:root {
  --bg: #faf7f0;
  --card: #ffffff;
  --text: #1f2933;
  --muted: #6b7280;
  --accent: #2f6f5e;
  --accent-2: #e8f3ef;
  --border: #e5e0d5;
  --danger: #b42318;
  --shadow: 0 1px 2px rgba(31, 41, 51, 0.04), 0 8px 24px rgba(31, 41, 51, 0.05);
}

* { box-sizing: border-box; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  font-size: 17px;
  line-height: 1.5;
}

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

.topbar {
  position: sticky;
  top: 0;
  z-index: 10;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  padding: 14px 22px;
  background: rgba(255, 255, 255, 0.92);
  border-bottom: 1px solid var(--border);
  backdrop-filter: blur(8px);
}

.brand {
  font-weight: 700;
  font-size: 20px;
  color: var(--text);
  letter-spacing: -0.01em;
}

.topbar nav { display: flex; gap: 18px; }
.topbar nav a { color: var(--muted); font-size: 15px; }
.topbar nav a:hover { color: var(--text); }

.wrap {
  max-width: 1100px;
  margin: 0 auto;
  padding: 22px;
}

.card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 18px;
  padding: 20px;
  box-shadow: var(--shadow);
  margin-bottom: 20px;
}

.card.narrow { max-width: 420px; margin: 70px auto; }

h1 { font-size: 28px; margin: 0 0 6px; letter-spacing: -0.02em; }
h2 { font-size: 20px; margin: 0 0 14px; letter-spacing: -0.01em; }

.muted { color: var(--muted); font-size: 14px; }
.error { color: var(--danger); font-size: 15px; }

.stack { display: grid; gap: 12px; margin-top: 18px; }

input[type="password"], input[type="text"], input:not([type]) {
  width: 100%;
  padding: 12px 14px;
  border: 1px solid var(--border);
  border-radius: 12px;
  font-size: 16px;
  background: #fff;
  color: var(--text);
}

input:focus { outline: 2px solid var(--accent-2); border-color: var(--accent); }

button {
  font-family: inherit;
  font-size: 16px;
  cursor: pointer;
}

button.primary {
  background: var(--accent);
  color: #fff;
  border: 1px solid var(--accent);
  border-radius: 12px;
  padding: 11px 18px;
  font-weight: 600;
}

button.primary:hover { background: #275c4e; }
button.primary:disabled { opacity: 0.55; cursor: default; }

button.ghost {
  background: transparent;
  color: var(--text);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 10px 16px;
}

button.ghost:hover { border-color: var(--accent); color: var(--accent); }

.lesson {
  display: grid;
  grid-template-columns: 300px minmax(0, 1fr);
  gap: 20px;
  align-items: start;
}

.skills { position: sticky; top: 80px; }

.skill {
  display: block;
  width: 100%;
  text-align: left;
  background: transparent;
  border: 1px solid var(--border);
  border-radius: 14px;
  padding: 12px 13px;
  margin-bottom: 8px;
  color: var(--text);
}

.skill:hover { border-color: var(--accent); }
.skill.active { border-color: var(--accent); background: var(--accent-2); }

.skill-title { display: block; font-weight: 600; font-size: 15px; }
.skill-sub { display: block; color: var(--muted); font-size: 13px; margin-top: 2px; }

.bar { display: inline-flex; gap: 3px; margin-top: 8px; }
.bar i {
  display: block;
  width: 18px;
  height: 5px;
  border-radius: 3px;
  background: #e5e0d5;
}
.bar i.on { background: var(--accent); }
.bar.big i { width: 26px; height: 7px; }

.chat {
  display: flex;
  flex-direction: column;
  min-height: 520px;
  height: calc(100vh - 140px);
  padding: 18px;
}

.chat-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 14px;
  padding-bottom: 12px;
  border-bottom: 1px solid var(--border);
}

.chat-title { font-weight: 700; font-size: 18px; }
.chat-sub { color: var(--muted); font-size: 14px; }

.messages {
  flex: 1;
  overflow-y: auto;
  padding: 12px 4px;
  display: flex;
  flex-direction: column;
}

.msg {
  max-width: 82%;
  padding: 10px 14px;
  border-radius: 14px;
  margin: 7px 0;
  white-space: pre-wrap;
  overflow-wrap: anywhere;
  line-height: 1.55;
}

.msg.assistant {
  align-self: flex-start;
  background: #f3f1ea;
  border-bottom-left-radius: 4px;
}

.msg.user {
  align-self: flex-end;
  background: var(--accent-2);
  border-bottom-right-radius: 4px;
}

.composer {
  display: flex;
  gap: 9px;
  padding-top: 12px;
  border-top: 1px solid var(--border);
}

.composer input { flex: 1; }

.stats {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 14px;
  margin-top: 18px;
}

.stats > div {
  background: #fbfaf6;
  border: 1px solid var(--border);
  border-radius: 14px;
  padding: 14px;
}

.stats b { display: block; font-size: 28px; line-height: 1.1; }
.stats span { color: var(--muted); font-size: 13px; }

.row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 14px;
}

table { width: 100%; border-collapse: collapse; }
th, td { text-align: left; padding: 10px 8px; border-bottom: 1px solid var(--border); vertical-align: top; }
th { color: var(--muted); font-size: 13px; font-weight: 600; }
tr:last-child td { border-bottom: none; }

@media (max-width: 860px) {
  .wrap { padding: 14px; }
  .lesson {
    display: flex;
    flex-direction: column;
    align-items: stretch;
  }
  .chat {
    order: 1;
    width: 100%;
    height: 68vh;
    min-height: 440px;
  }
  .skills {
    order: 2;
    width: 100%;
    position: static;
  }
  .stats { grid-template-columns: repeat(2, 1fr); }
  .topbar {
    flex-wrap: wrap;
    row-gap: 8px;
    padding: 12px 18px 12px 14px;
  }
  .topbar nav {
    flex-wrap: wrap;
    gap: 10px;
  }
  .topbar nav a { font-size: 14px; }
  .msg { max-width: 92%; }
  h1 { font-size: 24px; }
}