:root {
    --primary-color: #3b82f6;
    --secondary-color: #10b981;
    --background-color: #000000;
    --surface-color: #121212;
    --text-color: #e0e0e0;
    --danger-color: #ef4444;
    --border-color: #333333;
    --shadow: 0 4px 8px rgba(255, 255, 255, 0.05);
}

body {
    margin: 0;
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    background-color: var(--background-color);
    color: var(--text-color);
    display: grid;
    place-items: center;
    min-height: 100vh;
}

quiz-app {
    width: 90%;
    max-width: 800px;
    background: var(--surface-color);
    border-radius: 12px;
    box-shadow: var(--shadow);
    overflow: hidden;
    margin: 20px 0;
    border: 1px solid var(--border-color);
}

#welcome, #quiz, #results {
    padding: 30px;
}

h1, h2, h3 {
    color: #ffffff;
}

p {
    line-height: 1.6;
    color: var(--text-color);
}

button, .file-upload-label {
    display: inline-block;
    padding: 12px 20px;
    border: none;
    border-radius: 8px;
    cursor: pointer;
    font-size: 1rem;
    font-weight: 500;
    transition: all 0.3s ease;
    color: #FFFFFF;
    text-align: center;
    margin-top: 20px;
}

button:hover, .file-upload-label:hover {
    transform: translateY(-2px);
    filter: brightness(110%);
    box-shadow: 0 6px 12px rgba(255, 255, 255, 0.1);
}

.file-upload-label { background-color: var(--primary-color); }

#start-button { background-color: var(--secondary-color); }

#submit-quiz {
    background-color: var(--secondary-color);
    width: 100%;
}

#restart-quiz { background-color: var(--primary-color); }

.question-block {
    text-align: left;
    margin-bottom: 30px;
    border-bottom: 1px solid var(--border-color);
    padding-bottom: 20px;
}

.options-group {
    display: flex;
    flex-direction: column;
    gap: 10px;
}

.options-group label {
    display: flex;
    align-items: center;
    padding: 12px;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    cursor: pointer;
    transition: background-color 0.2s ease-in-out, border-color 0.2s ease-in-out;
    background-color: #1e1e1e;
    color: var(--text-color);
}

.options-group label:hover {
    background-color: #2d2d2d;
    border-color: var(--primary-color);
}

input[type="radio"] {
    margin-right: 12px;
    accent-color: var(--primary-color);
    width: 1.2em;
    height: 1.2em;
}

.result-item {
    text-align: left;
    margin-bottom: 20px;
    padding: 15px;
    border-radius: 8px;
}

.correct {
    background-color: rgba(21, 87, 36, 0.3);
    border-left: 5px solid #28a745;
    color: #e8f5e9;
}

.incorrect {
    background-color: rgba(114, 28, 36, 0.3);
    border-left: 5px solid #dc3545;
    color: #fce4ec;
}