/* ============================================
   DESIGN SYSTEM - CSS Variables & Base Styles
   ============================================ */

/* === CSS RESET === */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  font-size: 16px;
  -webkit-text-size-adjust: 100%;
  -webkit-tap-highlight-color: transparent;
}

body {
  font-family: var(--font-family);
  font-size: var(--font-size-base);
  line-height: var(--line-height-normal);
  color: var(--color-text-primary);
  background-color: var(--color-bg-primary);
  min-height: 100vh;
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* === CSS VARIABLES === */
:root {
  /* === PRIMARY COLORS === */
  --color-primary: #2180ce;
  --color-primary-hover: #1a6bb5;
  --color-primary-light: #e8f4fc;
  --color-primary-dark: #145a8c;
  
  /* === SECONDARY === */
  --color-secondary: #6c757d;
  --color-secondary-hover: #5a6268;
  
  /* === SEMANTIC COLORS === */
  --color-success: #31a24c;
  --color-success-light: #e8f5eb;
  --color-warning: #f0ad4e;
  --color-warning-light: #fef8e8;
  --color-error: #d33f49;
  --color-error-light: #fce8ea;
  --color-info: #17a2b8;
  --color-info-light: #e8f6f8;
  
  /* === TEXT COLORS === */
  --color-text-primary: #1a1a1a;
  --color-text-secondary: #666666;
  --color-text-muted: #999999;
  --color-text-inverse: #ffffff;
  
  /* === BACKGROUND COLORS === */
  --color-bg-primary: #ffffff;
  --color-bg-secondary: #f5f5f5;
  --color-bg-tertiary: #e9ecef;
  --color-bg-hover: #f0f0f0;
  
  /* === BORDER === */
  --color-border: #e0e0e0;
  --color-border-focus: #2180ce;
  --color-border-error: #d33f49;
  
  /* === PRIORITY COLORS === */
  --color-priority-low: #6c757d;
  --color-priority-normal: #2180ce;
  --color-priority-high: #f0ad4e;
  --color-priority-urgent: #d33f49;
  
  /* === STATUS COLORS === */
  --color-status-new: #17a2b8;
  --color-status-progress: #f0ad4e;
  --color-status-completed: #31a24c;
  --color-status-cancelled: #6c757d;
  
  /* === TYPOGRAPHY === */
  --font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Oxygen', 'Ubuntu', sans-serif;
  --font-family-mono: 'SF Mono', 'Consolas', 'Monaco', monospace;
  
  --font-size-xs: 11px;
  --font-size-sm: 13px;
  --font-size-base: 14px;
  --font-size-md: 15px;
  --font-size-lg: 16px;
  --font-size-xl: 18px;
  --font-size-2xl: 20px;
  --font-size-3xl: 24px;
  
  --font-weight-normal: 400;
  --font-weight-medium: 500;
  --font-weight-semibold: 600;
  --font-weight-bold: 700;
  
  --line-height-tight: 1.2;
  --line-height-normal: 1.5;
  --line-height-relaxed: 1.75;
  
  /* === SPACING (8px base) === */
  --space-0: 0;
  --space-1: 4px;
  --space-2: 8px;
  --space-3: 12px;
  --space-4: 16px;
  --space-5: 20px;
  --space-6: 24px;
  --space-8: 32px;
  --space-10: 40px;
  --space-12: 48px;
  --space-16: 64px;
  
  /* === BORDER RADIUS === */
  --radius-none: 0;
  --radius-sm: 4px;
  --radius-md: 8px;
  --radius-lg: 12px;
  --radius-xl: 16px;
  --radius-full: 9999px;
  
  /* === SHADOWS === */
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.07);
  --shadow-lg: 0 10px 15px rgba(0, 0, 0, 0.1);
  --shadow-xl: 0 20px 25px rgba(0, 0, 0, 0.15);
  --shadow-inner: inset 0 2px 4px rgba(0, 0, 0, 0.05);
  
  /* === Z-INDEX === */
  --z-base: 0;
  --z-dropdown: 100;
  --z-sticky: 200;
  --z-fixed: 300;
  --z-modal-backdrop: 400;
  --z-modal: 500;
  --z-toast: 600;
  --z-tooltip: 700;
  
