:root {
  --green: #58cc02;
  --green-dark: #4caf00;
  --blue: #1cb0f6;
  --red: #ff4b4b;
  --yellow: #ffc800;
  --gray-bg: #f7f7f7;
  --gray-border: #e5e5e5;
  --text: #3c3c3c;
  --text-light: #777;
  --radius: 14px;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  background: var(--gray-bg);
  color: var(--text);
}

a { color: inherit; text-decoration: none; }

/* ---------- Buttons ---------- */
.btn {
  display: inline-block;
  padding: 14px 20px;
  border-radius: 12px;
  border: none;
  font-size: 16px;
  font-weight: 700;
  cursor: pointer;
  text-align: center;
  box-shadow: 0 4px 0 rgba(0, 0, 0, 0.08);
  transition: transform 0.05s ease;
}
.btn:active { transform: translateY(2px); box-shadow: none; }
.btn-block { display: block; width: 100%; margin-top: 16px; }
.btn-primary { background: var(--green); color: #fff; }
.btn-primary:hover { background: var(--green-dark); }
.btn-secondary { background: #fff; color: var(--text); border: 2px solid var(--gray-border); box-shadow: none; }
.btn-link { background: none; border: none; color: var(--text-light); cursor: pointer; font-size: 14px; }

/* ---------- Top navigation ---------- */
.topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 14px 24px;
  background: #fff;
  border-bottom: 1px solid var(--gray-border);
  flex-wrap: wrap;
  gap: 12px;
}
.logo { font-weight: 800; font-size: 20px; color: var(--green-dark); }
.logo-sub { font-weight: 400; font-size: 13px; color: var(--text-light); }
.topnav { display: flex; gap: 18px; }
.topnav a { font-weight: 600; color: var(--text-light); }
.topnav a:hover { color: var(--text); }
.stats-bar { display: flex; align-items: center; gap: 14px; }
.stat { font-weight: 700; font-size: 15px; }
.stat-streak { color: #ff9600; }
.stat-hearts { color: var(--red); }
.mode-switch {
  font-size: 13px;
  font-weight: 700;
  color: #fff;
  background: #24292e;
  border-radius: 8px;
  padding: 6px 10px;
  white-space: nowrap;
}
.mode-switch:hover { background: #444d56; }
.stat-xp { color: var(--yellow); }

/* ---------- Page container ---------- */
.page { max-width: 720px; margin: 0 auto; padding: 24px 16px 64px; }

.alert {
  padding: 12px 16px;
  border-radius: 10px;
  margin-bottom: 16px;
  font-weight: 600;
}
.alert-warn { background: #fff4e0; color: #a15c00; border: 1px solid #ffd58a; }
.alert-error { background: #ffe5e5; color: #b30000; border: 1px solid #ffb3b3; }

/* ---------- XP progress card ---------- */
.xp-progress-card {
  background: #fff;
  border: 1px solid var(--gray-border);
  border-radius: var(--radius);
  padding: 16px 20px;
  margin-bottom: 24px;
}
.xp-progress-label { font-size: 13px; color: var(--text-light); font-weight: 600; margin: 4px 0; }
.xp-progress-bar { background: var(--gray-border); border-radius: 8px; height: 12px; overflow: hidden; }
.xp-progress-fill { background: var(--yellow); height: 100%; border-radius: 8px; transition: width 0.3s; }

/* ---------- Skill trees (sections) ---------- */
.tree-block {
  background: #fff;
  border: 1px solid var(--gray-border);
  border-radius: var(--radius);
  padding: 20px;
  margin-bottom: 28px;
}
.tree-header {
  display: flex;
  align-items: center;
  gap: 14px;
  padding-bottom: 14px;
  border-bottom: 2px solid var(--gray-bg);
  margin-bottom: 8px;
  flex-wrap: wrap;
}
.tree-icon { font-size: 34px; }
.tree-header-text { flex: 1; min-width: 180px; }
.tree-header-text h2 { margin: 0; }
.tree-header-text p { color: var(--text-light); margin: 2px 0 0; font-size: 14px; }
.tree-progress { display: flex; flex-direction: column; align-items: flex-end; gap: 4px; min-width: 110px; }
.tree-progress-label { font-size: 13px; font-weight: 700; color: var(--text-light); }
.tree-progress-bar { background: var(--gray-border); border-radius: 8px; height: 10px; overflow: hidden; width: 110px; }
.tree-progress-fill { background: var(--green); height: 100%; border-radius: 8px; transition: width 0.3s; }
.tree-progress-done { background: var(--yellow); }

/* ---------- Units / lesson path ---------- */
.unit-block { margin: 20px 0 8px; }
.unit-header h2, .unit-header h3 { margin-bottom: 2px; margin-top: 0; }
.unit-header p { color: var(--text-light); margin-top: 0; }

