/* =====================================================================
   Ryan Kim — Portfolio Stylesheet (shared by every page)
   ---------------------------------------------------------------------
   TABLE OF CONTENTS
    1. Theme variables  ← change colors, fonts and spacing here
    2. Base / reset
    3. Layout helpers
    4. Buttons, chips & tags
    5. Navigation
    6. Hero (home page)
    7. Sections & cards
    8. Home: goals, tech stack, call-to-action
    9. About: bio, education, timeline, skills
   10. Projects: filters & grid
   11. 404 page
   12. Footer
   13. Fade-in-on-scroll animation
   14. Responsive (tablet & phone)
   15. Reduced motion
   ===================================================================== */


/* =====================================================================
   1. THEME VARIABLES
   ===================================================================== */
:root {
  /* ---- Fonts ---- */
  --font-sans: "Inter", system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  --font-mono: ui-monospace, "SFMono-Regular", Menlo, Consolas, monospace;

  /* ---- Spacing scale ---- */
  --space-1: 0.25rem;   /*  4px */
  --space-2: 0.5rem;    /*  8px */
  --space-3: 0.75rem;   /* 12px */
  --space-4: 1rem;      /* 16px */
  --space-5: 1.5rem;    /* 24px */
  --space-6: 2rem;      /* 32px */
  --space-7: 3rem;      /* 48px */
  --space-8: 4rem;      /* 64px */
  --space-9: 6rem;      /* 96px */

  /* ---- Shapes, sizes & motion ---- */
  --container: 1120px;
  --nav-height: 68px;
  --radius-sm: 8px;
  --radius: 14px;
  --radius-lg: 20px;
  --radius-full: 999px;
  --transition: 200ms ease;

  /* ---- LIGHT theme colors (default) ---- */
  --color-bg: #f8fafc;
  --color-bg-alt: #f1f5f9;
  --color-surface: #ffffff;
  --color-text: #0f172a;
  --color-text-muted: #475569;
  --color-border: #e2e8f0;
  --color-accent: #4f46e5;
  --color-accent-hover: #4338ca;
  --color-accent-soft: rgba(79, 70, 229, 0.10);
  --color-on-accent: #ffffff;
  --color-header-bg: rgba(248, 250, 252, 0.85);
  --color-code-bg: #0f172a;
  --shadow-sm: 0 1px 2px rgba(15, 23, 42, 0.06);
  --shadow-md: 0 12px 30px -12px rgba(15, 23, 42, 0.20);
  --shadow-lg: 0 24px 48px -20px rgba(15, 23, 42, 0.35);
  color-scheme: light;
}

/* ---- DARK theme colors ----
   Used when the visitor picks dark mode (data-theme="dark"),
   or when their device is set to dark and they haven't picked.
   Keep the two blocks below identical. */
:root[data-theme="dark"] {
  --color-bg: #0b1120;
  --color-bg-alt: #0f172a;
  --color-surface: #131c31;
  --color-text: #e2e8f0;
  --color-text-muted: #94a3b8;
  --color-border: #1f2a44;
  --color-accent: #818cf8;
  --color-accent-hover: #a5b4fc;
  --color-accent-soft: rgba(129, 140, 248, 0.14);
  --color-on-accent: #0b1120;
  --color-header-bg: rgba(11, 17, 32, 0.82);
  --color-code-bg: #080d1a;
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.40);
  --shadow-md: 0 12px 30px -12px rgba(0, 0, 0, 0.60);
  --shadow-lg: 0 24px 48px -20px rgba(0, 0, 0, 0.75);
  color-scheme: dark;
}

