/* ==========================================================================
   CSF 2027 — International Conference on Chemistry for a Sustainable Future
   Prague Congress Centre · 15–19 September 2027
   Stylesheet
   ========================================================================== */

:root {
  --navy:        #1b3a6b;
  --navy-dark:   #12294d;
  --navy-deep:   #0d1f3c;
  --navy-light:  #2a5296;
  --green:       #2f9e5f;
  --green-dark:  #23784a;
  --green-light: #4cb87a;
  --sand:        #f5f8fc;
  --sand-2:      #eaf0f8;
  --line:        #d9e2ee;
  --text:        #17202f;
  --muted:       #5b6880;
  --white:       #ffffff;

  --serif: "Source Serif 4", Georgia, "Times New Roman", serif;
  --sans:  "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;

  --wrap: 1180px;
  --radius: 10px;
  --shadow-sm: 0 1px 3px rgba(19, 41, 77, .08);
  --shadow:    0 4px 18px rgba(19, 41, 77, .10);
  --shadow-lg: 0 14px 40px rgba(19, 41, 77, .16);
}

/* --- reset ---------------------------------------------------------------- */
*, *::before, *::after { box-sizing: border-box; }
html { scroll-behavior: smooth; scroll-padding-top: 88px; -webkit-text-size-adjust: 100%; }
body {
  margin: 0;
  font-family: var(--sans);
  font-size: 17px;
  line-height: 1.65;
  color: var(--text);
  background: var(--white);
  -webkit-font-smoothing: antialiased;
}
img, svg { max-width: 100%; height: auto; display: block; }
a { color: var(--navy-light); text-decoration: none; }
a:hover { text-decoration: underline; }
h1, h2, h3, h4 { font-family: var(--serif); font-weight: 600; line-height: 1.2; margin: 0 0 .6em; color: var(--navy-dark); }
h1 { font-size: clamp(2.1rem, 5vw, 3.4rem); }
h2 { font-size: clamp(1.7rem, 3.4vw, 2.4rem); }
h3 { font-size: 1.25rem; }
h4 { font-size: 1.05rem; font-family: var(--sans); font-weight: 700; }
p  { margin: 0 0 1.1em; }
ul, ol { margin: 0 0 1.1em; padding-left: 1.3em; }
li { margin-bottom: .4em; }
hr { border: 0; border-top: 1px solid var(--line); margin: 2.5rem 0; }
:focus-visible { outline: 3px solid var(--green-light); outline-offset: 2px; border-radius: 3px; }

/* --- layout --------------------------------------------------------------- */
.container { width: 100%; max-width: var(--wrap); margin: 0 auto; padding: 0 24px; }
.section { padding: 76px 0; }
.section--tight { padding: 52px 0; }
.section--sand { background: var(--sand); }
.section--line { border-top: 1px solid var(--line); }
.section-head { max-width: 760px; margin-bottom: 44px; }
.section-head.center { margin-left: auto; margin-right: auto; text-align: center; }
.eyebrow {
  font-family: var(--sans); font-size: .78rem; font-weight: 700;
  letter-spacing: .14em; text-transform: uppercase;
  color: var(--green-dark); margin: 0 0 .7em;
}
.lede { font-size: 1.15rem; color: var(--muted); }
.muted { color: var(--muted); }
.small { font-size: .9rem; }
.center { text-align: center; }

/* --- skip link ------------------------------------------------------------ */
.skip-link {
  position: absolute; left: -9999px; top: 0; z-index: 999;
  background: var(--navy); color: #fff; padding: 12px 20px; border-radius: 0 0 6px 0;
}
.skip-link:focus { left: 0; }

