/* =========================================================
   Alex Palecki - personal site
   Design system tokens per DESIGN.md
   ========================================================= */

@import url('https://fonts.googleapis.com/css2?family=Space+Grotesk:wght@500;600;700&family=IBM+Plex+Sans:wght@400;500;600&family=IBM+Plex+Mono:wght@400;500&display=swap');

:root {
  /* Color - OKLCH, per DESIGN.md */
  --bg:             oklch(1.000 0.000 0);
  --surface:        oklch(0.960 0.012 172);
  --surface-strong: oklch(0.925 0.014 172);
  --ink:            oklch(0.160 0.015 172);
  --muted:          oklch(0.460 0.020 172);
  --primary:        oklch(0.420 0.100 172);
  --primary-strong: oklch(0.320 0.095 172);
  --accent:         oklch(0.540 0.160 50);
  --accent-strong:  oklch(0.430 0.150 50);
  --border:         oklch(0.900 0.010 172);
  --on-fill:        oklch(0.995 0.000 0);

  /* Type */
  --font-display: 'Space Grotesk', ui-sans-serif, system-ui, sans-serif;
  --font-body: 'IBM Plex Sans', ui-sans-serif, system-ui, sans-serif;
  --font-mono: 'IBM Plex Mono', ui-monospace, 'SF Mono', Menlo, monospace;

  --text-xs:   0.8125rem;                                   /* 13px */
  --text-sm:   0.9375rem;                                   /* 15px */
  --text-base: 1.0625rem;                                   /* 17px */
  --text-lg:   1.25rem;                                     /* 20px */
  --text-xl:   clamp(1.375rem, 1.25rem + 0.6vw, 1.75rem);   /* 22-28px */
  --text-2xl:  clamp(1.75rem, 1.5rem + 1.2vw, 2.5rem);      /* 28-40px */
  --text-display: clamp(2.5rem, 1.9rem + 3vw, 4.25rem);     /* 40-68px */

  /* Space - 4pt scale */
  --space-3xs: 0.25rem;
  --space-2xs: 0.5rem;
  --space-xs:  0.75rem;
  --space-sm:  1rem;
  --space-md:  1.5rem;
  --space-lg:  2rem;
  --space-xl:  3rem;
  --space-2xl: 4.5rem;
  --space-3xl: 7rem;

  --measure: 62ch;
  --shadow-sm: 0 1px 2px oklch(0.16 0.015 172 / 0.06), 0 1px 1px oklch(0.16 0.015 172 / 0.04);
  --shadow-md: 0 8px 24px oklch(0.16 0.015 172 / 0.08), 0 2px 6px oklch(0.16 0.015 172 / 0.05);
  --ease-out-expo: cubic-bezier(0.16, 1, 0.3, 1);
  --radius-sm: 6px;
  --radius-md: 10px;

  --header-bg: oklch(1.000 0.000 0 / 0.82);

  color-scheme: light;
}

:root[data-theme="dark"] {
  --bg:             oklch(0.170 0.014 172);
  --surface:        oklch(0.230 0.016 172);
  --surface-strong: oklch(0.285 0.018 172);
  --ink:            oklch(0.950 0.006 172);
  --muted:          oklch(0.680 0.016 172);
  --primary:        oklch(0.750 0.110 172);
  --primary-strong: oklch(0.850 0.095 172);
  --accent:         oklch(0.720 0.150 50);
  --accent-strong:  oklch(0.800 0.140 50);
  --border:         oklch(0.330 0.018 172);
  --on-fill:        oklch(0.140 0.012 172);

  --header-bg: oklch(0.170 0.014 172 / 0.82);

  color-scheme: dark;
}

/* =========================================================
   Reset & base
   ========================================================= */

*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: var(--font-body);
  font-size: var(--text-base);
  line-height: 1.6;
  font-feature-settings: 'kern' 1;
  font-kerning: normal;
}

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

a { color: inherit; text-decoration: none; }

h1, h2, h3, h4 {
  font-family: var(--font-display);
  font-weight: 600;
  line-height: 1.15;
  margin: 0;
  text-wrap: balance;
}

p { margin: 0; text-wrap: pretty; }

ul { margin: 0; padding: 0; list-style: none; }

button {
  font: inherit;
  color: inherit;
  background: none;
  border: 0;
  cursor: pointer;
}

*, *::before, *::after {
  transition: background-color 0.25s var(--ease-out-expo), border-color 0.25s var(--ease-out-expo), color 0.25s var(--ease-out-expo);
}

::selection { background: var(--primary); color: var(--on-fill); }

:focus-visible {
  outline: 2px solid var(--primary);
  outline-offset: 3px;
  border-radius: 2px;
}