@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --color-bg: #0b1120;
    --color-bg-alt: #0f172a;
    --color-surface: #131c31;
    --color-text: #e2e8f0;
    --color-text-muted: #94a3b8;
    --color-border: #1f2a44;
    --color-accent: #818cf8;
    --color-accent-hover: #a5b4fc;
    --color-accent-soft: rgba(129, 140, 248, 0.14);
    --color-on-accent: #0b1120;
    --color-header-bg: rgba(11, 17, 32, 0.82);
    --color-code-bg: #080d1a;
    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.40);
    --shadow-md: 0 12px 30px -12px rgba(0, 0, 0, 0.60);
    --shadow-lg: 0 24px 48px -20px rgba(0, 0, 0, 0.75);
    color-scheme: dark;
  }
}


/* =====================================================================
   2. BASE / RESET
   ===================================================================== */
*,
*::before,
*::after {
  box-sizing: border-box;
}

html {
  -webkit-text-size-adjust: 100%;
  /* Keeps in-page links from hiding under the sticky nav */
  scroll-padding-top: calc(var(--nav-height) + var(--space-4));
}

@media (prefers-reduced-motion: no-preference) {
  html { scroll-behavior: smooth; }
}

body {
  margin: 0;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  font-family: var(--font-sans);
  font-size: 1rem;
  line-height: 1.65;
  color: var(--color-text);
  background-color: var(--color-bg);
  -webkit-font-smoothing: antialiased;
  transition: background-color var(--transition), color var(--transition);
}

main { flex: 1; }

img {
  display: block;
  max-width: 100%;
  height: auto;
}

h1, h2, h3 {
  margin: 0 0 var(--space-3);
  line-height: 1.2;
  letter-spacing: -0.02em;
  color: var(--color-text);
}
h1 { font-size: clamp(2.25rem, 5vw, 3.5rem); font-weight: 800; }
h2 { font-size: clamp(1.75rem, 3.5vw, 2.375rem); font-weight: 700; }
h3 { font-size: 1.125rem; font-weight: 600; }

p { margin: 0 0 var(--space-4); }
p:last-child { margin-bottom: 0; }

a {
  color: var(--color-accent);
  text-decoration: none;
  transition: color var(--transition);
}
a:hover { color: var(--color-accent-hover); }

/* Clear focus ring for keyboard users */
:focus-visible {
  outline: 3px solid var(--color-accent);
  outline-offset: 3px;
  border-radius: 4px;
}

[hidden] { display: none !important; }

/* Text that only screen readers announce */
.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;
}

/* "Skip to main content" link — appears when tabbing */
.skip-link {
  position: absolute;
  left: var(--space-4);
  top: -100px;
  z-index: 200;
  padding: var(--space-3) var(--space-4);
  border-radius: var(--radius-sm);
  background: var(--color-accent);
  color: var(--color-on-accent);
  font-weight: 600;
}
.skip-link:focus { top: var(--space-4); color: var(--color-on-accent); }


/* =====================================================================
   3. LAYOUT HELPERS
   ===================================================================== */
.container {
  width: 100%;
  max-width: var(--container);
  margin-inline: auto;
  padding-inline: var(--space-5);
}

.section { padding-block: var(--space-9); }
.section-tight { padding-top: var(--space-5); }
.section-alt {
  background-color: var(--color-bg-alt);
  border-block: 1px solid var(--color-border);
}

.section-head {
  max-width: 640px;
  margin-bottom: var(--space-7);
}

.eyebrow {
  margin-bottom: var(--space-2);
  font-size: 0.8125rem;
  font-weight: 600;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--color-accent);
}

.section-sub {
  font-size: 1.0625rem;
  color: var(--color-text-muted);
}


/* =====================================================================
   4. BUTTONS, CHIPS & TAGS
   ===================================================================== */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-2);
  padding: 0.8rem 1.4rem;
  border: 1.5px solid transparent;
  border-radius: var(--radius-full);
  font: inherit;
  font-size: 0.9375rem;
  font-weight: 600;
  line-height: 1.2;
  text-align: center;
  cursor: pointer;
  transition: transform var(--transition), background-color var(--transition),
              border-color var(--transition), color var(--transition), box-shadow var(--transition);
}
.btn svg { width: 18px; height: 18px; flex-shrink: 0; }

