/* ==========================================================
   Rasoul Samei — personal site
   Tokens → base → layout → sections → motion → dark → a11y
   ========================================================== */

:root {
  --ink:         #14151a;
  --ink-muted:   #5c6070;
  --ink-faint:   #82869a;
  --paper:       #faf9f7;
  --paper-alt:   #f2f0ec;
  --line:        #e3e0da;
  --accent:      #1f4f43;
  --accent-soft: #e8efec;

  --serif: "Instrument Serif", Georgia, "Times New Roman", serif;
  --sans:  "Inter", system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;

  --step--1: clamp(0.83rem, 0.80rem + 0.15vw, 0.94rem);
  --step-0:  clamp(1.00rem, 0.95rem + 0.25vw, 1.15rem);
  --step-1:  clamp(1.35rem, 1.20rem + 0.70vw, 1.85rem);
  --step-2:  clamp(1.80rem, 1.45rem + 1.60vw, 3.00rem);
  --step-3:  clamp(2.40rem, 1.70rem + 3.20vw, 4.80rem);
  --step-4:  clamp(3.00rem, 1.80rem + 5.50vw, 7.00rem);

  --s1: 0.5rem; --s2: 1rem; --s3: 1.5rem; --s4: 2rem; --s5: 3rem;
  --s6: 4rem; --s7: 6rem; --s8: 8rem;

  --container: 1180px;
  --gutter: clamp(1.25rem, 5vw, 4rem);
  --section-gap: clamp(6rem, 12vh, 10rem);

  --ease: cubic-bezier(0.22, 0.61, 0.36, 1);
  --dur-fast: 220ms;
  --dur: 420ms;
  --dur-slow: 700ms;
}

/* ---------- Base ---------- */
*, *::before, *::after { box-sizing: border-box; }
html { scroll-behavior: smooth; -webkit-text-size-adjust: 100%; }
body {
  margin: 0;
  font-family: var(--sans);
  font-size: var(--step-0);
  line-height: 1.65;
  color: var(--ink);
  background: var(--paper);
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}
h1, h2, h3 { font-family: var(--serif); font-weight: 400; line-height: 1.08; letter-spacing: -0.02em; margin: 0; text-wrap: balance; }
p { margin: 0 0 var(--s3); text-wrap: pretty; }
p:last-child { margin-bottom: 0; }
a { color: inherit; text-decoration: none; }
img { display: block; max-width: 100%; height: auto; }
ul, ol { margin: 0; padding: 0; list-style: none; }
strong { font-weight: 500; }
em { font-style: italic; }
::selection { background: var(--accent-soft); color: var(--ink); }

.container { max-width: var(--container); margin-inline: auto; padding-inline: var(--gutter); }
.prose { max-width: 68ch; }

.label {
  font-size: var(--step--1);
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--ink-muted);
  margin-bottom: var(--s3);
}

/* Animated underline for inline links */
.prose a, .pub-title, .hero-links a, .contact-links a:not(.btn), .site-header nav a {
  background-image: linear-gradient(var(--accent), var(--accent));
  background-size: 0% 1px;
  background-position: 0 100%;
  background-repeat: no-repeat;
  transition: background-size var(--dur) var(--ease), color var(--dur-fast) var(--ease);
  padding-bottom: 1px;
}
.prose a:hover, .pub-title:hover, .hero-links a:hover, .contact-links a:not(.btn):hover, .site-header nav a:hover {
  background-size: 100% 1px;
  color: var(--accent);
}

/* ---------- Skip link, progress ---------- */
.skip {
  position: absolute; left: var(--s2); top: -100px;
  background: var(--ink); color: var(--paper);
  padding: var(--s1) var(--s2); z-index: 100;
  transition: top var(--dur-fast) var(--ease);
}
.skip:focus { top: var(--s2); }

.progress {
  position: fixed; top: 0; left: 0; z-index: 60;
  width: 100%; height: 2px;
  background: var(--accent);
  transform: scaleX(0);
  transform-origin: left;
}

