body {
    font-family: 'Inter', sans-serif;
    overscroll-behavior-y: contain;
}
.screen {
    display: none;
    min-height: calc(100vh - 50px);
    max-width: 600px;
    margin: 0 auto;
}
.screen.active {
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
}
.hidden {
    display: none !important;
}
.loader {
    border: 4px solid #f3f3f3;
    border-top: 4px solid #3498db;
    border-radius: 50%;
    width: 30px;
    height: 30px;
    animation: spin 1s linear infinite;
}
@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}
.youtube-container {
    position: relative;
    width: 100%;
    max-width: 560px;
    padding-bottom: 56.25%;
    height: 0;
    overflow: hidden;
    margin: 1rem auto;
    border-radius: 0.5rem;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
}
.youtube-container iframe {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    border: 0;
}
#playerOverlay {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: 10;
    background-color: transparent;
}
.progress-bar-container {
    width: 100%;
    max-width: 560px;
    background-color: #e0e0e0;
    border-radius: 0.5rem;
    margin: 0.5rem auto;
    overflow: hidden;
}
.progress-bar {
    width: 0%;
    height: 10px;
    background-color: #3498db;
    transition: width 0.1s linear;
}
.choice-button {
    transition: background-color 0.2s ease-in-out, transform 0.1s ease-in-out;
    word-break: break-all;
}
.choice-button:hover {
    transform: translateY(-2px);
}
.choice-button.correct {
    background-color: #28a745 !important;
    color: white;
    border-color: #28a745;
}
.choice-button.incorrect {
    background-color: #dc3545 !important;
    color: white;
    border-color: #dc3545;
}
.choice-button.disabled {
    opacity: 0.7;
    pointer-events: none;
}
#messageArea {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    padding: 0.75rem;
    background-color: rgba(0, 0, 0, 0.7);
    color: white;
    text-align: center;
    z-index: 1000;
    display: none;
    font-size: 0.875rem;
    min-height: 50px;
}
button, .choice-button {
    padding: 0.75rem 1.5rem;
    border-radius: 0.5rem;
    font-size: 1rem;
    cursor: pointer;
}
.text-placeholder-color {
    color: #9ca3af;
}