/* =========================================================================
   Prathamesh Kalamkar — research portfolio
   One stylesheet, no build step, no external assets.

   Contents
     1. Tokens (light / dark)
     2. Reset and base
     3. Typography scale
     4. Layout shell: header, rail, main, footer
     5. Hero
     6. Section furniture: cards, figures, tables, callouts
     7. Entries, lists, timeline
     8. Utilities, motion, print
   ========================================================================= */

/* ---------- 1. Tokens ---------------------------------------------------- */

:root {
  /* Light is the default; dark is applied by media query or [data-theme]. */
  --bg:            #fbfaf7;
  --bg-tint:       #f4f1ea;
  --surface:       #ffffff;
  --surface-2:     #f7f5f0;
  --text:          #14181d;
  --text-soft:     #3c454e;
  --muted:         #5f6a75;
  --rule:          #e3ddd1;
  --rule-strong:   #cfc7b7;
  --accent:        #0d5c58;
  --accent-soft:   #e3f0ee;
  --accent-text:   #084440;
  --ochre:         #8a5a12;
  --ochre-soft:    #f6eeda;
  --warn:          #7a3b12;
  --warn-soft:     #f8ece2;
  --focus:         #0d5c58;
  --shadow:        0 1px 2px rgba(20, 24, 29, .05), 0 8px 24px -16px rgba(20, 24, 29, .35);

  --font-sans: ui-sans-serif, system-ui, -apple-system, "Segoe UI", Roboto,
               "Helvetica Neue", Arial, "Noto Sans", sans-serif;
  --font-serif: ui-serif, Georgia, "Iowan Old Style", "Palatino Linotype",
                "Times New Roman", serif;
  --font-mono: ui-monospace, SFMono-Regular, "SF Mono", Menlo, Consolas,
               "Liberation Mono", "Courier New", monospace;

  --measure: 68ch;
  --shell: 78rem;
  --gutter: clamp(1.15rem, 4vw, 3rem);
  --radius: 10px;
  --header-h: 4.25rem;
}

@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg:          #0e1113;
    --bg-tint:     #12171a;
    --surface:     #151a1d;
    --surface-2:   #1a2024;
    --text:        #e9ecee;
    --text-soft:   #c3cace;
    --muted:       #97a2aa;
    --rule:        #262d32;
    --rule-strong: #374148;
    --accent:      #5fd8c9;
    --accent-soft: #12302e;
    --accent-text: #8beadd;
    --ochre:       #e0b168;
    --ochre-soft:  #2a2113;
    --warn:        #eab183;
    --warn-soft:   #2b1d14;
    --focus:       #5fd8c9;
    --shadow:      0 1px 2px rgba(0, 0, 0, .5), 0 10px 28px -18px rgba(0, 0, 0, .9);
  }
}

:root[data-theme="dark"] {
  --bg:          #0e1113;
  --bg-tint:     #12171a;
  --surface:     #151a1d;
  --surface-2:   #1a2024;
  --text:        #e9ecee;
  --text-soft:   #c3cace;
  --muted:       #97a2aa;
  --rule:        #262d32;
  --rule-strong: #374148;
  --accent:      #5fd8c9;
  --accent-soft: #12302e;
  --accent-text: #8beadd;
  --ochre:       #e0b168;
  --ochre-soft:  #2a2113;
  --warn:        #eab183;
  --warn-soft:   #2b1d14;
  --focus:       #5fd8c9;
  --shadow:      0 1px 2px rgba(0, 0, 0, .5), 0 10px 28px -18px rgba(0, 0, 0, .9);
}

/* ---------- 2. Reset and base -------------------------------------------- */

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

html {
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
  scroll-padding-top: calc(var(--header-h) + 1rem);
}

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: var(--font-sans);
  font-size: clamp(1rem, .96rem + .2vw, 1.075rem);
  line-height: 1.65;
  text-rendering: optimizeLegibility;
  -webkit-font-smoothing: antialiased;
}

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

a {
  color: var(--accent-text);
  text-decoration-thickness: 1px;
  text-underline-offset: .18em;
}
a:hover { text-decoration-thickness: 2px; }

