/* OakBoard landing — design 2a (Oak tree logo, teal & ink). Self-contained. */

:root {
  --ink: #14181A;
  --ink-deep: #1B1E2E;
  --teal: #17B5CB;
  --teal-deep: #0E7E8E;
  --teal-bg: #DFF5F8;
  --teal-hi: #B9EBF1;
  --muted: #47555A;
  --muted-2: #93A3A8;
  --page: #FAFCFC;
  --border: #E8EEEF;
  --border-2: #DFE8EA;
  --board-bg: #EEF3F4;
  --board-dot: #C4D2D5;
  --streak-bg: #FDF1E3;
  --streak-fg: #C7761B;
  --ok-bg: #E4F5EB;
  --ok-fg: #3B9B62;
  --wrong: #D45B4E;
  --container: 1200px;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: "Plus Jakarta Sans", system-ui, -apple-system, "Segoe UI", sans-serif;
  color: var(--ink);
  background: var(--page);
  -webkit-font-smoothing: antialiased;
}

a { color: var(--teal-deep); text-decoration: none; }

.ob-container {
  max-width: var(--container);
  margin: 0 auto;
  padding-left: 48px;
  padding-right: 48px;
}

/* ---------- Buttons ---------- */

.ob-btn {
  display: inline-block;
  border: none;
  border-radius: 10px;
  font-weight: 700;
  cursor: pointer;
  text-decoration: none;
  white-space: nowrap;
  transition: transform 0.12s ease, background 0.15s ease, box-shadow 0.15s ease;
}
.ob-btn-lg { font-size: 17px; padding: 15px 32px; border-radius: 12px; }
.ob-btn-sm { font-size: 14px; padding: 10px 18px; }

.ob-btn-dark { background: var(--ink); color: #fff; padding: 10px 22px; }
.ob-btn-dark:hover { background: #000; }

.ob-btn-teal { background: var(--teal); color: #fff; font-weight: 800; }
.ob-btn-teal:hover { background: #0fa2b7; transform: translateY(-1px); }

.ob-btn-ghost { background: #fff; border: 1.5px solid var(--border-2); color: var(--ink); }
.ob-btn-ghost:hover { border-color: var(--teal); }

.ob-btn-check { background: #57B87B; color: #fff; }

/* ---------- Nav ---------- */

.ob-nav {
  background: #fff;
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  z-index: 20;
}
.ob-nav-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-top: 18px;
  padding-bottom: 18px;
}
.ob-brand img { height: 34px; display: block; }
.ob-nav-links {
  display: flex;
  align-items: center;
  gap: 28px;
  font-size: 15px;
  font-weight: 600;
}
.ob-nav-links > a:not(.ob-btn) { color: var(--muted); }
.ob-nav-links > a:not(.ob-btn):hover { color: var(--ink); }
.ob-lang {
  border: 1px solid var(--border-2);
  border-radius: 8px;
  padding: 6px 12px;
  font-size: 13px;
  cursor: pointer;
}
.ob-lang:hover { border-color: var(--teal); }

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

.ob-hero { text-align: center; padding-top: 72px; }
.ob-badge {
  display: inline-block;
  background: var(--teal-bg);
  color: var(--teal-deep);
  font-size: 14px;
  font-weight: 700;
  padding: 8px 18px;
  border-radius: 999px;
  margin-bottom: 24px;
}
.ob-hero h1 {
  margin: 0 auto;
  max-width: 780px;
  font-size: clamp(38px, 6vw, 58px);
  line-height: 1.08;
  font-weight: 800;
  letter-spacing: -1.5px;
  text-wrap: pretty;
}
.ob-hi { box-shadow: inset 0 -16px 0 var(--teal-hi); }
.ob-lead {
  margin: 22px auto 0;
  max-width: 580px;
  font-size: 19px;
  line-height: 1.55;
  color: var(--muted);
  text-wrap: pretty;
}
.ob-cta-row {
  display: flex;
  gap: 14px;
  justify-content: center;
  flex-wrap: wrap;
  margin-top: 32px;
}

