:root {
  --bg-color: var(--tg-theme-bg-color, #0f172a);
  --secondary-bg: var(--tg-theme-secondary-bg-color, #1e293b);
  --text-color: var(--tg-theme-text-color, #f8fafc);
  --hint-color: var(--tg-theme-hint-color, #94a3b8);
  --button-color: var(--tg-theme-button-color, #3b82f6);
  --button-text: var(--tg-theme-button-text-color, #ffffff);
  --accent-color: #f59e0b;
  --card-bg: #1e293b;
  --border-color: #334155;
  --success-color: #10b981;
}

* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  -webkit-tap-highlight-color: transparent;
}

body {
  background-color: var(--bg-color);
  color: var(--text-color);
  display: flex;
  flex-direction: column;
  height: 100vh;
  overflow: hidden;
}

#app {
  display: flex;
  flex-direction: column;
  height: 100%;
  max-width: 600px;
  margin: 0 auto;
  width: 100%;
}

.app-header {
  padding: 16px;
  background-color: var(--secondary-bg);
  border-bottom: 1px solid var(--border-color);
}

.course-title {
  font-size: 18px;
  font-weight: 700;
  color: var(--text-color);
}

.course-subtitle {
  font-size: 12px;
  color: var(--hint-color);
  margin-top: 2px;
}

.progress-widget {
  margin-top: 12px;
}

.progress-bar-bg {
  height: 6px;
  background-color: var(--border-color);
  border-radius: 3px;
  overflow: hidden;
}

.progress-bar-fill {
  height: 100%;
  background: linear-gradient(90deg, #3b82f6, #10b981);
  transition: width 0.3s ease;
}

.progress-text {
  font-size: 11px;
  color: var(--hint-color);
  margin-top: 4px;
  text-align: right;
}

.app-content {
  flex: 1;
  overflow-y: auto;
  padding: 16px;
}

.tab-view {
  display: none;
}

.tab-view.active {
  display: block;
}

.section-title {
  font-size: 15px;
  font-weight: 600;
  margin-bottom: 12px;
  color: var(--text-color);
}

.lessons-grid {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.lesson-card {
  background-color: var(--card-bg);
  border: 1px solid var(--border-color);
  border-radius: 12px;
  padding: 14px;
  cursor: pointer;
  transition: transform 0.1s, border-color 0.2s;

  display: flex;
  align-items: center;
  justify-content: space-between;
}

.lesson-card:active {
  transform: scale(0.98);
}

.lesson-card.completed {
  border-left: 4px solid var(--success-color);
}

.lesson-card.active-lesson {
  border-color: var(--button-color);
}

.lesson-card-info {
  flex: 1;
}

.lesson-num {
  font-size: 11px;
  font-weight: 700;
  color: var(--accent-color);

  margin-bottom: 2px;
}

.lesson-name {
  font-size: 14px;
  font-weight: 600;
  color: var(--text-color);
}

.check-icon {
  font-size: 18px;
  margin-left: 10px;
}

/* Chat view */
.chat-header {
  display: flex;
  align-items: center;
  gap: 10px;
  padding-bottom: 12px;
  border-bottom: 1px solid var(--border-color);
  margin-bottom: 12px;
}

.chat-header .avatar {
  font-size: 24px;
  background-color: var(--secondary-bg);
  padding: 8px;
  border-radius: 50%;
}

.chat-messages {
  display: flex;
  flex-direction: column;
  gap: 12px;
  height: 380px;
  overflow-y: auto;
  padding-right: 4px;

  margin-bottom: 12px;
}

.chat-bubble {
  max-width: 85%;
  padding: 10px 14px;
  border-radius: 14px;
  font-size: 14px;
  line-height: 1.4;
  white-space: pre-wrap;
}

.chat-bubble.assistant {
  background-color: var(--secondary-bg);
  align-self: flex-start;
  border-bottom-left-radius: 2px;
  border: 1px solid var(--border-color);
}

.chat-bubble.user {
  background-color: var(--button-color);
  color: var(--button-text);
  align-self: flex-end;
  border-bottom-right-radius: 2px;
}

.sources-box {
  margin-top: 8px;
  padding-top: 8px;
  border-top: 1px dashed var(--border-color);
  font-size: 11px;
  color: var(--hint-color);
}

.sources-box a {
  color: var(--button-color);
  text-decoration: none;
}

.chat-input-area {
  display: flex;
  gap: 8px;
}

.chat-input-area input {
  flex: 1;
  background-color: var(--secondary-bg);
  border: 1px solid var(--border-color);
  color: var(--text-color);
  padding: 10px 14px;
  border-radius: 20px;

  outline: none;
  font-size: 14px;
}

.chat-input-area button {
  background-color: var(--button-color);
  color: var(--button-text);
  border: none;
  padding: 10px 16px;
  border-radius: 20px;

  font-weight: 600;
  cursor: pointer;
}

/* Progress card */
.progress-card {
  background-color: var(--card-bg);
  border: 1px solid var(--border-color);
  border-radius: 12px;
  padding: 16px;
}

.stat-row {
  display: flex;
  justify-content: space-between;
  padding: 8px 0;
  border-bottom: 1px solid var(--border-color);
}

.stat-row:last-child {
  border-bottom: none;
}

/* Bottom Nav */
.bottom-nav {
  display: flex;
  background-color: var(--secondary-bg);
  border-top: 1px solid var(--border-color);
  padding: 6px 0;
}

.nav-btn {
  flex: 1;
  background: none;
  border: none;
  display: flex;
  flex-direction: column;
  align-items: center;
  color: var(--hint-color);
  cursor: pointer;

  padding: 4px 0;
}

.nav-btn.active {
  color: var(--button-color);
}

.nav-btn .icon {
  font-size: 20px;
}

.nav-btn .label {
  font-size: 10px;
  margin-top: 2px;
}

.loading-spinner {
  text-align: center;
  color: var(--hint-color);
  padding: 20px;
  font-size: 14px;
}

.btn-drive {
  display: inline-block;
  background-color: var(--button-color);
  color: var(--button-text);
  padding: 10px 16px;
  border-radius: 8px;
  text-decoration: none;
  font-size: 13px;
  font-weight: 600;
  margin-top: 12px;
}