/* ===============================
   ТЕМА / ЗМІННІ (єдина система)
   =============================== */
:root{
  --bg: #f5f9ff;
  --panel: #ffffff;
  --ink: #0f172a;
  --ink-2: #334155;
  --muted: #64748b;
  --line: #e5e7eb;
  --brand: #0ea5e9;
  --brand-ink: #083344;
  --ring: rgba(14,165,233,.35);
  --radius-lg: 16px;
  --radius-md: 12px;
  --shadow-1: 0 10px 30px rgba(2, 8, 23, .06);
  --shadow-2: 0 18px 50px rgba(2, 8, 23, .08);
}

html[data-theme="dark"]{
  --bg: #0b1220;
  --panel: #0f172a;
  --ink: #e5e7eb;
  --ink-2: #cbd5e1;
  --muted: #94a3b8;
  --line: #1f2937;
  --brand: #38bdf8;
  --brand-ink: #05202a;
  --shadow-1: none;
  --shadow-2: none;
}

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

html{ scroll-behavior: smooth; }
body{
  margin: 0;
  color: var(--ink);
  background: linear-gradient(180deg, rgba(255,255,255,.9), rgba(255,255,255,.9)), var(--bg);
  font-family: system-ui, -apple-system, "Segoe UI", Roboto, Ubuntu, "Helvetica Neue", Arial, "Noto Sans";
}

img{ max-width: 100%; height: auto; display: block; }
a{ color: inherit; text-decoration: none; }
:focus-visible{ outline: 2px solid var(--brand); outline-offset: 2px; }

.wrap{ max-width: 1200px; margin: 0 auto; padding: 0 20px; }
.courses-main{ padding: 22px 0 40px; }

/* ===============================
   КАРТКИ / СЕКЦІЇ
   =============================== */
.card{
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-1);
  padding: 18px 16px;
  margin: 16px 0;
  transition: transform .25s ease, box-shadow .25s ease, border-color .25s ease;
}
.card:hover{
  transform: translateY(-2px);
  box-shadow: var(--shadow-2);
  border-color: color-mix(in srgb, var(--brand) 30%, var(--line));
}
.card-head{
  text-align: center;
  margin-bottom: 8px;
}
.card-head h1{
  margin: 0 0 6px;
  font-size: clamp(1.5rem, 1.2rem + 1.2vw, 2rem);
}
.card-head .muted{ margin: 0; color: var(--muted); }

/* ===============================
   Заголовки сторінки
   =============================== */
h1, h2, h3 {
  text-align: center;
  font-weight: 800;
  color: var(--ink);
  margin-top: 0.5em;
  margin-bottom: 0.5em;
}

/* якщо всередині картки вже є .card-head, не дублюємо відступ */
.card-head h1, 
.card-head h2, 
.card-head h3 {
  text-align: center;
  margin: 0.4em 0;
}

/* уточнення для підписів у muted */
.card-head .muted {
  display: block;
  text-align: center;
  color: var(--muted);
  margin-top: 4px;
}


/* ===============================
   ТАБИ СЕМЕСТРІВ
   =============================== */
.tabs{
  display: flex; gap: 10px; justify-content: center; flex-wrap: wrap;
  margin: 6px 0 16px;
}
.tab-btn{
  background: color-mix(in srgb, var(--brand) 20%, #fff);
  color: var(--ink);
  border: 1px solid color-mix(in srgb, var(--brand) 35%, var(--line));
  border-radius: 999px;
  padding: 10px 16px;
  cursor: pointer;
  font-weight: 700;
  transition: background .2s ease, transform .2s ease, border-color .2s ease, color .2s ease;
}
.tab-btn:hover{ transform: translateY(-1px); }
.tab-btn.active{
  background: var(--brand);
  color: #fff;
  border-color: var(--brand);
}

.tab-panel{ margin-top: 10px; }

/* групові заголовки */
.group-title{
  background: #eef6ff;
  border: 1px solid #c7ddff;
  border-left: 6px solid #2a6df0;
  padding: 10px 12px;
  font-weight: 800;
  border-radius: 10px;
  margin: 18px 0 8px;
}

/* списки у панелях */
.list-dot{ margin: 8px 0 12px 1.2rem; padding: 0; }
.list-dot li{ margin: .25rem 0; list-style: "•  "; }

/* ===============================
   IFRAME РОЗКЛАД (Excel)
   =============================== */
.iframe-wrap{
  border-radius: 16px;
  overflow: hidden;
  box-shadow: var(--shadow-1);
  background: #fff;
  border: 1px solid var(--line);
}
.iframe-wrap iframe{
  display: block; width: 100%; height: 800px; border: 0;
}
@media (max-width: 760px){
  .iframe-wrap iframe{ height: 520px; }
}

/* ===============================
   REVEAL-АНІМАЦІЯ
   =============================== */
.reveal{
  opacity: 0;
  transform: translateY(14px);
  transition: opacity .5s ease, transform .5s ease;
  will-change: opacity, transform;
}
.reveal.is-visible{
  opacity: 1;
  transform: translateY(0);
}
@media (prefers-reduced-motion: reduce){
  .reveal{ opacity: 1 !important; transform: none !important; transition: none !important; }
}

/* ===============================
   ФУТЕР
   =============================== */
.site-footer{
  margin-top: 28px; padding: 20px; text-align: center; color: var(--muted);
}
.site-footer .banner{ margin: 12px auto 0; max-width: 320px; border-radius: 8px; }