/* Стили страницы бесплатного урока. Использует переменные из styles.css */

.lesson-nav {
  position: fixed;
  top: 0; left: 0; right: 0;
  z-index: 100;
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 18px 60px;
  background: rgba(13,13,15,0.85);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border);
}
.lesson-nav .nav-logo { font-size: 16px; font-weight: 700; letter-spacing: -0.03em; }
.lesson-nav .nav-logo span { color: var(--accent); }
.lesson-nav a.back { font-size: 14px; color: var(--muted); transition: color 0.2s; }
.lesson-nav a.back:hover { color: var(--text); }

/* progress */
#lesson-progress {
  position: fixed;
  top: 0; left: 0;
  height: 3px; width: 0%;
  background: var(--accent);
  z-index: 200;
  transition: width 0.1s linear;
}

.lesson {
  max-width: 760px;
  margin: 0 auto;
  padding: 140px 24px 100px;
}

.lesson-tag {
  display: inline-block;
  background: var(--accent);
  color: #000;
  font-size: 12px;
  font-weight: 800;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  padding: 5px 14px;
  border-radius: 100px;
  margin-bottom: 24px;
}

.lesson h1 {
  font-size: clamp(34px, 6vw, 56px);
  font-weight: 800;
  letter-spacing: -0.04em;
  line-height: 1.05;
  margin-bottom: 20px;
}
.lesson h1 em { font-style: normal; color: var(--accent); }

.lesson-lead {
  font-size: 19px;
  color: var(--muted);
  line-height: 1.7;
  margin-bottom: 16px;
}

.lesson-meta {
  display: flex;
  gap: 20px;
  font-size: 13px;
  color: var(--muted);
  margin-bottom: 56px;
  padding-bottom: 32px;
  border-bottom: 1px solid var(--border);
  flex-wrap: wrap;
}
.lesson-meta span { display: flex; align-items: center; gap: 6px; }

.lesson-block { margin-bottom: 56px; }

.lesson-step {
  font-size: 12px;
  font-weight: 700;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--accent);
  margin-bottom: 14px;
}

.lesson h2 {
  font-size: clamp(24px, 4vw, 34px);
  font-weight: 800;
  letter-spacing: -0.03em;
  line-height: 1.15;
  margin-bottom: 18px;
}

.lesson p {
  font-size: 17px;
  line-height: 1.75;
  color: #d6d6de;
  margin-bottom: 18px;
}
.lesson p.muted { color: var(--muted); font-size: 15px; }

.lesson strong { color: var(--text); }

/* good / bad examples */
.example {
  border-radius: var(--radius);
  padding: 22px 24px;
  margin: 16px 0;
  font-size: 16px;
  line-height: 1.6;
  border: 1px solid var(--border);
  background: var(--card);
}
.example .ex-label {
  display: inline-flex;
  align-items: center;
  gap: 7px;
  font-size: 12px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: 12px;
}
.example.bad { border-color: rgba(255,122,69,0.35); }
.example.bad .ex-label { color: var(--accent2); }
.example.good { border-color: rgba(95,227,161,0.35); background: rgba(95,227,161,0.04); }
.example.good .ex-label { color: var(--accent); }
.example .prompt-text { color: var(--text); font-style: italic; }
.example .ex-note { color: var(--muted); font-size: 14px; margin-top: 12px; font-style: normal; }

/* formula */
.formula {
  display: flex;
  align-items: stretch;
  gap: 12px;
  flex-wrap: wrap;
  margin: 28px 0;
}
.formula-part {
  flex: 1;
  min-width: 150px;
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 22px 20px;
  position: relative;
}
.formula-part .fp-num {
  font-size: 13px;
  font-weight: 700;
  color: var(--accent);
  margin-bottom: 8px;
}
.formula-part h4 { font-size: 17px; font-weight: 700; margin-bottom: 6px; }
.formula-part p { font-size: 14px; color: var(--muted); margin: 0; line-height: 1.5; }

/* practice box */
.practice {
  background: var(--card);
  border: 1px solid var(--accent);
  border-radius: var(--radius);
  padding: 32px;
  margin: 32px 0;
}
.practice h3 { font-size: 20px; font-weight: 800; margin-bottom: 10px; }
.practice p { font-size: 15px; color: var(--muted); margin-bottom: 18px; }

.practice textarea {
  width: 100%;
  min-height: 120px;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 10px;
  color: var(--text);
  font-family: var(--font);
  font-size: 15px;
  line-height: 1.6;
  padding: 16px;
  resize: vertical;
  transition: border-color 0.2s;
}
.practice textarea:focus { outline: none; border-color: var(--accent); }

.practice-btn {
  margin-top: 16px;
  background: var(--accent);
  color: #000;
  font-weight: 800;
  font-size: 15px;
  border: none;
  border-radius: 8px;
  padding: 14px 28px;
  cursor: pointer;
  font-family: var(--font);
  transition: transform 0.15s, box-shadow 0.15s, opacity 0.15s;
}
.practice-btn:hover { transform: translateY(-2px); box-shadow: 0 8px 24px rgba(95,227,161,0.25); }
.practice-btn:disabled { opacity: 0.5; cursor: default; transform: none; box-shadow: none; }

/* mentor feedback */
.mentor {
  margin-top: 24px;
  border-radius: 12px;
  padding: 20px 22px;
  background: rgba(95,227,161,0.07);
  border: 1px solid rgba(95,227,161,0.3);
  font-size: 15px;
  line-height: 1.65;
  display: none;
}
.mentor.show { display: block; animation: mentorIn 0.4s ease; }
@keyframes mentorIn {
  from { opacity: 0; transform: translateY(10px); }
  to   { opacity: 1; transform: translateY(0); }
}
.mentor .who {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 12px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--accent);
  margin-bottom: 10px;
}
.mentor ul { margin: 10px 0 0 18px; }
.mentor li { margin-bottom: 6px; }
.mentor .score { font-weight: 700; color: var(--text); }

/* CTA at the end */
.lesson-cta {
  margin-top: 72px;
  text-align: center;
  background:
    radial-gradient(ellipse 70% 100% at 50% 0%, rgba(95,227,161,0.08) 0%, transparent 70%),
    var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 56px 40px;
}
.lesson-cta h2 { font-size: clamp(26px, 4vw, 38px); font-weight: 800; letter-spacing: -0.03em; margin-bottom: 16px; line-height: 1.1; }
.lesson-cta h2 em { font-style: normal; color: var(--accent); }
.lesson-cta p { color: var(--muted); font-size: 16px; max-width: 460px; margin: 0 auto 28px; }

@media (max-width: 600px) {
  .lesson-nav { padding: 16px 24px; }
  .lesson { padding: 110px 20px 80px; }
}