:root {
  --bg-0: #0b1020;
  --bg-1: #131a36;
  --accent-a: #7c5cff;
  --accent-b: #22d3ee;
  --text: #e8ecf8;
  --muted: #9aa3c2;
  --card: rgba(255, 255, 255, 0.06);
  --card-border: rgba(255, 255, 255, 0.12);
  --danger: #ff5d6c;
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  padding: 0;
  min-height: 100%;
  font-family: -apple-system, BlinkMacSystemFont, "Inter", "Segoe UI", Roboto, sans-serif;
  color: var(--text);
  background:
    radial-gradient(1200px 800px at 80% -10%, rgba(124, 92, 255, 0.35), transparent 60%),
    radial-gradient(900px 700px at -10% 110%, rgba(34, 211, 238, 0.25), transparent 60%),
    linear-gradient(180deg, var(--bg-0) 0%, var(--bg-1) 100%);
  background-attachment: fixed;
  -webkit-font-smoothing: antialiased;
}

.shell {
  min-height: 100dvh;
  display: grid;
  place-items: center;
  padding: 32px 20px;
}

/* ---- Lock screen ---- */
.lock {
  width: 100%;
  max-width: 420px;
  padding: 36px 32px 28px;
  border-radius: 20px;
  background: var(--card);
  border: 1px solid var(--card-border);
  backdrop-filter: blur(18px);
  -webkit-backdrop-filter: blur(18px);
  box-shadow: 0 20px 60px rgba(0, 0, 0, 0.45);
  text-align: center;
}

.lock .badge {
  width: 56px;
  height: 56px;
  margin: 0 auto 16px;
  border-radius: 16px;
  display: grid;
  place-items: center;
  background: linear-gradient(135deg, var(--accent-a), var(--accent-b));
  box-shadow: 0 10px 30px rgba(124, 92, 255, 0.4);
}

.lock .badge svg { width: 28px; height: 28px; }

.lock h1 {
  margin: 0 0 6px;
  font-size: 22px;
  letter-spacing: -0.01em;
}

.lock p {
  margin: 0 0 22px;
  color: var(--muted);
  font-size: 14px;
}

.field { position: relative; margin-bottom: 12px; }

.field input {
  width: 100%;
  padding: 14px 44px 14px 16px;
  border-radius: 12px;
  border: 1px solid var(--card-border);
  background: rgba(0, 0, 0, 0.25);
  color: var(--text);
  font-size: 15px;
  outline: none;
  transition: border-color 120ms ease, box-shadow 120ms ease;
}

.field input:focus {
  border-color: rgba(124, 92, 255, 0.7);
  box-shadow: 0 0 0 3px rgba(124, 92, 255, 0.2);
}

.field button.toggle {
  position: absolute;
  right: 6px;
  top: 50%;
  transform: translateY(-50%);
  background: transparent;
  border: 0;
  padding: 8px;
  cursor: pointer;
  color: var(--muted);
  border-radius: 8px;
}

.field button.toggle:hover { color: var(--text); }

.submit {
  width: 100%;
  padding: 13px 16px;
  border-radius: 12px;
  border: 0;
  cursor: pointer;
  color: white;
  font-weight: 600;
  font-size: 15px;
  background: linear-gradient(135deg, var(--accent-a), var(--accent-b));
  box-shadow: 0 10px 30px rgba(124, 92, 255, 0.35);
  transition: transform 80ms ease, box-shadow 120ms ease;
}

.submit:hover { box-shadow: 0 14px 36px rgba(124, 92, 255, 0.5); }
.submit:active { transform: translateY(1px); }

.error {
  margin-top: 10px;
  min-height: 18px;
  color: var(--danger);
  font-size: 13px;
}

.shake { animation: shake 360ms ease; }
@keyframes shake {
  10%, 90% { transform: translateX(-2px); }
  20%, 80% { transform: translateX(4px); }
  30%, 50%, 70% { transform: translateX(-8px); }
  40%, 60% { transform: translateX(8px); }
}

/* ---- Page chrome ---- */
.page { width: 100%; max-width: 960px; }

.page-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 24px;
  gap: 12px;
}

.brand {
  display: flex;
  align-items: center;
  gap: 10px;
  text-decoration: none;
  color: inherit;
}