.btn-primary {
  background: var(--color-accent);
  color: var(--color-on-accent);
  box-shadow: 0 10px 24px -12px var(--color-accent);
}
.btn-primary:hover {
  background: var(--color-accent-hover);
  color: var(--color-on-accent);
  transform: translateY(-2px);
}

.btn-secondary {
  background: var(--color-surface);
  border-color: var(--color-border);
  color: var(--color-text);
}
.btn-secondary:hover {
  border-color: var(--color-accent);
  color: var(--color-accent);
  transform: translateY(-2px);
}

.btn-ghost {
  background: transparent;
  border-color: var(--color-border);
  color: var(--color-text);
}
.btn-ghost:hover {
  border-color: var(--color-accent);
  color: var(--color-accent);
}
/* Placeholder "#" links look slightly faded until a real link is added */
.btn[aria-disabled="true"] { opacity: 0.6; cursor: not-allowed; }

.btn-sm { padding: 0.55rem 1rem; font-size: 0.875rem; }

.btn-row {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-3);
}
.btn-row.center { justify-content: center; }

/* Chips: skills / tech stack */
.chip-list,
.tag-list,
.nav-links,
.footer-links {
  list-style: none;
  margin: 0;
  padding: 0;
}

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

.chip {
  padding: 0.45rem 0.95rem;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-full);
  background: var(--color-surface);
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--color-text);
  transition: border-color var(--transition), color var(--transition), transform var(--transition);
}
.chip:hover {
  border-color: var(--color-accent);
  color: var(--color-accent);
  transform: translateY(-1px);
}

/* Tags: small labels on project cards */
.tag-list {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
  margin-bottom: var(--space-5);
}
.tag {
  padding: 0.25rem 0.65rem;
  border-radius: var(--radius-full);
  background: var(--color-accent-soft);
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--color-accent);
}


/* =====================================================================
   5. NAVIGATION
   ===================================================================== */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: var(--color-header-bg);
  -webkit-backdrop-filter: saturate(180%) blur(12px);
  backdrop-filter: saturate(180%) blur(12px);
  border-bottom: 1px solid transparent;
  transition: border-color var(--transition), box-shadow var(--transition), background-color var(--transition);
}
.site-header.is-scrolled {
  border-bottom-color: var(--color-border);
  box-shadow: var(--shadow-sm);
}

.nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-4);
  height: var(--nav-height);
}

.nav-logo {
  display: inline-flex;
  align-items: center;
  gap: 0.6rem;
  font-size: 1.0625rem;
  font-weight: 700;
  color: var(--color-text);
}
.nav-logo:hover { color: var(--color-text); }

.logo-mark {
  display: grid;
  place-items: center;
  width: 36px;
  height: 36px;
  border-radius: 10px;
  background: var(--color-accent);
  color: var(--color-on-accent);
  font-size: 0.875rem;
  font-weight: 800;
  letter-spacing: 0.02em;
}

.nav-right {
  display: flex;
  align-items: center;
  gap: var(--space-2);
}

.nav-links {
  display: flex;
  gap: var(--space-1);
}
.nav-links a {
  display: block;
  padding: 0.5rem 0.9rem;
  border-radius: var(--radius-full);
  font-size: 0.9375rem;
  font-weight: 500;
  color: var(--color-text-muted);
  transition: color var(--transition), background-color var(--transition);
}
.nav-links a:hover {
  color: var(--color-text);
  background: var(--color-accent-soft);
}
/* Highlight the current page */
.nav-links a[aria-current="page"] {
  color: var(--color-accent);
  background: var(--color-accent-soft);
  font-weight: 600;
}

