/* probalbose.com: styled after Reading the Greek (pastel tiles, 4 field colours,
   Fira Sans for text, Libertinus Serif italic for Greek letters). */

@font-face { font-family: "Fira Sans"; src: url("../fonts/FiraSans-Regular.woff2") format("woff2"); font-weight: 400; font-display: swap; }
@font-face { font-family: "Fira Sans"; src: url("../fonts/FiraSans-Italic.woff2") format("woff2"); font-weight: 400; font-style: italic; font-display: swap; }
@font-face { font-family: "Fira Sans"; src: url("../fonts/FiraSans-Medium.woff2") format("woff2"); font-weight: 500; font-display: swap; }
@font-face { font-family: "Fira Sans"; src: url("../fonts/FiraSans-SemiBold.woff2") format("woff2"); font-weight: 600; font-display: swap; }
@font-face { font-family: "Fira Mono"; src: url("../fonts/FiraMono-Regular.woff2") format("woff2"); font-weight: 400; font-display: swap; }
@font-face { font-family: "Libertinus Serif"; src: url("../fonts/LibertinusSerif-Regular.woff2") format("woff2"); font-weight: 400; font-display: swap; }
@font-face { font-family: "Libertinus Serif"; src: url("../fonts/LibertinusSerif-Italic.woff2") format("woff2"); font-weight: 400; font-style: italic; font-display: swap; }
@font-face { font-family: "Libertinus Serif"; src: url("../fonts/LibertinusSerif-Semibold.woff2") format("woff2"); font-weight: 600; font-display: swap; }

:root {
  color-scheme: light;
  --paper: #FAF9F6;
  --card: #FFFFFF;
  --ink: #1F2433;
  --soft: #5A6276;
  --faint: #8A91A3;
  --rule: #E4E6EC;
  --accent: #1E3A78;

  --maths-line: #4C7BD9;   --maths-chip: #D6E4FB;   --maths-text: #1E3A78;   --maths-tint: #F4F8FE;
  --physics-line: #8B6FD6; --physics-chip: #E4DBFA; --physics-text: #4B2F8F; --physics-tint: #F8F5FE;
  --stats-line: #3AA586;   --stats-chip: #D2F0E6;   --stats-text: #1D5E4B;   --stats-tint: #F3FBF8;
  --finance-line: #DE9B3A; --finance-chip: #FBE8C8; --finance-text: #7A4E0F; --finance-tint: #FFFAF1;

  --sigma-tint: #CAEFBC; --sigma-deep: #2E6B2C;

  --radius: 18px;
  --shadow: 0 1px 2px rgba(31, 36, 51, .05), 0 8px 24px rgba(31, 36, 51, .07);
  --wrap: 1120px;
}

*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; scroll-behavior: smooth; }
body {
  margin: 0; background: var(--paper); color: var(--ink);
  font: 400 18px/1.6 "Fira Sans", system-ui, -apple-system, "Segoe UI", sans-serif;
  -webkit-font-smoothing: antialiased; text-rendering: optimizeLegibility;
}
img { max-width: 100%; height: auto; display: block; }
a { color: var(--accent); text-underline-offset: 3px; text-decoration-thickness: 1px; }
a:hover { text-decoration-thickness: 2px; }
:focus-visible { outline: 3px solid var(--maths-line); outline-offset: 3px; border-radius: 6px; }
h1, h2, h3 { text-wrap: balance; line-height: 1.2; letter-spacing: -.01em; margin: 0 0 .5em; font-weight: 600; }
h1 { font-size: clamp(2.1rem, 4.6vw, 3.3rem); letter-spacing: -.02em; }
h2 { font-size: clamp(1.6rem, 3vw, 2.2rem); }
h3 { font-size: 1.2rem; }
p { margin: 0 0 1em; }
.greek { font-family: "Libertinus Serif", serif; font-style: italic; font-weight: 400; }
.mono { font-family: "Fira Mono", ui-monospace, monospace; font-size: .9em; }
.wrap { width: min(var(--wrap), 100% - 32px); margin-inline: auto; }
.lede { font-size: 1.2rem; color: var(--soft); max-width: 38em; }
.eyebrow { font-size: .8rem; font-weight: 600; letter-spacing: .08em; text-transform: uppercase; color: var(--soft); margin-bottom: .6em; }
.skip { position: absolute; left: -999px; top: 8px; background: var(--card); padding: 8px 14px; border-radius: 8px; z-index: 10; }
.skip:focus { left: 16px; }