.brand .dot {
  width: 10px;
  height: 10px;
  border-radius: 99px;
  background: linear-gradient(135deg, var(--accent-a), var(--accent-b));
  box-shadow: 0 0 16px rgba(124, 92, 255, 0.7);
}

.brand strong { font-size: 15px; letter-spacing: 0.02em; }

.nav { display: flex; gap: 8px; align-items: center; }

.nav a, .nav button {
  color: var(--muted);
  text-decoration: none;
  font-size: 14px;
  padding: 8px 12px;
  border-radius: 10px;
  background: transparent;
  border: 1px solid transparent;
  cursor: pointer;
  font: inherit;
}

.nav a:hover, .nav button:hover {
  color: var(--text);
  background: rgba(255, 255, 255, 0.04);
  border-color: var(--card-border);
}

.title {
  text-align: center;
  margin-bottom: 28px;
}

.title h2 {
  margin: 0;
  font-size: clamp(28px, 4vw, 40px);
  letter-spacing: -0.02em;
  background: linear-gradient(135deg, #ffffff 0%, #c8d0ff 60%, #99e9ff 100%);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}

.title p {
  margin: 8px 0 0;
  color: var(--muted);
  font-size: 15px;
}

/* ---- Home cards ---- */
.cards {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 18px;
}

@media (max-width: 640px) {
  .cards { grid-template-columns: 1fr; }
}

.card {
  position: relative;
  display: block;
  padding: 24px 22px;
  border-radius: 18px;
  background: var(--card);
  border: 1px solid var(--card-border);
  color: inherit;
  text-decoration: none;
  overflow: hidden;
  transition: transform 160ms ease, border-color 160ms ease, box-shadow 160ms ease;
}

.card::before {
  content: "";
  position: absolute;
  inset: -1px;
  border-radius: inherit;
  padding: 1px;
  background: linear-gradient(135deg, rgba(124, 92, 255, 0.6), rgba(34, 211, 238, 0.4));
  -webkit-mask: linear-gradient(#000 0 0) content-box, linear-gradient(#000 0 0);
  -webkit-mask-composite: xor;
          mask-composite: exclude;
  opacity: 0;
  transition: opacity 160ms ease;
  pointer-events: none;
}

.card:hover {
  transform: translateY(-4px);
  box-shadow: 0 20px 50px rgba(0, 0, 0, 0.35);
}

.card:hover::before { opacity: 1; }

.card .month {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 6px 10px;
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.07);
  border: 1px solid var(--card-border);
  font-size: 12px;
  color: var(--muted);
  letter-spacing: 0.04em;
  text-transform: uppercase;
}

.card h3 {
  margin: 14px 0 6px;
  font-size: 22px;
  letter-spacing: -0.01em;
}

.card p { margin: 0; color: var(--muted); font-size: 14px; }

.card .go {
  margin-top: 18px;
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-weight: 600;
  color: #d2c9ff;
}

.card:hover .go { color: #ffffff; }

/* ---- Video sections ---- */
.modules {
  display: grid;
  gap: 28px;
}

.module {
  padding: 22px;
  border-radius: 18px;
  background: var(--card);
  border: 1px solid var(--card-border);
}

.module header {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 14px;
}

.module .num {
  display: inline-grid;
  place-items: center;
  width: 34px;
  height: 34px;
  border-radius: 10px;
  font-weight: 700;
  font-size: 14px;
  background: linear-gradient(135deg, var(--accent-a), var(--accent-b));
  color: white;
}

.module h3 {
  margin: 0;
  font-size: 18px;
  letter-spacing: -0.01em;
}

.module .video-wrap {
  position: relative;
  width: 100%;
  border-radius: 12px;
  overflow: hidden;
  background: #000;
  aspect-ratio: 16 / 9;
}

.module video {
  width: 100%;
  height: 100%;
  display: block;
}

.footer {
  margin-top: 32px;
  text-align: center;
  color: var(--muted);
  font-size: 12px;
}

/* ---- Homework block (a modul fukszája) ---- */
.homework {
  margin-top: 22px;
  padding-top: 22px;
  border-top: 1px dashed var(--card-border);
}

.homework-head {
  display: flex;
  align-items: center;
  gap: 10px;
  margin: 0 0 10px;
}

.homework-head h4 {
  margin: 0;
  font-size: 13px;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--muted);
}