/* Round icon buttons (theme + hamburger) */
.icon-btn {
  display: inline-grid;
  place-items: center;
  width: 40px;
  height: 40px;
  padding: 0;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-full);
  background: var(--color-surface);
  color: var(--color-text);
  cursor: pointer;
  transition: border-color var(--transition), color var(--transition), background-color var(--transition);
}
.icon-btn:hover {
  border-color: var(--color-accent);
  color: var(--color-accent);
}
.icon-btn svg { width: 18px; height: 18px; }

/* Show the moon in light mode, the sun in dark mode */
.icon-sun { display: none; }
:root[data-theme="dark"] .icon-sun { display: block; }
:root[data-theme="dark"] .icon-moon { display: none; }
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) .icon-sun { display: block; }
  :root:not([data-theme="light"]) .icon-moon { display: none; }
}

/* Hamburger icon (three lines that turn into an X) */
.nav-toggle { display: none; }

.hamburger,
.hamburger::before,
.hamburger::after {
  display: block;
  position: relative;
  width: 18px;
  height: 2px;
  border-radius: 2px;
  background: currentColor;
  transition: transform var(--transition), background-color var(--transition), top var(--transition);
}
.hamburger::before,
.hamburger::after {
  content: "";
  position: absolute;
  left: 0;
}
.hamburger::before { top: -6px; }
.hamburger::after  { top: 6px; }

.nav-toggle[aria-expanded="true"] .hamburger { background: transparent; }
.nav-toggle[aria-expanded="true"] .hamburger::before { top: 0; transform: rotate(45deg); }
.nav-toggle[aria-expanded="true"] .hamburger::after  { top: 0; transform: rotate(-45deg); }


/* =====================================================================
   6. HERO (home page)
   ===================================================================== */
.hero,
.page-hero {
  position: relative;
  isolation: isolate;
  overflow: hidden;
}

/* Soft accent glow behind the hero */
.hero::before,
.page-hero::before {
  content: "";
  position: absolute;
  z-index: -1;
  top: -220px;
  right: -160px;
  width: 620px;
  height: 620px;
  border-radius: 50%;
  background: radial-gradient(circle, var(--color-accent-soft) 0%, transparent 65%);
  pointer-events: none;
}

.hero { padding-block: var(--space-9) var(--space-8); }

.hero-grid {
  display: grid;
  grid-template-columns: 1.15fr 1fr;
  gap: var(--space-8);
  align-items: center;
}
.hero-grid > * { min-width: 0; }

.hero-title {
  margin-bottom: var(--space-3);
  font-size: clamp(2.75rem, 7vw, 4.5rem);
}
.accent-dot { color: var(--color-accent); }

.hero-role {
  margin-bottom: var(--space-4);
  font-size: clamp(1.0625rem, 2vw, 1.25rem);
  font-weight: 600;
}
.hero-role .divider {
  margin-inline: 0.4rem;
  color: var(--color-accent);
}

.hero-intro {
  max-width: 34rem;
  margin-bottom: var(--space-6);
  font-size: 1.125rem;
  color: var(--color-text-muted);
}

.hero-meta {
  margin-top: var(--space-6);
  font-size: 0.9rem;
  color: var(--color-text-muted);
}

/* "Open to work" pill */
.status-pill {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  margin-bottom: var(--space-5);
  padding: 0.35rem 0.85rem;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-full);
  background: var(--color-surface);
  font-size: 0.8125rem;
  font-weight: 600;
  color: var(--color-text);
  box-shadow: var(--shadow-sm);
}
.status-dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: #22c55e;
  box-shadow: 0 0 0 3px rgba(34, 197, 94, 0.2);
}