/* ---------- Параллельные ветки (латиница/кириллица) ---------- */
.branch-row { display: flex; gap: 20px; align-items: flex-start; }
.branch-col { flex: 1; min-width: 0; }
.branch-tag {
  display: inline-block;
  font-size: 12px;
  font-weight: 800;
  color: var(--blue);
  background: #e7f7ff;
  border-radius: 8px;
  padding: 3px 8px;
  margin-bottom: 4px;
}
.branch-locked-note { font-size: 13px; color: var(--text-light); font-weight: 600; margin: 6px 0 0; }

@media (max-width: 600px) {
  .branch-row { flex-direction: column; gap: 0; }
}
.lesson-path { display: flex; flex-direction: column; gap: 10px; margin-top: 12px; }
.lesson-node {
  display: flex;
  align-items: center;
  gap: 12px;
  background: #fff;
  border: 2px solid var(--gray-border);
  border-radius: 12px;
  padding: 14px 18px;
  font-weight: 700;
}
.lesson-node-icon { font-size: 18px; width: 24px; text-align: center; }
.lesson-node-title { flex: 1; }
.lesson-locked { color: #b5b5b5; }
.lesson-available { border-color: var(--green); color: var(--green-dark); }
.lesson-available:hover { background: #f0fdea; }
.lesson-completed { border-color: var(--blue); color: var(--blue); }
.lesson-node-score { font-size: 13px; color: var(--text-light); }

/* ---------- Auth pages ---------- */
.auth-page { min-height: 100vh; display: flex; align-items: center; justify-content: center; padding: 20px; }
.auth-card { background: #fff; border-radius: var(--radius); padding: 32px; width: 100%; max-width: 380px; box-shadow: 0 4px 20px rgba(0,0,0,0.06); }
.auth-card h1 { color: var(--green-dark); margin-bottom: 0; }
.auth-sub { color: var(--text-light); margin-top: 4px; }
.auth-form { display: flex; flex-direction: column; gap: 14px; margin-top: 20px; }
.auth-form label { font-size: 13px; font-weight: 700; color: var(--text-light); display: flex; flex-direction: column; gap: 6px; }
.auth-form input {
  padding: 12px 14px;
  border-radius: 10px;
  border: 2px solid var(--gray-border);
  font-size: 15px;
  font-weight: 400;
  color: var(--text);
}
.auth-form input:focus { outline: none; border-color: var(--blue); }
.auth-switch { text-align: center; margin-top: 18px; font-size: 14px; color: var(--text-light); }
.auth-switch a { color: var(--blue); font-weight: 700; }

/* ---------- Lesson / review distraction-free page ---------- */
.lesson-page { min-height: 100vh; display: flex; flex-direction: column; background: #fff; }
.lesson-topbar { display: flex; align-items: center; gap: 16px; padding: 16px 20px; }
.lesson-close { font-size: 22px; color: var(--text-light); font-weight: 700; }
.lesson-progress-track { flex: 1; height: 14px; background: var(--gray-border); border-radius: 8px; overflow: hidden; }
.lesson-progress-fill { height: 100%; background: var(--green); width: 0%; transition: width 0.3s; }
.lesson-hearts { font-weight: 800; color: var(--red); white-space: nowrap; }

.lesson-body { flex: 1; max-width: 640px; width: 100%; margin: 0 auto; padding: 24px 20px 40px; }

.intro-screen h1 { margin-bottom: 6px; }
.grammar-note { background: #f0f8ff; border: 1px solid #cbe8ff; border-radius: 12px; padding: 16px 18px; line-height: 1.6; margin: 16px 0; }
.dialogue-box { background: var(--gray-bg); border-radius: 12px; padding: 16px 18px; margin: 16px 0; }
.dialogue-line { margin-bottom: 10px; }
.dialogue-speaker { font-weight: 800; color: var(--green-dark); }
.dialogue-sr { font-weight: 600; }
.dialogue-ru { color: var(--text-light); font-size: 14px; }

.exercise-screen { display: flex; flex-direction: column; }
.exercise-prompt { font-size: 22px; font-weight: 800; margin-bottom: 20px; }
.listen-btn { margin-bottom: 20px; align-self: flex-start; }
.exercise-hint { font-size: 13px; color: var(--text-light); margin-top: 10px; }

.options-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 12px; }
.option-btn {
  padding: 16px;
  border-radius: 12px;
  border: 2px solid var(--gray-border);
  background: #fff;
  font-size: 16px;
  font-weight: 600;
  cursor: pointer;
  text-align: left;
}
.option-btn:hover { border-color: var(--blue); }
.option-selected { border-color: var(--blue); background: #e7f7ff; }
.option-btn:disabled { cursor: default; }