.homework-badge {
  display: inline-grid;
  place-items: center;
  width: 26px;
  height: 26px;
  border-radius: 8px;
  color: white;
  background: linear-gradient(135deg, var(--accent-a), var(--accent-b));
  box-shadow: 0 6px 18px rgba(124, 92, 255, 0.35);
}

.homework-intro {
  margin: 0 0 18px;
  color: var(--text);
  opacity: 0.85;
  font-size: 14.5px;
  line-height: 1.6;
}

.days {
  margin: 0;
  padding: 0;
  display: grid;
  gap: 12px;
}

.day {
  position: relative;
  border-radius: 12px;
  background: rgba(0, 0, 0, 0.22);
  border: 1px solid var(--card-border);
  transition: border-color 140ms ease, background 140ms ease;
  overflow: hidden;
}

.day[open] {
  border-color: rgba(124, 92, 255, 0.45);
  background: rgba(0, 0, 0, 0.28);
}

.day > summary {
  list-style: none;
  cursor: pointer;
  user-select: none;
  padding: 14px 18px;
  display: flex;
  align-items: center;
  gap: 14px;
  flex-wrap: wrap;
  background: linear-gradient(180deg, rgba(124, 92, 255, 0.10), rgba(34, 211, 238, 0.04));
  border-bottom: 1px solid transparent;
  transition: background 160ms ease, border-color 200ms ease;
}

.day > summary::-webkit-details-marker { display: none; }
.day > summary::marker { content: ""; }

.day > summary:hover {
  background: linear-gradient(180deg, rgba(124, 92, 255, 0.16), rgba(34, 211, 238, 0.06));
}

.day > summary:focus-visible {
  outline: 2px solid rgba(124, 92, 255, 0.55);
  outline-offset: -2px;
}

.day[open] > summary {
  border-bottom-color: rgba(124, 92, 255, 0.28);
  background: linear-gradient(180deg, rgba(124, 92, 255, 0.18), rgba(34, 211, 238, 0.08));
}

.day-name {
  display: inline-block;
  padding: 5px 12px;
  border-radius: 999px;
  font-weight: 700;
  font-size: 11.5px;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: white;
  background: linear-gradient(135deg, var(--accent-a), var(--accent-b));
  box-shadow: 0 6px 16px rgba(124, 92, 255, 0.32);
  white-space: nowrap;
}

.day-title {
  flex: 1;
  min-width: 0;
  font-size: 15px;
  color: var(--text);
  font-weight: 600;
  letter-spacing: -0.005em;
}

.chevron {
  flex-shrink: 0;
  color: var(--muted);
  transition: transform 420ms cubic-bezier(0.16, 1, 0.3, 1), color 200ms ease;
}

.day:hover .chevron { color: var(--text); }
.day[open] .chevron { transform: rotate(180deg); color: var(--text); }

/* The wrapper animates HEIGHT via the grid-fr trick.
   The inner <p> animates OPACITY + TRANSLATE so it feels like the content
   drops in from above on open and lifts away on close. */
.day > .day-body {
  display: grid;
  grid-template-rows: 0fr;
  transition: grid-template-rows 420ms cubic-bezier(0.16, 1, 0.3, 1);
}

.day[open] > .day-body {
  grid-template-rows: 1fr;
}

.day > .day-body > p {
  margin: 0;
  padding: 18px 22px 22px;
  min-height: 0;
  overflow: hidden;
  font-size: 14.5px;
  color: var(--muted);
  line-height: 1.7;
  /* Close-state values + close-state timings (no [open] selector). */
  opacity: 0;
  transform: translateY(-6px);
  transition:
    opacity 200ms cubic-bezier(0.4, 0, 0.2, 1),
    transform 280ms cubic-bezier(0.4, 0, 0.2, 1);
}

.day[open] > .day-body > p {
  opacity: 1;
  transform: translateY(0);
  /* Open-state timings — slightly longer + delayed so content reveals
     after the height has begun expanding (drop-down feel). */
  transition:
    opacity 320ms cubic-bezier(0.16, 1, 0.3, 1) 80ms,
    transform 420ms cubic-bezier(0.16, 1, 0.3, 1) 60ms;
}

@media (prefers-reduced-motion: reduce) {
  .day > .day-body,
  .day > .day-body > p,
  .chevron { transition: none; }
}

.hidden { display: none !important; }