/* Base: reset, the blueprint paper, type, links, focus, page frame (header + footer). */

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

html {
  -webkit-text-size-adjust: 100%;
  text-size-adjust: 100%;
  scroll-padding-top: 5.5rem;
}

body {
  margin: 0;
  min-height: 100dvh;
  display: flex;
  flex-direction: column;
  font-family: var(--font-sans);
  font-size: var(--step-0);
  line-height: 1.6;
  color: var(--ink);
  background-color: var(--paper);
  /* The notebook: a faint minor grid every 24px and a major line every 120px. */
  background-image:
    linear-gradient(var(--grid-major) 1px, transparent 1px),
    linear-gradient(90deg, var(--grid-major) 1px, transparent 1px),
    linear-gradient(var(--grid-minor) 1px, transparent 1px),
    linear-gradient(90deg, var(--grid-minor) 1px, transparent 1px);
  background-size: 120px 120px, 120px 120px, 24px 24px, 24px 24px;
  background-position: -1px -1px;
  font-optical-sizing: auto;
  overflow-wrap: break-word;
}

main {
  flex: 1 0 auto;
}

/* `hidden` always wins over component display rules (e.g. .btn is inline-flex). */
[hidden] {
  display: none !important;
}

img,
svg {
  max-width: 100%;
  display: block;
}

img {
  height: auto;
}

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

button {
  cursor: pointer;
}

h1,
h2,
h3,
h4 {
  line-height: 1.12;
  letter-spacing: -0.02em;
  font-weight: 700;
  margin: 0 0 var(--space-xs);
  text-wrap: balance;
}

h1 { font-size: var(--step-4); font-weight: 800; letter-spacing: -0.035em; }
h2 { font-size: var(--step-3); letter-spacing: -0.03em; }
h3 { font-size: var(--step-1); }

p {
  margin: 0 0 var(--space-s);
  text-wrap: pretty;
}

a {
  color: var(--violet-text);
  text-decoration-thickness: 1px;
  text-underline-offset: 0.2em;
}

a:hover {
  text-decoration-thickness: 2px;
}

code,
kbd,
pre {
  font-family: var(--font-mono);
  font-size: 0.9em;
}

:focus-visible {
  outline: 3px solid var(--focus);
  outline-offset: 3px;
  border-radius: 4px;
}

::selection {
  background: var(--violet-tint);
  color: var(--ink);
}

.sr-only {
  position: absolute !important;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0 0 0 0);
  white-space: nowrap;
  border: 0;
}

.skip-link {
  position: absolute;
  left: var(--gutter);
  top: -4rem;
  z-index: calc(var(--z-header) + 1);
  padding: 0.75rem 1rem;
  background: var(--violet);
  color: var(--on-accent);
  border-radius: var(--radius-s);
  font-weight: 600;
}

.skip-link:focus {
  top: 0.75rem;
}

/* ---------- Layout helpers ---------- */

.wrap {
  width: min(100% - 2 * var(--gutter), var(--wrap));
  margin-inline: auto;
}

.wrap--narrow {
  width: min(100% - 2 * var(--gutter), 52rem);
  margin-inline: auto;
}

.stack > * + * {
  margin-top: var(--space-s);
}

/* Mono annotation, like a label written on a technical drawing. */
.annot {
  font-family: var(--font-mono);
  font-size: var(--step--2);
  font-weight: 500;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--ink-faint);
}

.annot--violet { color: var(--violet-text); }
.annot--ai { color: var(--ai); }
.annot--key { color: var(--key); }

/* ---------- Site header ---------- */

.site-header {
  position: sticky;
  top: 0;
  z-index: var(--z-header);
  background: color-mix(in srgb, var(--paper) 88%, transparent);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--line);
}

.site-header__bar {
  display: flex;
  align-items: center;
  gap: var(--space-s);
  min-height: 4.25rem;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 0.6rem;
  color: var(--ink);
  text-decoration: none;
  min-height: 44px;
  margin-right: auto;
}

.brand img {
  width: auto;
  height: 2.25rem;
}

.brand__name {
  display: flex;
  flex-direction: column;
  line-height: 1.05;
  font-weight: 700;
  font-size: 1.02rem;
  letter-spacing: -0.02em;
}

.brand__name small {
  font-family: var(--font-mono);
  font-weight: 500;
  font-size: 0.66rem;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--violet-text);
}

.logo-dark { display: none; }

@media (prefers-color-scheme: dark) {
  .logo-light { display: none; }
  .logo-dark { display: block; }
}

.site-nav {
  display: flex;
  align-items: center;
  gap: clamp(0.25rem, 1vw, 0.75rem);
}

.site-nav__link {
  display: inline-flex;
  align-items: center;
  min-height: 44px;
  padding: 0 0.6rem;
  color: var(--ink-soft);
  text-decoration: none;
  font-weight: 600;
  border-radius: var(--radius-s);
}

.site-nav__link:hover,
.site-nav__link[aria-current="page"] {
  color: var(--ink);
  background: var(--sheet-sunk);
}

.auth-slot {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  min-width: 0;
}

.auth-slot__name {
  font-weight: 600;
  max-width: 12ch;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

@media (max-width: 40rem) {
  .site-nav__link--wide,
  .auth-slot__name,
  .auth-slot .link-signin {
    display: none;
  }

  .brand__name small {
    display: none;
  }
}

@media (max-width: 22rem) {
  .brand__name {
    display: none;
  }
}

/* ---------- Footer ---------- */

.site-footer {
  margin-top: var(--space-2xl);
  border-top: 1px solid var(--line);
  background: var(--sheet);
  padding-block: var(--space-l);
  color: var(--ink-soft);
  font-size: var(--step--1);
}

.site-footer__inner {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-s) var(--space-l);
  align-items: center;
  justify-content: space-between;
}

.site-footer nav {
  display: flex;
  flex-wrap: wrap;
  gap: 0.25rem 1rem;
}

.site-footer a {
  color: var(--ink-soft);
  display: inline-flex;
  align-items: center;
  min-height: 44px;
}

/* ---------- Motion safety ---------- */

@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;
  }
}