.skip-link {
  position: absolute;
  left: var(--space-sm);
  top: -3rem;
  background: var(--primary);
  color: var(--on-fill);
  padding: var(--space-2xs) var(--space-sm);
  border-radius: var(--radius-sm);
  z-index: 100;
  transition: top 0.2s var(--ease-out-expo);
}
.skip-link:focus { top: var(--space-sm); }

/* =========================================================
   Layout primitives
   ========================================================= */

.wrap {
  width: 100%;
  max-width: 68rem;
  margin-inline: auto;
  padding-inline: var(--space-lg);
}

@media (max-width: 640px) {
  .wrap { padding-inline: var(--space-md); }
}

section {
  padding-block: var(--space-3xl);
  border-top: 1px solid var(--border);
  scroll-margin-top: 84px;
}

section:first-of-type,
#top { border-top: none; }

.section-head {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: var(--space-md);
  margin-bottom: var(--space-xl);
}

.section-index {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  color: var(--muted);
  letter-spacing: 0.06em;
}

.section-head h2 {
  font-size: var(--text-2xl);
  letter-spacing: -0.02em;
}

.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2xs);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--primary);
}
.eyebrow::before {
  content: '';
  width: 0.5rem;
  height: 1px;
  background: var(--primary);
}

/* =========================================================
   Header / nav
   ========================================================= */

.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  background: var(--header-bg);
  backdrop-filter: blur(10px) saturate(1.4);
  -webkit-backdrop-filter: blur(10px) saturate(1.4);
  border-bottom: 1px solid var(--border);
}

.site-header .wrap {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-md);
  padding-block: var(--space-sm);
  max-width: 68rem;
}

.logo {
  font-family: var(--font-mono);
  font-weight: 500;
  font-size: var(--text-sm);
  letter-spacing: 0.01em;
  display: flex;
  align-items: center;
  gap: var(--space-2xs);
}
.logo .dot { color: var(--accent); }

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

.nav-links {
  display: flex;
  gap: var(--space-md);
  font-size: var(--text-sm);
}

.nav-links a {
  position: relative;
  color: var(--muted);
  padding-block: var(--space-3xs);
  transition: color 0.2s var(--ease-out-expo);
}
.nav-links a:hover,
.nav-links a.is-active { color: var(--ink); }
.nav-links a.is-active::after {
  content: '';
  position: absolute;
  left: 0; right: 0; bottom: -3px;
  height: 2px;
  background: var(--accent);
  border-radius: 2px;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-2xs);
  min-height: 44px;
  font-size: var(--text-sm);
  font-weight: 500;
  padding: 0.6rem 1.1rem;
  border-radius: var(--radius-sm);
  transition: transform 0.2s var(--ease-out-expo), background-color 0.2s var(--ease-out-expo), box-shadow 0.2s var(--ease-out-expo);
  white-space: nowrap;
}

.btn-primary {
  background: var(--primary);
  color: var(--on-fill);
  box-shadow: var(--shadow-sm);
}
.btn-primary:hover { background: var(--primary-strong); box-shadow: var(--shadow-md); }
.btn-primary:active { transform: translateY(1px); }

.btn-ghost {
  border: 1px solid var(--border);
  color: var(--ink);
}
.btn-ghost:hover { border-color: var(--primary); color: var(--primary); }

.nav-toggle {
  display: none;
  align-items: center;
  justify-content: center;
  width: 44px;
  height: 44px;
  margin-right: -10px;
}
.nav-toggle svg { width: 22px; height: 22px; }

.theme-toggle {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  flex: none;
  width: 40px;
  height: 40px;
  border-radius: 999px;
  color: var(--muted);
  transition: color 0.2s var(--ease-out-expo), background-color 0.2s var(--ease-out-expo);
}
.theme-toggle:hover { color: var(--primary); background: var(--surface); }
.theme-toggle svg { width: 19px; height: 19px; }
.theme-toggle .icon-sun { display: none; }
.theme-toggle .icon-moon { display: block; }
:root[data-theme="dark"] .theme-toggle .icon-sun { display: block; }
:root[data-theme="dark"] .theme-toggle .icon-moon { display: none; }

@media (max-width: 760px) {
  .nav-links { display: none; }
  .nav-toggle { display: inline-flex; }
  .site-nav { gap: var(--space-sm); }
}