/* Highlight numbers under the intro */
.hero-stats {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: var(--space-4);
  max-width: 34rem;
  margin: 0 0 var(--space-6);
  padding: var(--space-4) 0 0;
  border-top: 1px solid var(--color-border);
  list-style: none;
}
.hero-stats li { display: flex; flex-direction: column; gap: 0.15rem; }
.hero-stats strong {
  font-size: 1.625rem;
  font-weight: 800;
  line-height: 1.1;
  letter-spacing: -0.02em;
  color: var(--color-accent);
}
.hero-stats span {
  font-size: 0.8125rem;
  line-height: 1.4;
  color: var(--color-text-muted);
}
@media (max-width: 480px) {
  .hero-stats strong { font-size: 1.375rem; }
}

/* Decorative code card */
.code-card {
  overflow: hidden;
  border: 1px solid rgba(148, 163, 184, 0.18);
  border-radius: var(--radius-lg);
  background: var(--color-code-bg);
  box-shadow: var(--shadow-lg);
}
.code-card-bar {
  display: flex;
  align-items: center;
  gap: 6px;
  padding: 0.8rem 1rem;
  border-bottom: 1px solid rgba(148, 163, 184, 0.14);
}
.code-card-bar .dot {
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background: #334155;
}
.code-file {
  margin-left: 0.75rem;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: #94a3b8;
}
.code-card pre {
  margin: 0;
  padding: 1.25rem 1.4rem;
  overflow-x: auto;
  font-family: var(--font-mono);
  font-size: 0.8125rem;
  line-height: 1.8;
  color: #e2e8f0;
}
.tk-key  { color: #c4b5fd; }
.tk-prop { color: #7dd3fc; }
.tk-str  { color: #86efac; }


/* =====================================================================
   7. SECTIONS & CARDS
   ===================================================================== */
.page-hero { padding-block: var(--space-8) var(--space-6); }
.page-sub {
  max-width: 40rem;
  font-size: 1.125rem;
  color: var(--color-text-muted);
}

.card {
  padding: var(--space-6);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  background: var(--color-surface);
  box-shadow: var(--shadow-sm);
  transition: transform var(--transition), box-shadow var(--transition),
              border-color var(--transition), background-color var(--transition);
}

/* Cards that lift on hover */
.card-hover:hover,
.project-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-md);
  border-color: var(--color-accent-soft);
}

.card-grid {
  display: grid;
  gap: var(--space-5);
}


/* =====================================================================
   8. HOME: GOALS, TECH STACK, CALL-TO-ACTION
   ===================================================================== */
.goals-grid { grid-template-columns: repeat(auto-fit, minmax(min(240px, 100%), 1fr)); }

.goal-icon {
  display: grid;
  place-items: center;
  flex-shrink: 0;
  width: 48px;
  height: 48px;
  margin-bottom: var(--space-4);
  border-radius: 12px;
  background: var(--color-accent-soft);
  font-size: 1.5rem;
  line-height: 1;
}

.goal-card p {
  font-size: 0.9375rem;
  color: var(--color-text-muted);
}

.stack {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: var(--space-7) var(--space-8);
}

/* Chips with a logo */
.chip--icon {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding-left: 0.7rem;
}
.chip-icon {
  width: 18px;
  height: 18px;
  flex-shrink: 0;
}
.chip-icon--line { color: var(--color-accent); }
.chip-badge {
  display: inline-grid;
  place-items: center;
  width: 18px;
  height: 18px;
  flex-shrink: 0;
  border-radius: 4px;
  font-size: 0.5625rem;
  font-weight: 800;
  letter-spacing: -0.02em;
  line-height: 1;
}
/* Black logos (GitHub, Unity) turn white in dark mode */
:root[data-theme="dark"] .chip-icon--mono { filter: invert(1); }
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) .chip-icon--mono { filter: invert(1); }
}
.stack-label {
  margin-bottom: var(--space-3);
  font-size: 0.8125rem;
  font-weight: 600;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--color-text-muted);
}