/* ---------- Header ---------- */
.site-header {
  position: fixed; top: 0; left: 0; right: 0; z-index: 50;
  padding-block: var(--s4);
  border-bottom: 1px solid transparent;
  transition: padding var(--dur) var(--ease), background-color var(--dur) var(--ease), border-color var(--dur) var(--ease);
}
.site-header.is-scrolled {
  padding-block: var(--s2);
  background: color-mix(in srgb, var(--paper) 80%, transparent);
  -webkit-backdrop-filter: blur(12px);
  backdrop-filter: blur(12px);
  border-bottom-color: var(--line);
}
.header-inner { display: flex; align-items: center; justify-content: space-between; }
.header-right { display: flex; align-items: center; gap: var(--s4); }
.wordmark { font-weight: 500; font-size: var(--step--1); letter-spacing: 0.02em; }
.site-header nav { display: flex; gap: var(--s4); font-size: var(--step--1); color: var(--ink-muted); }
@media (max-width: 767px) { .site-header nav { display: none; } }

.theme-toggle {
  appearance: none; background: none; border: 1px solid var(--line); border-radius: 999px;
  width: 40px; height: 22px; padding: 0; cursor: pointer; position: relative;
  transition: border-color var(--dur-fast) var(--ease);
}
.theme-toggle:hover { border-color: var(--ink-faint); }
.theme-dot {
  position: absolute; top: 4px; left: 4px; width: 12px; height: 12px; border-radius: 50%;
  background: var(--ink);
  transition: transform var(--dur) var(--ease), background-color var(--dur) var(--ease);
}
.theme-toggle[aria-pressed="true"] .theme-dot { transform: translateX(18px); }

/* Grain */
.grain {
  position: fixed; inset: 0; z-index: 70; pointer-events: none;
  opacity: 0.035;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='200' height='200'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.9' numOctaves='2' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23n)'/%3E%3C/svg%3E");
  background-size: 200px 200px;
}

/* ---------- Hero ---------- */
.hero {
  position: relative;
  min-height: 100svh;
  display: flex; align-items: center;
  padding-top: var(--s8);
  padding-bottom: var(--s6);
}
.hero-grid {
  display: grid;
  grid-template-columns: 7fr 5fr;
  gap: var(--s6);
  align-items: center;
  width: 100%;
}
.hero-name {
  font-size: clamp(3rem, 1.8rem + 4.6vw, 6rem);
  margin-bottom: var(--s4);
  line-height: 0.95;
}
.hero-lede {
  font-size: clamp(1.15rem, 1rem + 0.6vw, 1.5rem);
  line-height: 1.35;
  color: var(--ink-muted);
  max-width: 30ch;
  margin-bottom: var(--s4);
  letter-spacing: -0.01em;
}
.hero-links { display: flex; gap: var(--s4); font-size: var(--step--1); font-weight: 500; }
.hero-photo { margin: 0; }
.hero-photo img {
  width: 100%;
  aspect-ratio: 4 / 5;
  object-fit: cover;
  border-radius: 2px;
  filter: grayscale(0.15);
  transition: filter 1.2s var(--ease);
}
.hero-photo.is-visible img { filter: grayscale(0); }

/* Masked line reveal: .line clips, inner span rises */
.line { display: block; overflow: hidden; padding-bottom: 0.08em; margin-bottom: -0.08em; }
.line > span { display: block; }

/* Signature figure */
.spark {
  margin: var(--s5) 0 0;
  max-width: 420px;
  position: relative;
}
.spark-svg { width: 100%; height: 96px; overflow: visible; display: block; }
.spark-axis { stroke: var(--line); stroke-width: 1; }
.spark-grid { stroke: var(--line); stroke-width: 1; stroke-dasharray: 2 3; }
.spark-area { fill: var(--accent); opacity: 0.08; }
.spark-line {
  fill: none; stroke: var(--accent); stroke-width: 2; stroke-linejoin: round; stroke-linecap: round;
  vector-effect: non-scaling-stroke;
  stroke-dasharray: 1; stroke-dashoffset: 1;
}
.spark-end { fill: var(--accent); }
.spark-label, .spark-tick, .spark-series { font-family: var(--sans); font-size: 9px; fill: var(--ink-faint); letter-spacing: 0.04em; }
.spark-series { fill: var(--ink-muted); font-weight: 500; letter-spacing: 0.08em; text-transform: uppercase; }
.spark-label { fill: var(--ink-muted); font-weight: 500; }
.spark-hover { opacity: 0; transition: opacity var(--dur-fast) var(--ease); }
.spark.is-hover .spark-hover { opacity: 1; }
.spark-cross { stroke: var(--ink-faint); stroke-width: 1; stroke-dasharray: 2 2; vector-effect: non-scaling-stroke; }
.spark-pt { fill: var(--paper); stroke: var(--accent); stroke-width: 2; vector-effect: non-scaling-stroke; }
.spark-tip {
  position: absolute; top: -4px; left: 0;
  transform: translate(-50%, -100%);
  font-size: var(--step--1); color: var(--ink); background: var(--paper);
  border: 1px solid var(--line); border-radius: 2px; padding: 2px 8px;
  white-space: nowrap; pointer-events: none; opacity: 0;
  transition: opacity var(--dur-fast) var(--ease);
  font-variant-numeric: tabular-nums;
}
.spark.is-hover .spark-tip { opacity: 1; }
.spark-caption { font-size: var(--step--1); color: var(--ink-faint); margin-top: var(--s2); max-width: 44ch; }