/* Mobile menu panel */
.mobile-menu {
  display: none;
  position: fixed;
  inset: 0;
  z-index: 60;
  background: var(--bg);
  padding: var(--space-lg);
  flex-direction: column;
}
.mobile-menu.is-open { display: flex; }
.mobile-menu-head {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: var(--space-2xl);
}
.mobile-menu-controls {
  display: flex;
  align-items: center;
  gap: var(--space-2xs);
}
.mobile-menu ul {
  display: flex;
  flex-direction: column;
  gap: var(--space-lg);
}
.mobile-menu a {
  font-family: var(--font-display);
  font-size: var(--text-2xl);
  font-weight: 600;
}
.mobile-menu .btn { margin-top: var(--space-xl); align-self: flex-start; }

/* =========================================================
   Hero
   ========================================================= */

.hero {
  padding-top: var(--space-2xl);
  padding-bottom: var(--space-3xl);
}

.hero-grid {
  display: grid;
  grid-template-columns: 1.4fr 1fr;
  gap: var(--space-2xl);
  align-items: start;
}

@media (max-width: 860px) {
  .hero-grid { grid-template-columns: 1fr; gap: var(--space-xl); }
}

.hero h1 {
  font-size: var(--text-display);
  letter-spacing: -0.03em;
  margin-top: var(--space-md);
}

.hero .tagline {
  font-family: var(--font-display);
  font-weight: 500;
  font-size: var(--text-lg);
  color: var(--primary);
  margin-top: var(--space-sm);
}

.hero .lede {
  margin-top: var(--space-md);
  max-width: var(--measure);
  color: var(--muted);
  font-size: var(--text-base);
}

.hero .cta-row {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: var(--space-sm);
  margin-top: var(--space-xl);
}

.hero .cta-row .btn { padding: 0.75rem 1.3rem; font-size: var(--text-base); }

/* Shown only on mobile/tablet - desktop nav already exposes resume/nav links */
@media (min-width: 861px) {
  .hero .cta-row { display: none; }
}

.hero-meta {
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: var(--space-lg);
  background: var(--surface);
  font-size: var(--text-sm);
}

.hero-meta dl { display: grid; gap: var(--space-sm); }
.hero-meta > dl > div { display: grid; gap: 0.2rem; }
.hero-meta dt {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  color: var(--muted);
  letter-spacing: 0.05em;
  text-transform: uppercase;
}
.hero-meta dd { margin: 0; }
.hero-meta dd a {
  color: var(--primary);
  text-decoration: underline;
  text-decoration-color: oklch(0.420 0.100 172 / 0.35);
  text-underline-offset: 2px;
  transition: color 0.2s var(--ease-out-expo), text-decoration-color 0.2s var(--ease-out-expo);
}
.hero-meta dd a:hover,
.hero-meta dd a:focus-visible {
  color: var(--primary-strong);
  text-decoration-color: currentColor;
}

/* =========================================================
   Timeline (Experience)
   ========================================================= */

.timeline { display: grid; gap: var(--space-xl); }

.timeline-item {
  display: grid;
  grid-template-columns: 11rem 1fr;
  gap: var(--space-lg);
}

@media (max-width: 700px) {
  .timeline-item { grid-template-columns: 1fr; gap: var(--space-2xs); }
}

.timeline-when {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  color: var(--muted);
  letter-spacing: 0.03em;
  padding-top: 0.3rem;
}

.timeline-body h3 {
  font-size: var(--text-lg);
  letter-spacing: -0.01em;
}

.timeline-body .org {
  display: block;
  margin-top: 0.2rem;
  color: var(--primary);
  font-size: var(--text-sm);
  font-weight: 500;
}

.timeline-body ul {
  margin-top: var(--space-sm);
  display: grid;
  gap: var(--space-2xs);
}

.timeline-body li {
  position: relative;
  padding-left: var(--space-md);
  color: var(--ink);
  font-size: var(--text-sm);
  line-height: 1.65;
  text-wrap: pretty;
}
.timeline-body li::before {
  content: '';
  position: absolute;
  left: 0.2rem;
  top: 0.65em;
  width: 4px; height: 4px;
  background: var(--border);
  border-radius: 50%;
}

/* =========================================================
   Projects
   ========================================================= */

.project-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
  gap: var(--space-lg);
}

.project-card {
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: var(--space-lg);
  background: var(--bg);
  display: flex;
  flex-direction: column;
  gap: var(--space-sm);
  transition: border-color 0.2s var(--ease-out-expo), box-shadow 0.2s var(--ease-out-expo), transform 0.2s var(--ease-out-expo);
}
.project-card:hover {
  border-color: var(--primary);
  box-shadow: var(--shadow-md);
  transform: translateY(-2px);
}

.project-card-head {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: var(--space-sm);
}

