/* FPGA Professional Association — site styles
 * Single CSS file. Custom properties for theming.
 * No frameworks. No preprocessor. No external fonts.
 * See BUILD_PLAN.md §6 for the full design system.
 */

:root {
  /* Colors — BUILD_PLAN.md §6.1 */
  --color-bg: #fdfdfc;
  --color-fg: #1a1a1a;
  --color-fg-muted: #555555;
  --color-border: #e5e5e3;
  --color-accent: #1f4e8c;
  --color-accent-hover: #163a6a;
  --color-code-bg: #f4f4f1;

  /* Typography — BUILD_PLAN.md §6.2 */
  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto,
               "Helvetica Neue", Arial, sans-serif;
  --font-mono: ui-monospace, SFMono-Regular, "SF Mono", Menlo,
               Consolas, "Liberation Mono", monospace;
  --font-serif: Charter, "Bitstream Charter", "Sitka Text", Cambria, serif;

  /* Spacing scale — BUILD_PLAN.md §6.3. Use only these values. */
  --space-1: 4px;
  --space-2: 8px;
  --space-3: 16px;
  --space-4: 24px;
  --space-5: 32px;
  --space-6: 48px;
  --space-7: 64px;

  /* Layout */
  --width-prose: 720px;
  --width-landing: 960px;
}

/* Reset / base */

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

html {
  font-size: 17px;
  -webkit-text-size-adjust: 100%;
  /* Reserve scrollbar space on every page so short pages (e.g. /tools.html)
     don't shift the centered header sideways relative to taller pages. */
  scrollbar-gutter: stable;
}

body {
  margin: 0;
  font-family: var(--font-sans);
  font-size: 1rem;
  line-height: 1.6;
  color: var(--color-fg);
  background: var(--color-bg);
  text-rendering: optimizeLegibility;
}

main {
  display: block;
}

img,
svg {
  max-width: 100%;
  height: auto;
}

/* Skip link */

.skip-link {
  position: absolute;
  left: -9999px;
  top: 0;
  background: var(--color-fg);
  color: var(--color-bg);
  padding: var(--space-2) var(--space-3);
  text-decoration: none;
  z-index: 100;
}

.skip-link:focus {
  left: var(--space-2);
  top: var(--space-2);
}

/* Headings */

h1,
h2,
h3,
h4 {
  font-family: var(--font-sans);
  font-weight: 600;
  line-height: 1.25;
  margin: 0 0 var(--space-3);
  color: var(--color-fg);
}

h1 {
  font-size: 2rem;
  margin-top: 0;
}

h2 {
  font-size: 1.5rem;
  margin-top: var(--space-6);
}

h3 {
  font-size: 1.25rem;
  margin-top: var(--space-5);
}

main > article > h2:first-of-type,
main > section > h2:first-of-type {
  margin-top: var(--space-5);
}

/* Body text */

p,
ul,
ol,
dl,
pre,
table {
  margin: 0 0 var(--space-3);
}

p {
  max-width: 70ch;
}

.lead {
  font-size: 1.125rem;
  color: var(--color-fg-muted);
  max-width: 70ch;
}

small,
.small {
  font-size: 0.875rem;
}

em {
  font-style: italic;
  color: var(--color-fg-muted);
}

/* Lists */

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

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

dl {
  display: block;
}

dt {
  font-weight: 600;
  margin-top: var(--space-3);
}

dd {
  margin: 0 0 var(--space-2) 0;
  color: var(--color-fg-muted);
}

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

/* Links */

a {
  color: var(--color-accent);
  text-decoration: underline;
  text-underline-offset: 2px;
}

