/* ===================================================
   TextKit – base.css
   Global variables, reset, layout, typography
   =================================================== */

/* ---------- CSS Custom Properties ---------- */
:root {
  /* Brand */
  --color-primary:       #6366f1;
  --color-primary-hover: #4f46e5;
  --color-primary-light: #e0e7ff;

  /* Backgrounds */
  --color-bg:            #f8fafc;
  --color-surface:       #ffffff;
  --color-surface-2:     #f1f5f9;

  /* Text */
  --color-text:          #0f172a;
  --color-text-muted:    #64748b;
  --color-text-faint:    #94a3b8;

  /* Borders */
  --color-border:        #e2e8f0;
  --color-border-focus:  #6366f1;

  /* Status */
  --color-success:       #22c55e;
  --color-error:         #ef4444;

  /* Spacing */
  --sp-xs:  4px;
  --sp-sm:  8px;
  --sp-md:  16px;
  --sp-lg:  24px;
  --sp-xl:  40px;
  --sp-2xl: 64px;

  /* Typography */
  --font-sans: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto,
               'Helvetica Neue', Arial, sans-serif;
  --font-mono: 'SFMono-Regular', Consolas, 'Liberation Mono', Menlo,
               Courier, monospace;
  --text-xs:   0.75rem;
  --text-sm:   0.875rem;
  --text-base: 1rem;
  --text-lg:   1.125rem;
  --text-xl:   1.25rem;
  --text-2xl:  1.5rem;
  --text-3xl:  1.875rem;
  --text-4xl:  2.25rem;

  /* Radius */
  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 16px;

  /* Shadow */
  --shadow-sm: 0 1px 3px rgba(0,0,0,.06), 0 1px 2px rgba(0,0,0,.04);
  --shadow-md: 0 4px 12px rgba(0,0,0,.08), 0 2px 4px rgba(0,0,0,.04);
  --shadow-lg: 0 10px 30px rgba(0,0,0,.10), 0 4px 8px rgba(0,0,0,.04);

  /* Transition */
  --transition: 0.18s ease;

  /* Layout */
  --max-w: 1080px;
  --header-h: 60px;
}

/* ---------- Dark Mode ---------- */
@media (prefers-color-scheme: dark) {
  :root {
    --color-bg:          #0f172a;
    --color-surface:     #1e293b;
    --color-surface-2:   #273449;
    --color-text:        #f1f5f9;
    --color-text-muted:  #94a3b8;
    --color-text-faint:  #64748b;
    --color-border:      #334155;
    --color-primary-light: #312e81;
    --shadow-sm: 0 1px 3px rgba(0,0,0,.3);
    --shadow-md: 0 4px 12px rgba(0,0,0,.4);
    --shadow-lg: 0 10px 30px rgba(0,0,0,.5);
  }
}

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

html {
  font-size: 16px;
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
}

body {
  font-family: var(--font-sans);
  font-size: var(--text-base);
  line-height: 1.6;
  color: var(--color-text);
  background: var(--color-bg);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

img, svg { display: block; max-width: 100%; }
a { color: var(--color-primary); text-decoration: none; }
a:hover { text-decoration: underline; }
ul, ol { list-style: none; }
button { cursor: pointer; font: inherit; border: none; background: none; }

/* ---------- Layout ---------- */
.container {
  width: 100%;
  max-width: var(--max-w);
  margin-inline: auto;
  padding-inline: var(--sp-lg);
}

main { flex: 1; }

/* ---------- Header ---------- */
.site-header {
  height: var(--header-h);
  background: var(--color-surface);
  border-bottom: 1px solid var(--color-border);
  position: sticky;
  top: 0;
  z-index: 100;
  box-shadow: var(--shadow-sm);
}

.site-header .container {
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--sp-md);
}

.site-logo {
  font-size: var(--text-xl);
  font-weight: 700;
  color: var(--color-primary);
  text-decoration: none;
  letter-spacing: -0.02em;
  display: flex;
  align-items: center;
  gap: var(--sp-sm);
}
.site-logo:hover { text-decoration: none; }

.site-logo svg {
  width: 28px;
  height: 28px;
}

.site-nav {
  display: flex;
  gap: var(--sp-md);
  align-items: center;
}

.site-nav a {
  font-size: var(--text-sm);
  color: var(--color-text-muted);
  transition: color var(--transition);
}
.site-nav a:hover { color: var(--color-primary); text-decoration: none; }

/* ---------- Footer ---------- */
.site-footer {
  background: var(--color-surface);
  border-top: 1px solid var(--color-border);
  padding-block: var(--sp-xl);
  margin-top: var(--sp-2xl);
  font-size: var(--text-sm);
  color: var(--color-text-muted);
}

.footer-inner {
  display: flex;
  flex-wrap: wrap;
  gap: var(--sp-lg);
  justify-content: space-between;
  align-items: center;
}

.footer-links {
  display: flex;
  flex-wrap: wrap;
  gap: var(--sp-md);
}

/* ---------- Breadcrumb ---------- */
.breadcrumb {
  padding-block: var(--sp-md);
  font-size: var(--text-sm);
  color: var(--color-text-muted);
}

.breadcrumb ol {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: var(--sp-xs);
}

.breadcrumb li { display: flex; align-items: center; gap: var(--sp-xs); }
.breadcrumb li + li::before { content: '/'; color: var(--color-text-faint); }
.breadcrumb a { color: var(--color-text-muted); }
.breadcrumb a:hover { color: var(--color-primary); }
.breadcrumb [aria-current="page"] { color: var(--color-text); }

/* ---------- Utility ---------- */
.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;
}

.text-muted    { color: var(--color-text-muted); }
.text-sm       { font-size: var(--text-sm); }
.mt-sm         { margin-top: var(--sp-sm); }
.mt-md         { margin-top: var(--sp-md); }
.mt-lg         { margin-top: var(--sp-lg); }
.mt-xl         { margin-top: var(--sp-xl); }

/* ---------- Responsive ---------- */
@media (max-width: 640px) {
  :root { --sp-lg: 16px; }
  .site-nav { gap: var(--sp-sm); }
  .footer-inner { flex-direction: column; align-items: flex-start; }
}