/* --- header / nav --------------------------------------------------------- */
.site-header {
  position: sticky; top: 0; z-index: 100;
  background: rgba(255,255,255,.96);
  backdrop-filter: saturate(160%) blur(10px);
  border-bottom: 1px solid var(--line);
}
.nav-inner { display: flex; align-items: center; justify-content: space-between; gap: 20px; min-height: 74px; }
.brand { display: flex; align-items: center; gap: 12px; text-decoration: none; }
.brand:hover { text-decoration: none; }
.brand img { width: 42px; height: 42px; }
.brand-text strong {
  display: block; font-family: var(--serif); font-size: 1.24rem;
  color: var(--navy-dark); letter-spacing: .01em; line-height: 1.1;
}
.brand-text span { display: block; font-size: .7rem; color: var(--muted); letter-spacing: .07em; text-transform: uppercase; }

.nav-links { display: flex; align-items: center; gap: 4px; list-style: none; margin: 0; padding: 0; }
.nav-links li { margin: 0; }
.nav-links a {
  display: block; padding: 9px 13px; border-radius: 6px;
  font-size: .93rem; font-weight: 500; color: var(--navy-dark);
}
.nav-links a:hover { background: var(--sand-2); text-decoration: none; }
.nav-links a.active { color: var(--green-dark); font-weight: 700; }
.nav-links .nav-cta {
  background: var(--green); color: #fff; font-weight: 600; padding: 10px 18px; margin-left: 8px;
}
.nav-links .nav-cta:hover { background: var(--green-dark); }

.nav-toggle {
  display: none; background: none; border: 1px solid var(--line); border-radius: 7px;
  padding: 9px 11px; cursor: pointer; color: var(--navy-dark);
}
.nav-toggle span { display: block; width: 21px; height: 2px; background: currentColor; margin: 4px 0; border-radius: 2px; }

/* --- buttons -------------------------------------------------------------- */
.btn {
  display: inline-block; padding: 14px 30px; border-radius: 7px;
  font-family: var(--sans); font-size: .97rem; font-weight: 600; letter-spacing: .01em;
  text-align: center; cursor: pointer; border: 2px solid transparent;
  transition: background .18s ease, color .18s ease, border-color .18s ease, transform .12s ease;
}
.btn:hover { text-decoration: none; transform: translateY(-1px); }
.btn-primary { background: var(--green); color: #fff; }
.btn-primary:hover { background: var(--green-dark); color: #fff; }
.btn-navy { background: var(--navy); color: #fff; }
.btn-navy:hover { background: var(--navy-dark); color: #fff; }
.btn-outline { border-color: rgba(255,255,255,.55); color: #fff; }
.btn-outline:hover { background: rgba(255,255,255,.12); color: #fff; }
.btn-outline-navy { border-color: var(--navy); color: var(--navy); }
.btn-outline-navy:hover { background: var(--navy); color: #fff; }
.btn-row { display: flex; flex-wrap: wrap; gap: 14px; }
.btn-row.center { justify-content: center; }

/* --- hero ----------------------------------------------------------------- */
.hero {
  position: relative; overflow: hidden;
  background: linear-gradient(160deg, var(--navy) 0%, var(--navy-dark) 55%, var(--navy-deep) 100%);
  color: #fff; padding: 88px 0 92px; text-align: center;
}
.hero::before, .hero::after {
  content: ""; position: absolute; border-radius: 50%; pointer-events: none;
  background: radial-gradient(circle, rgba(76,184,122,.24) 0%, rgba(76,184,122,0) 70%);
}
.hero::before { width: 620px; height: 620px; top: -260px; right: -180px; }
.hero::after  { width: 520px; height: 520px; bottom: -280px; left: -160px; }
.hero .container { position: relative; z-index: 1; }
.hero h1 { color: #fff; margin-bottom: .35em; text-wrap: balance; }
.hero-logo { width: 132px; margin: 0 auto 28px; background: #fff; border-radius: 14px; padding: 14px; box-shadow: var(--shadow-lg); }
.hero-badge {
  display: inline-block; padding: 7px 18px; border-radius: 999px;
  background: rgba(255,255,255,.13); border: 1px solid rgba(255,255,255,.28);
  font-size: .8rem; font-weight: 600; letter-spacing: .12em; text-transform: uppercase;
  margin-bottom: 26px;
}
.hero-meta {
  font-family: var(--serif); font-size: clamp(1.05rem, 2.2vw, 1.35rem);
  color: rgba(255,255,255,.9); margin-bottom: 34px;
}
.hero-meta strong { color: #fff; font-weight: 600; }
.hero .btn-row { justify-content: center; margin-bottom: 8px; }

