/**
 * BASE STYLES & RESET
 * YouTube Creator Toolbox
 */

*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  font-size: var(--font-size-md);
  font-family: var(--font-family-primary);
  line-height: var(--line-height-base);
  color: var(--color-text-primary);
  background-color: var(--color-surface-base);
  -webkit-text-size-adjust: 100%;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  scroll-behavior: smooth;
}

body {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  background-color: var(--color-surface-base);
  color: var(--color-text-primary);
  overflow-x: hidden;
}

/* Accessible Focus Indicators - WCAG 2.2 AA */
:focus {
  outline: none;
}

:focus-visible {
  outline: 2px solid var(--color-focus-ring) !important;
  outline-offset: 2px !important;
}

/* Typography Hierarchy */
h1, h2, h3, h4, h5, h6 {
  color: var(--color-text-primary);
  line-height: var(--line-height-tight);
  font-weight: var(--font-weight-bold);
  letter-spacing: -0.015em;
}

h1 {
  font-size: var(--font-size-3xl);
  font-weight: var(--font-weight-extrabold);
}

h2 {
  font-size: var(--font-size-2xl);
  font-weight: var(--font-weight-bold);
}

h3 {
  font-size: var(--font-size-xl);
  font-weight: var(--font-weight-bold);
}

h4 {
  font-size: var(--font-size-lg);
  font-weight: var(--font-weight-semibold);
}

p {
  color: var(--color-text-secondary);
  font-size: var(--font-size-md);
  line-height: var(--line-height-base);
}

small, .text-xs {
  font-size: var(--font-size-xs);
  line-height: 1.4;
}

.text-sm {
  font-size: var(--font-size-sm);
}

.text-md {
  font-size: var(--font-size-md);
}

.text-lg {
  font-size: var(--font-size-lg);
}

.text-primary {
  color: var(--color-text-primary);
}

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

.text-tertiary {
  color: var(--color-text-tertiary);
}

.font-mono {
  font-family: var(--font-family-mono);
}

a {
  color: var(--color-brand-primary);
  text-decoration: none;
  transition: color var(--motion-duration-fast) var(--motion-easing-standard);
}

a:hover {
  color: var(--color-brand-hover);
  text-decoration: underline;
}

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

/* Layout Utilities */
.container {
  width: 100%;
  max-width: 1240px;
  margin-left: auto;
  margin-right: auto;
  padding-left: var(--space-4);
  padding-right: var(--space-4);
}

.main-content {
  flex: 1 0 auto;
}

.section {
  padding-top: var(--space-7);
  padding-bottom: var(--space-7);
}

.section-muted {
  background-color: var(--color-surface-muted);
}

.section-header {
  margin-bottom: var(--space-6);
}

.section-title {
  font-size: var(--font-size-2xl);
  margin-bottom: var(--space-2);
}

.section-subtitle {
  color: var(--color-text-secondary);
  font-size: var(--font-size-md);
  max-width: 680px;
}

/* Grids */
.grid {
  display: grid;
  gap: var(--space-5);
}

.grid-cols-1 { grid-template-columns: 1fr; }
.grid-cols-2 { grid-template-columns: repeat(2, 1fr); }
.grid-cols-3 { grid-template-columns: repeat(3, 1fr); }
.grid-cols-4 { grid-template-columns: repeat(4, 1fr); }

@media (max-width: 1024px) {
  .grid-cols-4 { grid-template-columns: repeat(2, 1fr); }
  .grid-cols-3 { grid-template-columns: repeat(2, 1fr); }
}

@media (max-width: 640px) {
  .grid-cols-4, .grid-cols-3, .grid-cols-2 {
    grid-template-columns: 1fr;
  }
  .container {
    padding-left: var(--space-3);
    padding-right: var(--space-3);
  }
  .section {
    padding-top: var(--space-5);
    padding-bottom: var(--space-5);
  }
}

/* Flex 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; }
.justify-between { justify-content: space-between; }
.justify-center { justify-content: center; }
.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); }
.gap-5 { gap: var(--space-5); }