/* ==========================================================================
   Kaloyan K. — Personal site
   Vanilla CSS, no build step, no framework.
   Light-only. Typography, whitespace, and hierarchy carry the design —
   the component list on purpose is very short.
   ========================================================================== */

/* ---------- 1. Reset ---------- */

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

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

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

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

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

ol,
ul {
  list-style: none;
}

/* ---------- 2. Tokens ---------- */

:root {
  /* Color — light only */
  --bg: #ffffff;
  --bg-alt: #fbfbfd;
  --text: #1d1d1f;
  --text-secondary: #6e6e73;
  --text-tertiary: #86868b;
  --line: rgba(0, 0, 0, 0.08);
  --line-strong: rgba(0, 0, 0, 0.14);
  --focus-ring: #1d1d1f;

  /* Type */
  --font-sans: -apple-system, BlinkMacSystemFont, "SF Pro Display", "SF Pro Text",
    "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  --font-mono: ui-monospace, "SF Mono", "SFMono-Regular", Menlo, Consolas, monospace;

  /* Spacing — 8px base unit */
  --space-1: 0.5rem;   /* 8px */
  --space-2: 1rem;     /* 16px */
  --space-3: 1.5rem;   /* 24px */
  --space-4: 2rem;     /* 32px */
  --space-5: 3rem;     /* 48px */
  --space-6: 4.5rem;   /* 72px */
  --space-7: 7rem;     /* 112px */
  --space-8: 9.5rem;   /* 152px */

  /* Layout */
  --container-w: 1120px;

  /* Motion */
  --ease: cubic-bezier(0.16, 1, 0.3, 1);
  --dur-fast: 200ms;
  --dur-base: 420ms;
  --dur-slow: 800ms;
}

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }
  * {
    animation-duration: 0.001ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.001ms !important;
    scroll-behavior: auto !important;
  }
}

/* ---------- 3. Base / typography ---------- */

body {
  background: var(--bg);
  color: var(--text);
  font-family: var(--font-sans);
  font-size: 17px;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

h1,
h2,
h3 {
  font-weight: 600;
  letter-spacing: -0.03em;
  line-height: 1.08;
  color: var(--text);
}

h1 {
  font-size: clamp(2.75rem, 3.6vw + 1.8rem, 6.25rem);
  letter-spacing: -0.035em;
}

h2 {
  font-size: clamp(2.25rem, 2.6vw + 1.2rem, 3.75rem);
}

h3 {
  font-size: 1.25rem;
  letter-spacing: -0.015em;
}

p {
  color: var(--text-secondary);
}

::selection {
  background: var(--text);
  color: var(--bg);
}

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

.skip-link {
  position: fixed;
  top: -100%;
  left: var(--space-2);
  z-index: 300;
  background: var(--text);
  color: var(--bg);
  padding: var(--space-1) var(--space-2);
  border-radius: 6px;
  font-weight: 600;
  transition: top var(--dur-fast) var(--ease);
}

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

/* ---------- 4. Layout utilities ---------- */

.wrap {
  width: 100%;
  max-width: var(--container-w);
  margin-inline: auto;
  padding-inline: var(--space-3);
}

main section {
  padding-block: var(--space-8);
}

.eyebrow {
  font-size: 0.8125rem;
  font-weight: 600;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--text-tertiary);
  margin-bottom: var(--space-3);
}

/* ---------- 5. Reveal on scroll ---------- */

.reveal {
  opacity: 0;
  transform: translateY(22px);
  transition: opacity var(--dur-slow) var(--ease), transform var(--dur-slow) var(--ease);
}

.reveal.is-visible {
  opacity: 1;
  transform: translateY(0);
}

/* ---------- 6. Navigation ---------- */

.nav {
  position: sticky;
  top: 0;
  z-index: 200;
  border-bottom: 1px solid transparent;
  transition: border-color var(--dur-base) var(--ease), background var(--dur-base) var(--ease),
    backdrop-filter var(--dur-base) var(--ease);
}

.nav.is-scrolled {
  background: color-mix(in srgb, var(--bg) 78%, transparent);
  backdrop-filter: blur(16px) saturate(160%);
  -webkit-backdrop-filter: blur(16px) saturate(160%);
  border-bottom-color: var(--line);
}

.nav-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-block: var(--space-2);
}

.nav-brand {
  font-size: 0.9375rem;
  font-weight: 600;
  letter-spacing: -0.01em;
  color: var(--text);
}

.nav-links {
  display: flex;
  align-items: center;
  gap: var(--space-4);
}

.nav-links a {
  font-size: 0.9375rem;
  color: var(--text-secondary);
  transition: color var(--dur-fast) var(--ease);
}

.nav-links a:hover {
  color: var(--text);
}

.nav-toggle {
  display: none;
  flex-direction: column;
  justify-content: center;
  gap: 5px;
  width: 32px;
  height: 32px;
}

.nav-toggle span {
  display: block;
  height: 1.5px;
  width: 20px;
  margin-inline: auto;
  background: var(--text);
  transition: transform var(--dur-fast) var(--ease), opacity var(--dur-fast) var(--ease);
}