/* page hero (inner pages) */
.page-hero {
  background: linear-gradient(160deg, var(--navy) 0%, var(--navy-dark) 100%);
  color: #fff; padding: 62px 0 58px;
}
.page-hero h1 { color: #fff; margin-bottom: .25em; }
.page-hero p { color: rgba(255,255,255,.82); max-width: 720px; margin: 0; font-size: 1.08rem; }
.page-hero .eyebrow { color: var(--green-light); }

/* --- countdown / key facts strip ------------------------------------------ */
.factstrip { background: var(--navy-deep); color: #fff; padding: 0; }
.factstrip-grid {
  display: grid; grid-template-columns: repeat(4, 1fr);
  border-left: 1px solid rgba(255,255,255,.12);
}
.factstrip-item {
  padding: 26px 22px; text-align: center;
  border-right: 1px solid rgba(255,255,255,.12);
}
.factstrip-item .num {
  display: block; font-family: var(--serif); font-size: 2rem; font-weight: 600; color: #fff; line-height: 1.1;
}
.factstrip-item .lbl {
  display: block; font-size: .74rem; letter-spacing: .13em; text-transform: uppercase;
  color: rgba(255,255,255,.6); margin-top: 6px;
}

/* --- cards / grids -------------------------------------------------------- */
.grid { display: grid; gap: 26px; }
.grid-2 { grid-template-columns: repeat(2, 1fr); }
.grid-3 { grid-template-columns: repeat(3, 1fr); }
.grid-4 { grid-template-columns: repeat(4, 1fr); }

.card {
  background: #fff; border: 1px solid var(--line); border-radius: var(--radius);
  padding: 30px 28px; box-shadow: var(--shadow-sm);
  transition: box-shadow .2s ease, transform .2s ease, border-color .2s ease;
}
.card h3 { margin-bottom: .45em; }
.card p:last-child { margin-bottom: 0; }
.card--hover:hover { box-shadow: var(--shadow); transform: translateY(-3px); border-color: #c4d3e6; }
.card-num {
  display: inline-flex; align-items: center; justify-content: center;
  width: 40px; height: 40px; border-radius: 9px; margin-bottom: 16px;
  background: var(--sand-2); color: var(--navy); font-weight: 700; font-size: .95rem;
}

/* track cards */
.track {
  background: #fff; border: 1px solid var(--line); border-radius: var(--radius);
  border-top: 4px solid var(--green); padding: 26px 24px; box-shadow: var(--shadow-sm);
}
.track .track-id {
  font-size: .74rem; font-weight: 700; letter-spacing: .13em; text-transform: uppercase;
  color: var(--green-dark); display: block; margin-bottom: 8px;
}
.track h3 { font-size: 1.14rem; margin-bottom: .4em; }
.track p { font-size: .94rem; color: var(--muted); margin: 0; }

/* --- key dates ------------------------------------------------------------ */
.dates { list-style: none; padding: 0; margin: 0; }
.dates li {
  display: grid; grid-template-columns: 210px 1fr; gap: 20px; align-items: baseline;
  padding: 17px 0; border-bottom: 1px solid var(--line); margin: 0;
}
.dates li:last-child { border-bottom: 0; }
.dates .d { font-family: var(--serif); font-weight: 600; color: var(--navy); font-size: 1.05rem; }
.dates .e { color: var(--text); }
.dates li.is-passed .d, .dates li.is-passed .e { color: var(--muted); }
.pill {
  display: inline-block; padding: 3px 10px; border-radius: 999px; font-size: .72rem;
  font-weight: 700; letter-spacing: .07em; text-transform: uppercase; margin-left: 8px;
  background: var(--sand-2); color: var(--navy);
}
.pill--green { background: #dff3e6; color: var(--green-dark); }
.pill--amber { background: #fdf0d9; color: #8a5a10; }

