/* 
 * CODED:UK Base Styles - 2025/26
 * Modern CSS foundation with progressive enhancement
 * Uses design tokens for consistency
 */

/* ================================
   RESET & FOUNDATION
   ================================ */

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

html {
  /* Modern viewport units */
  block-size: 100dvh;
  font-family: var(--font-sans);
  font-size: var(--text-base);
  line-height: var(--leading-normal);
  color: var(--text-primary);
  background-color: var(--surface-base);
  
  /* Font rendering optimizations */
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-rendering: optimizeLegibility;
  
  /* Scroll behavior */
  scroll-behavior: smooth;
  scroll-padding-top: var(--space-16);
}

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }
}

body {
  min-block-size: 100dvh;
  background-color: var(--surface-base);
  color: var(--text-primary);
  transition: background-color var(--duration-normal) var(--ease-out);
}

/* ================================
   TYPOGRAPHY
   ================================ */

h1, h2, h3, h4, h5, h6 {
  font-weight: var(--weight-bold);
  line-height: var(--leading-tight);
  color: var(--text-primary);
  margin-block-end: var(--space-4);
  
  /* Improve rendering for headings */
  text-wrap: balance;
}

h1 {
  font-size: var(--text-5xl);
  font-weight: var(--weight-bold);
  letter-spacing: -0.025em;
}

h2 {
  font-size: var(--text-4xl);
  font-weight: var(--weight-bold);
  letter-spacing: -0.02em;
}

h3 {
  font-size: var(--text-3xl);
  font-weight: var(--weight-semibold);
  letter-spacing: -0.015em;
}

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

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

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

p {
  margin-block-end: var(--space-4);
  color: var(--text-secondary);
  text-wrap: pretty;
  max-inline-size: 65ch;
}

/* Text size utilities */
.text-xs { font-size: var(--text-xs); }
.text-sm { font-size: var(--text-sm); }
.text-base { font-size: var(--text-base); }
.text-lg { font-size: var(--text-lg); }
.text-xl { font-size: var(--text-xl); }
.text-2xl { font-size: var(--text-2xl); }
.text-3xl { font-size: var(--text-3xl); }
.text-4xl { font-size: var(--text-4xl); }
.text-5xl { font-size: var(--text-5xl); }

/* Text color utilities */
.text-primary { color: var(--text-primary); }
.text-secondary { color: var(--text-secondary); }
.text-muted { color: var(--text-muted); }
.text-brand { color: var(--brand-primary); }
.text-success { color: var(--success); }
.text-warning { color: var(--warning); }
.text-error { color: var(--error); }

/* ================================
   LAYOUT PRIMITIVES
   ================================ */

.container {
  max-inline-size: var(--container-7xl);
  margin-inline: auto;
  padding-inline: var(--space-4);
}

@container (min-width: 48rem) {
  .container {
    padding-inline: var(--space-6);
  }
}

@container (min-width: 64rem) {
  .container {
    padding-inline: var(--space-8);
  }
}

/* Modern 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-start { justify-content: flex-start; }
.justify-end { justify-content: flex-end; }

/* Modern grid utilities */
.grid { display: grid; }
.grid-cols-1 { grid-template-columns: repeat(1, 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); }

/* Container queries for responsive grids */
@container (max-width: 48rem) {
  .grid-cols-2, .grid-cols-3, .grid-cols-4 {
    grid-template-columns: 1fr;
  }
}

@container (max-width: 64rem) and (min-width: 48rem) {
  .grid-cols-3, .grid-cols-4 {
    grid-template-columns: repeat(2, 1fr);
  }
}

/* Gap utilities */
.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-6 { gap: var(--space-6); }
.gap-8 { gap: var(--space-8); }

/* ================================
   INTERACTIVE ELEMENTS
   ================================ */

/* Links */
a {
  color: var(--brand-primary);
  text-decoration: none;
  transition: color var(--duration-fast) var(--ease-out);
}

a:hover {
  color: var(--interactive-hover);
  text-decoration: underline;
  text-decoration-thickness: 2px;
  text-underline-offset: 0.2em;
}

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

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-2);
  padding-block: var(--space-3);
  padding-inline: var(--space-6);
  font-family: inherit;
  font-size: var(--text-base);
  font-weight: var(--weight-medium);
  line-height: var(--leading-normal);
  border: 1px solid transparent;
  border-radius: var(--radius-lg);
  cursor: pointer;
  transition: all var(--duration-fast) var(--ease-out);
  text-decoration: none;
  
  /* Modern interaction features */
  user-select: none;
  touch-action: manipulation;
}

.btn:focus-visible {
  outline: var(--focus-ring);
  outline-offset: 2px;
}

.btn:disabled {
  opacity: 0.6;
  cursor: not-allowed;
  pointer-events: none;
}

/* Button variants */
.btn-primary {
  background-color: var(--brand-primary);
  color: var(--text-inverse);
  border-color: var(--brand-primary);
}

