/* ==========================================================================
   app.css - iOS Human Interface Guidelines (HIG) Base Styles & Layout
   ========================================================================== */

:root {
  --font-family: -apple-system, BlinkMacSystemFont, "SF Pro Display", "SF Pro Text", "Helvetica Neue", Arial, sans-serif;
  
  /* Light Theme Palette */
  --bg-primary: #F2F2F7;
  --bg-secondary: #FFFFFF;
  --bg-tertiary: #E5E5EA;
  --card-bg: #FFFFFF;
  --card-elevated: #FFFFFF;
  --card-border: rgba(60, 60, 67, 0.08);
  
  --text-primary: #000000;
  --text-secondary: #8E8E93;
  --text-tertiary: #C7C7CC;
  
  --accent-blue: #007AFF;
  --accent-blue-subtle: rgba(0, 122, 255, 0.12);
  --accent-green: #34C759;
  --accent-green-subtle: rgba(52, 199, 89, 0.15);
  --accent-orange: #FF9500;
  --accent-orange-subtle: rgba(255, 149, 0, 0.15);
  --accent-red: #FF3B30;
  --accent-red-subtle: rgba(255, 59, 48, 0.15);
  
  --separator: rgba(60, 60, 67, 0.12);
  --nav-bg: rgba(249, 249, 249, 0.88);
  --modal-overlay: rgba(0, 0, 0, 0.4);
  
  --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.06);
  --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.08);
  --shadow-lg: 0 10px 30px rgba(0, 0, 0, 0.15);
  
  --radius-sm: 8px;
  --radius-md: 14px;
  --radius-lg: 20px;
  --radius-full: 9999px;
  
  --safe-top: env(safe-area-inset-top, 0px);
  --safe-bottom: env(safe-area-inset-bottom, 0px);
  --tab-bar-height: 60px;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg-primary: #000000;
    --bg-secondary: #1C1C1E;
    --bg-tertiary: #2C2C2E;
    --card-bg: #1C1C1E;
    --card-elevated: #2C2C2E;
    --card-border: rgba(255, 255, 255, 0.08);
    
    --text-primary: #FFFFFF;
    --text-secondary: #8E8E93;
    --text-tertiary: #48484A;
    
    --accent-blue: #0A84FF;
    --accent-blue-subtle: rgba(10, 132, 255, 0.2);
    --accent-green: #30D158;
    --accent-green-subtle: rgba(48, 209, 88, 0.2);
    --accent-orange: #FF9F0A;
    --accent-orange-subtle: rgba(255, 159, 10, 0.2);
    --accent-red: #FF453A;
    --accent-red-subtle: rgba(255, 69, 58, 0.2);
    
    --separator: rgba(84, 84, 88, 0.35);
    --nav-bg: rgba(28, 28, 30, 0.88);
    --modal-overlay: rgba(0, 0, 0, 0.65);
    
    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.4);
    --shadow-md: 0 4px 14px rgba(0, 0, 0, 0.5);
    --shadow-lg: 0 10px 30px rgba(0, 0, 0, 0.7);
  }
}

/* ==========================================================================
   Reset & Base Setup
   ========================================================================== */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
  -webkit-tap-highlight-color: transparent;
}

html, body {
  width: 100%;
  height: 100%;
  overflow-x: hidden;
  font-family: var(--font-family);
  background-color: var(--bg-primary);
  color: var(--text-primary);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  user-select: none;
  -webkit-user-select: none;
}

input, button, select, textarea {
  font-family: inherit;
  color: inherit;
  user-select: auto;
  -webkit-user-select: auto;
}

/* ==========================================================================
   App Shell & Screen Layout
   ========================================================================== */
#app {
  display: flex;
  flex-direction: column;
  min-height: 100%;
  padding-bottom: calc(var(--tab-bar-height) + var(--safe-bottom) + 16px);
}

/* Top App Header */
.app-header {
  position: sticky;
  top: 0;
  z-index: 50;
  padding-top: calc(var(--safe-top) + 12px);
  padding-bottom: 12px;
  padding-left: 20px;
  padding-right: 20px;
  background-color: var(--nav-bg);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border-bottom: 0.5px solid var(--separator);
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.app-title {
  font-size: 20px;
  font-weight: 700;
  letter-spacing: -0.4px;
}

