition: background-color var(--transition-fast), color var(--transition-fast);
}

.nav-link:hover, .nav-link.active {
  color: var(--color-primary);
  background-color: var(--color-primary-subtle);
}

.icon-btn {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
  border-radius: var(--radius-full);
  color: var(--color-text-secondary);
  background-color: transparent;
  transition: background-color var(--transition-fast), color var(--transition-fast), transform 100ms ease;
}

.icon-btn:hover {
  background-color: var(--color-badge-bg);
  color: var(--color-text-primary);
}

.icon-btn:active {
  transform: scale(0.92);
}

/* Install Header CTA */
.btn-install-header {
  display: none;
  align-items: center;
  gap: 6px;
  background-color: var(--color-primary);
  color: var(--color-text-inverse);
  font-size: var(--font-size-sm);
  font-weight: var(--font-weight-medium);
  padding: 8px 16px;
  border-radius: var(--radius-full);
  transition: background-color var(--transition-fast), transform 100ms ease;
}

.btn-install-header:hover {
  background-color: var(--color-primary-hover);
}

.btn-install-header:active {
  transform: scale(0.96);
}

.btn-install-header.visible {
  display: inline-flex;
}

/* ==========================================================================
   Main App Container
   ========================================================================== */

.app-main {
  flex: 1;
  max-width: var(--max-width-content);
  width: 100%;
  margin: 0 auto;
  padding: var(--space-md);
  padding-bottom: calc(var(--bottom-nav-height) + var(--space-lg) + env(safe-area-inset-bottom));
}

@media (min-width: 768px) {
  .app-main {
    padding: var(--space-xl) var(--space-md);
    padding-bottom: var(--space-3xl);
  }
}

/* Page Transition Animation */
.view-container {
  animation: fadeIn 220ms cubic-bezier(0.2, 0, 0, 1);
}

@keyframes fadeIn {
  from {
    opacity: 0;
    transform: translateY(6px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

/* ==========================================================================
   Mobile Bottom Navigation
   ========================================================================== */

.bottom-nav {
  position: fixed;
  bottom: 0;
  left: 0;
  right: 0;
  height: calc(var(--bottom-nav-height) + env(safe-area-inset-bottom));
  padding-bottom: env(safe-area-inset-bottom);
  background-color: var(--color-surface);
  border-top: 1px solid var(--color-border-subtle);
  display: flex;
  align-items: center;
  justify-content: space-around;
  z-index: var(--z-header);
  box-shadow: 0 -2px 10px rgba(0, 0, 0, 0.04);
}

@media (min-width: 768px) {
  .bottom-nav {
    display: none;
  }
}

.bottom-nav-item {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  flex: 1;
  height: 100%;
  color: var(--color-text-secondary);
  font-size: var(--font-size-xs);
  font-weight: var(--font-weight-medium);
  gap: 3px;
  transition: color var(--transition-fast);
}

.bottom-nav-item svg {
  width: 22px;
  height: 22px;
  transition: transform var(--transition-fast);
}

.bottom-nav-item.active {
  color: var(--color-primary);
}

.bottom-nav-item.active svg {
  transform: translateY(-1px);
}

/* ==========================================================================
   Footer (Desktop)
   ========================================================================== */

.app-footer {
  border-top: 1px solid var(--color-divider);
  background-color: var(--color-surface);
  padding: var(--space-xl) var(--space-md);
  margin-top: auto;
  color: var(--color-text-secondary);
  font-size: var(--font-size-sm);
  display: none;
}

@media (min-width: 768px) {
  .app-footer {
    display: block;
  }
}

.footer-container {
  max-width: var(--max-width-content);
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: var(--space-md);
}

.footer-links {
  display: flex;
  gap: var(--space-lg);
}

.footer-links a {
  color: var(--color-text-secondary);
}

.footer-links a:hover {
  color: var(--color-primary);
}

/* ==========================================================================
   Global Utilities & Skeletons
   ========================================================================== */

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border-width: 0;
}

.skeleton {
  background: linear-gradient(90deg, var(--color-surface-variant) 25%, var(--color-border-subtle) 50%, var(--color-surface-variant) 75%);
  background-size: 200% 100%;
  animation: skeletonLoading 1.5s infinite;
  border-radius: var(--radius-sm);
}

@keyframes skeletonLoading {
  0% {
    background-position: 200% 0;
  }
  100% {
    background-position: -200% 0;
  }
}