:root {
  --bg: #f4f6f8;
  --card: #ffffff;
  --text: #222222;
  --muted: #6b7280;
  --border: #dddddd;
  --top: #1f2937;
  --primary: #2563eb;
  --success: #16a34a;
  --warning-bg: #fff7ed;
  --warning-border: #f97316;
}

body.dark {
  --bg: #111827;
  --card: #1f2937;
  --text: #f9fafb;
  --muted: #d1d5db;
  --border: #374151;
  --top: #030712;
  --primary: #60a5fa;
  --success: #22c55e;
  --warning-bg: #292014;
  --warning-border: #f97316;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: Arial, sans-serif;
  background: var(--bg);
  color: var(--text);
}

.top {
  padding: 18px 20px;
  background: var(--top);
  color: white;
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 12px;
}

.top h1 { margin: 0 0 6px; }
.top p { margin: 0; opacity: 0.85; }

.small-btn {
  padding: 9px 12px;
  border: 1px solid var(--border);
  border-radius: 10px;
  background: var(--card);
  color: var(--text);
  cursor: pointer;
}

.tabs {
  display: flex;
  gap: 8px;
  padding: 12px;
  overflow-x: auto;
  background: var(--card);
  border-bottom: 1px solid var(--border);
}

.tab {
  padding: 10px 14px;
  border: 1px solid var(--border);
  background: var(--card);
  color: var(--text);
  border-radius: 10px;
  cursor: pointer;
  white-space: nowrap;
}

.tab.active {
  background: var(--top);
  color: white;
}

.layout {
  max-width: 1100px;
  margin: 20px auto;
  padding: 0 12px;
  display: grid;
  grid-template-columns: 260px 1fr;
  gap: 16px;
}

.sidebar,
.card {
  background: var(--card);
  border-radius: 16px;
  padding: 18px;
  box-shadow: 0 4px 18px rgba(0,0,0,0.08);
}

.sidebar h2 {
  margin-top: 0;
}

.task-list {
  display: grid;
  gap: 8px;
}

.task-item {
  text-align: left;
  padding: 10px 12px;
  border: 1px solid var(--border);
  background: var(--card);
  color: var(--text);
  border-radius: 10px;
  cursor: pointer;
}

.task-item.active {
  border-color: var(--primary);
  outline: 2px solid var(--primary);
}

.task-item.done::before {
  content: "✓ ";
  color: var(--success);
  font-weight: bold;
}

.hidden { display: none; }

.task-head {
  display: flex;
  justify-content: space-between;
  gap: 12px;
  align-items: center;
}

audio {
  width: 100%;
  margin: 12px 0;
}

.speed-row {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  align-items: center;
  margin-bottom: 16px;
}

.speed,
.text-buttons button,
.nav-buttons button,
.main-btn {
  padding: 10px 14px;
  border: 1px solid var(--border);
  border-radius: 10px;
  background: var(--card);
  color: var(--text);
  cursor: pointer;
}

.speed.active {
  background: var(--primary);
  color: white;
  border-color: var(--primary);
}

.question {
  font-size: 18px;
  font-weight: bold;
}

.answers {
  display: grid;
  gap: 10px;
  margin: 16px 0;
}

.answer {
  display: block;
  padding: 12px;
  border: 1px solid var(--border);
  border-radius: 12px;
  cursor: pointer;
}

.answer input { margin-right: 8px; }

.main-btn {
  width: 100%;
  background: var(--success);
  color: white;
  border-color: var(--success);
  font-weight: bold;
}

.result {
  font-weight: bold;
  min-height: 24px;
}

.text-buttons,
.nav-buttons {
  display: flex;
  gap: 10px;
  margin-top: 14px;
  flex-wrap: wrap;
}

.text-box {
  margin-top: 12px;
  padding: 14px;
  background: var(--bg);
  border-left: 4px solid var(--primary);
  border-radius: 8px;
  white-space: pre-wrap;
}

#empty-message {
  padding: 14px;
  background: var(--warning-bg);
  border-left: 4px solid var(--warning-border);
  border-radius: 8px;
}

@media (max-width: 760px) {
  .layout {
    grid-template-columns: 1fr;
  }

  .task-head {
    display: block;
  }

  .text-buttons button,
  .nav-buttons button {
    width: 100%;
  }
}