/* --- programme ------------------------------------------------------------ */
.day-nav {
  position: sticky; top: 74px; z-index: 50;
  background: #fff; border-bottom: 1px solid var(--line);
  padding: 12px 0; overflow-x: auto;
}
.day-nav ul { display: flex; gap: 8px; list-style: none; margin: 0; padding: 0; }
.day-nav li { margin: 0; white-space: nowrap; }
.day-nav a {
  display: block; padding: 9px 16px; border-radius: 7px; font-size: .9rem; font-weight: 600;
  background: var(--sand); color: var(--navy-dark); border: 1px solid var(--line);
}
.day-nav a:hover { background: var(--sand-2); text-decoration: none; }

.day { margin-bottom: 58px; }
.day-head {
  background: var(--navy); color: #fff; border-radius: var(--radius) var(--radius) 0 0;
  padding: 22px 28px;
}
.day-head .day-label {
  font-size: .76rem; font-weight: 700; letter-spacing: .14em; text-transform: uppercase;
  color: var(--green-light); display: block; margin-bottom: 5px;
}
.day-head h3 { color: #fff; margin: 0; font-size: 1.5rem; }
.day-head p { margin: 6px 0 0; color: rgba(255,255,255,.78); font-size: .95rem; }

.day-body { border: 1px solid var(--line); border-top: 0; border-radius: 0 0 var(--radius) var(--radius); background: #fff; }

.slot {
  display: grid; grid-template-columns: 148px 1fr; gap: 24px;
  padding: 20px 28px; border-bottom: 1px solid var(--line);
}
.slot:last-child { border-bottom: 0; }
.slot-time { font-weight: 700; color: var(--navy); font-size: .92rem; font-variant-numeric: tabular-nums; padding-top: 2px; }
.slot-title { font-family: var(--serif); font-size: 1.12rem; font-weight: 600; color: var(--navy-dark); margin: 0 0 4px; }
.slot-desc { margin: 0; color: var(--muted); font-size: .94rem; }
.slot-tag {
  display: inline-block; font-size: .68rem; font-weight: 700; letter-spacing: .1em;
  text-transform: uppercase; padding: 3px 9px; border-radius: 4px; margin-bottom: 7px;
}
.tag-plenary  { background: #e4ecfa; color: var(--navy); }
.tag-keynote  { background: #dff3e6; color: var(--green-dark); }
.tag-parallel { background: #f0e9fa; color: #5b3d96; }
.tag-social   { background: #fdf0d9; color: #8a5a10; }
.tag-break    { background: #eef1f5; color: var(--muted); }
.tag-poster   { background: #fde9ec; color: #96324a; }
.slot--break { background: var(--sand); }
.slot--break .slot-title { font-family: var(--sans); font-size: 1rem; font-weight: 600; }

.rooms { display: grid; grid-template-columns: repeat(4, 1fr); gap: 14px; margin-top: 14px; }
.room {
  background: var(--sand); border: 1px solid var(--line); border-radius: 8px; padding: 14px 15px;
}
.room .room-name {
  font-size: .68rem; font-weight: 700; letter-spacing: .1em; text-transform: uppercase;
  color: var(--muted); display: block; margin-bottom: 6px;
}
.room .room-topic { font-size: .93rem; font-weight: 600; color: var(--navy-dark); line-height: 1.35; }
.room .room-sub { font-size: .82rem; color: var(--muted); margin-top: 4px; }