/* ---------- 7. Mobile menu ---------- */

.menu-scrim {
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.3);
  opacity: 0;
  pointer-events: none;
  transition: opacity var(--dur-base) var(--ease);
  z-index: 210;
}

.menu-scrim.is-open {
  opacity: 1;
  pointer-events: auto;
}

.mobile-menu {
  position: fixed;
  top: 0;
  right: 0;
  bottom: 0;
  width: min(320px, 84vw);
  background: var(--bg);
  border-left: 1px solid var(--line);
  z-index: 220;
  padding: var(--space-4) var(--space-3);
  display: flex;
  flex-direction: column;
  gap: var(--space-3);
  transform: translateX(100%);
  transition: transform var(--dur-base) var(--ease);
}

.mobile-menu.is-open {
  transform: translateX(0);
}

.mobile-menu-close {
  align-self: flex-end;
  font-size: 0.875rem;
  color: var(--text-secondary);
  padding: var(--space-1) 0;
  margin-bottom: var(--space-2);
}

.mobile-menu a {
  font-size: 1.5rem;
  font-weight: 500;
  letter-spacing: -0.02em;
  padding-block: var(--space-1);
  border-bottom: 1px solid var(--line);
}

/* ---------- 8. Hero ---------- */

.hero {
  padding-top: var(--space-7);
  padding-bottom: var(--space-7);
}

.hero h1 {
  max-width: 16ch;
  margin-bottom: var(--space-4);
}

.hero-lede {
  font-size: clamp(1.0625rem, 0.5vw + 1rem, 1.25rem);
  max-width: 42ch;
  margin-bottom: var(--space-4);
}

.hero-links {
  display: flex;
  align-items: center;
  gap: var(--space-4);
}

.hero-links a {
  font-size: 1rem;
  font-weight: 500;
  color: var(--text);
  border-bottom: 1px solid var(--line-strong);
  padding-bottom: 2px;
  transition: border-color var(--dur-fast) var(--ease), color var(--dur-fast) var(--ease);
}

.hero-links a:hover {
  border-color: var(--text);
}

/* ---------- 9. Selected work ---------- */

.work {
  background: var(--bg);
  border-top: 1px solid var(--line);
}

.project {
  padding-block: var(--space-7);
  border-bottom: 1px solid var(--line);
}

.project:last-child {
  border-bottom: none;
  padding-bottom: var(--space-3);
}

.project-head {
  display: flex;
  align-items: baseline;
  gap: var(--space-2);
  margin-bottom: var(--space-2);
}

.project-index {
  font-family: var(--font-mono);
  font-size: 0.8125rem;
  color: var(--text-tertiary);
}

.project-category {
  font-size: 0.8125rem;
  font-weight: 600;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: var(--text-tertiary);
}

.project h2 {
  font-size: clamp(2.5rem, 4.5vw + 1rem, 5rem);
  margin-bottom: var(--space-3);
  transition: transform var(--dur-slow) var(--ease);
}

.project-desc {
  font-size: 1.0625rem;
  max-width: 56ch;
  margin-bottom: var(--space-3);
}

.project-meta {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: var(--space-1) var(--space-3);
  font-family: var(--font-mono);
  font-size: 0.8125rem;
  color: var(--text-tertiary);
  margin-bottom: var(--space-3);
}

.project-stat.is-loading {
  opacity: 0;
}

.project-link {
  display: inline-block;
  font-size: 0.9375rem;
  font-weight: 500;
  color: var(--text);
  border-bottom: 1px solid var(--line-strong);
  padding-bottom: 2px;
  transition: border-color var(--dur-fast) var(--ease);
}

.project-link:hover {
  border-color: var(--text);
}

/* ---------- 9b. Featured project ---------- */

.project--featured {
  padding-top: var(--space-6);
}

.project-tagline {
  font-size: clamp(1.125rem, 0.6vw + 1rem, 1.375rem);
  font-weight: 600;
  letter-spacing: -0.015em;
  color: var(--text);
  max-width: 40ch;
  margin-bottom: var(--space-2);
}

.project-actions {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: var(--space-3);
  margin-bottom: var(--space-5);
}

.project-cta {
  display: inline-block;
  background: var(--text);
  color: var(--bg);
  font-size: 0.9375rem;
  font-weight: 500;
  padding: 0.75rem 1.375rem;
  border-radius: 8px;
  transition: opacity var(--dur-fast) var(--ease);
}

.project-cta:hover {
  opacity: 0.82;
}

.project-source {
  font-size: 0.9375rem;
  font-weight: 500;
  color: var(--text-secondary);
  border-bottom: 1px solid var(--line-strong);
  padding-bottom: 2px;
  transition: border-color var(--dur-fast) var(--ease), color var(--dur-fast) var(--ease);
}

.project-source:hover {
  color: var(--text);
  border-color: var(--text);
}

.featured-media {
  display: flex;
  justify-content: center;
  padding: var(--space-4);
  background: var(--bg-alt);
  border: 1px solid var(--line);
  border-radius: 16px;
}

.featured-media img {
  width: 100%;
  max-width: 860px;
  height: auto;
  border-radius: 10px;
  border: 1px solid var(--line);
}