  /* === TRANSITIONS === */
  --transition-fast: 150ms ease;
  --transition-normal: 250ms ease;
  --transition-slow: 350ms ease;
  --transition-bounce: 500ms cubic-bezier(0.68, -0.55, 0.265, 1.55);
  
  /* === LAYOUT === */
  --header-height: 56px;
  --bottom-nav-height: 64px;
  --safe-area-bottom: env(safe-area-inset-bottom, 0px);
}

/* === BASE ELEMENTS === */
a {
  color: var(--color-primary);
  text-decoration: none;
}

a:hover {
  text-decoration: underline;
}

img {
  max-width: 100%;
  height: auto;
  display: block;
}

button {
  font-family: inherit;
  font-size: inherit;
  cursor: pointer;
  border: none;
  background: none;
}

button:disabled {
  cursor: not-allowed;
  opacity: 0.6;
}

input, textarea, select {
  font-family: inherit;
  font-size: inherit;
}

ul, ol {
  list-style: none;
}

/* === UTILITY CLASSES === */
.hidden {
  display: none !important;
}

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

.truncate {
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.text-center { text-align: center; }
.text-left { text-align: left; }
.text-right { text-align: right; }

.text-primary { color: var(--color-text-primary); }
.text-secondary { color: var(--color-text-secondary); }
.text-muted { color: var(--color-text-muted); }
.text-success { color: var(--color-success); }
.text-error { color: var(--color-error); }
.text-warning { color: var(--color-warning); }

.font-medium { font-weight: var(--font-weight-medium); }
.font-semibold { font-weight: var(--font-weight-semibold); }
.font-bold { font-weight: var(--font-weight-bold); }

/* === FLEXBOX UTILITIES === */
.flex { display: flex; }
.flex-col { flex-direction: column; }
.flex-wrap { flex-wrap: wrap; }
.items-center { align-items: center; }
.items-start { align-items: flex-start; }
.items-end { align-items: flex-end; }
.justify-center { justify-content: center; }
.justify-between { justify-content: space-between; }
.justify-end { justify-content: flex-end; }
.gap-1 { gap: var(--space-1); }
.gap-2 { gap: var(--space-2); }
.gap-3 { gap: var(--space-3); }
.gap-4 { gap: var(--space-4); }
.flex-1 { flex: 1; }
.flex-shrink-0 { flex-shrink: 0; }

/* === SPACING UTILITIES === */
.m-0 { margin: 0; }
.m-2 { margin: var(--space-2); }
.m-4 { margin: var(--space-4); }
.mt-2 { margin-top: var(--space-2); }
.mt-4 { margin-top: var(--space-4); }
.mb-2 { margin-bottom: var(--space-2); }
.mb-4 { margin-bottom: var(--space-4); }
.ml-2 { margin-left: var(--space-2); }
.mr-2 { margin-right: var(--space-2); }

.p-0 { padding: 0; }
.p-2 { padding: var(--space-2); }
.p-3 { padding: var(--space-3); }
.p-4 { padding: var(--space-4); }
.px-2 { padding-left: var(--space-2); padding-right: var(--space-2); }
.px-4 { padding-left: var(--space-4); padding-right: var(--space-4); }
.py-2 { padding-top: var(--space-2); padding-bottom: var(--space-2); }
.py-4 { padding-top: var(--space-4); padding-bottom: var(--space-4); }

/* === WIDTH/HEIGHT === */
.w-full { width: 100%; }
.h-full { height: 100%; }
.min-h-screen { min-height: 100vh; }

/* === SCROLLBAR === */
::-webkit-scrollbar {
  width: 6px;
  height: 6px;
}

::-webkit-scrollbar-track {
  background: var(--color-bg-secondary);
}

::-webkit-scrollbar-thumb {
  background: var(--color-border);
  border-radius: var(--radius-full);
}

::-webkit-scrollbar-thumb:hover {
  background: var(--color-text-muted);
}

/* === SELECTION === */
::selection {
  background-color: var(--color-primary-light);
  color: var(--color-primary-dark);
}

/* === FOCUS VISIBLE === */
:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: 2px;
}

button:focus:not(:focus-visible),
input:focus:not(:focus-visible) {
  outline: none;
}