/* ---------- Whiteboard mock ---------- */

.ob-board-wrap { margin-top: 56px; }
.ob-board {
  border: 1px solid var(--border-2);
  border-radius: 16px 16px 0 0;
  overflow: hidden;
  box-shadow: 0 -10px 40px rgba(23, 181, 203, 0.1);
}
.ob-board-top {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  padding: 10px 16px;
  background: #fff;
  border-bottom: 1px solid #ECF1F2;
  flex-wrap: wrap;
}
.ob-board-tabs { display: flex; gap: 8px; align-items: center; }
.ob-chip {
  background: #F0F4F5;
  font-size: 13px;
  font-weight: 600;
  padding: 6px 12px;
  border-radius: 8px;
}
.ob-chip-outline { background: none; border: 1px solid var(--border-2); }
.ob-chip-user { font-weight: 700; }
.ob-streak {
  background: var(--streak-bg);
  color: var(--streak-fg);
  font-size: 13px;
  font-weight: 700;
  padding: 6px 12px;
  border-radius: 999px;
}

.ob-board-canvas {
  background-color: var(--board-bg);
  background-image: radial-gradient(var(--board-dot) 1.3px, transparent 1.3px);
  background-size: 26px 26px;
  padding: 36px clamp(20px, 9vw, 120px) 0;
}
.ob-paper {
  background: #fff;
  border-radius: 4px 4px 0 0;
  box-shadow: 0 4px 24px rgba(20, 24, 26, 0.08);
  padding: 32px 40px;
  min-height: 310px;
  position: relative;
}
.ob-points { position: absolute; top: 24px; right: 40px; font-size: 14px; font-weight: 700; }
.ob-task { display: flex; gap: 24px; }
.ob-task-num, .ob-task-label { font-weight: 700; font-size: 15px; }
.ob-task-eq { font-family: Georgia, serif; font-size: 17px; margin-top: 8px; }

.ob-hand {
  font-family: "Caveat", cursive;
  font-size: 30px;
  color: var(--teal-deep);
  margin-top: 8px;
  transform: rotate(-2deg);
  min-height: 40px;
  display: flex;
  align-items: center;
  gap: 12px;
}
.ob-hand-wrong { margin-top: 14px; }
.ob-hand-wrong.is-wrong > span:first-child { text-decoration: line-through var(--wrong); opacity: 0.55; }
.ob-wrong-mark {
  color: var(--wrong);
  font-family: "Plus Jakarta Sans", sans-serif;
  font-size: 18px;
  font-weight: 800;
}
.ob-tutor-slot { min-height: 46px; }
.ob-tutor {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  background: var(--teal-bg);
  border-radius: 12px;
  padding: 10px 16px;
  font-size: 14px;
  font-weight: 600;
  color: var(--teal-deep);
  animation: ob-fade-up 0.3s ease-out;
}
.ob-correct-badge {
  background: var(--ok-bg);
  color: var(--ok-fg);
  font-family: "Plus Jakarta Sans", sans-serif;
  font-size: 13px;
  font-weight: 800;
  padding: 6px 12px;
  border-radius: 999px;
  transform: rotate(2deg);
  animation: ob-pop 0.3s cubic-bezier(0.18, 1.4, 0.4, 1);
}

.ob-board-toolbar {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 12px 16px;
  background: #fff;
  border-top: 1px solid #ECF1F2;
}
.ob-tool {
  width: 36px;
  height: 36px;
  flex: 0 0 auto;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  background: #F6F9F9;
  border-radius: 8px;
  transition: transform 0.15s, background 0.15s;
}
.ob-tool-active { background: var(--teal-bg); }
.ob-input {
  flex: 1;
  min-width: 0;
  border: 1px solid var(--border-2);
  border-radius: 10px;
  padding: 9px 14px;
  font-size: 14px;
  color: var(--muted-2);
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

[hidden] { display: none !important; }

/* ---------- Sections ---------- */

.ob-section { padding-top: 72px; }
.ob-h2 {
  margin: 0;
  font-size: clamp(28px, 4vw, 34px);
  font-weight: 800;
  letter-spacing: -0.8px;
  text-align: center;
}
.ob-sub {
  margin: 12px auto 0;
  max-width: 520px;
  text-align: center;
  font-size: 16px;
  line-height: 1.6;
  color: var(--muted);
  text-wrap: pretty;
}