/* Load choreography (hero only, time-based) */
.js [data-load] {
  opacity: 0;
  transform: translateY(110%);
  animation: rise var(--dur-slow) var(--ease) forwards;
  animation-delay: calc(120ms + var(--i, 0) * 90ms);
}
.js .hero-lede[data-load], .js .hero-links[data-load], .js .label[data-load], .js .spark[data-load] { transform: translateY(16px); }
@keyframes rise { to { opacity: 1; transform: none; } }

.js .spark-line { animation: draw 1.6s var(--ease) forwards; animation-delay: 700ms; }
.js .spark-end, .js .spark-label { opacity: 0; animation: fade var(--dur) var(--ease) forwards; animation-delay: 2.2s; }
/* pathLength normalises the dash to user space, but non-scaling-stroke draws it in
   screen space and the viewBox is stretched, so the dash never covers the whole line.
   Clearing the dash on the last frame leaves the line fully drawn. */
@keyframes draw {
  from { stroke-dasharray: 1; stroke-dashoffset: 1; }
  99%  { stroke-dasharray: 1; stroke-dashoffset: 0; }
  to   { stroke-dasharray: none; stroke-dashoffset: 0; }
}
@keyframes fade { to { opacity: 1; } }



.scroll-hint {
  position: absolute; left: 50%; bottom: var(--s4);
  width: 1px; height: 48px;
  background: var(--line);
  overflow: hidden;
}
.scroll-hint span {
  display: block; width: 100%; height: 100%;
  background: var(--ink-faint);
  transform-origin: top;
  animation: hint 2.2s var(--ease) infinite;
}
@keyframes hint {
  0%   { transform: scaleY(0); transform-origin: top; }
  50%  { transform: scaleY(1); transform-origin: top; }
  51%  { transform-origin: bottom; }
  100% { transform: scaleY(0); transform-origin: bottom; }
}

@media (max-width: 767px) {
  .hero { min-height: auto; padding-top: var(--s8); }
  .hero-grid { grid-template-columns: 1fr; gap: var(--s5); }
  .hero-photo { max-width: 260px; }
  .hero-lede { max-width: 30ch; }
  .scroll-hint { display: none; }
}

/* ---------- Sections ---------- */
.section { padding-block: var(--section-gap); }
.section-alt { background: var(--paper-alt); }
.section-grid {
  display: grid;
  grid-template-columns: repeat(12, 1fr);
  column-gap: var(--s4);
}
.section-label { grid-column: 1 / 4; }
.section-body  { grid-column: 4 / 13; }
@media (max-width: 767px) {
  .section-grid { display: block; }
  .section-label { margin-bottom: var(--s4); }
}

.label-num {
  display: block;
  font-size: var(--step--1);
  color: var(--accent);
  font-variant-numeric: tabular-nums;
  letter-spacing: 0.12em;
  margin-bottom: var(--s2);
}
.section-title { font-size: var(--step-2); position: sticky; top: var(--s8); }
@media (max-width: 767px) { .section-title { position: static; } }

