/* ==========================================================================
   Base Styles
   Reset, typography defaults, and foundational element styles
   ========================================================================== */

/* -------------------------------------------------------------------------
   CSS Reset (Modern)
   ------------------------------------------------------------------------- */

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

* {
  margin: 0;
  padding: 0;
}

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

body {
  min-height: 100vh;
  line-height: var(--leading-body);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-rendering: optimizeLegibility;
}

img,
picture,
video,
canvas,
svg {
  display: block;
  max-width: 100%;
  height: auto;
}

input,
button,
textarea,
select {
  font: inherit;
}

p,
h1,
h2,
h3,
h4,
h5,
h6 {
  overflow-wrap: break-word;
}

/* -------------------------------------------------------------------------
   Document
   ------------------------------------------------------------------------- */

html {
  font-family: var(--font-sans);
  font-size: 100%;
  background-color: var(--surface-primary);
  color: var(--text-primary);
}

body {
  font-size: var(--text-body);
  font-weight: var(--weight-regular);
  letter-spacing: var(--tracking-normal);
}

/* -------------------------------------------------------------------------
   Typography
   ------------------------------------------------------------------------- */

h1,
h2,
h3,
h4 {
  line-height: var(--leading-heading);
  font-weight: var(--weight-semibold);
  color: var(--text-primary);
  letter-spacing: var(--tracking-tight);
}

h1 {
  font-size: var(--text-h1);
  font-weight: var(--weight-bold);
}

h2 {
  font-size: var(--text-h2);
}

h3 {
  font-size: var(--text-h3);
}

p {
  max-width: 65ch;
  color: var(--text-secondary);
}

.lead {
  font-size: var(--text-body-lg);
  line-height: var(--leading-body);
}

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

.caption {
  font-size: var(--text-caption);
  color: var(--text-tertiary);
  letter-spacing: var(--tracking-wide);
  text-transform: uppercase;
  font-weight: var(--weight-medium);
}

strong {
  font-weight: var(--weight-semibold);
}

/* -------------------------------------------------------------------------
   Links
   ------------------------------------------------------------------------- */

a {
  color: var(--color-teal);
  text-decoration: none;
  position: relative;
  transition: color var(--transition-fast);
}

/* Underline animation - slides in from left */
a:not(.btn):not(.site-header__logo):not(.site-nav__link)::after {
  content: '';
  position: absolute;
  bottom: -1px;
  left: 0;
  width: 0;
  height: 1px;
  background-color: currentColor;
  transition: width var(--transition-base);
}

a:not(.btn):not(.site-header__logo):not(.site-nav__link):hover::after {
  width: 100%;
}

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

a:focus-visible {
  outline: 2px solid var(--color-teal);
  outline-offset: 2px;
  border-radius: var(--radius-sm);
}

/* -------------------------------------------------------------------------
   Lists
   ------------------------------------------------------------------------- */

ul,
ol {
  padding-left: var(--space-4);
}

li {
  margin-bottom: var(--space-1);
}

li::marker {
  color: var(--color-teal);
}

/* -------------------------------------------------------------------------
   Focus States (Accessibility)
   ------------------------------------------------------------------------- */

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

/* Skip to main content link */
.skip-link {
  position: absolute;
  top: -100px;
  left: var(--space-3);
  background: var(--surface-inverse);
  color: var(--text-inverse);
  padding: var(--space-2) var(--space-3);
  z-index: 1000;
  text-decoration: none;
  border-radius: var(--radius-md);
  font-weight: var(--weight-medium);
  transition: top var(--transition-fast);
}

.skip-link:focus {
  top: var(--space-3);
}

/* -------------------------------------------------------------------------
   Selection
   ------------------------------------------------------------------------- */

::selection {
  background-color: var(--color-teal);
  color: var(--color-white);
}

[data-theme="dark"] ::selection {
  background-color: var(--color-teal);
  color: var(--surface-primary);
}

/* -------------------------------------------------------------------------
   Utilities
   ------------------------------------------------------------------------- */

.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;
}

/* -------------------------------------------------------------------------
   Reduced Motion
   ------------------------------------------------------------------------- */

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }
}