/* ---------- Write it your way ---------- */

.ob-ways {
  display: grid;
  grid-template-columns: 1fr 1.15fr;
  gap: 48px;
  align-items: center;
  margin-top: 44px;
}
.ob-way-list { display: flex; flex-direction: column; gap: 16px; }
.ob-way {
  display: flex;
  gap: 18px;
  background: #fff;
  border: 1px solid var(--border);
  border-radius: 16px;
  padding: 22px 24px;
}
.ob-way-featured {
  border: 1.5px solid var(--teal);
  box-shadow: 0 8px 24px rgba(23, 181, 203, 0.12);
}
.ob-way-icon {
  width: 44px;
  height: 44px;
  flex: 0 0 auto;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--teal-bg);
  border-radius: 12px;
  font-size: 20px;
}
.ob-way-title { font-weight: 700; font-size: 17px; }
.ob-way-text { font-size: 14.5px; line-height: 1.55; color: var(--muted); margin-top: 4px; }

/* ---------- QR mock ---------- */

.ob-qr-mock {
  border: 1px solid var(--border-2);
  border-radius: 16px;
  overflow: hidden;
  background: #fff;
  box-shadow: 0 16px 48px rgba(20, 24, 26, 0.1);
}
.ob-qr-canvas {
  position: relative;
  background-color: var(--board-bg);
  background-image: radial-gradient(var(--board-dot) 1.3px, transparent 1.3px);
  background-size: 26px 26px;
  height: 340px;
  overflow: hidden;
}
.ob-qr-paper {
  position: absolute;
  left: 60px;
  right: 60px;
  top: 28px;
  bottom: 0;
  background: #fff;
  border-radius: 4px 4px 0 0;
  box-shadow: 0 4px 24px rgba(20, 24, 26, 0.08);
  padding: 22px 28px;
}
.ob-qr-head { font-weight: 700; font-size: 14px; }
.ob-qr-head span { float: right; }
.ob-qr-eq { font-family: Georgia, serif; font-size: 15px; margin-top: 6px; }

.ob-photo {
  width: 270px;
  margin-top: 14px;
  opacity: 0;
  transform: rotate(-2.5deg) scale(0.7);
  transition: opacity 0.45s, transform 0.45s;
}
.ob-photo.is-in { opacity: 1; transform: rotate(-2.5deg) scale(1); }
.ob-photo-frame {
  background: #fff;
  border-radius: 3px;
  padding: 6px;
  box-shadow: 0 12px 30px rgba(20, 24, 26, 0.22), 0 2px 6px rgba(20, 24, 26, 0.12);
}
.ob-photo-note {
  background: linear-gradient(180deg, #F2EFE7 0%, #EDEAE0 100%);
  background-image: repeating-linear-gradient(180deg, transparent 0px, transparent 27px, #C9D4E2 27px, #C9D4E2 28px);
  border-radius: 2px;
  padding: 12px 16px 14px;
  font-family: "Caveat", cursive;
  font-size: 23px;
  line-height: 28px;
  color: #3A4159;
}
.ob-circled {
  border: 2px solid #3A4159;
  border-radius: 50%;
  padding: 0 8px;
  display: inline-block;
  transform: rotate(3deg);
}
.ob-photo-tag {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  background: var(--ink);
  color: #fff;
  font-size: 11px;
  font-weight: 700;
  padding: 5px 10px;
  border-radius: 999px;
  margin-top: -12px;
  margin-left: 10px;
  position: relative;
  box-shadow: 0 4px 12px rgba(20, 24, 26, 0.25);
}
.ob-photo-badge {
  display: inline-block;
  background: var(--ok-bg);
  color: var(--ok-fg);
  font-size: 12px;
  font-weight: 800;
  padding: 5px 11px;
  border-radius: 999px;
  margin-left: 8px;
  transform: rotate(2deg);
  opacity: 0;
  transition: opacity 0.4s;
}
.ob-photo-badge.is-in { opacity: 1; }

