body {
    background: linear-gradient(135deg, #0d0d0d, #1a1a2e);
    color: #ffffff;
    font-family: 'Arial', sans-serif;
    text-align: center;
    margin: 0;
    padding: 0;
    min-height: 100vh;
}

.skip-link {
    position: absolute;
    top: -100px;
    left: 0;
    background: #00ffcc;
    color: #000;
    padding: 10px 14px;
    z-index: 9999;
    border-radius: 8px;
    text-decoration: none;
}

.skip-link:focus-visible {
    top: 10px;
    outline: 2px solid #00ffcc;
    outline-offset: 3px;
}

.sr-only {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border: 0;
}

:focus-visible {
    outline: 3px solid #00ffcc;
    outline-offset: 3px;
}

.container {
    max-width: 900px;
    margin: auto;
    padding: 20px;
    animation: fadeIn 1.5s ease-in-out;
}

@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(-20px);
    }

    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.title {
    font-size: 2.5rem;
    text-shadow: 0 0 10px cyan;
}

.description {
    font-size: 1.2rem;
    margin-bottom: 20px;
    opacity: 0.8;
}

/* Progress Bar */
.progress-container {
    width: 100%;
    background: #333;
    height: 10px;
    border-radius: 5px;
    margin-bottom: 15px;
}

#progress-bar {
    height: 100%;
    width: 0;
    background: #00ffcc;
    transition: width 0.5s ease-in-out;
    border-radius: 5px;
}

.options-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 15px;
    margin: 20px 0;
}

.option {
    background: #007bff;
    color: white;
    padding: 12px;
    border-radius: 8px;
    font-size: 1rem;
    transition: 0.3s;
    cursor: pointer;
    text-align: center;
    box-shadow: 0 4px 8px rgba(0, 123, 255, 0.3);
    border: none;
}

.option:focus-visible {
    outline: 3px solid #00ffcc;
    outline-offset: 3px;
}

.option:hover {
    background: #0056b3;
    transform: scale(1.05);
}

.option.selected {
    background: #ffcc00;
    color: #000;
    font-weight: bold;
}

.button-group {
    display: flex;
    justify-content: center;
    gap: 10px;
}

button {
    background: #28a745;
    color: white;
    padding: 12px 15px;
    border-radius: 8px;
    font-size: 1rem;
    cursor: pointer;
    border: none;
    transition: 0.3s;
}

button:focus-visible {
    outline: 3px solid #00ffcc;
    outline-offset: 3px;
}

button:disabled {
    background: #444;
    cursor: not-allowed;
}

button:hover:enabled {
    background: #218838;
    transform: scale(1.05);
}

.hidden {
    display: none;
}

/* Popup Warning */
.popup {
    display: none;
    position: fixed;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    background: rgba(0, 0, 0, 0.9);
    padding: 20px;
    border-radius: 10px;
    text-align: center;
    color: white;
    box-shadow: 0 0 15px rgba(255, 255, 255, 0.3);
    animation: fadeIn 0.3s ease-in-out;
    z-index: 1000;
}

.popup:focus-visible {
    outline: 3px solid #00ffcc;
    outline-offset: 3px;
}

.correct {
    color: green;
    font-weight: bold;
}

.incorrect {
    color: red;
    font-weight: bold;
}

.correct-answer {
    color: green;
    font-weight: bold;
}

.wrong-answer {
    color: red;
    font-weight: bold;
}

.option.correct {
    background-color: green !important;
    color: blueviolet;
}

.option.wrong {
    background-color: red !important;
    color: white;
}

@media (max-width: 560px) {
    .options-grid {
        grid-template-columns: 1fr;
    }

    .button-group {
        flex-direction: column;
        align-items: stretch;
    }
}

@media (prefers-reduced-motion: reduce) {
    * {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
        scroll-behavior: auto !important;
    }
}