:root {
  --bg: #f7f8fa;
  --bg-panel: #ffffff;
  --text: #1c2127;
  --text-soft: #55606b;
  --border: #e3e6ea;
  --accent: #2f6fed;
  --accent-soft: #eaf1ff;
  --code-bg: #1e2530;
  --code-text: #e8ecf1;
  --warn-bg: #fff8e6;
  --warn-border: #f0c869;
  --tip-bg: #e9f9f0;
  --tip-border: #52c98a;
  --radius: 10px;
  --sidebar-w: 300px;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #12151a;
    --bg-panel: #191d24;
    --text: #e7ebf0;
    --text-soft: #9aa5b1;
    --border: #2a2f38;
    --accent: #6d9bff;
    --accent-soft: #1c2740;
    --code-bg: #0d1117;
    --code-text: #dbe4ee;
    --warn-bg: #2c260f;
    --warn-border: #7a611c;
    --tip-bg: #10261b;
    --tip-border: #2f7d54;
  }
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  padding: 0;
  background: var(--bg);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  line-height: 1.65;
}

a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }

.layout {
  display: flex;
  min-height: 100vh;
}

#sidebar {
  width: var(--sidebar-w);
  flex-shrink: 0;
  border-right: 1px solid var(--border);
  background: var(--bg-panel);
  padding: 20px 14px 60px;
  overflow-y: auto;
  height: 100vh;
  position: sticky;
  top: 0;
}

.sidebar-brand {
  display: block;
  font-weight: 700;
  font-size: 1.05rem;
  margin-bottom: 4px;
  color: var(--text);
}
.sidebar-brand:hover { text-decoration: none; opacity: .85; }
.sidebar-sub {
  color: var(--text-soft);
  font-size: .78rem;
  margin-bottom: 18px;
}

.nav-track { margin-bottom: 6px; }
.nav-track-title {
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: .82rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: .03em;
  color: var(--text-soft);
  padding: 8px 8px;
  border-radius: 6px;
  user-select: none;
}
.nav-track-title:hover { background: var(--accent-soft); color: var(--text); }
.nav-track-title .chevron { transition: transform .15s ease; font-size: .7rem; }
.nav-track.open .chevron { transform: rotate(90deg); }
.nav-track-num {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 20px; height: 20px;
  border-radius: 50%;
  background: var(--accent-soft);
  color: var(--accent);
  font-size: .68rem;
  font-weight: 800;
}

.nav-lessons {
  display: none;
  flex-direction: column;
  padding-left: 10px;
  border-left: 2px solid var(--border);
  margin: 2px 0 10px 18px;
}
.nav-track.open .nav-lessons { display: flex; }

.nav-lessons a {
  color: var(--text-soft);
  font-size: .86rem;
  padding: 6px 10px;
  border-radius: 6px;
  margin: 1px 0;
}
.nav-lessons a:hover { background: var(--accent-soft); color: var(--text); text-decoration: none; }
.nav-lessons a.active {
  background: var(--accent);
  color: #fff;
  font-weight: 600;
}

.content-wrap {
  flex: 1;
  display: flex;
  justify-content: center;
  padding: 40px 24px 100px;
}

main.content {
  max-width: 760px;
  width: 100%;
}
main.content.content-wide {
  max-width: 1180px;
}

.breadcrumb {
  font-size: .82rem;
  color: var(--text-soft);
  margin-bottom: 10px;
}

.lesson-title {
  font-size: 2rem;
  margin: 0 0 6px;
  line-height: 1.2;
}
.lesson-subtitle {
  color: var(--text-soft);
  font-size: 1.05rem;
  margin: 0 0 30px;
}

main.content h2 {
  margin-top: 42px;
  padding-top: 6px;
  border-top: 1px solid var(--border);
  font-size: 1.4rem;
}
main.content h3 {
  font-size: 1.12rem;
  margin-top: 28px;
}

main.content p, main.content li { color: var(--text); }
main.content ul, main.content ol { padding-left: 22px; }

pre {
  background: var(--code-bg);
  color: var(--code-text);
  padding: 16px 18px;
  border-radius: var(--radius);
  overflow-x: auto;
  font-size: .88rem;
  line-height: 1.55;
}
code {
  font-family: "SFMono-Regular", Consolas, "Liberation Mono", Menlo, monospace;
  background: var(--accent-soft);
  padding: .15em .4em;
  border-radius: 4px;
  font-size: .88em;
}
pre code { background: none; padding: 0; }