/* header */
.site-head { position: sticky; top: 0; z-index: 5; background: color-mix(in srgb, var(--paper) 88%, transparent);
  backdrop-filter: saturate(1.4) blur(10px); -webkit-backdrop-filter: saturate(1.4) blur(10px); border-bottom: 1px solid transparent; }
.site-head.scrolled { border-bottom-color: var(--rule); }
.site-head .wrap { display: flex; align-items: center; justify-content: space-between; gap: 16px; height: 68px; }
.brand { display: inline-flex; align-items: center; gap: 12px; color: var(--ink); text-decoration: none; font-weight: 600; font-size: 1.05rem; }
.brand .mark { width: 36px; height: 36px; border-radius: 10px; display: grid; place-items: center;
  background: var(--sigma-tint); color: var(--sigma-deep); font: italic 400 22px/1 "Libertinus Serif", serif; }
.nav { display: flex; gap: 4px; }
.nav a { color: var(--soft); text-decoration: none; font-weight: 500; font-size: .95rem; padding: 8px 12px; border-radius: 10px; }
.nav a:hover, .nav a[aria-current="page"] { color: var(--ink); background: rgba(31, 36, 51, .06); }

/* buttons */
.btns { display: flex; flex-wrap: wrap; gap: 12px; margin-top: 1.4em; }
.btn { display: inline-flex; align-items: center; gap: 10px; padding: 12px 20px; border-radius: 12px; font-weight: 600; font-size: 1rem;
  text-decoration: none; border: 1px solid transparent; transition: transform .15s ease, box-shadow .15s ease; line-height: 1.2; }
.btn:hover { transform: translateY(-1px); text-decoration: none; }
.btn-primary { background: var(--ink); color: #fff; box-shadow: var(--shadow); }
.btn-soft { background: var(--card); color: var(--ink); border-color: var(--rule); }
.btn small { font-weight: 400; color: inherit; opacity: .75; white-space: nowrap; }

/* sections */
section { padding: clamp(56px, 8vw, 96px) 0; }
.section-head { max-width: 44em; margin-bottom: 36px; }
.band { background: var(--card); border-block: 1px solid var(--rule); }

/* hero */
.hero { padding-top: clamp(40px, 6vw, 72px); }
.hero .wrap { display: grid; grid-template-columns: 1.1fr .9fr; gap: clamp(32px, 5vw, 64px); align-items: center; }
.hero h1 .wave { color: var(--sigma-deep); }
.tiles { display: grid; grid-template-columns: repeat(6, 1fr); gap: 10px; }
.tiles span { aspect-ratio: 1; border-radius: 14px; display: grid; place-items: center;
  font: italic 400 clamp(22px, 2.6vw, 34px)/1 "Libertinus Serif", serif; }

/* book feature */
.hero .wrap.book { grid-template-columns: minmax(220px, 360px) 1fr; }
.book { display: grid; grid-template-columns: minmax(220px, 340px) 1fr; gap: clamp(28px, 5vw, 64px); align-items: center; }
.cover { border-radius: 6px; box-shadow: 0 2px 4px rgba(0,0,0,.08), 0 18px 40px rgba(31,36,51,.18); }
.book h2 .sub { display: block; font-size: .55em; font-weight: 400; color: var(--soft); margin-top: .5em; letter-spacing: 0; line-height: 1.35; }
.chips { display: flex; flex-wrap: wrap; gap: 8px; margin: 18px 0; }
.chip { font-size: .8rem; font-weight: 600; padding: 5px 12px; border-radius: 99px; }
.chip.maths { background: var(--maths-chip); color: var(--maths-text); }
.chip.physics { background: var(--physics-chip); color: var(--physics-text); }
.chip.stats { background: var(--stats-chip); color: var(--stats-text); }
.chip.finance { background: var(--finance-chip); color: var(--finance-text); }