.cta-card {
  padding: var(--space-8) var(--space-6);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  background:
    radial-gradient(circle at top left, var(--color-accent-soft), transparent 60%),
    var(--color-surface);
  text-align: center;
}
.cta-card p {
  max-width: 36rem;
  margin: 0 auto var(--space-6);
  color: var(--color-text-muted);
}
.cta-compact {
  margin-top: var(--space-8);
  padding-block: var(--space-7);
}
.cta-compact h2 { font-size: clamp(1.5rem, 3vw, 1.875rem); }


/* =====================================================================
   9. ABOUT: BIO, EDUCATION, TIMELINE, SKILLS
   ===================================================================== */
.bio-grid {
  display: grid;
  grid-template-columns: 1.6fr 1fr;
  gap: var(--space-7);
  align-items: start;
}
.bio-grid > * { min-width: 0; }

.bio-text p {
  font-size: 1.0625rem;
  color: var(--color-text-muted);
}

.facts {
  display: grid;
  gap: var(--space-4);
  margin: 0 0 var(--space-6);
}
.facts dt {
  font-size: 0.75rem;
  font-weight: 600;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--color-text-muted);
}
.facts dd {
  margin: 0;
  font-weight: 500;
}
.facts-card .btn { width: 100%; }

/* Education */
.edu-card {
  display: flex;
  align-items: flex-start;
  gap: var(--space-5);
  max-width: 760px;
}
.edu-card .goal-icon { margin-bottom: 0; }
.edu-card h3 { font-size: 1.25rem; margin-bottom: var(--space-1); }
.edu-degree {
  margin-bottom: var(--space-2);
  font-weight: 600;
  color: var(--color-accent);
}
.edu-meta {
  font-size: 0.9375rem;
  color: var(--color-text-muted);
}
.edu-detail {
  font-size: 0.9375rem;
  color: var(--color-text-muted);
}
.edu-detail strong { color: var(--color-text); }

/* Timeline */
.timeline {
  position: relative;
  max-width: 760px;
  margin: 0;
  padding: 0;
  list-style: none;
}
/* Vertical line */
.timeline::before {
  content: "";
  position: absolute;
  top: 8px;
  bottom: 8px;
  left: 11px;
  width: 2px;
  background: var(--color-border);
}
.timeline-item {
  position: relative;
  padding-left: var(--space-7);
  padding-bottom: var(--space-5);
}
.timeline-item:last-child { padding-bottom: 0; }
.timeline-dot {
  position: absolute;
  top: 1.6rem;
  left: 4px;
  width: 16px;
  height: 16px;
  border: 3px solid var(--color-accent);
  border-radius: 50%;
  background: var(--color-surface);
  box-shadow: 0 0 0 4px var(--color-bg);
}
.timeline-content { padding: var(--space-5) var(--space-6); }
.timeline-date {
  margin-bottom: var(--space-1);
  font-size: 0.8125rem;
  font-weight: 600;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: var(--color-accent);
}
.timeline-content p:not(.timeline-date) {
  font-size: 0.9375rem;
  color: var(--color-text-muted);
}

/* Clubs */
.clubs-grid { grid-template-columns: repeat(auto-fit, minmax(min(240px, 100%), 1fr)); }
.club-card {
  display: flex;
  align-items: center;
  gap: var(--space-4);
}
.club-card .goal-icon { margin-bottom: 0; }
.club-card h3 { margin-bottom: 0.15rem; font-size: 1rem; }
.club-card p { font-size: 0.875rem; color: var(--color-text-muted); }

/* Skills */
.skills-grid { grid-template-columns: repeat(auto-fit, minmax(min(180px, 100%), 1fr)); }
.skill-card h3 {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  margin-bottom: var(--space-4);
}