.btn-primary:hover {
  background-color: var(--interactive-hover);
  border-color: var(--interactive-hover);
  transform: translateY(-1px);
  box-shadow: var(--shadow-md);
}

.btn-secondary {
  background-color: var(--surface-elevated);
  color: var(--text-primary);
  border-color: var(--border-strong);
}

.btn-secondary:hover {
  background-color: var(--surface-high);
  transform: translateY(-1px);
  box-shadow: var(--shadow-sm);
}

.btn-outline {
  background-color: transparent;
  color: var(--brand-primary);
  border-color: var(--border-brand);
}

.btn-outline:hover {
  background-color: var(--brand-primary);
  color: var(--text-inverse);
}

/* Button sizes */
.btn-sm {
  padding-block: var(--space-2);
  padding-inline: var(--space-4);
  font-size: var(--text-sm);
}

.btn-lg {
  padding-block: var(--space-4);
  padding-inline: var(--space-8);
  font-size: var(--text-lg);
}

/* ================================
   FORM ELEMENTS
   ================================ */

input,
textarea,
select {
  font-family: inherit;
  font-size: var(--text-base);
  color: var(--text-primary);
  background-color: var(--surface-elevated);
  border: 1px solid var(--border-default);
  border-radius: var(--radius-lg);
  padding-block: var(--space-3);
  padding-inline: var(--space-4);
  transition: all var(--duration-fast) var(--ease-out);
  width: 100%;
}

input:focus,
textarea:focus,
select:focus {
  outline: var(--focus-ring);
  outline-offset: 0;
  border-color: var(--brand-primary);
}

input:invalid,
textarea:invalid {
  border-color: var(--error);
}

::placeholder {
  color: var(--text-muted);
  opacity: 1;
}

/* ================================
   CARDS & SURFACES
   ================================ */

.card {
  background-color: var(--surface-elevated);
  border: 1px solid var(--border-default);
  border-radius: var(--radius-xl);
  padding: var(--space-6);
  box-shadow: var(--shadow-sm);
  transition: all var(--duration-normal) var(--ease-out);
}

.card:hover {
  border-color: var(--border-strong);
  box-shadow: var(--shadow-md);
}

.surface {
  background-color: var(--surface-elevated);
  border-radius: var(--radius-lg);
  padding: var(--space-4);
}

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

/* ================================
   UTILITIES
   ================================ */

/* Spacing utilities */
.p-0 { padding: 0; }
.p-1 { padding: var(--space-1); }
.p-2 { padding: var(--space-2); }
.p-3 { padding: var(--space-3); }
.p-4 { padding: var(--space-4); }
.p-6 { padding: var(--space-6); }
.p-8 { padding: var(--space-8); }

.m-0 { margin: 0; }
.m-1 { margin: var(--space-1); }
.m-2 { margin: var(--space-2); }
.m-3 { margin: var(--space-3); }
.m-4 { margin: var(--space-4); }
.m-6 { margin: var(--space-6); }
.m-8 { margin: var(--space-8); }

/* Text alignment */
.text-left { text-align: start; }
.text-center { text-align: center; }
.text-right { text-align: end; }

/* Display utilities */
.hidden { display: none; }
.block { display: block; }
.inline { display: inline; }
.inline-block { display: inline-block; }

/* Border radius utilities */
.rounded-none { border-radius: 0; }
.rounded-sm { border-radius: var(--radius-sm); }
.rounded { border-radius: var(--radius-base); }
.rounded-lg { border-radius: var(--radius-lg); }
.rounded-xl { border-radius: var(--radius-xl); }
.rounded-full { border-radius: var(--radius-full); }

/* ================================
   MODERN CSS FEATURES
   ================================ */

/* :has() selector support */
@supports selector(:has(*)) {
  .card:has(.btn-primary) {
    border-color: var(--border-brand);
  }
  
  .form-group:has(input:focus) {
    background-color: var(--surface-high);
  }
}

/* Container queries */
@supports (container-type: inline-size) {
  .responsive-container {
    container-type: inline-size;
  }
  
  @container (min-width: 400px) {
    .responsive-content {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: var(--space-4);
    }
  }
}

/* ================================
   ACCESSIBILITY ENHANCEMENTS
   ================================ */

/* Focus management */
.skip-link {
  position: absolute;
  top: -40px;
  left: var(--space-4);
  background-color: var(--brand-primary);
  color: var(--text-inverse);
  padding: var(--space-2) var(--space-4);
  border-radius: var(--radius-md);
  text-decoration: none;
  z-index: var(--z-skip);
  transition: top var(--duration-fast) var(--ease-out);
}

.skip-link:focus {
  top: var(--space-4);
}

/* Screen reader only content */
.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;
}

/* Reduce motion preferences */
@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;
  }
}

/* High contrast mode */
@media (prefers-contrast: high) {
  .btn {
    border-width: 2px;
  }
  
  .card {
    border-width: 2px;
  }
  
  input,
  textarea,
  select {
    border-width: 2px;
  }
}