/* ==========================================================================
   ethanlsk.com — shared stylesheet
   Palette: 003135 / 024950 / 964734 / 0FA4AF / AFDDE5
   ========================================================================== */

:root {
  --ink:        #003135;  /* page background        */
  --deep:       #024950;  /* raised surfaces        */
  --rust:       #964734;  /* secondary accent       */
  --cyan:       #0FA4AF;  /* primary accent         */
  --pale:       #AFDDE5;  /* body text              */

  --ink-deeper: #001f22;  /* code wells, insets     */
  --pale-dim:   #7fa9b4;  /* muted text             */
  --line:       rgba(15, 164, 175, 0.26);
  --line-soft:  rgba(175, 221, 229, 0.13);

  --sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Inter, Roboto, Helvetica, Arial, sans-serif;
  --mono: ui-monospace, SFMono-Regular, "SF Mono", Menlo, Consolas, monospace;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  background: var(--ink);
  color: var(--pale);
  font-family: var(--sans);
  font-size: 16px;
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
}

.wrap { max-width: 50rem; margin: 0 auto; padding: 0 1.5rem; }
.narrow { max-width: 42rem; }

a { color: var(--cyan); text-decoration-color: var(--line); text-underline-offset: 3px; }
a:hover { color: #3fc4ce; }

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

/* ---------- site header / tab nav ---------- */

.site-header {
  border-bottom: 1px solid var(--line-soft);
  background: rgba(0, 31, 34, 0.55);
  position: sticky;
  top: 0;
  z-index: 20;
  backdrop-filter: blur(10px);
}
.site-header .wrap {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  flex-wrap: wrap;
  padding-top: .85rem;
  padding-bottom: .85rem;
}
.brand {
  font-weight: 650;
  letter-spacing: -0.01em;
  color: #eaf7fa;
  text-decoration: none;
  font-size: 1.02rem;
  white-space: nowrap;
}
.brand span { color: var(--cyan); }

.tabs { display: flex; gap: .3rem; flex-wrap: wrap; }
.tabs a {
  font-size: .9rem;
  color: var(--pale);
  text-decoration: none;
  padding: .4rem .85rem;
  border-radius: 6px;
  border: 1px solid transparent;
  transition: background .15s, border-color .15s, color .15s;
  white-space: nowrap;
}
.tabs a:hover { background: var(--deep); border-color: var(--line); }
.tabs a.active {
  background: var(--deep);
  border-color: var(--cyan);
  color: #eaf7fa;
}

/* ---------- hero ---------- */

.hero { padding: 4.5rem 0 3rem; }
.eyebrow {
  font-family: var(--mono);
  font-size: .78rem;
  letter-spacing: .16em;
  text-transform: uppercase;
  color: var(--cyan);
  margin: 0 0 1rem;
}
.hero h1 {
  font-size: clamp(2.3rem, 7vw, 3.5rem);
  line-height: 1.05;
  letter-spacing: -0.03em;
  margin: 0 0 1rem;
  color: #f2fbfd;
}
.hero .lede {
  font-size: 1.14rem;
  color: var(--pale);
  max-width: 34rem;
  margin: 0 0 2rem;
}
.rule {
  height: 3px;
  width: 4rem;
  background: var(--rust);
  border-radius: 2px;
  margin: 0 0 1.75rem;
}

/* ---------- link buttons ---------- */

.linkrow { display: flex; flex-wrap: wrap; gap: .6rem; }
.btn {
  display: inline-flex;
  align-items: center;
  gap: .5rem;
  font-size: .92rem;
  font-weight: 500;
  text-decoration: none;
  color: var(--pale);
  background: var(--deep);
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: .6rem 1.1rem;
  transition: background .15s, border-color .15s, transform .12s, color .15s;
}
.btn:hover {
  background: #036069;
  border-color: var(--cyan);
  color: #eaf7fa;
  transform: translateY(-1px);
}
.btn.primary {
  background: var(--cyan);
  color: #002225;
  border-color: var(--cyan);
  font-weight: 600;
}
.btn.primary:hover { background: #2fbcc6; color: #002225; }
.btn.rust { border-color: rgba(150,71,52,.6); }
.btn.rust:hover { background: var(--rust); border-color: var(--rust); color: #fff; }

/* ---------- sections ---------- */

section { padding: 2.75rem 0; }
section + section { border-top: 1px solid var(--line-soft); }

h2 {
  font-size: 1.45rem;
  letter-spacing: -0.02em;
  color: #eaf7fa;
  margin: 0 0 1.25rem;
}
h2.kicker {
  font-family: var(--mono);
  font-size: .78rem;
  font-weight: 600;
  letter-spacing: .16em;
  text-transform: uppercase;
  color: var(--cyan);
  margin-bottom: 1.5rem;
}
h3 { font-size: 1.08rem; margin: 0; color: #eaf7fa; letter-spacing: -0.01em; }
h4 {
  font-size: .82rem;
  font-family: var(--mono);
  text-transform: uppercase;
  letter-spacing: .1em;
  color: var(--cyan);
  margin: 1.75rem 0 .6rem;
}

p { margin: 0 0 1rem; }
p:last-child { margin-bottom: 0; }

ul { margin: .6rem 0 0; padding-left: 1.15rem; }
li { margin-bottom: .5rem; }
li::marker { color: var(--cyan); }

/* ---------- cards ---------- */

.card {
  background: var(--deep);
  border: 1px solid var(--line-soft);
  border-radius: 10px;
  padding: 1.5rem;
  margin-bottom: 1rem;
}
.card:last-child { margin-bottom: 0; }

