/* ---------- Базовые стили ---------- */
:root{
  --green-1: #0a8f3a;
  --green-2: #28c76f;
  --bg: #f8fdf8;
  --muted: #999;
  --card: #ffffff;
  --accent-border: #cce8d6;
  --light-accent: #eaf7ec;
}

* { box-sizing: border-box; }

html,body{
  height: 100%;
  margin: 0;
  background: var(--bg);
  font-family: 'Segoe UI', Roboto, Arial, sans-serif;
  color: #222;
  -webkit-font-smoothing:antialiased;
  -moz-osx-font-smoothing:grayscale;
  line-height: 1.6;
}

/* ---------- Header ---------- */
header{
  text-align: center;
  background: linear-gradient(135deg, var(--green-1), var(--green-2));
  color: #fff;
  padding: 2rem 1rem;
  border-bottom: 4px solid var(--green-1);
}
header h1{ margin: 0; font-size: 2.25rem; font-weight: 700; }
header .subtitle{ font-size: 1rem; opacity: 0.95; margin-top: 6px; }

/* ---------- Layout main ---------- */
main{
  padding: 2rem 1rem;
  max-width: 980px;
  margin: 0 auto 4rem;
}

/* ---------- Intro ---------- */
.intro { margin-bottom: 1.5rem; font-size: 1.05rem; color: #233; }

/* ---------- Headings ---------- */
h2 { color: var(--green-1); margin: 0 0 0.75rem 0; font-size: 1.25rem; }

/* ---------- Lessons list (index) ---------- */
.lessons ul{ list-style: none; padding: 0; margin: 0; }
.lesson{
  background: var(--card);
  border: 2px solid var(--accent-border);
  border-radius: 12px;
  padding: 1rem;
  margin-bottom: 1rem;
  transition: transform .16s ease, box-shadow .16s ease;
}
.lesson.unlocked{ border-color: var(--green-2); cursor: pointer; }
.lesson.unlocked:hover{ transform: translateY(-4px); box-shadow: 0 10px 30px rgba(10,143,58,0.06); }
.lesson.locked{ color: var(--muted); background: #f0f5f0; }

/* ---------- Progress bar (cards) ---------- */
.progress{ background: #e0f2e9; border-radius: 6px; height: 10px; margin: 0.5rem 0; overflow: hidden; }
.progress .bar{ background: linear-gradient(135deg,var(--green-1),var(--green-2)); height:100%; width:0%; border-radius:6px; transition: width .35s ease; }

/* ---------- Top progress (on lesson page) ---------- */
.top-progress{
  background: #f3fff4;
  border: 1px solid #d6efdf;
  border-radius: 10px;
  padding: 10px 12px;
  margin: 12px 0 18px 0;
  box-shadow: 0 6px 20px rgba(0,0,0,0.03);
}
.top-progress-row{ display:flex; justify-content:space-between; align-items:center; gap:12px; margin-bottom:8px; }
.top-progress-label{ font-weight:600; color: var(--green-1); }
.top-progress-percent{ font-weight:700; color: var(--green-1); }
.top-progress-bar{ background: var(--light-accent); border-radius:8px; height:10px; overflow:hidden; }
.top-progress-fill{ background: linear-gradient(135deg,var(--green-1),var(--green-2)); height:100%; width:0%; transition: width .25s ease; border-radius:8px; }

/* ---------- Compact home button near top ---------- */
.home-top{
  display:inline-flex; align-items:center; gap:8px;
  background: transparent; color: var(--green-1);
  border: 1px solid rgba(10,143,58,0.12); padding:6px 10px; border-radius:10px;
  font-weight:700; text-decoration:none;
  transition: background .12s, transform .12s;
}
.home-top:hover{ background: rgba(10,143,58,0.06); transform: translateY(-2px); }

/* ---------- Lesson content ---------- */
.lesson-content{
 position: relative; padding-bottom: 100px;
}

/* ---------- Buttons (primary styles used by action block) ---------- */
.btn{
  border-radius: 12px;
  padding: 10px 18px;
  font-weight: 700;
  font-size: 1rem;
  cursor: pointer;
  border: none;
  min-width: 170px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
  transition: transform .12s ease, box-shadow .12s ease, opacity .12s ease;
}

/* Back (left) — neutral outline */
.btn-back{
  background: transparent;
  color: var(--green-1);
  border: 2px solid rgba(10,143,58,0.12);
  box-shadow: none;
}
.btn-back::before{ content: "←"; margin-right: 6px; font-size: 1.05rem; opacity: 0.95; }

/* Next (right) — accent */
.btn-next{
  background: linear-gradient(135deg,var(--green-1),var(--green-2));
  color: #fff;
  border: 0;
  box-shadow: 0 8px 22px rgba(10,143,58,0.14);
}
.btn-next::after{ content: "→"; margin-left: 6px; font-size: 1.05rem; opacity: 0.95; }

.btn-disabled {
  background: #ccc !important;
  color: #666 !important;
  cursor: not-allowed;
  box-shadow: none !important;
}

.btn:hover{ transform: translateY(-3px); }
.btn:active{ transform: translateY(0); opacity: 0.95; }

/* ---------- Lesson actions: centered in the viewport ---------- */
.lesson-actions{
  position: fixed;
  left: 50%;
  bottom: 24px;
  transform: translateX(-50%);
  display: flex;
  gap: 18px;
  align-items: center;
  z-index: 900;
  padding: 12px 14px;
  background: rgba(255,255,255,0.96);
  border-radius: 14px;
  box-shadow: 0 12px 40px rgba(0,0,0,0.08);
  border: 1px solid rgba(10,143,58,0.06);
  max-width: calc(100% - 48px);
}

/* Compact layout on narrow screens: column, full-width, Next large at bottom */
@media (max-width: 720px){
  .lesson-actions{
    flex-direction: column-reverse;
    align-items: stretch;
    gap: 10px;
    width: calc(100% - 24px);
    max-width: 720px;
    padding: 10px;
    left: 50%;
    bottom: 12px;
    transform: translateX(-50%);
  }
  .btn { width: 100%; min-width: 0; padding: 14px 16px; font-size: 1rem; }
}

/* Small height screens */
@media (max-height: 520px){
  .lesson-actions { bottom: 12px; }
}

/* Footer */
footer{
  text-align: center;
  padding: 1.5rem;
  background: var(--green-1);
  color: white;
  margin-top: 2.5rem;
  font-size: 0.9rem;
}