/* Echem-Tools — site stylesheet (the home page and the pages of CVSim, DataFit and SECPlot, in English and French) */

:root {
  --paper: #F6F8FA;
  --surface: #FFFFFF;
  --ink: #14212B;
  --muted: #56646F;
  --rule: #D3DCE3;
  --accent: #1F5A85;
  --accent-deep: #163F5E;
  --accent-soft: #E6EEF5;

  --serif: "Source Serif 4", Georgia, "Times New Roman", serif;
  --sans: "Source Sans 3", "Segoe UI", Helvetica, Arial, sans-serif;

  --measure: 68ch;
  --wide: 1080px;
  --gutter: clamp(16px, 4vw, 40px);
}

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

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

body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--sans);
  font-size: 1.0625rem;
  line-height: 1.6;
}

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

a { color: var(--accent); text-underline-offset: 0.15em; }
a:hover { color: var(--accent-deep); }

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

sub, sup { font-size: 0.72em; line-height: 0; }

/* ---------- Top bar ---------- */

.topbar {
  max-width: var(--wide);
  margin: 0 auto;
  padding: 18px var(--gutter);
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  gap: 16px;
  font-size: 0.95rem;
  color: var(--muted);
}

.topbar .lab { color: var(--muted); text-decoration: none; }
.topbar .lab:hover { color: var(--ink); text-decoration: underline; }

.lang { display: flex; gap: 14px; }
.lang a, .lang span { text-decoration: none; }
.lang [aria-current="page"] { color: var(--ink); font-weight: 600; }

/* ---------- Hero ---------- */

.hero {
  max-width: var(--wide);
  margin: 0 auto;
  padding: clamp(24px, 6vw, 72px) var(--gutter) clamp(32px, 6vw, 64px);
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(0, 1.15fr);
  gap: clamp(24px, 5vw, 64px);
  align-items: center;
}

.hero h1 {
  font-family: var(--serif);
  font-weight: 600;
  font-size: clamp(3.4rem, 9vw, 6.2rem);
  line-height: 0.95;
  letter-spacing: -0.02em;
  color: var(--accent);
  margin: 0 0 0.3em;
}

.hero .tagline {
  font-family: var(--serif);
  font-size: clamp(1.25rem, 2.4vw, 1.6rem);
  line-height: 1.3;
  margin: 0 0 0.6em;
}

.hero .platform { color: var(--muted); margin: 0 0 1.6em; }

.actions { display: flex; flex-wrap: wrap; gap: 12px; }

.btn {
  display: inline-block;
  padding: 0.62em 1.15em;
  border-radius: 6px;
  font-weight: 600;
  text-decoration: none;
  border: 1.5px solid var(--accent);
}
.btn-primary { background: var(--accent); color: #fff; }
.btn-primary:hover { background: var(--accent-deep); border-color: var(--accent-deep); color: #fff; }
.btn-secondary { background: transparent; color: var(--accent); }
.btn-secondary:hover { background: var(--accent-soft); }

.hero-figure { margin: 0; }
.hero-figure figcaption {
  margin-top: 10px;
  font-size: 0.85rem;
  color: var(--muted);
}

/* ---------- Mechanism strip ---------- */

.board {
  background: var(--accent-deep);
  color: #EAF1F7;
}
.board-inner {
  max-width: var(--wide);
  margin: 0 auto;
  padding: clamp(28px, 5vw, 48px) var(--gutter);
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(0, 1.4fr);
  gap: clamp(20px, 5vw, 64px);
  align-items: center;
}
.board .equations {
  font-family: var(--serif);
  font-style: italic;
  font-size: clamp(1.5rem, 3.4vw, 2.3rem);
  line-height: 1.45;
  margin: 0;
}
.board p.lead { margin: 0; font-size: 1.1rem; max-width: 52ch; }

/* ---------- Content ---------- */

main { padding-bottom: 24px; }

.section {
  max-width: var(--wide);
  margin: 0 auto;
  padding: clamp(36px, 6vw, 64px) var(--gutter) 0;
}

.section h2,
.split h2 {
  font-family: var(--serif);
  font-weight: 600;
  font-size: clamp(1.55rem, 2.6vw, 1.95rem);
  line-height: 1.2;
  margin: 0 0 0.6em;
  color: var(--ink);
}

.section h3 {
  font-family: var(--serif);
  font-weight: 600;
  font-size: 1.2rem;
  margin: 0 0 0.5em;
  color: var(--accent);
}

.prose { max-width: var(--measure); }
.prose p { margin: 0 0 1em; }

ul.plain { margin: 0; padding-left: 1.15em; }
ul.plain li { margin: 0 0 0.45em; }
ul.plain li::marker { color: var(--accent); }

.split {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(0, 1fr);
  gap: clamp(24px, 5vw, 56px);
  align-items: start;
}

.columns {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: clamp(20px, 4vw, 40px);
  border-top: 1px solid var(--rule);
  padding-top: 24px;
}