.ob-qr-modal {
  position: absolute;
  inset: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  background: rgba(20, 24, 26, 0.35);
  opacity: 0;
  transition: opacity 0.35s;
  pointer-events: none;
}
.ob-qr-modal.is-open { opacity: 1; }
.ob-qr-dialog {
  background: #fff;
  border-radius: 16px;
  padding: 24px 32px;
  text-align: center;
  box-shadow: 0 24px 60px rgba(20, 24, 26, 0.3);
  transform: scale(0.9);
  transition: transform 0.35s;
}
.ob-qr-modal.is-open .ob-qr-dialog { transform: scale(1); }
.ob-qr-title { font-weight: 800; font-size: 17px; }
.ob-qr-desc { font-size: 13px; color: var(--muted); margin-top: 4px; }
.ob-qr-code {
  display: inline-block;
  background: #fff;
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 10px;
  margin-top: 14px;
}
.ob-qr-grid { display: grid; grid-template-columns: repeat(21, 5px); grid-auto-rows: 5px; }
.ob-qr-status { font-size: 13px; font-weight: 600; color: var(--muted-2); margin-top: 14px; }
.ob-qr-status.is-received { color: var(--ok-fg); }

/* ---------- How it works ---------- */

.ob-steps {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
  margin-top: 40px;
}
.ob-step {
  background: #fff;
  border: 1px solid var(--border);
  border-radius: 16px;
  padding: 28px;
}
.ob-step-num {
  width: 40px;
  height: 40px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--teal-bg);
  color: var(--teal-deep);
  font-weight: 800;
  font-size: 18px;
  border-radius: 12px;
}
.ob-step-num-dark { background: var(--ink); color: #fff; }
.ob-step h3 { margin: 18px 0 8px; font-size: 19px; font-weight: 700; }
.ob-step p { margin: 0; font-size: 15px; line-height: 1.6; color: var(--muted); }

/* ---------- CTA ---------- */

.ob-cta {
  background: var(--ink);
  color: #fff;
  text-align: center;
  padding: 64px 48px;
  position: relative;
  overflow: hidden;
  margin-top: 72px;
}
.ob-cta-accent { position: absolute; left: 0; right: 0; top: 0; height: 6px; background: var(--teal); }
.ob-cta h2 { margin: 0; font-size: clamp(28px, 4vw, 36px); font-weight: 800; letter-spacing: -0.8px; }
.ob-cta p { margin: 14px 0 0; font-size: 17px; color: #9FB4B9; }
.ob-cta .ob-btn { margin-top: 28px; }

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

.ob-footer {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 16px;
  padding-top: 24px;
  padding-bottom: 24px;
  font-size: 13.5px;
  color: var(--muted-2);
  flex-wrap: wrap;
}
.ob-footer-logo { height: 22px; display: block; opacity: 0.7; }
.ob-footer-links { display: flex; gap: 20px; align-items: center; }
.ob-footer-links a { color: var(--muted-2); }

/* ---------- Animations ---------- */

@keyframes ob-fade-up {
  from { opacity: 0; transform: translateY(6px); }
  to { opacity: 1; transform: translateY(0); }
}
@keyframes ob-pop {
  from { opacity: 0; transform: rotate(2deg) scale(0.6); }
  to { opacity: 1; transform: rotate(2deg) scale(1); }
}

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

@media (max-width: 900px) {
  .ob-container { padding-left: 24px; padding-right: 24px; }
  .ob-ways { grid-template-columns: 1fr; gap: 32px; }
  .ob-steps { grid-template-columns: 1fr; }
  .ob-hero { padding-top: 56px; }
}

@media (max-width: 560px) {
  .ob-nav-links { gap: 16px; }
  .ob-nav-links > a:not(.ob-btn) { display: none; }
  .ob-paper { padding: 24px 20px; }
  .ob-points { position: static; text-align: right; }
  .ob-qr-paper { left: 24px; right: 24px; }
  .ob-photo { width: 210px; }
  .ob-btn-lg { padding: 14px 24px; font-size: 16px; }
}

@media (prefers-reduced-motion: reduce) {
  .ob-tutor, .ob-correct-badge { animation: none; }
  .ob-photo, .ob-photo-badge, .ob-qr-modal, .ob-qr-dialog { transition: none; }
}

/* cenová poznámka pod hlavním CTA */
.ob-price {
  margin: 14px 0 0;
  font-size: 14px;
  color: var(--muted);
}