/* =====================================================================
   10. PROJECTS: FILTERS & GRID
   ===================================================================== */
.filter-bar {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2);
  margin-bottom: var(--space-3);
}
.filter-btn {
  padding: 0.55rem 1.1rem;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-full);
  background: var(--color-surface);
  font: inherit;
  font-size: 0.9rem;
  font-weight: 500;
  color: var(--color-text-muted);
  cursor: pointer;
  transition: background-color var(--transition), border-color var(--transition), color var(--transition);
}
.filter-btn:hover {
  border-color: var(--color-accent);
  color: var(--color-text);
}
.filter-btn[aria-pressed="true"] {
  border-color: var(--color-accent);
  background: var(--color-accent);
  color: var(--color-on-accent);
}

.filter-status {
  min-height: 1.5em;
  margin-bottom: var(--space-5);
  font-size: 0.875rem;
  color: var(--color-text-muted);
}

.project-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(min(300px, 100%), 1fr));
  gap: var(--space-5);
}

.project-card {
  display: flex;
  flex-direction: column;
  overflow: hidden;
  padding: 0;
}

/* Screenshot area (16:10) */
.project-media {
  position: relative;
  aspect-ratio: 16 / 10;
  overflow: hidden;
  border-bottom: 1px solid var(--color-border);
  background: var(--color-bg-alt);
}
.project-media img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  transition: transform 400ms ease;
}
.project-card:hover .project-media img { transform: scale(1.04); }

/* Gray "Screenshot coming soon" box (shown when the image is missing) */
.media-fallback {
  display: none;
  position: absolute;
  inset: 0;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: var(--space-2);
  background:
    repeating-linear-gradient(45deg,
      transparent 0 14px,
      rgba(148, 163, 184, 0.08) 14px 28px),
    var(--color-bg-alt);
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--color-text-muted);
}
.media-fallback svg { width: 34px; height: 34px; opacity: 0.7; }
.project-media.is-missing img { display: none; }
.project-media.is-missing .media-fallback { display: flex; }

/* Thumbnails that should never be cropped (e.g. text in the image) */
.project-media--fit { background: #0b1120; }
.project-media--fit img { object-fit: contain; }

/* Charts: white background, never cropped */
.project-media--chart { background: #ffffff; }
.project-media--chart img { object-fit: contain; }

/* Logo images: show the whole logo on white instead of cropping it */
.project-media--logo { background: #ffffff; }
.project-media--logo img {
  object-fit: contain;
  padding: var(--space-4);
}
.project-card:hover .project-media--logo img { transform: scale(1.02); }

.project-meta {
  margin-bottom: var(--space-3);
  font-size: 0.8125rem;
  font-weight: 500;
  color: var(--color-text);
}

.project-body {
  display: flex;
  flex: 1;
  flex-direction: column;
  padding: var(--space-5) var(--space-5) var(--space-6);
}
.project-category {
  margin-bottom: var(--space-1);
  font-size: 0.75rem;
  font-weight: 600;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--color-accent);
}
.project-title { margin-bottom: var(--space-2); }
.project-desc {
  font-size: 0.9375rem;
  color: var(--color-text-muted);
}
.project-links {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2);
  margin-top: auto;
}

.empty-state {
  padding: var(--space-7);
  border: 1px dashed var(--color-border);
  border-radius: var(--radius);
  text-align: center;
  color: var(--color-text-muted);
}

/* Little "pop in" when a card reappears after filtering */
@keyframes card-in {
  from { opacity: 0; transform: translateY(12px) scale(0.98); }
  to   { opacity: 1; transform: none; }
}
.project-card.is-entering { animation: card-in 350ms ease both; }


/* =====================================================================
   11. 404 PAGE
   ===================================================================== */
.notfound {
  display: grid;
  place-items: center;
  padding-block: var(--space-9);
  text-align: center;
}
.notfound-code {
  margin-bottom: var(--space-4);
  font-size: clamp(5rem, 18vw, 9rem);
  font-weight: 800;
  line-height: 1;
  letter-spacing: -0.05em;
  background: linear-gradient(135deg, var(--color-accent), var(--color-text-muted));
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}
.notfound-inner > p:not(.notfound-code) {
  max-width: 28rem;
  margin: 0 auto var(--space-6);
  color: var(--color-text-muted);
}