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

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

/* Code */

code,
kbd,
samp,
pre {
  font-family: var(--font-mono);
  font-size: 0.9375rem;
}

code {
  background: var(--color-code-bg);
  padding: 1px 4px;
  border-radius: 2px;
}

pre {
  background: var(--color-code-bg);
  padding: var(--space-3);
  border-radius: 4px;
  overflow-x: auto;
  line-height: 1.5;
}

pre code {
  background: transparent;
  padding: 0;
}

/* Tables */

table {
  border-collapse: collapse;
  width: 100%;
  font-size: 0.9375rem;
}

th,
td {
  padding: var(--space-2) var(--space-3);
  text-align: left;
  border-bottom: 1px solid var(--color-border);
  vertical-align: top;
}

th {
  font-weight: 600;
  border-bottom-color: var(--color-fg);
}

/* Buttons (styled links) */

.btn {
  display: inline-block;
  padding: var(--space-2) var(--space-4);
  border-radius: 4px;
  font-weight: 600;
  text-decoration: none;
  border: 1px solid var(--color-border);
  background: transparent;
  color: var(--color-fg);
  transition: border-color 100ms, background-color 100ms;
}

.btn:hover {
  border-color: var(--color-fg);
  color: var(--color-fg);
}

.btn--primary {
  background: var(--color-accent);
  border-color: var(--color-accent);
  color: var(--color-bg);
}

.btn--primary:hover {
  background: var(--color-accent-hover);
  border-color: var(--color-accent-hover);
  color: var(--color-bg);
}

/* Layout containers */

.container {
  max-width: var(--width-prose);
  margin: 0 auto;
  padding: 0 var(--space-3);
}

.container--landing {
  max-width: var(--width-landing);
}

/* Header */

.site-header {
  border-bottom: 1px solid var(--color-border);
  padding: var(--space-3) 0;
}

.site-header__inner {
  max-width: var(--width-landing);
  margin: 0 auto;
  padding: 0 var(--space-3);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-3);
}

.site-header__brand {
  font-family: var(--font-mono);
  font-weight: 600;
  font-size: 1rem;
  text-decoration: none;
  color: var(--color-fg);
  letter-spacing: 0.5px;
}

.site-header__brand:hover {
  color: var(--color-fg);
}

.site-nav ul {
  display: flex;
  gap: var(--space-4);
  margin: 0;
  padding: 0;
  list-style: none;
}

.site-nav li + li {
  margin-top: 0;
}

.site-nav a {
  color: var(--color-fg);
  text-decoration: none;
  font-weight: 500;
}

.site-nav a:hover,
.site-nav a[aria-current="page"] {
  color: var(--color-accent);
}

.site-nav a[aria-current="page"] {
  text-decoration: underline;
  text-underline-offset: 4px;
}

/* Main */

.site-main {
  padding: var(--space-6) 0 var(--space-7);
}

/* Hero */

.hero {
  padding: var(--space-6) 0 var(--space-5);
}

.hero h1 {
  font-size: 2.5rem;
  letter-spacing: -0.5px;
}

.hero .lead {
  font-size: 1.25rem;
  margin-bottom: var(--space-5);
}

.hero__actions {
  display: flex;
  gap: var(--space-2);
  flex-wrap: wrap;
}

/* Section spacing */

section + section {
  margin-top: var(--space-6);
}

/* Footer */

.site-footer {
  border-top: 1px solid var(--color-border);
  padding: var(--space-5) 0;
  font-size: 0.875rem;
  color: var(--color-fg-muted);
}

.site-footer__inner {
  max-width: var(--width-landing);
  margin: 0 auto;
  padding: 0 var(--space-3);
}

.site-footer p {
  margin: 0 0 var(--space-1);
}

.site-footer__contact {
  font-size: 1rem;
  color: var(--color-fg);
  margin-bottom: var(--space-2);
}

.site-footer__contact a {
  color: var(--color-accent);
  text-decoration: underline;
}

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

.site-footer a {
  color: var(--color-fg-muted);
  text-decoration: underline;
}

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

/* Mobile */

@media (max-width: 600px) {
  .site-header__inner {
    flex-direction: column;
    align-items: flex-start;
    gap: var(--space-2);
  }

  .site-nav ul {
    gap: var(--space-3);
    flex-wrap: wrap;
  }

  .hero h1 {
    font-size: 2rem;
  }

  .hero .lead {
    font-size: 1.125rem;
  }
}

/* Print */

@media print {
  .site-header,
  .site-footer,
  .skip-link {
    display: none;
  }
}