/* Stats */
.stats {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: var(--s4);
  margin-top: var(--s6);
  padding-top: var(--s4);
  border-top: 1px solid var(--line);
}
.stat-num {
  display: block;
  font-family: var(--serif);
  font-size: var(--step-3);
  line-height: 1;
  font-variant-numeric: tabular-nums;
  margin-bottom: var(--s1);
}
.stat-label { font-size: var(--step--1); color: var(--ink-muted); line-height: 1.4; display: block; }
@media (max-width: 767px) { .stats { grid-template-columns: repeat(2, 1fr); } }

/* Publications */
.pubs { margin-top: var(--s5); border-top: 1px solid var(--line); }
.pub {
  display: grid;
  grid-template-columns: 5rem 1fr;
  gap: var(--s3);
  padding-block: var(--s4);
  border-bottom: 1px solid var(--line);
}
.pub-year { font-variant-numeric: tabular-nums; color: var(--ink-faint); font-size: var(--step--1); padding-top: 0.5em; }
.pub-title { font-family: var(--serif); font-size: var(--step-1); line-height: 1.2; display: inline; }
.pub-authors { font-size: var(--step--1); color: var(--ink-muted); margin: var(--s2) 0 var(--s1); }
.pub-venue { font-size: var(--step--1); color: var(--ink-muted); margin-bottom: var(--s2); }
.pub-note { font-size: var(--step--1); color: var(--ink-muted); max-width: 60ch; }
@media (max-width: 767px) { .pub { grid-template-columns: 1fr; gap: var(--s1); } }

/* Work rows */
.rows { border-top: 1px solid var(--line); }
.row { padding-block: var(--s5); border-bottom: 1px solid var(--line); max-width: 68ch; }
.row-head { display: flex; flex-wrap: wrap; align-items: baseline; justify-content: space-between; gap: var(--s2); margin-bottom: var(--s3); }
.row h3 { font-size: var(--step-1); }
.row-meta { font-size: var(--step--1); color: var(--ink-faint); white-space: nowrap; }
.row p { color: var(--ink-muted); }
.row-outcome { color: var(--ink) !important; }
.row-stack { font-size: var(--step--1); color: var(--ink-faint); margin-top: var(--s3); }

/* Timeline */
.timeline li {
  display: grid; grid-template-columns: 8rem 1fr; gap: var(--s3);
  padding-block: var(--s3);
  border-bottom: 1px solid var(--line);
}
.timeline li:first-child { border-top: 1px solid var(--line); }
.tl-when { font-variant-numeric: tabular-nums; color: var(--ink-faint); font-size: var(--step--1); padding-top: 0.2em; }
.tl-what { color: var(--ink-muted); }
.tl-what strong { color: var(--ink); }
@media (max-width: 767px) { .timeline li { grid-template-columns: 1fr; gap: var(--s1); } }

/* Skills */
.skills { margin: 0; }
.skills > div {
  display: grid; grid-template-columns: 10rem 1fr; gap: var(--s3);
  padding-block: var(--s3);
  border-bottom: 1px solid var(--line);
}
.skills > div:first-child { border-top: 1px solid var(--line); }
.skills dt { font-size: var(--step--1); letter-spacing: 0.12em; text-transform: uppercase; color: var(--ink-muted); padding-top: 0.3em; }
.skills dd { margin: 0; }
@media (max-width: 767px) { .skills > div { grid-template-columns: 1fr; gap: var(--s1); } }

/* Contact */
.contact { background: var(--paper-alt); }
.contact-title { font-size: var(--step-4); line-height: 0.95; margin-bottom: var(--s4); }
.contact-lede { color: var(--ink-muted); max-width: 48ch; font-size: var(--step-1); line-height: 1.35; margin-bottom: var(--s6); }
.contact-email {
  font-family: var(--serif); font-size: var(--step-2); display: inline-block;
  border-bottom: 1px solid var(--line);
  transition: border-color var(--dur) var(--ease), color var(--dur-fast) var(--ease);
  margin-bottom: var(--s6);
  word-break: break-all;
}
.contact-email:hover { border-color: var(--accent); color: var(--accent); }
.contact-links { display: flex; flex-wrap: wrap; gap: var(--s4); align-items: center; font-size: var(--step--1); font-weight: 500; }
.btn {
  border: 1px solid var(--ink); padding: 0.7em 1.4em; border-radius: 2px;
  transition: background-color var(--dur-fast) var(--ease), color var(--dur-fast) var(--ease), border-color var(--dur-fast) var(--ease);
}
.btn:hover { background: var(--ink); color: var(--paper); }

