/* Detra Education – farby cez CSS premenné */
:root{
  /* BRAND */
  --c-primary: #5F7F7B;        /* tyrkysová (logo) */
  --c-primary-2: #4F6D69;      /* tmavšia */
  --c-accent: rgba(95,127,123,.22);

  /* UI */
  --c-bg: #0d0f10;
  --c-bg-2: #0a0c0d;
  --c-panel: rgba(255,255,255,.06);
  --c-panel-2: rgba(255,255,255,.03);
  --c-text: #e8eef0;
  --c-muted: #aeb9bd;
  --c-border: rgba(255,255,255,.12);

  --radius: 18px;
  --shadow: 0 14px 40px rgba(0,0,0,.40);
  --max: 1100px;
}

*{ box-sizing:border-box; }
html,body{
  margin:0;
  font-family: system-ui, -apple-system, Segoe UI, Roboto, Arial, sans-serif;
  color: var(--c-text);
  /* Smoother background (bez pásov/banding) */
  background:
    radial-gradient(1100px 650px at 15% 0%,
      rgba(95,127,123,.26) 0%,
      rgba(95,127,123,.14) 22%,
      rgba(13,15,16,0) 70%),
    radial-gradient(900px 520px at 95% 18%,
      rgba(95,127,123,.18) 0%,
      rgba(95,127,123,.10) 24%,
      rgba(13,15,16,0) 72%),
    radial-gradient(700px 420px at 60% 105%,
      rgba(95,127,123,.12) 0%,
      rgba(95,127,123,.06) 26%,
      rgba(13,15,16,0) 74%),
    linear-gradient(180deg, var(--c-bg) 0%, var(--c-bg-2) 100%);
}
body{
  margin:0;
  font-family: system-ui, -apple-system, Segoe UI, Roboto, Arial, sans-serif;
  color: var(--c-text);
  /* Smoother background (bez pásov/banding) */
  background:
    radial-gradient(1100px 650px at 15% 0%,
      rgba(95,127,123,.26) 0%,
      rgba(95,127,123,.14) 22%,
      rgba(13,15,16,0) 70%),
    radial-gradient(900px 520px at 95% 18%,
      rgba(95,127,123,.18) 0%,
      rgba(95,127,123,.10) 24%,
      rgba(13,15,16,0) 72%),
    radial-gradient(700px 420px at 60% 105%,
      rgba(95,127,123,.12) 0%,
      rgba(95,127,123,.06) 26%,
      rgba(13,15,16,0) 74%),
    linear-gradient(180deg, var(--c-bg) 0%, var(--c-bg-2) 100%);
}

a{ color:inherit; text-decoration:none; }
.container{ width:min(var(--max), calc(100% - 40px)); margin:0 auto; }

/* Header */
header{
  position: sticky;
  top: 0;
  z-index: 10;
  backdrop-filter: blur(10px);
  background: rgba(13,15,16,.72);
  border-bottom: 1px solid rgba(95,127,123,.35);
}
.navbar{
  display:flex;
  align-items:center;
  justify-content:space-between;
  gap: 16px;
  padding: 14px 0;
}
.brand{
  display:flex;
  align-items:center;
  gap: 12px;
  min-width: 220px;
}
.brand img{
  width: 164px;
  height:auto;
  display:block;
  filter: drop-shadow(0 10px 24px rgba(0,0,0,.45));
}

nav{ display:flex; gap:6px; flex-wrap:wrap; justify-content:flex-end; }
.navlink{
  padding: 10px 12px;
  border-radius: 999px;
  color: var(--c-muted);
  border: 1px solid transparent;
  transition: .15s ease;
}
.navlink:hover{
  color: var(--c-text);
  background: rgba(255,255,255,.05);
  border-color: rgba(255,255,255,.10);
}
.navlink.active{
  color: var(--c-text);
  background: rgba(95,127,123,.22);
  border-color: rgba(95,127,123,.55);
  box-shadow: 0 10px 24px rgba(0,0,0,.25);
}

/* Hero */
.hero{ padding: 56px 0 26px; }
.kicker{
  display:inline-flex;
  align-items:center;
  gap:10px;
  padding: 8px 12px;
  border-radius: 999px;
  border: 1px solid rgba(95,127,123,.55);
  background: rgba(95,127,123,.12);
}
.dot{
  width:10px; height:10px; border-radius:999px;
  background: var(--c-primary);
  box-shadow: 0 0 0 4px rgba(95,127,123,.20);
}
h1{
  font-size: clamp(30px, 4vw, 52px);
  letter-spacing: -0.02em;
  line-height:1.05;
  margin: 16px 0 12px;
}
.lead{
  margin: 0 0 22px;
  color: var(--c-muted);
  font-size: 18px;
  max-width: 70ch;
}