.tba { color: var(--muted); font-style: italic; }

/* --- tables --------------------------------------------------------------- */
.table-wrap { overflow-x: auto; border: 1px solid var(--line); border-radius: var(--radius); background: #fff; }
table { width: 100%; border-collapse: collapse; font-size: .95rem; min-width: 560px; }
thead th {
  background: var(--navy); color: #fff; text-align: left; font-weight: 600;
  padding: 15px 18px; font-size: .82rem; letter-spacing: .07em; text-transform: uppercase;
}
tbody td, tbody th { padding: 15px 18px; border-bottom: 1px solid var(--line); text-align: left; vertical-align: top; }
tbody tr:last-child td, tbody tr:last-child th { border-bottom: 0; }
tbody tr:nth-child(even) { background: var(--sand); }
tbody th { font-weight: 600; color: var(--navy-dark); }
td .price { font-family: var(--serif); font-size: 1.12rem; font-weight: 600; color: var(--navy); white-space: nowrap; }

/* --- speakers ------------------------------------------------------------- */
.speaker {
  background: #fff; border: 1px solid var(--line); border-radius: var(--radius);
  overflow: hidden; box-shadow: var(--shadow-sm); text-align: center;
}
.speaker-photo {
  aspect-ratio: 1 / 1; background: var(--sand-2);
  display: flex; align-items: center; justify-content: center;
  color: #a9bad0; font-size: .8rem; letter-spacing: .1em; text-transform: uppercase;
}
.speaker-photo img { width: 100%; height: 100%; object-fit: cover; }
.speaker-body { padding: 22px 20px; }
.speaker-body h3 { font-size: 1.1rem; margin-bottom: .2em; }
.speaker-role { font-size: .9rem; color: var(--green-dark); font-weight: 600; margin: 0 0 4px; }
.speaker-org { font-size: .88rem; color: var(--muted); margin: 0; }

.notice {
  border-left: 4px solid var(--green); background: var(--sand);
  padding: 20px 24px; border-radius: 0 var(--radius) var(--radius) 0; margin-bottom: 36px;
}
.notice p:last-child { margin-bottom: 0; }
.notice--amber { border-left-color: #d99b28; background: #fdf7ec; }

/* --- forms ---------------------------------------------------------------- */
.form { display: grid; gap: 18px; }
.field { display: grid; gap: 7px; }
.field label { font-weight: 600; font-size: .92rem; color: var(--navy-dark); }
.field .req { color: #c0392b; }
.field input, .field select, .field textarea {
  font-family: var(--sans); font-size: 1rem; color: var(--text);
  padding: 12px 14px; border: 1px solid var(--line); border-radius: 7px; background: #fff; width: 100%;
}
.field input:focus, .field select:focus, .field textarea:focus { border-color: var(--navy-light); outline: none; box-shadow: 0 0 0 3px rgba(42,82,150,.14); }
.field textarea { min-height: 150px; resize: vertical; }
.field-hint { font-size: .84rem; color: var(--muted); }
.hp { position: absolute; left: -9999px; }
.form-note { font-size: .88rem; color: var(--muted); }

.alert { padding: 16px 20px; border-radius: 8px; margin-bottom: 24px; font-size: .95rem; }
.alert-ok  { background: #e6f6ec; border: 1px solid #b8e2c8; color: #1e6b3c; }
.alert-err { background: #fdeaea; border: 1px solid #f3c4c4; color: #96271f; }

/* --- CTA band ------------------------------------------------------------- */
.cta-band {
  background: linear-gradient(135deg, var(--green-dark) 0%, var(--green) 100%);
  color: #fff; padding: 60px 0; text-align: center;
}
.cta-band h2 { color: #fff; }
.cta-band p { color: rgba(255,255,255,.92); max-width: 620px; margin: 0 auto 28px; font-size: 1.08rem; }
.cta-band .btn-white { background: #fff; color: var(--green-dark); }
.cta-band .btn-white:hover { background: var(--sand); color: var(--green-dark); }