.project-card h3 { font-size: var(--text-lg); letter-spacing: -0.01em; }

.status-pill {
  flex: none;
  font-family: var(--font-mono);
  font-size: 0.7rem;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  padding: 0.25rem 0.55rem;
  border-radius: 999px;
  background: var(--accent);
  color: var(--on-fill);
  white-space: nowrap;
}

.project-card ul {
  display: grid;
  gap: var(--space-2xs);
}

.project-card li {
  position: relative;
  padding-left: var(--space-md);
  font-size: var(--text-sm);
  color: var(--muted);
  line-height: 1.6;
  text-wrap: pretty;
}
.project-card li::before {
  content: '';
  position: absolute;
  left: 0.2rem;
  top: 0.65em;
  width: 4px; height: 4px;
  background: var(--border);
  border-radius: 50%;
}

.project-card .stack {
  margin-top: auto;
  padding-top: var(--space-sm);
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2xs);
}

.tag {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  color: var(--primary);
  background: var(--surface);
  border: 1px solid var(--border);
  padding: 0.2rem 0.5rem;
  border-radius: var(--radius-sm);
}

/* =========================================================
   Skills & Education
   ========================================================= */

.split-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--space-2xl);
}

@media (max-width: 820px) {
  .split-grid { grid-template-columns: 1fr; gap: var(--space-2xl); }
}

.skills-group { margin-bottom: var(--space-lg); }
.skills-group:last-child { margin-bottom: 0; }

.skills-group h3 {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--muted);
  margin-bottom: var(--space-sm);
  font-weight: 500;
}

.chip-row {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2xs);
}

.chip {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  padding: 0.35rem 0.65rem;
  border-radius: var(--radius-sm);
  background: var(--surface);
  border: 1px solid var(--border);
  color: var(--ink);
}

.edu-card {
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: var(--space-lg);
}

.edu-card h3 { font-size: var(--text-lg); }
.edu-card .school-meta {
  margin-top: 0.3rem;
  font-size: var(--text-sm);
  color: var(--muted);
}

.course-list {
  margin-top: var(--space-lg);
  display: grid;
  gap: var(--space-sm);
}

.course {
  display: grid;
  grid-template-columns: auto 1fr auto;
  align-items: baseline;
  gap: var(--space-sm);
  padding-bottom: var(--space-sm);
  border-bottom: 1px solid var(--border);
}
.course:last-child { border-bottom: none; padding-bottom: 0; }

.course-code {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  color: var(--primary);
  white-space: nowrap;
}

.course-name { font-size: var(--text-sm); }

.course-status {
  font-family: var(--font-mono);
  font-size: 0.65rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--accent-strong);
  white-space: nowrap;
}

/* =========================================================
   Contact / footer
   ========================================================= */

.contact-section .wrap {
  display: grid;
  grid-template-columns: 1.2fr 1fr;
  gap: var(--space-2xl);
  align-items: start;
}

@media (max-width: 820px) {
  .contact-section .wrap { grid-template-columns: 1fr; }
}

.contact-section h2 { font-size: var(--text-2xl); letter-spacing: -0.02em; max-width: 20ch; }
.contact-section .lede { margin-top: var(--space-md); color: var(--muted); max-width: var(--measure); }

.contact-links {
  display: grid;
  gap: var(--space-2xs);
}

.contact-link {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-sm);
  padding: var(--space-md);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  transition: border-color 0.2s var(--ease-out-expo), background-color 0.2s var(--ease-out-expo);
}
.contact-link:hover { border-color: var(--primary); background: var(--surface); }

.contact-link .label {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  color: var(--muted);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}
.contact-link .value { font-size: var(--text-sm); font-weight: 500; margin-top: 0.15rem; }
.contact-link svg { width: 16px; height: 16px; color: var(--muted); flex: none; }

.site-footer {
  border-top: 1px solid var(--border);
  padding-block: var(--space-lg);
}
.site-footer .wrap {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: var(--space-md);
  flex-wrap: wrap;
}
.site-footer p {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  color: var(--muted);
}

/* =========================================================
   Reveal-on-scroll
   ========================================================= */

.reveal {
  opacity: 0;
  transform: translateY(14px);
  transition: opacity 0.6s var(--ease-out-expo), transform 0.6s var(--ease-out-expo);
}
.reveal.is-visible { opacity: 1; transform: translateY(0); }

@media (prefers-reduced-motion: reduce) {
  .reveal { opacity: 1; transform: none; transition: none; }
  *, *::before, *::after { scroll-behavior: auto !important; transition: none !important; }
}

html { scroll-behavior: smooth; }

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