/* Footer */
.site-footer { padding-block: var(--s5); font-size: var(--step--1); color: var(--ink-faint); border-top: 1px solid var(--line); }

/* ---------- Motion ---------- */
/* Baseline: IntersectionObserver toggles .is-visible */
.js [data-reveal] {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity var(--dur-slow) var(--ease), transform var(--dur-slow) var(--ease);
  transition-delay: calc(var(--i, 0) * 70ms);
}
.js .line > [data-reveal] { transform: translateY(110%); opacity: 1; }
.js [data-reveal].is-visible { opacity: 1; transform: none; }

/* Clip reveal for the photo. The clip lives on the inner <picture>, not on the
   observed element, because a zero-area clip makes IntersectionObserver report
   no intersection. */
.js [data-reveal="clip"] { opacity: 1; transform: none; transition: none; }
.js [data-reveal="clip"] picture {
  display: block;
  clip-path: inset(50% 0 50% 0);
  transition: clip-path 1.1s var(--ease);
}
.js [data-reveal="clip"].is-visible picture { clip-path: inset(0 0 0 0); }

/* Enhancement: native scroll-driven reveal, runs off the main thread.
   Once the animation has finished (.is-done, set on animationend) the end
   state is pinned so nothing re-hides when scrolling back up. */
@supports (animation-timeline: view()) {
  .sda [data-reveal]:not([data-reveal="clip"]):not(.is-done) {
    transition: none;
    animation: reveal linear both;
    animation-timeline: view();
    /* Completes once the element is fully inside the viewport, so items at the
       very bottom of the page can still finish. */
    animation-range: entry calc(0% + var(--i, 0) * 5%) entry calc(65% + var(--i, 0) * 5%);
  }
  .sda .line > [data-reveal]:not(.is-done) { animation-name: reveal-line; }
  .sda [data-reveal].is-done { opacity: 1; transform: none; transition: none; }
  @keyframes reveal { from { opacity: 0; transform: translateY(24px); } to { opacity: 1; transform: none; } }
  @keyframes reveal-line { from { transform: translateY(110%); } to { transform: none; } }
}

[data-parallax] { will-change: transform; }

/* View transition for the theme switch: a plain crossfade */
::view-transition-old(root), ::view-transition-new(root) { animation-duration: 420ms; animation-timing-function: var(--ease); }

/* ---------- Dark mode ---------- */
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --ink:         #e8e6e1;
    --ink-muted:   #a3a6b3;
    --ink-faint:   #6f7384;
    --paper:       #101114;
    --paper-alt:   #16171b;
    --line:        #26282e;
    --accent:      #7fb3a4;
    --accent-soft: #1d2a27;
  }
  :root:not([data-theme="light"]) .hero-photo img { filter: grayscale(0.15) brightness(0.92); }
  :root:not([data-theme="light"]) .hero-photo.is-visible img { filter: grayscale(0) brightness(0.92); }
  :root:not([data-theme="light"]) .grain { opacity: 0.06; }
}
:root[data-theme="dark"] {
  --ink:         #e8e6e1;
  --ink-muted:   #a3a6b3;
  --ink-faint:   #6f7384;
  --paper:       #101114;
  --paper-alt:   #16171b;
  --line:        #26282e;
  --accent:      #7fb3a4;
  --accent-soft: #1d2a27;
}
:root[data-theme="dark"] .hero-photo img { filter: grayscale(0.15) brightness(0.92); }
:root[data-theme="dark"] .hero-photo.is-visible img { filter: grayscale(0) brightness(0.92); }
:root[data-theme="dark"] .grain { opacity: 0.06; }

/* ---------- Accessibility ---------- */
:focus-visible { outline: 2px solid var(--accent); outline-offset: 3px; }

@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;
  }
  .js [data-reveal], .js [data-load] { opacity: 1 !important; transform: none !important; animation: none !important; clip-path: none !important; }
  .js .spark-line { stroke-dasharray: none !important; stroke-dashoffset: 0 !important; animation: none !important; }
  .js .spark-end, .js .spark-label { opacity: 1 !important; animation: none !important; }
  .scroll-hint { display: none; }
}