/* --- footer --------------------------------------------------------------- */
.site-footer { background: var(--navy-deep); color: rgba(255,255,255,.72); padding: 62px 0 0; font-size: .93rem; }
.site-footer h4 { color: #fff; font-family: var(--sans); font-size: .8rem; letter-spacing: .13em; text-transform: uppercase; margin-bottom: 16px; }
.site-footer a { color: rgba(255,255,255,.72); }
.site-footer a:hover { color: #fff; }
.footer-grid { display: grid; grid-template-columns: 1.6fr 1fr 1fr 1.2fr; gap: 40px; padding-bottom: 46px; }
.footer-brand { display: flex; align-items: center; gap: 12px; margin-bottom: 16px; }
.footer-brand img { width: 46px; height: 46px; background: #fff; border-radius: 8px; padding: 5px; }
.footer-brand strong { font-family: var(--serif); font-size: 1.2rem; color: #fff; display: block; line-height: 1.2; }
.footer-links { list-style: none; padding: 0; margin: 0; }
.footer-links li { margin-bottom: 9px; }
.footer-bottom {
  border-top: 1px solid rgba(255,255,255,.12); padding: 22px 0;
  display: flex; justify-content: space-between; gap: 16px; flex-wrap: wrap;
  font-size: .86rem; color: rgba(255,255,255,.55);
}

/* --- responsive ----------------------------------------------------------- */
@media (max-width: 980px) {
  .grid-4 { grid-template-columns: repeat(2, 1fr); }
  .grid-3 { grid-template-columns: repeat(2, 1fr); }
  .rooms  { grid-template-columns: repeat(2, 1fr); }
  .footer-grid { grid-template-columns: repeat(2, 1fr); gap: 32px; }
  .factstrip-grid { grid-template-columns: repeat(2, 1fr); }
  .factstrip-item { border-bottom: 1px solid rgba(255,255,255,.12); }
}

@media (max-width: 820px) {
  .nav-toggle { display: block; }
  .nav-links {
    display: none; position: absolute; top: 100%; left: 0; right: 0;
    flex-direction: column; align-items: stretch; gap: 2px;
    background: #fff; border-bottom: 1px solid var(--line);
    padding: 12px 24px 20px; box-shadow: var(--shadow);
  }
  .nav-links.open { display: flex; }
  .nav-links a { padding: 12px 10px; font-size: 1rem; }
  .nav-links .nav-cta { margin: 8px 0 0; text-align: center; }
  .site-header { position: relative; }
  .day-nav { top: 0; }
  html { scroll-padding-top: 20px; }
}

@media (max-width: 700px) {
  body { font-size: 16px; }
  .section { padding: 54px 0; }
  .grid-2, .grid-3, .grid-4 { grid-template-columns: 1fr; }
  .rooms { grid-template-columns: 1fr; }
  .slot { grid-template-columns: 1fr; gap: 8px; padding: 18px 20px; }
  .slot-time { padding-top: 0; }
  .dates li { grid-template-columns: 1fr; gap: 4px; }
  .footer-grid { grid-template-columns: 1fr; }
  .factstrip-grid { grid-template-columns: 1fr; }
  .day-head { padding: 18px 20px; }
  .hero { padding: 60px 0 66px; }
  .btn { padding: 13px 24px; width: 100%; }
  .btn-row { flex-direction: column; }
}

/* --- print ---------------------------------------------------------------- */
@media print {
  .site-header, .day-nav, .cta-band, .site-footer, .btn-row, .hero::before, .hero::after { display: none !important; }
  body { font-size: 11pt; }
  .day-head { background: #eee !important; color: #000 !important; }
  .day-head h3, .day-head .day-label { color: #000 !important; }
  .section { padding: 12pt 0; }
  a[href^="http"]::after { content: " (" attr(href) ")"; font-size: 8pt; color: #555; }
}