.header-action-btn {
  background: none;
  border: none;
  color: var(--accent-blue);
  font-size: 16px;
  font-weight: 600;
  cursor: pointer;
  padding: 6px 10px;
  border-radius: var(--radius-sm);
  transition: opacity 0.15s ease;
}

.header-action-btn:active {
  opacity: 0.6;
}

/* Tab Views Container */
.main-content {
  flex: 1;
  padding: 16px 18px 24px 18px;
  max-width: 600px;
  margin: 0 auto;
  width: 100%;
}

.view-section {
  display: none;
  animation: fadeIn 0.2s ease-in-out;
}

.view-section.active {
  display: block;
}

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(4px); }
  to { opacity: 1; transform: translateY(0); }
}

/* ==========================================================================
   Bottom Navigation Bar
   ========================================================================== */
.bottom-tab-bar {
  position: fixed;
  bottom: 0;
  left: 0;
  right: 0;
  height: calc(var(--tab-bar-height) + var(--safe-bottom));
  padding-bottom: var(--safe-bottom);
  background-color: var(--nav-bg);
  backdrop-filter: blur(24px);
  -webkit-backdrop-filter: blur(24px);
  border-top: 0.5px solid var(--separator);
  display: flex;
  align-items: center;
  justify-content: space-around;
  z-index: 60;
}

.tab-item {
  flex: 1;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 3px;
  height: 100%;
  background: none;
  border: none;
  color: var(--text-secondary);
  cursor: pointer;
  transition: color 0.15s ease, transform 0.1s ease;
}

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

.tab-icon {
  font-size: 21px;
  line-height: 1;
}

.tab-label {
  font-size: 10.5px;
  font-weight: 500;
  letter-spacing: -0.1px;
}

.tab-item.active {
  color: var(--accent-blue);
}

.tab-item.active .tab-label {
  font-weight: 600;
}

/* Floating Action Button (Quick Add) */
.fab-quick-add {
  position: fixed;
  right: 20px;
  bottom: calc(var(--tab-bar-height) + var(--safe-bottom) + 16px);
  width: 56px;
  height: 56px;
  border-radius: var(--radius-full);
  background: linear-gradient(135deg, var(--accent-blue), #5E5CE6);
  color: #FFFFFF;
  border: none;
  box-shadow: 0 6px 18px rgba(0, 122, 255, 0.42);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 28px;
  font-weight: 300;
  cursor: pointer;
  z-index: 55;
  transition: transform 0.15s ease, box-shadow 0.15s ease;
}

.fab-quick-add:active {
  transform: scale(0.92);
  box-shadow: 0 3px 10px rgba(0, 122, 255, 0.3);
}

/* ==========================================================================
   Toast Notifications
   ========================================================================== */
.toast-container {
  position: fixed;
  top: calc(var(--safe-top) + 60px);
  left: 50%;
  transform: translateX(-50%);
  z-index: 100;
  pointer-events: none;
  display: flex;
  flex-direction: column;
  gap: 8px;
  width: 90%;
  max-width: 380px;
}

.toast {
  background: rgba(30, 30, 32, 0.94);
  color: #FFFFFF;
  padding: 12px 18px;
  border-radius: var(--radius-md);
  font-size: 14px;
  font-weight: 500;
  box-shadow: var(--shadow-lg);
  display: flex;
  align-items: center;
  gap: 10px;
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  animation: toastSlideDown 0.25s cubic-bezier(0.16, 1, 0.3, 1) forwards;
}

@keyframes toastSlideDown {
  from { opacity: 0; transform: translateY(-12px) scale(0.96); }
  to { opacity: 1; transform: translateY(0) scale(1); }
}

.toast.toast-fadeout {
  animation: toastFadeOut 0.25s forwards;
}

@keyframes toastFadeOut {
  from { opacity: 1; transform: translateY(0); }
  to { opacity: 0; transform: translateY(-8px); }
}