/* ---------- Figures ---------- */

figure.fig { margin: 0; }
figure.fig img {
  width: 100%;
  background: var(--surface);
  border: 1px solid var(--rule);
  border-radius: 4px;
}
figure.fig figcaption {
  margin-top: 10px;
  font-size: 0.9rem;
  color: var(--muted);
  max-width: 60ch;
}

/* Shown only while an image file has not been added to /images yet */
figure.fig.missing img { display: none; }
figure.fig.missing::before {
  content: attr(data-file);
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 220px;
  border: 1.5px dashed var(--rule);
  border-radius: 4px;
  color: var(--muted);
  font-size: 0.9rem;
  background: var(--surface);
}

/* ---------- Obtain / cite ---------- */

.panel {
  background: var(--surface);
  border: 1px solid var(--rule);
  border-left: 4px solid var(--accent);
  border-radius: 4px;
  padding: clamp(20px, 3vw, 32px);
}
.panel p { margin: 0 0 0.9em; }
.panel p:last-child { margin-bottom: 0; }

.warranty { font-weight: 600; }

blockquote.cite {
  margin: 0 0 14px;
  padding: 0;
  font-family: var(--serif);
  font-size: 1.08rem;
  line-height: 1.55;
}

.copy {
  font: inherit;
  font-size: 0.95rem;
  font-weight: 600;
  padding: 0.45em 0.95em;
  border-radius: 6px;
  border: 1.5px solid var(--accent);
  background: transparent;
  color: var(--accent);
  cursor: pointer;
}
.copy:hover { background: var(--accent-soft); }
.copy-status { margin-left: 10px; font-size: 0.9rem; color: var(--muted); }

/* ---------- Footer ---------- */

footer {
  margin-top: clamp(48px, 8vw, 88px);
  border-top: 1px solid var(--rule);
}
.footer-inner {
  max-width: var(--wide);
  margin: 0 auto;
  padding: 28px var(--gutter) 40px;
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  gap: 12px 32px;
  font-size: 0.92rem;
  color: var(--muted);
}
.footer-inner p { margin: 0; }
.footer-inner a { color: var(--muted); }
.footer-inner a:hover { color: var(--ink); }

/* ---------- Responsive ---------- */

@media (max-width: 820px) {
  .hero,
  .board-inner,
  .split { grid-template-columns: minmax(0, 1fr); }
  .columns { grid-template-columns: minmax(0, 1fr); }
  .hero-figure { order: 2; }
}

@media (max-width: 480px) {
  .topbar { flex-direction: column; gap: 6px; }
  .btn { width: 100%; text-align: center; }
}

@media print {
  .actions, .copy, .lang { display: none; }
  body { background: #fff; }
  .board { background: #fff; color: var(--ink); }
}

/* Prose followed by a full-width figure (wide window captures) */
.stack { display: grid; gap: clamp(20px, 3vw, 32px); }
.stack figure.fig figcaption { max-width: 80ch; }

.footer-inner .note { flex-basis: 100%; font-size: 0.85rem; }

/* ---------- One site, three programs (Echem-Tools) ---------- */

body.app-datafit { --accent: #5A3D8F; --accent-deep: #3F2A66; --accent-soft: #EEEAF5; }
body.app-secplot { --accent: #1D6B66; --accent-deep: #134B47; --accent-soft: #E4F1EF; }

.sitenav { display: flex; flex-wrap: wrap; gap: 6px 18px; align-items: baseline; }
.sitenav a { color: var(--muted); text-decoration: none; }
.sitenav a:hover { color: var(--ink); text-decoration: underline; }
.sitenav .brand { color: var(--ink); font-weight: 600; }
.sitenav [aria-current="page"] { color: var(--accent); font-weight: 600; }

.cards {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: clamp(16px, 3vw, 28px);
}
.card {
  background: var(--surface);
  border: 1px solid var(--rule);
  border-top: 4px solid var(--card, var(--accent));
  border-radius: 4px;
  padding: 0 0 18px;
  display: flex;
  flex-direction: column;
}
.card img { width: 100%; border-bottom: 1px solid var(--rule); background: var(--paper); }
.card h3 {
  font-family: var(--serif);
  font-size: 1.6rem;
  color: var(--card, var(--accent));
  margin: 16px 20px 4px;
}
.card p { margin: 0 20px 12px; }
.card .more { margin-top: auto; font-weight: 600; }
.card .more a { color: var(--card, var(--accent)); }
.card.cvsim { --card: #1F5A85; }
.card.datafit { --card: #5A3D8F; }
.card.secplot { --card: #1D6B66; }

@media (max-width: 860px) {
  .cards { grid-template-columns: minmax(0, 1fr); }
}

.hero.solo { grid-template-columns: minmax(0, 1fr); }
.hero.solo h1 { font-size: clamp(3rem, 7vw, 5rem); }
.hero.solo .tagline { max-width: 40ch; }