:root {
  --primary: #58cc02;
  --primary-dark: #46a302;
  --secondary: #1cb0f6;
  --danger: #ff4b4b;
  --bg: #fff;
  --text: #3c3c3c;
  --light-gray: #e5e5e5;
  --gray: #777;
  --locked: #e5e5e5;
}

* { box-sizing: border-box; margin: 0; padding: 0; }

body {
  font-family: 'Segoe UI', system-ui, sans-serif;
  background-color: #f7f7f7;
  color: var(--text);
  line-height: 1.6;
}

#app {
  max-width: 800px;
  margin: 0 auto;
  padding: 20px;
  background: var(--bg);
  min-height: 100vh;
  box-shadow: 0 0 15px rgba(0,0,0,0.05);
}

header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  border-bottom: 2px solid var(--light-gray);
  padding-bottom: 15px;
  margin-bottom: 20px;
  flex-wrap: wrap;
  gap: 10px;
}

header h1 {
  color: var(--primary);
  font-size: 1.8rem;
}

header nav {
  display: flex;
  gap: 10px;
}

header nav button, header nav label {
  background: var(--light-gray);
  color: var(--gray);
  border: none;
  padding: 8px 12px;
  border-radius: 8px;
  cursor: pointer;
  font-size: 0.9rem;
  font-weight: bold;
  transition: 0.2s;
}

header nav button:hover, header nav label:hover {
  filter: brightness(0.95);
}

#statsBar {
  display: flex;
  justify-content: center;
  gap: 20px;
  margin-bottom: 20px;
}

.stat {
  font-weight: bold;
  color: var(--gray);
  background: #fff;
  padding: 5px 15px;
  border-radius: 20px;
  border: 2px solid var(--light-gray);
}

#levelTabs {
  display: flex;
  justify-content: space-between;
  margin-bottom: 30px;
  background: var(--light-gray);
  border-radius: 12px;
  padding: 5px;
}

.tab {
  flex: 1;
  background: transparent;
  border: none;
  padding: 10px;
  cursor: pointer;
  font-weight: bold;
  color: var(--gray);
  border-radius: 8px;
  transition: 0.2s;
  font-size: 1rem;
}

.tab.active {
  background: var(--bg);
  color: var(--primary);
  box-shadow: 0 1px 3px rgba(0,0,0,0.1);
}

#mainContent h2 {
  color: var(--primary);
  margin-bottom: 20px;
  text-align: center;
}

.module-list {
  list-style: none;
}

.module-item {
  display: flex;
  align-items: center;
  background: var(--bg);
  border: 2px solid var(--light-gray);
  border-radius: 12px;
  padding: 15px 20px;
  margin-bottom: 15px;
  cursor: pointer;
  transition: 0.2s;
  position: relative;
}

.module-item:not(.locked):hover {
  border-color: var(--primary);
  transform: translateY(-2px);
}

.module-item.completed {
  border-color: var(--primary);
  background: #f0ffe5;
}

.module-item.locked {
  cursor: not-allowed;
  opacity: 0.6;
  background: #f5f5f5;
}

.module-icon {
  width: 40px;
  height: 40px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  margin-right: 15px;
  font-weight: bold;
  color: #fff;
  background: var(--primary);
  flex-shrink: 0;
}

.module-item.completed .module-icon { background: var(--primary); }
.module-item.locked .module-icon { background: var(--gray); }

.module-info { flex-grow: 1; }
.module-info h3 { font-size: 1.1rem; margin-bottom: 4px; }
.module-info p { font-size: 0.9rem; color: var(--gray); }

.module-lock-icon { font-size: 1.2rem; color: var(--gray); }

/* Lesson View */
#lessonView h2 { margin-bottom: 10px; }
.lesson-progress {
  height: 12px;
  background: var(--light-gray);
  border-radius: 6px;
  margin-bottom: 30px;
  overflow: hidden;
}
.lesson-progress-bar {
  height: 100%;
  background: var(--primary);
  width: 0%;
  transition: width 0.3s;
  border-radius: 6px;
}

.question-box {
  background: #fff;
  padding: 20px;
  border-radius: 16px;
  box-shadow: 0 4px 12px rgba(0,0,0,0.05);
  margin-bottom: 20px;
}

.question-text { font-size: 1.2rem; font-weight: bold; margin-bottom: 20px; }

input[type="text"] {
  width: 100%;
  padding: 15px;
  border: 2px solid var(--light-gray);
  border-radius: 12px;
  font-size: 1rem;
  margin-bottom: 20px;
  outline: none;
  transition: 0.2s;
}
input[type="text"]:focus { border-color: var(--secondary); }

.options { display: flex; flex-direction: column; gap: 10px; margin-bottom: 20px; }
.option-btn {
  background: #fff;
  border: 2px solid var(--light-gray);
  padding: 15px;
  border-radius: 12px;
  cursor: pointer;
  font-size: 1rem;
  text-align: left;
  transition: 0.2s;
}
.option-btn:hover:not(.disabled) { border-color: var(--secondary); background: #f0f8ff; }
.option-btn.selected { border-color: var(--secondary); background: #e8f4fd; }
.option-btn.correct { border-color: var(--primary); background: #f0ffe5; color: var(--primary-dark); }
.option-btn.wrong { border-color: var(--danger); background: #ffe5e5; color: var(--danger); }

.word-bank { display: flex; flex-wrap: wrap; gap: 10px; margin-bottom: 20px; min-height: 50px; }
.word-chip {
  background: #fff;
  border: 2px solid var(--light-gray);
  padding: 8px 15px;
  border-radius: 20px;
  cursor: pointer;
  user-select: none;
  transition: 0.2s;
}
.word-chip:hover { border-color: var(--secondary); }
.word-chip.placed { opacity: 0.3; pointer-events: none; }

.answer-area {
  border: 2px dashed var(--light-gray);
  padding: 15px;
  border-radius: 12px;
  min-height: 60px;
  margin-bottom: 20px;
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  align-items: center;
}
.answer-area .placeholder { color: var(--gray); font-style: italic; }

.feedback {
  padding: 15px;
  border-radius: 12px;
  margin-bottom: 20px;
  display: none;
}
.feedback.show { display: block; }
.feedback.correct { background: #f0ffe5; color: var(--primary-dark); border: 1px solid var(--primary); }
.feedback.wrong { background: #ffe5e5; color: var(--danger); border: 1px solid var(--danger); }

.btn {
  width: 100%;
  padding: 15px;
  border: none;
  border-radius: 12px;
  background: var(--primary);
  color: #fff;
  font-size: 1rem;
  font-weight: bold;
  cursor: pointer;
  text-transform: uppercase;
  letter-spacing: 1px;
  transition: 0.2s;
  margin-bottom: 10px;
}
.btn:hover { background: var(--primary-dark); }
.btn:disabled { background: var(--light-gray); color: var(--gray); cursor: not-allowed; }
.btn.secondary { background: var(--secondary); }
.btn.danger { background: var(--danger); }

.back-link { display: block; text-align: center; margin-top: 20px; color: var(--secondary); cursor: pointer; text-decoration: underline; }