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

code {
  font-family: var(--font-mono);
  font-size: .875em;
  background: var(--surface-2);
  border: 1px solid var(--rule);
  border-radius: 4px;
  padding: .08em .34em;
  overflow-wrap: anywhere;
}

strong, b { font-weight: 650; }

.skip-link {
  position: absolute;
  left: -9999px;
  top: 0;
  z-index: 100;
  background: var(--accent);
  color: var(--bg);
  padding: .7rem 1.1rem;
  font-weight: 600;
  border-radius: 0 0 var(--radius) 0;
}
.skip-link:focus { left: 0; }

/* ---------- 3. Typography ------------------------------------------------ */

h1, h2, h3 {
  font-family: var(--font-serif);
  font-weight: 600;
  line-height: 1.18;
  letter-spacing: -.012em;
  text-wrap: balance;
  margin: 0;
}

h1 { font-size: clamp(1.85rem, 1.15rem + 2.7vw, 3.1rem); letter-spacing: -.022em; }
h2 { font-size: clamp(1.45rem, 1.1rem + 1.3vw, 2rem); }
h3 { font-size: clamp(1.08rem, 1rem + .38vw, 1.22rem); }

p { margin: 0 0 1em; max-width: var(--measure); }
p:last-child { margin-bottom: 0; }

.eyebrow {
  font-family: var(--font-mono);
  font-size: .78rem;
  letter-spacing: .13em;
  text-transform: uppercase;
  color: var(--muted);
  margin-bottom: 1.1rem;
}

.sec-num {
  font-family: var(--font-mono);
  font-size: .62em;
  font-weight: 500;
  letter-spacing: .06em;
  color: var(--accent);
  vertical-align: .35em;
  margin-right: .7em;
}

.subhead {
  font-family: var(--font-mono);
  font-size: .8rem;
  font-weight: 600;
  letter-spacing: .12em;
  text-transform: uppercase;
  color: var(--muted);
  margin: 2.5rem 0 1rem;
}

.section-intro {
  color: var(--text-soft);
  font-size: 1.05em;
}

/* ---------- 4. Layout shell ---------------------------------------------- */

.site-header {
  position: sticky;
  top: 0;
  z-index: 20;
  background: color-mix(in srgb, var(--bg) 88%, transparent);
  backdrop-filter: saturate(1.4) blur(10px);
  border-bottom: 1px solid var(--rule);
}
@supports not (backdrop-filter: blur(1px)) {
  .site-header { background: var(--bg); }
}

.site-header__inner {
  max-width: var(--shell);
  margin: 0 auto;
  padding: 0 var(--gutter);
  min-height: var(--header-h);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
}

.wordmark {
  display: inline-flex;
  align-items: center;
  gap: .7rem;
  color: var(--text);
  text-decoration: none;
  padding: .35rem 0;
}
.wordmark__mark {
  font-family: var(--font-serif);
  font-size: 1.5rem;
  line-height: 1;
  color: var(--bg);
  background: var(--accent);
  width: 2rem;
  height: 2rem;
  display: grid;
  place-items: center;
  border-radius: 6px;
  flex: none;
}
.wordmark__text { display: flex; flex-direction: column; line-height: 1.25; }
.wordmark__text b { font-size: .98rem; letter-spacing: -.005em; }
.wordmark__text span {
  font-family: var(--font-mono);
  font-size: .68rem;
  letter-spacing: .04em;
  color: var(--muted);
}
@media (max-width: 26rem) {
  .wordmark__text span { display: none; }
}

.theme-toggle {
  display: inline-flex;
  align-items: center;
  gap: .5rem;
  font: inherit;
  font-size: .82rem;
  color: var(--text-soft);
  background: var(--surface);
  border: 1px solid var(--rule-strong);
  border-radius: 999px;
  padding: .35rem .8rem;
  cursor: pointer;
}
.theme-toggle:hover { border-color: var(--accent); color: var(--text); }
.theme-toggle__icon {
  width: .8rem;
  height: .8rem;
  border-radius: 50%;
  background: linear-gradient(90deg, var(--text) 0 50%, transparent 50% 100%);
  border: 1.5px solid var(--text);
  flex: none;
}