/* cards */
.cards { display: grid; grid-template-columns: repeat(auto-fit, minmax(240px, 1fr)); gap: 20px; }
.card { background: var(--card); border: 1px solid var(--rule); border-radius: var(--radius); padding: 24px; }
.card h3 { margin-bottom: .4em; }
.card p { color: var(--soft); margin: 0; font-size: 1rem; }
.card .icon { width: 44px; height: 44px; border-radius: 12px; display: grid; place-items: center; margin-bottom: 16px;
  font: italic 400 26px/1 "Libertinus Serif", serif; }

/* about */
.about { display: grid; grid-template-columns: 1fr 1.4fr; gap: clamp(28px, 5vw, 64px); align-items: start; }
.about .portrait { aspect-ratio: 1; border-radius: 28px; background: var(--sigma-tint); display: grid; place-items: center;
  color: var(--sigma-deep); font: italic 400 clamp(96px, 14vw, 160px)/1 "Libertinus Serif", serif; }
.facts { list-style: none; padding: 0; margin: 20px 0 0; display: grid; gap: 10px; }
.facts li { display: flex; gap: 12px; align-items: baseline; color: var(--soft); }
.facts li b { color: var(--ink); font-weight: 600; min-width: 7.5em; }

/* downloads */
.downloads { display: grid; grid-template-columns: repeat(auto-fit, minmax(300px, 1fr)); gap: 24px; }
.download { background: var(--card); border: 1px solid var(--rule); border-radius: var(--radius); overflow: hidden; display: flex; flex-direction: column; }
.download .preview { background: #EEF0F4; padding: 28px 28px 0; height: 280px; overflow: hidden; }
.download .preview img { border-radius: 6px 6px 0 0; box-shadow: 0 6px 24px rgba(31,36,51,.16); margin-inline: auto; width: 82%; }
.download .body { padding: 24px; display: flex; flex-direction: column; gap: 6px; flex: 1; }
.download .body p { color: var(--soft); font-size: 1rem; }
.download .btn { align-self: flex-start; margin-top: auto; }

/* book page */
.buy-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(230px, 1fr)); gap: 14px; margin-top: 22px; }
.store { background: var(--card); border: 1px solid var(--rule); border-radius: 14px; padding: 16px 18px; }
.store h3 { font-size: 1rem; margin-bottom: 10px; }
.store a { display: flex; justify-content: space-between; gap: 8px; padding: 8px 0; border-top: 1px solid var(--rule); text-decoration: none; color: var(--ink); font-weight: 500; font-size: .98rem; }
.store a:first-of-type { border-top: 0; }
.store a span { color: var(--soft); font-weight: 400; }
.store a:hover { color: var(--accent); }
.note { font-size: .9rem; color: var(--faint); margin-top: 12px; }

.fields { display: grid; grid-template-columns: repeat(4, 1fr); gap: 18px; }
.field { border-radius: var(--radius); overflow: hidden; background: var(--card); border: 1px solid var(--rule); }
.field img { width: 100%; }
.field .body { padding: 16px 18px 20px; }
.field h3 { font-size: 1.05rem; margin-bottom: .3em; }
.field p { font-size: .95rem; color: var(--soft); margin: 0; }

.spread { border-radius: var(--radius); overflow: hidden; box-shadow: var(--shadow); background: #ECEEF2; }
.trio { display: grid; grid-template-columns: repeat(3, 1fr); gap: 20px; margin-top: 28px; }
.trio figure { margin: 0; background: var(--card); border: 1px solid var(--rule); border-radius: var(--radius); overflow: hidden; }
.trio figcaption { padding: 14px 18px 18px; font-size: .95rem; color: var(--soft); }
.trio figcaption b { display: block; color: var(--ink); font-size: 1.02rem; margin-bottom: 2px; }