.card-head {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  gap: 1rem;
  flex-wrap: wrap;
  margin-bottom: .4rem;
}
.meta {
  font-family: var(--mono);
  font-size: .78rem;
  color: var(--pale-dim);
  white-space: nowrap;
}
.course {
  font-size: .86rem;
  color: var(--pale-dim);
  margin: 0 0 .9rem;
}

/* ---------- tags ---------- */

.tags { display: flex; flex-wrap: wrap; gap: .35rem; margin: .9rem 0 0; }
.tag {
  font-family: var(--mono);
  font-size: .72rem;
  letter-spacing: .02em;
  color: var(--pale);
  background: rgba(15,164,175,.14);
  border: 1px solid var(--line);
  border-radius: 4px;
  padding: .18rem .5rem;
}
.tag.rust {
  color: #e7b3a5;
  background: rgba(150,71,52,.2);
  border-color: rgba(150,71,52,.5);
}

/* ---------- key-results table ---------- */

.results {
  width: 100%;
  border-collapse: collapse;
  font-size: .9rem;
  margin: .5rem 0 0;
}
.results th, .results td {
  text-align: left;
  padding: .45rem .7rem .45rem 0;
  border-bottom: 1px solid var(--line-soft);
}
.results th {
  font-family: var(--mono);
  font-size: .74rem;
  text-transform: uppercase;
  letter-spacing: .08em;
  color: var(--pale-dim);
  font-weight: 500;
}
.results td.val {
  font-family: var(--mono);
  color: #eaf7fa;
  white-space: nowrap;
}
.tablescroll { overflow-x: auto; }

/* ---------- figures (light plate for MATLAB plots) ---------- */

figure { margin: 1.25rem 0 0; }
.plate {
  background: #fff;
  border-radius: 8px;
  padding: .75rem;
  border: 1px solid var(--line-soft);
}
figcaption {
  font-size: .84rem;
  color: var(--pale-dim);
  margin-top: .6rem;
  line-height: 1.5;
}

/* ---------- code ---------- */

code {
  font-family: var(--mono);
  font-size: .88em;
  background: rgba(15,164,175,.13);
  color: #6fd6de;
  padding: .12em .38em;
  border-radius: 3px;
}
pre {
  background: var(--ink-deeper);
  border: 1px solid var(--line-soft);
  border-radius: 8px;
  padding: 1rem;
  overflow-x: auto;
  margin: .75rem 0 0;
}
pre code {
  background: none;
  padding: 0;
  color: var(--pale);
  font-size: .82rem;
  line-height: 1.6;
}

/* ---------- disclosure (dropdown) groups ---------- */

details.group {
  border: 1px solid var(--line);
  border-radius: 10px;
  margin-bottom: 1rem;
  background: rgba(2,73,80,.35);
  overflow: hidden;
}
details.group[open] { background: rgba(2,73,80,.18); }

details.group > summary {
  cursor: pointer;
  list-style: none;
  padding: 1.1rem 1.4rem;
  display: flex;
  align-items: center;
  gap: .85rem;
  font-weight: 600;
  color: #eaf7fa;
  transition: background .15s;
  user-select: none;
}
details.group > summary::-webkit-details-marker { display: none; }
details.group > summary:hover { background: rgba(15,164,175,.09); }

.chev {
  flex: 0 0 auto;
  width: .6rem; height: .6rem;
  border-right: 2px solid var(--cyan);
  border-bottom: 2px solid var(--cyan);
  transform: rotate(-45deg);
  transition: transform .2s;
  margin-left: .1rem;
}
details.group[open] > summary .chev { transform: rotate(45deg); }

.summary-text { flex: 1 1 auto; }
.count {
  font-family: var(--mono);
  font-size: .76rem;
  color: var(--pale-dim);
  font-weight: 400;
}
.group-body { padding: 0 1.4rem 1.4rem; }

/* nested code disclosure */
details.code-toggle { margin-top: 1rem; }
details.code-toggle > summary {
  cursor: pointer;
  font-family: var(--mono);
  font-size: .8rem;
  color: var(--cyan);
  list-style: none;
  padding: .3rem 0;
}
details.code-toggle > summary::-webkit-details-marker { display: none; }
details.code-toggle > summary:hover { color: #3fc4ce; }
details.code-toggle > summary::before { content: "▸ "; }
details.code-toggle[open] > summary::before { content: "▾ "; }

/* ---------- misc ---------- */

.note {
  border-left: 3px solid var(--rust);
  padding: .1rem 0 .1rem 1rem;
  color: var(--pale-dim);
  font-size: .93rem;
  margin: 1.25rem 0 0;
}

.grid2 {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(15rem, 1fr));
  gap: 1rem;
}

.stat { border-left: 2px solid var(--cyan); padding-left: .9rem; }
.stat .num {
  font-family: var(--mono);
  font-size: 1.3rem;
  color: #eaf7fa;
  display: block;
  line-height: 1.3;
}
.stat .lbl { font-size: .82rem; color: var(--pale-dim); }

footer {
  border-top: 1px solid var(--line-soft);
  padding: 2.25rem 0 3.5rem;
  font-size: .87rem;
  color: var(--pale-dim);
}
footer a { color: var(--cyan); }

@media (max-width: 34rem) {
  .site-header .wrap { justify-content: center; }
  .hero { padding-top: 3rem; }
  .card { padding: 1.15rem; }
  .group-body { padding: 0 1rem 1.1rem; }
  details.group > summary { padding: .95rem 1rem; }
}