.layout {
  max-width: var(--shell);
  margin: 0 auto;
  padding: 0 var(--gutter);
  display: grid;
  grid-template-columns: 1fr;
  gap: 0;
}

@media (min-width: 68rem) {
  .layout {
    grid-template-columns: 13.5rem minmax(0, 1fr);
    gap: 3.5rem;
    align-items: start;
  }
}

/* Table of contents: a sticky left rail on wide screens, a horizontally
   scrollable strip under the header on narrow ones. */
.rail { position: relative; }

.toc {
  position: sticky;
  top: var(--header-h);
  z-index: 10;
  background: var(--bg);
  border-bottom: 1px solid var(--rule);
  margin: 0 calc(-1 * var(--gutter));
  padding: .55rem var(--gutter);
}
.toc__title { display: none; }
.toc ol {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  gap: .35rem;
  overflow-x: auto;
  scrollbar-width: thin;
  -webkit-overflow-scrolling: touch;
}
.toc a {
  display: inline-block;
  white-space: nowrap;
  font-size: .84rem;
  color: var(--muted);
  text-decoration: none;
  padding: .3rem .6rem;
  border-radius: 6px;
  border: 1px solid transparent;
}
.toc a:hover { color: var(--text); background: var(--surface-2); }
.toc a.is-active {
  color: var(--accent-text);
  background: var(--accent-soft);
  border-color: color-mix(in srgb, var(--accent) 35%, transparent);
}
.toc__num {
  font-family: var(--font-mono);
  font-size: .72em;
  color: var(--accent);
  margin-right: .45em;
}

@media (min-width: 68rem) {
  .toc {
    top: calc(var(--header-h) + 2.5rem);
    background: none;
    border-bottom: 0;
    border-left: 1px solid var(--rule);
    margin: 0;
    padding: .25rem 0 .25rem 1rem;
  }
  .toc__title {
    display: block;
    font-family: var(--font-mono);
    font-size: .68rem;
    letter-spacing: .14em;
    text-transform: uppercase;
    color: var(--muted);
    margin: 0 0 .7rem;
  }
  .toc ol { flex-direction: column; gap: .1rem; overflow: visible; }
  .toc a { display: block; white-space: normal; padding: .3rem .5rem; }
}

main {
  padding: clamp(2rem, 5vw, 3.75rem) 0 4rem;
  min-width: 0;
}

main > section + section {
  margin-top: clamp(3rem, 7vw, 5.25rem);
  padding-top: clamp(2rem, 5vw, 3rem);
  border-top: 1px solid var(--rule);
}

main > section > h2 { margin-bottom: 1.1rem; }

.site-footer {
  border-top: 1px solid var(--rule);
  background: var(--bg-tint);
  margin-top: 2rem;
}
.site-footer__inner {
  max-width: var(--shell);
  margin: 0 auto;
  padding: 2.25rem var(--gutter);
  color: var(--muted);
  font-size: .875rem;
}
.site-footer p { max-width: 60ch; margin-bottom: .5rem; }

/* ---------- 5. Hero ------------------------------------------------------ */

.hero h1 { max-width: 22ch; margin-bottom: 1.4rem; }

.hero .lead {
  font-size: clamp(1.02rem, .97rem + .35vw, 1.16rem);
  color: var(--text-soft);
  max-width: 62ch;
}

.idlinks {
  list-style: none;
  display: flex;
  flex-wrap: wrap;
  gap: .4rem 1.4rem;
  margin: 1.75rem 0 0;
  padding: 0;
  font-family: var(--font-mono);
  font-size: .84rem;
}
.idlinks a { color: var(--accent-text); }

.disclosure {
  margin-top: 2.25rem;
  padding: 1.15rem 1.3rem;
  background: var(--surface);
  border: 1px solid var(--rule-strong);
  border-left: 4px solid var(--ochre);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  font-size: .95rem;
  color: var(--text-soft);
}
.disclosure__title {
  font-family: var(--font-mono);
  font-size: .74rem;
  letter-spacing: .12em;
  text-transform: uppercase;
  color: var(--ochre);
  margin-bottom: .55rem;
}

