:root {
    --primary-color: #4A90E2;
    --secondary-color: #2C3E50;
    --success-color: #27AE60;
    --error-color: #E74C3C;
    --background-color: #F5F6FA;
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, 'Open Sans', 'Helvetica Neue', sans-serif;
    line-height: 1.6;
    background-color: var(--background-color);
}

#app {
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    padding: 1rem;
    box-sizing: border-box;
}

.screen {
    width: 100%;
    max-width: 600px;
}

.main-header {
    text-align: center;
    padding: 2rem 0;
    background: var(--primary-color);
    color: white;
    margin-bottom: 2rem;
}

.main-header h1 {
    margin: 0;
    font-size: 2.5em;
}

.main-header .tagline {
    margin: 0.5rem 0 0;
    font-size: 1.2em;
    opacity: 0.9;
}

.quiz-list-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 1rem;
}

.quiz-card {
    background: white;
    border-radius: 10px;
    padding: 20px;
    margin-bottom: 20px;
    box-shadow: 0 2px 5px rgba(0,0,0,0.1);
    transition: transform 0.3s, box-shadow 0.3s;
    text-decoration: none;
    color: inherit;
    display: block;
}

.quiz-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 5px 15px rgba(0,0,0,0.2);
}

.quiz-card h3 {
    color: var(--primary-color);
    margin-bottom: 10px;
}

.quiz-progress {
    margin-top: 15px;
    color: var(--secondary-color);
    font-weight: bold;
}

.quiz-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 2rem;
    padding: 0.5rem 1rem;
    background: transparent;
    color: var(--secondary-color);
    font-size: 0.85em;
    opacity: 0.7;
}

.back-button, .exit-button {
    color: var(--primary-color);
    text-decoration: none;
    padding: 0.5rem 1rem;
    border-radius: 5px;
    transition: background-color 0.3s;
    display: inline-block;
    margin-bottom: 20px;
}

.exit-button {
    color: var(--secondary-color);
    text-decoration: none;
    padding: 0.25rem 0.5rem;
    border-radius: 3px;
    transition: opacity 0.3s;
    display: inline-block;
    margin: 0;
}

.back-button:hover, .exit-button:hover {
    opacity: 1;
    background-color: transparent;
}

.question-container {
    background: white;
    padding: 2rem;
    border-radius: 10px;
    box-shadow: 0 4px 6px rgba(0,0,0,0.1);
    width: 100%;
    box-sizing: border-box;
}

#question-text {
    font-size: 1.4em;
    line-height: 1.4;
    color: var(--secondary-color);
    margin-bottom: 2rem;
    text-align: center;
    font-weight: 500;
}

#options-container {
    margin: 2rem 0;
}

.option {
    padding: 1.2rem;
    margin: 1rem 0;
    border: 2px solid #ddd;
    border-radius: 8px;
    cursor: pointer;
    transition: all 0.3s;
    font-size: 1.1em;
}

.option:first-child {
    margin-top: 0;
}

.option:last-child {
    margin-bottom: 0;
}

.option:hover {
    border-color: var(--primary-color);
    background-color: rgba(74, 144, 226, 0.05);
    transform: translateY(-1px);
}

.option.selected {
    border-color: var(--primary-color);
    background-color: rgba(74, 144, 226, 0.1);
}

.option.correct {
    border-color: var(--success-color);
    background-color: rgba(39, 174, 96, 0.1);
}

.option.incorrect {
    border-color: var(--error-color);
    background-color: rgba(231, 76, 60, 0.1);
}

.quiz-option {
    display: flex;
    align-items: center;
    padding: 1.2rem;
    margin: 1rem 0;
    border: 2px solid #ddd;
    border-radius: 8px;
    cursor: pointer;
    transition: all 0.3s;
    font-size: 1.1em;
}

.quiz-option:hover {
    border-color: var(--primary-color);
    background-color: rgba(74, 144, 226, 0.05);
    transform: translateY(-1px);
}

.quiz-icon {
    font-size: 2rem;
    margin-right: 1rem;
}

.quiz-details h3 {
    margin: 0 0 0.5rem 0;
    color: var(--secondary-color);
}

.quiz-details p {
    margin: 0;
    color: #666;
    font-size: 0.9em;
}

#quiz-list .quiz-header {
    display: flex;
    justify-content: center;
    align-items: center;
    margin-bottom: 2rem;
}

#quiz-list .quiz-header h2 {
    color: var(--secondary-color);
    font-size: 1.4em;
    text-align: center;
}

.confirm-button {
    display: block;
    width: 100%;
    padding: 1.2rem;
    margin-top: 2rem;
    background-color: var(--primary-color);
    color: white;
    border: none;
    border-radius: 8px;
    cursor: pointer;
    font-size: 1.1em;
    transition: all 0.3s;
}

.confirm-button:disabled {
    background-color: #ccc;
    cursor: not-allowed;
}

.confirm-button:not(:disabled):hover {
    background-color: #357ABD;
    transform: translateY(-1px);
}

.score-display {
    font-size: 0.9em;
    font-weight: normal;
    color: var(--secondary-color);
    text-align: right;
    display: flex;
    align-items: center;
    gap: 0.5rem;
    min-height: 1.5em;
    justify-content: flex-end;
}

.score-summary {
    white-space: nowrap;
    cursor: help;
}

.score-change {
    font-size: 0.9em;
    padding: 2px 6px;
    border-radius: 3px;
    min-width: 2.5em;
    text-align: center;
    opacity: 0;
    transition: opacity 0.3s ease-out;
    order: -1;
    margin-right: 0.5rem;
}

.score-change.visible {
    opacity: 1;
}

.score-change.positive {
    background-color: var(--success-color);
    color: white;
}

.score-change.negative {
    background-color: var(--error-color);
    color: white;
}

.hidden {
    display: none;
}

@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(10px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}