/* letter explorer */
.explorer { display: grid; grid-template-columns: 1fr minmax(300px, 400px); gap: 28px; align-items: start; }
.letter-grid { display: grid; grid-template-columns: repeat(6, 1fr); gap: 10px; }
.letter-grid button { aspect-ratio: 1; border: 0; border-radius: 14px; cursor: pointer; display: grid; place-items: center;
  font: italic 400 clamp(22px, 2.8vw, 36px)/1 "Libertinus Serif", serif; transition: transform .12s ease, box-shadow .12s ease; }
.letter-grid button:hover { transform: translateY(-2px); box-shadow: var(--shadow); }
.letter-grid button[aria-pressed="true"] { box-shadow: 0 0 0 3px var(--ink); }
.letter-card { background: var(--card); border: 1px solid var(--rule); border-radius: var(--radius); overflow: hidden; position: sticky; top: 88px; }
.letter-card .top { display: flex; gap: 16px; align-items: center; padding: 18px 20px; }
.letter-card .big { font: italic 400 52px/1 "Libertinus Serif", serif; min-width: 1.9em; text-align: center; }
.letter-card .name { font-weight: 600; font-size: 1.3rem; }
.letter-card .say { color: var(--ink); font-size: .95rem; }
.letter-card dl { margin: 0; padding: 8px 20px 18px; display: grid; gap: 10px; }
.letter-card dt { font-size: .75rem; font-weight: 600; letter-spacing: .06em; text-transform: uppercase; }
.letter-card dd { margin: 2px 0 0; font-size: .98rem; }
.letter-card dd.none { color: var(--faint); font-style: italic; }
.letter-card dt.maths { color: var(--maths-text); } .letter-card dt.physics { color: var(--physics-text); }
.letter-card dt.stats { color: var(--stats-text); } .letter-card dt.finance { color: var(--finance-text); }

.details { display: grid; grid-template-columns: repeat(4, 1fr); gap: 0; border: 1px solid var(--rule); border-radius: var(--radius); background: var(--card); overflow: hidden; }
.details div { padding: 16px 20px; border-right: 1px solid var(--rule); border-bottom: 1px solid var(--rule); margin: 0 -1px -1px 0; }
.details dt { font-size: .78rem; color: var(--soft); text-transform: uppercase; letter-spacing: .06em; font-weight: 600; }
.details dd { margin: 4px 0 0; font-weight: 500; }

/* footer */
.site-foot { padding: 40px 0 56px; color: var(--soft); font-size: .92rem; border-top: 1px solid var(--rule); }
.site-foot .wrap { display: flex; flex-wrap: wrap; justify-content: space-between; gap: 16px; }
.site-foot a { color: var(--soft); }

/* responsive */
@media (max-width: 900px) {
  .hero .wrap, .book, .about, .explorer { grid-template-columns: 1fr; }
  .hero .tiles { max-width: 460px; }
  .book .cover-col { max-width: 260px; }
  .fields { grid-template-columns: repeat(2, 1fr); }
  .details { grid-template-columns: repeat(2, 1fr); }
  .hero .wrap.book { grid-template-columns: 1fr; }
  .trio { grid-template-columns: 1fr; }
  .letter-card { position: static; }
  .about .portrait { max-width: 220px; }
}
@media (max-width: 560px) {
  body { font-size: 17px; }
  .nav a { padding: 8px 8px; font-size: .9rem; }
  .brand .name { display: none; }
  .fields { grid-template-columns: 1fr; }
  .letter-grid { gap: 7px; }
  .letter-grid button, .tiles span { border-radius: 10px; }
  .download .preview { height: 220px; }
}
@media (prefers-reduced-motion: reduce) { * { transition: none !important; scroll-behavior: auto !important; } }

/* ---- personal site layout (v2) ---- */
.wrap.narrow { width: min(760px, 100% - 32px); }
.page-hero { padding-bottom: clamp(32px, 5vw, 56px); }
.page-hero .wrap { display: block; }
.page-hero h1 { font-size: clamp(2rem, 4.2vw, 3rem); }
.eyebrow a { color: inherit; text-decoration: none; }
.eyebrow a:hover { text-decoration: underline; }

.home-hero .wrap { grid-template-columns: 1.35fr .65fr; }
.portrait-col { display: flex; justify-content: center; }
.portrait { width: min(320px, 100%); aspect-ratio: 1; border-radius: 32px; background: var(--sigma-tint); display: grid; place-items: center;
  box-shadow: var(--shadow); object-fit: cover; }
.portrait span { font: 600 clamp(64px, 9vw, 112px)/1 "Fira Sans", sans-serif; color: var(--sigma-deep); letter-spacing: -.03em; }

