/* base.css - Base styles, resets, and typography */

/* ============================================
   Modern CSS Reset
   ============================================ */

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

html {
  -webkit-text-size-adjust: 100%;
  -moz-tab-size: 4;
  tab-size: 4;
}

body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 
    'Helvetica Neue', Arial, sans-serif, 'Apple Color Emoji', 'Segoe UI Emoji', 
    'Segoe UI Symbol';
  font-size: var(--font-size-base);
  line-height: var(--line-height-normal);
  color: var(--color-text);
  background-color: var(--color-bg);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* Remove list styles on ul, ol elements with a class */
ul[class],
ol[class] {
  list-style: none;
}

/* Make images easier to work with */
img,
picture,
svg {
  max-width: 100%;
  display: block;
}

/* Inherit fonts for inputs and buttons */
input,
button,
textarea,
select {
  font: inherit;
}

/* Remove default button styles */
button {
  background: none;
  border: none;
  cursor: pointer;
}

/* ============================================
   Typography
   ============================================ */

h1, h2, h3, h4, h5, h6 {
  font-weight: var(--font-weight-bold);
  line-height: var(--line-height-tight);
  margin-bottom: var(--space-md);
}

h1 {
  font-size: var(--font-size-5xl);
  font-weight: var(--font-weight-black);
}

h2 {
  font-size: var(--font-size-4xl);
}

h3 {
  font-size: var(--font-size-3xl);
}

h4 {
  font-size: var(--font-size-2xl);
}

h5 {
  font-size: var(--font-size-xl);
}

h6 {
  font-size: var(--font-size-lg);
}

p {
  margin-bottom: var(--space-md);
}

a {
  color: var(--color-primary);
  text-decoration: underline;
  text-decoration-thickness: 2px;
  text-underline-offset: 2px;
  transition: color var(--transition-fast);
}

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

a:focus {
  outline: 3px solid var(--color-accent);
  outline-offset: 2px;
}

strong, b {
  font-weight: var(--font-weight-bold);
}

em, i {
  font-style: italic;
}

code {
  font-family: 'Courier New', Courier, monospace;
  background-color: var(--color-surface-alt);
  padding: 2px 6px;
  border-radius: var(--radius-sm);
  font-size: 0.9em;
}

/* ============================================
   Accessibility
   ============================================ */

/* Skip link */
.skip-link {
  position: absolute;
  top: -40px;
  left: 0;
  background-color: var(--color-primary);
  color: var(--color-bg);
  padding: var(--space-sm) var(--space-md);
  text-decoration: none;
  font-weight: var(--font-weight-bold);
  border: var(--border-width) solid var(--color-border);
  box-shadow: var(--shadow);
  z-index: var(--z-modal);
}

.skip-link:focus {
  top: var(--space-md);
  left: var(--space-md);
  outline: 3px solid var(--color-accent);
  outline-offset: 2px;
}

/* Focus visible - modern approach */
:focus-visible {
  outline: 3px solid var(--color-accent);
  outline-offset: 2px;
}

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

/* Screen reader only */
.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;
}

/* ============================================
   Layout Utilities
   ============================================ */

.container {
  width: 100%;
  max-width: var(--container-xl);
  margin-left: auto;
  margin-right: auto;
  padding-left: var(--space-lg);
  padding-right: var(--space-lg);
}

@media (max-width: 768px) {
  .container {
    padding-left: var(--space-md);
    padding-right: var(--space-md);
  }
}

/* ============================================
   Responsive Typography
   ============================================ */

@media (max-width: 768px) {
  :root {
    --font-size-5xl: 2.25rem;
    --font-size-4xl: 1.875rem;
    --font-size-3xl: 1.5rem;
    --font-size-2xl: 1.25rem;
  }
}

@media (max-width: 480px) {
  :root {
    --font-size-5xl: 1.875rem;
    --font-size-4xl: 1.5rem;
    --font-size-3xl: 1.25rem;
  }
}