body { font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif; background-color: #f0f2f5; display: flex; justify-content: center; align-items: center; min-height: 100vh; margin: 0; color: #333; text-align: center; }
.container { background-color: #fff; padding: 2rem 3rem; border-radius: 12px; box-shadow: 0 8px 30px rgba(0, 0, 0, 0.1); width: 90%; max-width: 650px; }
#home-screen, #quiz-screen, #end-screen { display: none; }
#home-screen.active, #quiz-screen.active, #end-screen.active { display: block; }
h1, h2 { color: #0056b3; margin-bottom: 0.5em; }
h2#question { margin-bottom: 1.5em; font-size: 1.5rem; line-height: 1.5; }
p { line-height: 1.6; margin-bottom: 1.5em; }
input[type="text"] { width: calc(100% - 24px); padding: 12px; margin-bottom: 1.5em; border: 1px solid #ccc; border-radius: 8px; font-size: 1rem; }
input[type="text"]:focus { outline: none; border-color: #007bff; }
button { background-color: #007bff; color: white; padding: 12px 24px; border: none; border-radius: 8px; cursor: pointer; font-size: 1.1rem; font-weight: bold; transition: background-color 0.3s, transform 0.2s; margin: 0 5px; }
button#hint-btn { background-color: #ffc107; color: #333; }
button:hover { transform: translateY(-2px); }
button#next-btn { background-color: #28a745; }
button:disabled { background-color: #a0a0a0; cursor: not-allowed; transform: none; }
.info-box { margin-top: 1.5em; padding: 1em; border-radius: 8px; text-align: left; min-height: 24px; background-color: #f8f9fa; border-left: 5px solid #ccc; }
.info-box.feedback { font-weight: bold; }
.info-box.correct { border-left-color: #4CAF50; color: #4CAF50; }
.info-box.incorrect { border-left-color: #F44336; color: #F44336; }
.info-box#hint-display { border-left-color: #ffc107; }
.info-box#explanation-display { border-left-color: #17a2b8; }
.progress-container { margin: 1.5em 0; font-size: 1.1rem; font-weight: bold; }
.lives { color: #F44336; font-size: 1.5rem; margin: 0 0.5rem; vertical-align: middle; }
#end-screen h2 { font-size: 2.5rem; margin-bottom: 1rem; }