/* ---------- 6. Cards, figures, tables, callouts -------------------------- */

.grid { display: grid; gap: 1.1rem; margin-top: 1.75rem; }
@media (min-width: 42rem) { .grid--2 { grid-template-columns: repeat(2, minmax(0, 1fr)); } }
@media (min-width: 54rem) { .grid--3 { grid-template-columns: repeat(3, minmax(0, 1fr)); } }

.card {
  background: var(--surface);
  border: 1px solid var(--rule);
  border-radius: var(--radius);
  padding: 1.25rem 1.3rem;
}
.card h3 { margin-bottom: .6rem; }
.card p { font-size: .95rem; color: var(--text-soft); max-width: none; }

.card--project { border-top: 3px solid var(--accent); }
.card--project h3 a { color: var(--text); text-decoration-color: var(--rule-strong); }
.card--project h3 a:hover { color: var(--accent-text); }

.card__kicker {
  font-family: var(--font-mono);
  font-size: .74rem !important;
  letter-spacing: .06em;
  text-transform: uppercase;
  color: var(--muted) !important;
  margin-bottom: .8rem !important;
}

.card__caveat, .entry__caveat {
  margin-top: .9rem;
  padding-top: .75rem;
  border-top: 1px dashed var(--rule-strong);
  font-size: .875rem !important;
  color: var(--muted) !important;
}

/* Figures */
.figure {
  margin: 2rem 0 0;
  padding: 0;
}
.figure figcaption {
  font-size: .95rem;
  color: var(--text-soft);
  max-width: var(--measure);
  margin-bottom: .9rem;
}
.figure__label {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: .72rem;
  letter-spacing: .1em;
  text-transform: uppercase;
  color: var(--accent-text);
  background: var(--accent-soft);
  border-radius: 4px;
  padding: .12rem .45rem;
  margin-right: .55rem;
  vertical-align: .1em;
}
.figure__note {
  margin-top: .85rem;
  font-size: .875rem;
  color: var(--muted);
}

/* Tables */
.table-wrap {
  overflow-x: auto;
  border: 1px solid var(--rule);
  border-radius: var(--radius);
  background: var(--surface);
}
.table-wrap + .table-wrap { margin-top: 1rem; }
.table-wrap:focus-visible { outline-offset: 0; }

table {
  width: 100%;
  border-collapse: collapse;
  font-size: .9rem;
}
caption { text-align: left; }

th, td {
  padding: .6rem .85rem;
  text-align: left;
  vertical-align: baseline;
  border-bottom: 1px solid var(--rule);
}
thead th {
  font-family: var(--font-mono);
  font-size: .72rem;
  font-weight: 600;
  letter-spacing: .06em;
  text-transform: uppercase;
  color: var(--muted);
  background: var(--surface-2);
  white-space: nowrap;
}
tbody th {
  font-weight: 500;
  color: var(--text);
}
tbody tr:last-child th,
tbody tr:last-child td { border-bottom: 0; }
tbody tr:hover { background: var(--bg-tint); }

.num {
  text-align: right;
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  white-space: nowrap;
}
td.strong { color: var(--accent-text); font-weight: 600; }

.tag {
  display: inline-block;
  font-family: var(--font-sans);
  font-size: .7rem;
  font-weight: 400;
  color: var(--muted);
  margin-left: .35rem;
}

/* Callouts */
.callout {
  margin-top: 2rem;
  padding: 1.2rem 1.35rem;
  background: var(--accent-soft);
  border: 1px solid color-mix(in srgb, var(--accent) 32%, transparent);
  border-radius: var(--radius);
}
.callout p { color: var(--text-soft); font-size: .95rem; }
.callout__title {
  font-family: var(--font-serif);
  font-size: 1.05rem;
  font-weight: 600;
  color: var(--text) !important;
  margin-bottom: .55rem !important;
}
.callout--negative {
  background: var(--warn-soft);
  border-color: color-mix(in srgb, var(--warn) 34%, transparent);
}