.text-input {
  padding: 14px 16px;
  font-size: 18px;
  border-radius: 12px;
  border: 2px solid var(--gray-border);
  width: 100%;
}
.text-input:focus { outline: none; border-color: var(--blue); }

.word-bank-answer { min-height: 48px; border-bottom: 2px solid var(--gray-border); margin-bottom: 20px; display: flex; flex-wrap: wrap; gap: 8px; padding-bottom: 10px; }
.word-bank-options { display: flex; flex-wrap: wrap; gap: 10px; }
.token-btn, .token-chip {
  padding: 10px 16px;
  border-radius: 10px;
  border: 2px solid var(--gray-border);
  background: #fff;
  font-weight: 700;
  cursor: pointer;
}
.token-btn:disabled { opacity: 0.25; cursor: default; }
.token-chip { border-color: var(--blue); background: #e7f7ff; }

.feedback-bar { margin-top: 20px; padding: 14px 16px; border-radius: 12px; font-size: 15px; }
.feedback-correct { background: #eaffd8; color: var(--green-dark); }
.feedback-wrong { background: #ffe5e5; color: #c40000; }

.finish-screen { text-align: center; }
.finish-stats { display: flex; justify-content: center; gap: 28px; margin: 24px 0; }
.finish-stat { display: flex; flex-direction: column; align-items: center; }
.finish-stat-num { font-size: 26px; font-weight: 800; color: var(--green-dark); }
.finish-stat span:last-child { font-size: 13px; color: var(--text-light); }

/* ---------- Review flashcards ---------- */
.review-card { text-align: center; padding-top: 20px; }
.review-card-label { color: var(--text-light); font-weight: 700; margin-bottom: 12px; }
.review-card-front { font-size: 32px; font-weight: 800; margin-bottom: 20px; }
.review-card-back { font-size: 22px; font-weight: 600; color: var(--blue); margin-bottom: 20px; }
.review-rate-row { display: grid; grid-template-columns: repeat(4, 1fr); gap: 8px; margin-top: 16px; }
.btn-rate { padding: 12px 6px; font-size: 13px; border-radius: 10px; border: none; color: #fff; font-weight: 700; cursor: pointer; }
.btn-rate-again { background: var(--red); }
.btn-rate-hard { background: #ff9600; }
.btn-rate-good { background: var(--blue); }
.btn-rate-easy { background: var(--green); }

/* ---------- Profile & leaderboard ---------- */
.profile-card { background: #fff; border-radius: var(--radius); border: 1px solid var(--gray-border); padding: 24px; margin-bottom: 24px; }
.profile-stats-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 16px; margin-top: 16px; }
.profile-stat { display: flex; flex-direction: column; align-items: center; background: var(--gray-bg); border-radius: 10px; padding: 14px 8px; }
.profile-stat-num { font-size: 20px; font-weight: 800; }
.profile-stat span:last-child { font-size: 12px; color: var(--text-light); margin-top: 2px; }

.leaderboard-block { background: #fff; border-radius: var(--radius); border: 1px solid var(--gray-border); padding: 20px 24px; margin-bottom: 20px; }
.leaderboard-list { list-style: none; margin: 12px 0 0; padding: 0; }
.leaderboard-list li { display: flex; align-items: center; gap: 12px; padding: 10px 0; border-bottom: 1px solid var(--gray-bg); font-weight: 600; }
.leaderboard-rank { width: 22px; color: var(--text-light); font-weight: 800; }
.leaderboard-name { flex: 1; }
.leaderboard-xp { color: var(--text-light); font-weight: 700; }
.leaderboard-me { color: var(--green-dark); }

/* ---------- Кабинет: график активности ---------- */
.week-chart { display: flex; gap: 10px; align-items: flex-end; margin-top: 16px; height: 140px; }
.week-col { flex: 1; display: flex; flex-direction: column; align-items: center; gap: 6px; height: 100%; }
.week-xp { font-size: 12px; font-weight: 700; color: var(--text-light); min-height: 15px; }
.week-bar-track { flex: 1; width: 100%; max-width: 42px; display: flex; align-items: flex-end; background: var(--gray-bg); border-radius: 8px; overflow: hidden; }
.week-bar { width: 100%; background: var(--yellow); border-radius: 8px 8px 0 0; transition: height 0.3s; }
.week-col-today .week-bar { background: var(--green); }
.week-label { font-size: 12px; font-weight: 700; color: var(--text-light); }
.week-col-today .week-label { color: var(--green-dark); }