/* =====================================================================
   12. FOOTER
   ===================================================================== */
.site-footer {
  padding-block: var(--space-6);
  border-top: 1px solid var(--color-border);
  background: var(--color-bg);
}
.footer-inner {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-4);
}
.footer-copy {
  margin: 0;
  font-size: 0.875rem;
  color: var(--color-text-muted);
}
.footer-links {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2);
}
.footer-links a {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  padding: 0.45rem 0.85rem;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-full);
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--color-text-muted);
  transition: color var(--transition), border-color var(--transition);
}
.footer-links a:hover {
  border-color: var(--color-accent);
  color: var(--color-accent);
}
.footer-links svg { width: 16px; height: 16px; }


/* =====================================================================
   13. FADE-IN-ON-SCROLL
   Elements with class="reveal" start hidden and fade up when they
   scroll into view (main.js adds "is-visible"). The "js" class makes
   sure content is never hidden if JavaScript is turned off.
   Uses the separate `translate` property so card hover lifts
   (which use `transform`) still work.
   ===================================================================== */
.js .reveal {
  opacity: 0;
  translate: 0 20px;
  transition:
    opacity 600ms ease var(--reveal-delay, 0ms),
    translate 600ms ease var(--reveal-delay, 0ms),
    transform var(--transition),
    box-shadow var(--transition),
    border-color var(--transition),
    background-color var(--transition);
}
.js .reveal.is-visible {
  opacity: 1;
  translate: 0 0;
}


/* =====================================================================
   14. RESPONSIVE
   ===================================================================== */

/* ---- Tablet ---- */
@media (max-width: 900px) {
  .hero-grid,
  .bio-grid {
    grid-template-columns: 1fr;
    gap: var(--space-7);
  }
  .hero-visual { max-width: 560px; }
}

/* ---- Mobile menu ---- */
@media (max-width: 760px) {
  .js .nav-toggle { display: inline-grid; }

  .js .nav-links {
    display: none;
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    flex-direction: column;
    gap: var(--space-1);
    padding: var(--space-3) var(--space-4) var(--space-5);
    border-bottom: 1px solid var(--color-border);
    background: var(--color-surface);
    box-shadow: var(--shadow-md);
  }
  .js .nav-links.is-open { display: flex; }
  .js .nav-links a {
    padding: 0.85rem 1rem;
    border-radius: var(--radius-sm);
    font-size: 1rem;
  }

  /* Without JavaScript the links simply stay in the bar */
  .nav-links a { padding: 0.45rem 0.6rem; }
}

/* ---- Phone ---- */
@media (max-width: 640px) {
  .container { padding-inline: var(--space-4); }
  .section { padding-block: var(--space-8); }
  .section-tight { padding-top: var(--space-4); }
  .hero { padding-block: var(--space-7); }
  .page-hero { padding-block: var(--space-7) var(--space-5); }
  .section-head { margin-bottom: var(--space-6); }

  .card { padding: var(--space-5); }
  .timeline-content { padding: var(--space-5); }
  .timeline-item { padding-left: var(--space-6); }

  .stack { grid-template-columns: 1fr; gap: var(--space-6); }
  .edu-card { flex-direction: column; }
  .cta-card { padding: var(--space-7) var(--space-5); }

  .hero .btn-row .btn { flex: 1 1 auto; }
  .footer-inner { flex-direction: column; align-items: flex-start; }
}


/* =====================================================================
   15. REDUCED MOTION
   Visitors who ask their device for less motion get no animations.
   ===================================================================== */
@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    transition-delay: 0ms !important;
    scroll-behavior: auto !important;
  }
  .js .reveal { opacity: 1; translate: none; }
  .btn:hover,
  .chip:hover,
  .card-hover:hover,
  .project-card:hover,
  .project-card:hover .project-media img { transform: none; }
}