/* Reproducibility strip */
.strip {
  margin-top: 2rem;
  padding: 1.3rem 1.4rem;
  background: var(--surface-2);
  border: 1px solid var(--rule);
  border-radius: var(--radius);
}
.strip__title {
  font-family: var(--font-mono);
  font-size: .76rem;
  font-weight: 600;
  letter-spacing: .12em;
  text-transform: uppercase;
  color: var(--muted);
  margin: 0 0 1rem;
}
.strip__list { margin: 0; display: grid; gap: .9rem; }
@media (min-width: 48rem) { .strip__list { grid-template-columns: repeat(2, minmax(0, 1fr)); } }
.strip__list dt {
  font-family: var(--font-mono);
  font-size: .84rem;
  color: var(--accent-text);
  margin-bottom: .2rem;
}
.strip__list dd {
  margin: 0;
  font-size: .875rem;
  color: var(--text-soft);
}

/* Banner (artifact status) */
.banner {
  margin: 1.25rem 0 2rem;
  padding: 1rem 1.2rem;
  border: 1px solid var(--rule-strong);
  border-left: 4px solid var(--warn);
  border-radius: var(--radius);
  background: var(--warn-soft);
  font-size: .95rem;
}
.banner p { color: var(--text-soft); }

/* ---------- 7. Entries, lists, timeline ---------------------------------- */

.entry {
  padding: 1.5rem 0 0;
}
.entry + .entry {
  margin-top: 2.25rem;
  padding-top: 2.25rem;
  border-top: 1px solid var(--rule);
}
.entry__head { margin-bottom: 1rem; }
.entry__title { margin-bottom: .55rem; font-size: clamp(1.2rem, 1.05rem + .6vw, 1.5rem); }
.entry__meta { display: flex; flex-wrap: wrap; align-items: center; gap: .5rem .8rem; margin: 0; }
.entry__sub { color: var(--muted); font-size: .92rem; }

.pill {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: .7rem;
  letter-spacing: .07em;
  text-transform: uppercase;
  color: var(--warn);
  background: var(--warn-soft);
  border: 1px solid color-mix(in srgb, var(--warn) 40%, transparent);
  border-radius: 999px;
  padding: .15rem .6rem;
  white-space: nowrap;
}

.entry p { color: var(--text-soft); }

.factlist {
  list-style: none;
  margin: 1.1rem 0;
  padding: 0;
  max-width: var(--measure);
}
.factlist li {
  position: relative;
  padding-left: 1.35rem;
  margin-bottom: .45rem;
  font-size: .93rem;
  color: var(--text-soft);
}
.factlist li::before {
  content: "";
  position: absolute;
  left: 0;
  top: .62em;
  width: .5rem;
  height: .5rem;
  border: 1.5px solid var(--accent);
  border-radius: 2px;
  transform: rotate(45deg);
}

.entry__links { margin-top: 1.2rem; }
.link-btn {
  display: inline-block;
  font-size: .87rem;
  font-weight: 550;
  color: var(--accent-text);
  background: var(--surface);
  border: 1px solid var(--rule-strong);
  border-radius: 999px;
  padding: .4rem 1rem;
  text-decoration: none;
}
.link-btn:hover { border-color: var(--accent); background: var(--accent-soft); }
.link-btn::after { content: " →"; }

.linklist {
  list-style: none;
  margin: 0;
  padding: 0;
  max-width: var(--measure);
}
.linklist li {
  padding: .7rem 0;
  border-bottom: 1px solid var(--rule);
  font-size: .93rem;
  color: var(--muted);
}
.linklist li:last-child { border-bottom: 0; }
.linklist a { font-family: var(--font-mono); font-size: .93em; }