.social { display: inline-flex; gap: 14px; align-items: center; }
.social a { display: inline-flex; align-items: center; gap: 8px; color: var(--soft); text-decoration: none; font-weight: 500; }
.social a:hover { color: var(--ink); }
.social svg { width: 18px; height: 18px; }
.social.btn-row { margin-top: 22px; }
.foot-social { margin-left: 14px; }
.foot-social span { display: none; }

.cards.three { grid-template-columns: repeat(3, 1fr); }
.link-card { display: flex; flex-direction: column; text-decoration: none; color: var(--ink); transition: transform .15s ease, box-shadow .15s ease; }
.link-card:hover { transform: translateY(-2px); box-shadow: var(--shadow); }
.link-card p { margin-bottom: 14px; }
.link-card .more { margin-top: auto; font-weight: 600; color: var(--accent); font-size: .95rem; }

.news { display: grid; gap: 16px; }
.news-item { display: grid; grid-template-columns: 92px 1fr; gap: 22px; align-items: center; background: var(--card); border: 1px solid var(--rule);
  border-radius: var(--radius); padding: 18px 22px; text-decoration: none; color: var(--ink); }
.news-item:hover { box-shadow: var(--shadow); }
.news-item img { border-radius: 4px; box-shadow: 0 4px 14px rgba(31,36,51,.18); }
.news-item h3 { margin-bottom: .25em; }
.news-item p { margin: 0; color: var(--soft); font-size: 1rem; }
.news-item .date { font-size: .8rem; font-weight: 600; letter-spacing: .06em; text-transform: uppercase; margin-bottom: 4px; }

.timeline { list-style: none; margin: 24px 0 0; padding: 0; display: grid; gap: 26px; position: relative; }
.timeline::before { content: ""; position: absolute; left: 21px; top: 10px; bottom: 10px; width: 2px; background: var(--rule); }
.timeline li { display: grid; grid-template-columns: 44px 1fr; gap: 18px; position: relative; }
.timeline .dot { width: 44px; height: 44px; border-radius: 12px; display: grid; place-items: center; font: italic 400 24px/1 "Libertinus Serif", serif; }
.timeline h3 { margin: 8px 0 .3em; }
.timeline p { margin: 0; color: var(--soft); }

.projects { display: grid; gap: 22px; }
.project { background: var(--card); border: 1px solid var(--rule); border-radius: var(--radius); padding: 26px 28px; }
.project .p-head { display: flex; gap: 16px; align-items: center; margin-bottom: 14px; }
.project .icon { width: 48px; height: 48px; flex: none; border-radius: 12px; display: grid; place-items: center; font: italic 400 28px/1 "Libertinus Serif", serif; }
.project h2 { font-size: 1.35rem; margin: 0; }
.project p { color: var(--soft); }
.status { margin: 2px 0 0; font-size: .85rem; font-weight: 600; color: var(--soft); }
.status.soon { color: var(--finance-text); }
.tags { display: flex; flex-wrap: wrap; gap: 8px; margin: 0; }
.tags span { font-size: .8rem; font-weight: 500; padding: 4px 10px; border-radius: 99px; background: #F0F1F4; color: var(--soft); }

.book-row { display: grid; grid-template-columns: minmax(180px, 260px) 1fr; gap: clamp(24px, 4vw, 48px); align-items: center; }
.book-row h2 a { color: var(--ink); text-decoration: none; }
.book-row h2 .sub { display: block; font-size: .55em; font-weight: 400; color: var(--soft); margin-top: .5em; letter-spacing: 0; line-height: 1.35; }
.note-lg { font-size: 1.1rem; color: var(--soft); margin: 0; }

@media (max-width: 900px) {
  .home-hero .wrap { grid-template-columns: 1fr; }
  .portrait-col { justify-content: flex-start; }
  .portrait { width: 200px; border-radius: 24px; }
  .cards.three { grid-template-columns: 1fr; }
  .book-row { grid-template-columns: 1fr; }
  .book-row .cover-link { max-width: 220px; }
}
@media (max-width: 560px) {
  .nav { gap: 0; }
  .nav a { padding: 8px 6px; font-size: .85rem; }
  .news-item { grid-template-columns: 64px 1fr; padding: 14px 16px; gap: 14px; }
  .project { padding: 20px; }
}