/* Buttons */
.cta-row{ display:flex; gap:10px; flex-wrap:wrap; margin-top: 18px; }
.btn{
  display:inline-flex;
  align-items:center;
  justify-content:center;
  gap: 10px;
  padding: 12px 16px;
  border-radius: 14px;
  border: 1px solid rgba(255,255,255,.12);
  background: rgba(255,255,255,.06);
  box-shadow: var(--shadow);
  transition: .15s ease;
}
.btn:hover{ transform: translateY(-1px); background: rgba(255,255,255,.08); }
.btn.primary{
  border-color: rgba(95,127,123,.70);
  background: linear-gradient(180deg, rgba(95,127,123,.48), rgba(95,127,123,.18));
}
.btn.primary:hover{
  background: linear-gradient(180deg, rgba(95,127,123,.62), rgba(95,127,123,.22));
}

/* Cards / sections */
.section{ padding: 26px 0 50px; }
.section h2{ margin:0 0 8px; font-size: 28px; letter-spacing:-0.01em; }
.section p{ margin:0 0 14px; color: var(--c-muted); max-width: 85ch; }

.grid{
  display:grid;
  grid-template-columns: repeat(12, 1fr);
  gap: 14px;
  padding: 18px 0 42px;
}
.card{
  grid-column: span 4;
  padding: 18px;
  border-radius: var(--radius);
  border: 1px solid rgba(255,255,255,.10);
  background: linear-gradient(180deg, var(--c-panel), var(--c-panel-2));
  box-shadow: var(--shadow);
  position: relative;
  overflow: hidden;
}
.card::before{
  content:"";
  position:absolute;
  inset:-40px -40px auto -40px;
  height: 80px;
  background: radial-gradient(220px 80px at 20% 50%, rgba(95,127,123,.35), transparent 65%);
  pointer-events:none;
}
.card h3{ margin:0 0 8px; font-size: 18px; }
.card p{ margin:0; color: var(--c-muted); }

.panel{
  padding: 18px;
  border-radius: var(--radius);
  border: 1px solid rgba(95,127,123,.28);
  background: linear-gradient(180deg, rgba(95,127,123,.10), rgba(255,255,255,.03));
  box-shadow: var(--shadow);
}

.split{
  display:grid;
  grid-template-columns: 1.1fr .9fr;
  gap: 14px;
  align-items:start;
}

.list{ margin:0; padding-left:18px; color: var(--c-muted); }
.list li{ margin: 6px 0; }

/* Form */
.form{ display:grid; gap:10px; }
.field label{ display:block; font-size: 13px; color: var(--c-muted); margin-bottom:6px; }
.field input, .field textarea{
  width: 100%;
  padding: 12px 12px;
  border-radius: 12px;
  border: 1px solid rgba(255,255,255,.14);
  background: rgba(255,255,255,.06);
  color: var(--c-text);
}
.field input:focus, .field textarea:focus{
  border-color: rgba(95,127,123,.75);
  box-shadow: 0 0 0 4px rgba(95,127,123,.18);
  outline: none;
}
.field textarea{ min-height: 120px; resize: vertical; }

.footer{
  border-top: 1px solid rgba(95,127,123,.25);
  padding: 22px 0;
  color: rgba(255,255,255,.55);
  font-size: 14px;
}

/* Responsive */
@media (max-width: 900px){
  .card{ grid-column: span 6; }
  .split{ grid-template-columns: 1fr; }
}
@media (max-width: 560px){
  .brand{ min-width: 0; }
  .brand img{ width: 140px; }
  .card{ grid-column: span 12; }
}



/* Accordion (itkurzy) */
.acc{ margin-top:14px; display:grid; gap:10px; }
.acc-item{
  border-radius: var(--radius);
  border: 1px solid rgba(95,127,123,.30);
  background: linear-gradient(180deg, rgba(255,255,255,.05), rgba(255,255,255,.03));
  box-shadow: var(--shadow);
  overflow:hidden;
}
.acc-btn{
  width:100%;
  text-align:left;
  border:0;
  background: transparent;
  color: var(--c-text);
  padding: 14px 16px;
  display:grid;
  grid-template-columns: 1fr auto auto;
  gap: 10px;
  align-items:center;
  cursor:pointer;
}
.acc-btn:hover{ background: rgba(95,127,123,.10); }
.acc-title{ font-weight: 650; }
.acc-meta{ color: var(--c-muted); font-size: 14px; white-space: nowrap; }
.acc-icon{ transition: transform .15s ease; opacity:.9; }
.acc-btn[aria-expanded="true"] .acc-icon{ transform: rotate(180deg); }
.acc-panel{
  padding: 0 16px 16px;
  border-top: 1px solid rgba(255,255,255,.10);
}
.acc-panel h4{
  margin: 14px 0 8px;
  font-size: 16px;
}
.acc-panel p{ color: var(--c-muted); margin: 0 0 10px; }
@media (max-width: 720px){
  .acc-btn{ grid-template-columns: 1fr auto; }
  .acc-meta{ grid-column: 1 / -1; white-space: normal; }
}