.principles {
  counter-reset: pr;
  list-style: none;
  margin: 1.75rem 0 0;
  padding: 0;
  display: grid;
  gap: 1.5rem;
}
@media (min-width: 48rem) { .principles { grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 1.75rem 2.5rem; } }
.principles > li { counter-increment: pr; position: relative; padding-left: 2.5rem; }
.principles > li::before {
  content: counter(pr, decimal-leading-zero);
  position: absolute;
  left: 0;
  top: .05em;
  font-family: var(--font-mono);
  font-size: .8rem;
  color: var(--accent);
  border-top: 2px solid var(--accent);
  padding-top: .3rem;
}
.principles h3 { font-family: var(--font-sans); font-size: 1rem; font-weight: 650; margin-bottom: .4rem; }
.principles p { font-size: .93rem; color: var(--text-soft); max-width: none; }

.timeline { list-style: none; margin: 0; padding: 0; }
.timeline > li {
  position: relative;
  padding: 0 0 1.25rem 1.35rem;
  border-left: 2px solid var(--rule);
}
.timeline > li:last-child { padding-bottom: 0; }
.timeline > li::before {
  content: "";
  position: absolute;
  left: -5px;
  top: .55em;
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--accent);
}
.timeline p { margin: 0; max-width: none; }
.timeline__when {
  font-family: var(--font-mono);
  font-size: .74rem;
  letter-spacing: .05em;
  color: var(--muted);
  margin-bottom: .15rem !important;
}
.timeline__what { font-size: .97rem; }
.timeline__where { font-size: .89rem; color: var(--muted); }

.tools {
  font-family: var(--font-mono);
  font-size: .87rem;
  color: var(--text-soft);
  line-height: 2;
  max-width: var(--measure);
}

.contact {
  list-style: none;
  margin: 1.75rem 0 1.25rem;
  padding: 0;
  display: grid;
  gap: .1rem;
  max-width: 40rem;
}
.contact li {
  display: grid;
  grid-template-columns: 7.5rem minmax(0, 1fr);
  gap: .5rem 1rem;
  padding: .7rem 0;
  border-bottom: 1px solid var(--rule);
  align-items: baseline;
}
.contact li:last-child { border-bottom: 0; }
.contact__label {
  font-family: var(--font-mono);
  font-size: .72rem;
  letter-spacing: .12em;
  text-transform: uppercase;
  color: var(--muted);
}
.contact a, .contact span:not(.contact__label) {
  font-family: var(--font-mono);
  font-size: .9rem;
  overflow-wrap: anywhere;
}
@media (max-width: 34rem) {
  .contact li { grid-template-columns: 1fr; gap: .15rem; }
}

/* ---------- 8. Utilities, motion, print ---------------------------------- */

.nowrap { white-space: nowrap; }

/* 404 */
.notfound {
  max-width: var(--shell);
  margin: 0 auto;
  padding: clamp(3rem, 12vh, 7rem) var(--gutter) 5rem;
}
.notfound h1 { margin-bottom: 1rem; }
.notfound__code {
  font-family: var(--font-mono);
  font-size: clamp(3rem, 12vw, 6rem);
  line-height: 1;
  color: var(--accent);
  letter-spacing: -.04em;
  margin: 0 0 1rem;
}
.notfound ul {
  list-style: none;
  margin: 2rem 0 0;
  padding: 0;
  max-width: var(--measure);
}
.notfound li { padding: .65rem 0; border-bottom: 1px solid var(--rule); font-size: .95rem; }
.notfound li:last-child { border-bottom: 0; }

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after {
    animation-duration: .01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: .01ms !important;
  }
}

@media (prefers-contrast: more) {
  :root { --rule: var(--rule-strong); --muted: var(--text-soft); }
  a { text-decoration-thickness: 2px; }
}

@media print {
  .site-header, .rail, .theme-toggle, .skip-link { display: none !important; }
  body { background: #fff; color: #000; font-size: 10.5pt; }
  .layout { display: block; padding: 0; max-width: none; }
  main > section + section { border-top: 1pt solid #999; }
  .card, .figure, .callout, .strip, .banner, .disclosure, .table-wrap {
    break-inside: avoid;
    box-shadow: none;
  }
  a::after { content: " (" attr(href) ")"; font-size: 8pt; color: #444; word-break: break-all; }
  a[href^="#"]::after { content: ""; }
}