.box {
  border-radius: var(--radius);
  padding: 16px 18px;
  margin: 22px 0;
  border: 1px solid var(--border);
}
.box-analogia { background: var(--accent-soft); border-color: var(--accent); }
.box-dica { background: var(--tip-bg); border-color: var(--tip-border); }
.box-atencao { background: var(--warn-bg); border-color: var(--warn-border); }
.box-titulo {
  font-weight: 700;
  font-size: .82rem;
  text-transform: uppercase;
  letter-spacing: .03em;
  margin-bottom: 8px;
  display: block;
}

table {
  width: 100%;
  border-collapse: collapse;
  margin: 20px 0;
  font-size: .92rem;
}
th, td {
  border: 1px solid var(--border);
  padding: 8px 12px;
  text-align: left;
}
th { background: var(--accent-soft); }

.lesson-footer-nav {
  display: flex;
  justify-content: space-between;
  gap: 16px;
  margin-top: 60px;
  padding-top: 20px;
  border-top: 1px solid var(--border);
}
.lesson-footer-nav a {
  flex: 1;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 14px 16px;
  color: var(--text);
}
.lesson-footer-nav a:hover { border-color: var(--accent); text-decoration: none; }
.lesson-footer-nav .dir { display: block; font-size: .74rem; color: var(--text-soft); margin-bottom: 4px; }
.lesson-footer-nav .next { text-align: right; }

.checklist { list-style: none; padding-left: 0; }
.checklist li { padding-left: 28px; position: relative; margin-bottom: 8px; }
.checklist li::before {
  content: "✓";
  position: absolute;
  left: 0;
  color: var(--tip-border);
  font-weight: 700;
}

.home-hero {
  padding: 10px 0 20px;
}
.home-hero h1 { font-size: 2.3rem; margin-bottom: 8px; }
.track-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
  gap: 16px;
  margin-top: 24px;
}
.track-card {
  border: 1px solid var(--border);
  background: var(--bg-panel);
  border-radius: var(--radius);
  padding: 18px;
}
.track-card:hover { border-color: var(--accent); }
.track-card h3 { margin: 0 0 6px; font-size: 1.05rem; }
.track-card p { margin: 0; color: var(--text-soft); font-size: .86rem; }

/* ===== Dashboard (home) ===== */

.dash-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  flex-wrap: wrap;
  margin-bottom: 26px;
}
.dash-header-left {
  display: flex;
  align-items: center;
  gap: 10px;
}
.dash-icon { font-size: 1.3rem; }
.dash-title { font-weight: 700; font-size: 1.15rem; }

.dash-header-right {
  display: flex;
  align-items: center;
  gap: 10px;
}
.dash-progress-mini {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: .8rem;
  color: var(--text-soft);
}
.dash-progress-track {
  width: 130px;
  height: 6px;
  border-radius: 4px;
  background: var(--border);
  overflow: hidden;
}
.dash-progress-fill {
  height: 100%;
  background: var(--accent);
  border-radius: 4px;
}
.icon-btn {
  border: 1px solid var(--border);
  background: var(--bg-panel);
  color: var(--text-soft);
  width: 34px;
  height: 34px;
  border-radius: 8px;
  cursor: default;
  font-size: .95rem;
  display: inline-flex;
  align-items: center;
  justify-content: center;
}

.stat-cards {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
  gap: 14px;
  margin-bottom: 22px;
}
.stat-card {
  display: flex;
  align-items: center;
  gap: 12px;
  border: 1px solid var(--border);
  background: var(--bg-panel);
  border-radius: var(--radius);
  padding: 14px 16px;
}
.stat-card .stat-icon {
  width: 34px;
  height: 34px;
  border-radius: 8px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1rem;
  flex-shrink: 0;
}
.stat-card .stat-label {
  font-size: .68rem;
  font-weight: 700;
  letter-spacing: .03em;
  color: var(--text-soft);
}
.stat-card .stat-value { font-size: 1.4rem; font-weight: 700; }

.stat-ok .stat-icon { background: var(--tip-bg); color: var(--tip-border); }
.stat-progress { border-color: var(--warn-border); }
.stat-progress .stat-icon { background: var(--warn-bg); color: var(--warn-border); }
.stat-bad .stat-icon { background: #fbe6e6; color: #d64545; }
@media (prefers-color-scheme: dark) {
  .stat-bad .stat-icon { background: #3a1c1c; color: #e07a7a; }
}
.stat-available .stat-icon { background: var(--accent-soft); color: var(--text-soft); }

.continue-card {
  border: 1px solid var(--accent);
  background: var(--accent-soft);
  border-radius: var(--radius);
  padding: 16px 20px;
  margin-bottom: 34px;
}
.continue-label {
  font-size: .7rem;
  font-weight: 700;
  letter-spacing: .04em;
  color: var(--accent);
  margin-bottom: 8px;
}
.continue-body {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  flex-wrap: wrap;
}
.continue-title { font-weight: 700; font-size: 1.05rem; margin-bottom: 4px; }
.continue-meta { font-size: .8rem; color: var(--text-soft); }
.continue-btn {
  background: var(--accent);
  color: #fff;
  padding: 10px 18px;
  border-radius: 8px;
  font-size: .88rem;
  font-weight: 600;
  white-space: nowrap;
}
.continue-btn:hover { text-decoration: none; opacity: .92; }