/* ---------- 10. About ---------- */

.about {
  background: var(--bg-alt);
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
}

.about h2 {
  max-width: 18ch;
  margin-bottom: var(--space-5);
}

.about-copy {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: var(--space-5);
  max-width: 100%;
}

.about-copy p {
  font-size: 1.0625rem;
}

/* ---------- 11. Technologies ---------- */

.technologies {
  background: var(--bg);
}

.tech-list {
  font-size: clamp(1.375rem, 1.8vw + 0.8rem, 2.125rem);
  line-height: 1.5;
  letter-spacing: -0.01em;
  max-width: 46ch;
  color: var(--text);
  overflow-wrap: break-word;
}

.tech-item {
  color: var(--text);
}

.tech-sep {
  color: var(--text-tertiary);
  margin-inline: 0.35em;
}

/* ---------- 12. Timeline ---------- */

.timeline {
  background: var(--bg-alt);
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
}

.timeline-list {
  display: flex;
  flex-direction: column;
}

.timeline-item {
  display: grid;
  grid-template-columns: 220px 1fr;
  gap: var(--space-4);
  padding-block: var(--space-4);
  border-top: 1px solid var(--line);
}

.timeline-item:last-child {
  border-bottom: 1px solid var(--line);
}

.timeline-year {
  font-family: var(--font-mono);
  font-size: 0.9375rem;
  color: var(--text-secondary);
  padding-top: 0.2rem;
}

.timeline-body h3 {
  margin-bottom: var(--space-1);
}

.timeline-body p {
  font-size: 1rem;
  max-width: 60ch;
}

/* ---------- 13. Contact ---------- */

.contact {
  background: var(--bg);
}

.contact h2 {
  max-width: 14ch;
  margin-bottom: var(--space-3);
}

.contact-lede {
  font-size: 1.0625rem;
  max-width: 46ch;
  margin-bottom: var(--space-5);
}

.contact-links {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: var(--space-2) var(--space-5);
}

.contact-link {
  font-size: clamp(1.375rem, 1.6vw + 0.7rem, 1.875rem);
  font-weight: 500;
  letter-spacing: -0.015em;
  color: var(--text);
  border-bottom: 1px solid var(--line-strong);
  padding-bottom: 3px;
  transition: border-color var(--dur-fast) var(--ease), color var(--dur-fast) var(--ease);
}

.contact-link:hover {
  border-color: var(--text);
}

/* ---------- 14. Footer ---------- */

footer {
  border-top: 1px solid var(--line);
  padding-block: var(--space-4);
}

.footer-inner {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-2) var(--space-4);
}

.footer-brand {
  font-size: 0.9375rem;
  font-weight: 600;
  letter-spacing: -0.01em;
  color: var(--text);
}

.footer-links {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-1) var(--space-3);
}

.footer-links a {
  font-size: 0.875rem;
  color: var(--text-secondary);
  transition: color var(--dur-fast) var(--ease);
}

.footer-links a:hover {
  color: var(--text);
}

.footer-copyright {
  font-size: 0.8125rem;
  color: var(--text-tertiary);
}

/* ---------- 15. Toast ---------- */

.toast {
  position: fixed;
  left: 50%;
  bottom: var(--space-4);
  transform: translate(-50%, 12px);
  background: var(--text);
  color: var(--bg);
  font-size: 0.875rem;
  font-weight: 500;
  padding: 0.75rem 1.15rem;
  border-radius: 8px;
  opacity: 0;
  pointer-events: none;
  transition: opacity var(--dur-base) var(--ease), transform var(--dur-base) var(--ease);
  z-index: 260;
}

.toast.is-active {
  opacity: 1;
  transform: translate(-50%, 0);
}

/* ---------- 16. Responsive ---------- */

@media (max-width: 900px) {
  .nav-links {
    display: none;
  }

  .nav-toggle {
    display: flex;
  }

  .about-copy {
    grid-template-columns: 1fr;
    gap: var(--space-3);
  }

  main section {
    padding-block: var(--space-7);
  }

  .project {
    padding-block: var(--space-6);
  }
}

@media (max-width: 640px) {
  body {
    font-size: 16px;
  }

  main section {
    padding-block: var(--space-6);
  }

  .hero {
    padding-top: var(--space-5);
    padding-bottom: var(--space-5);
  }

  .hero h1 {
    max-width: 12ch;
  }

  .hero-links {
    gap: var(--space-3);
  }

  .project {
    padding-block: var(--space-5);
  }

  .project-meta {
    flex-direction: column;
    align-items: flex-start;
    gap: var(--space-1);
  }

  .project--featured {
    padding-top: var(--space-4);
  }

  .project-actions {
    margin-bottom: var(--space-4);
  }

  .featured-media {
    padding: var(--space-2);
    border-radius: 12px;
  }

  .featured-media img {
    border-radius: 8px;
  }

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

  .contact-links {
    flex-direction: column;
    align-items: flex-start;
    gap: var(--space-3);
  }

  .footer-inner {
    flex-direction: column;
    align-items: flex-start;
  }
}