/* ---------- Кабинет: прогресс по древам ---------- */
.tree-progress-list { display: flex; flex-direction: column; gap: 12px; margin-top: 16px; }
.tree-progress-row { display: flex; align-items: center; gap: 12px; }
.tree-progress-icon { font-size: 22px; }
.tree-progress-title { flex: 1; font-weight: 700; }
.tree-progress-row .tree-progress-bar { width: 140px; }
.tree-progress-row .tree-progress-label { min-width: 48px; text-align: right; }

/* ---------- Кабинет: достижения ---------- */
.achievements-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 12px; margin-top: 16px; }
.achievement {
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  gap: 4px;
  background: var(--gray-bg);
  border: 2px solid var(--gray-border);
  border-radius: 12px;
  padding: 14px 8px;
}
.achievement-earned { background: #fffbe6; border-color: var(--yellow); }
.achievement-locked { opacity: 0.45; filter: grayscale(1); }
.achievement-icon { font-size: 26px; }
.achievement-title { font-weight: 800; font-size: 13px; }
.achievement-desc { font-size: 11px; color: var(--text-light); }

/* ---------- Алфавит и тренажёр печати ---------- */
.alphabet-intro { color: var(--text-light); line-height: 1.5; }
.alphabet-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 12px; margin-top: 16px; }
.alphabet-card { background: var(--gray-bg); border: 2px solid var(--gray-border); border-radius: 12px; padding: 12px; text-align: center; }
.alphabet-letters { display: flex; justify-content: center; align-items: baseline; gap: 10px; }
.alphabet-lat { font-size: 24px; font-weight: 800; color: var(--green-dark); }
.alphabet-cyr { font-size: 18px; font-weight: 700; color: var(--blue); }
.alphabet-pron { font-size: 12px; color: var(--text-light); margin: 6px 0; min-height: 28px; }
.alphabet-example { font-size: 13px; }

.trainer-mode-row { display: grid; grid-template-columns: 1fr 1fr; gap: 12px; margin-top: 16px; }
.trainer-mode-btn { line-height: 1.4; }
.trainer-mode-sub { font-size: 12px; font-weight: 400; color: var(--text-light); }
.trainer-progress-row { display: flex; align-items: center; gap: 12px; margin: 16px 0; }
.trainer-counter { font-weight: 800; color: var(--text-light); white-space: nowrap; }
.trainer-prompt { font-size: 42px; font-weight: 800; text-align: center; margin: 10px 0 2px; }
.trainer-hint { text-align: center; color: var(--text-light); margin-bottom: 16px; min-height: 20px; }
.trainer-input { text-align: center; font-size: 22px; }
.special-chars { display: flex; justify-content: center; gap: 10px; margin-top: 12px; }
.special-chars .token-btn { font-size: 18px; min-width: 44px; }
.trainer-after { margin-top: 8px; font-size: 14px; font-weight: 400; }
#trainer-check { margin-top: 16px; }

@media (max-width: 480px) {
  .alphabet-grid { grid-template-columns: repeat(2, 1fr); }
  .trainer-mode-row { grid-template-columns: 1fr; }
}

@media (max-width: 480px) {
  .options-grid { grid-template-columns: 1fr; }
  .stats-bar { gap: 10px; }
  .achievements-grid { grid-template-columns: repeat(2, 1fr); }
  .tree-progress-row .tree-progress-bar { width: 90px; }
}

/* Материалы */
.materials-tabs { display: flex; flex-wrap: wrap; gap: 10px; margin-top: 18px; }
.materials-tab-btn {
  background: var(--gray-bg);
  border: 2px solid var(--gray-border);
  border-radius: 999px;
  padding: 8px 16px;
  font-weight: 700;
  font-size: 14px;
  cursor: pointer;
  color: var(--text);
}
.materials-tab-btn:hover { border-color: var(--blue); }
.materials-tab-btn.active { background: var(--green); border-color: var(--green); color: #fff; }

.materials-articles { display: flex; flex-direction: column; gap: 10px; margin-top: 16px; }
.materials-article { border: 1px solid var(--gray-border); border-radius: 12px; overflow: hidden; }
.materials-article-toggle {
  width: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  background: var(--gray-bg);
  border: none;
  padding: 14px 16px;
  font-weight: 700;
  font-size: 15px;
  text-align: left;
  cursor: pointer;
  color: var(--text);
}
.materials-chevron { color: var(--text-light); transition: transform 0.2s; flex-shrink: 0; }
.materials-article.open .materials-chevron { transform: rotate(180deg); }
.materials-article-body { display: none; padding: 16px 18px; line-height: 1.65; }
.materials-article.open .materials-article-body { display: block; }
.materials-article-body p { margin: 0 0 12px; }
.materials-article-body p:last-child { margin-bottom: 0; }