.section-title {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 1.1rem;
  margin: 0 0 16px;
}

.track-section {
  border: 1px solid var(--border);
  background: var(--bg-panel);
  border-radius: var(--radius);
  padding: 18px 20px 20px;
  margin-bottom: 20px;
}
.track-section-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  flex-wrap: wrap;
  margin-bottom: 10px;
}
.track-section-name {
  display: flex;
  align-items: center;
  gap: 8px;
  font-weight: 700;
  font-size: 1rem;
}
.track-section-count {
  font-size: .76rem;
  color: var(--text-soft);
}
.track-progress-track {
  width: 100%;
  height: 6px;
  border-radius: 4px;
  background: var(--border);
  overflow: hidden;
  margin-bottom: 16px;
}
.track-progress-fill {
  height: 100%;
  background: var(--tip-border);
  border-radius: 4px;
}

.lesson-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
  gap: 12px;
}
.lesson-card {
  display: flex;
  align-items: center;
  gap: 12px;
  border: 1px solid var(--border);
  border-left: 3px solid var(--border);
  background: var(--bg);
  border-radius: 8px;
  padding: 12px 14px;
  color: var(--text);
}
.lesson-card:hover { border-color: var(--accent); text-decoration: none; }
.lesson-card.status-current { border-left-color: var(--warn-border); }
.lesson-card.status-done { border-left-color: var(--tip-border); }
.lesson-card.status-bad { border-left-color: #d64545; }

.lesson-badge {
  flex-shrink: 0;
  width: 30px;
  height: 30px;
  border-radius: 7px;
  background: var(--accent-soft);
  color: var(--accent);
  font-size: .68rem;
  font-weight: 800;
  display: flex;
  align-items: center;
  justify-content: center;
}
.lesson-card-title {
  font-size: .88rem;
  font-weight: 600;
  line-height: 1.3;
  margin-bottom: 3px;
}
.lesson-card-time {
  font-size: .74rem;
  color: var(--text-soft);
}

/* ===== Lesson feedback widget ===== */

.feedback-box {
  border: 1px solid var(--border);
  background: var(--bg-panel);
  border-radius: var(--radius);
  padding: 22px 24px;
  margin-top: 50px;
}
.feedback-question {
  text-align: center;
  font-size: .95rem;
  margin-bottom: 16px;
}
.feedback-ok-label {
  text-align: center;
  font-size: .72rem;
  font-weight: 700;
  letter-spacing: .04em;
  color: var(--text-soft);
  margin-bottom: 10px;
}
.feedback-buttons {
  display: flex;
  gap: 10px;
  margin-bottom: 14px;
}
.fb-btn {
  flex: 1;
  border: 1px solid var(--border);
  background: var(--bg);
  color: var(--text);
  border-radius: 8px;
  padding: 10px 12px;
  font-size: .86rem;
  font-weight: 600;
  cursor: pointer;
}
.fb-btn:hover { border-color: var(--accent); }
.fb-btn.fb-ok.active { background: var(--tip-bg); border-color: var(--tip-border); color: var(--tip-border); }
.fb-btn.fb-mid.active { background: var(--warn-bg); border-color: var(--warn-border); color: var(--warn-border); }
.fb-btn.fb-bad.active { background: #fbe6e6; border-color: #d64545; color: #d64545; }
@media (prefers-color-scheme: dark) {
  .fb-btn.fb-bad.active { background: #3a1c1c; color: #e07a7a; }
}

.feedback-note {
  width: 100%;
  min-height: 70px;
  resize: vertical;
  border: 1px solid var(--border);
  background: var(--bg);
  color: var(--text);
  border-radius: 8px;
  padding: 10px 12px;
  font-family: inherit;
  font-size: .88rem;
  margin-bottom: 16px;
}

.feedback-actions {
  display: flex;
  gap: 10px;
  flex-wrap: wrap;
}
.fa-btn {
  flex: 1;
  min-width: 140px;
  border: 1px solid var(--border);
  background: var(--bg);
  color: var(--text-soft);
  border-radius: 8px;
  padding: 9px 10px;
  font-size: .78rem;
  cursor: pointer;
}
.fa-btn:hover { border-color: var(--accent); color: var(--text); }

.menu-toggle {
  display: none;
}

@media (max-width: 860px) {
  .layout { flex-direction: column; }
  #sidebar {
    position: static;
    height: auto;
    width: 100%;
    border-right: none;
    border-bottom: 1px solid var(--border);
  }
  .content-wrap { padding: 24px 16px 80px; }
}