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

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background: linear-gradient(135deg, #0a1929 0%, #05131c 100%);
    min-height: 100vh;
    color: #fff;
    padding: 20px;
}

.container {
    max-width: 800px;
    margin: 0 auto;
}

h1 {
    text-align: center;
    margin-bottom: 40px;
    font-size: 2.5em;
    color: #fff;
    text-shadow: 0 2px 10px rgba(5, 19, 28, 0.5);
}

.screen {
    display: none;
    animation: fadeIn 0.4s ease-in;
}

.screen.active {
    display: block;
}

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

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

.card {
    background: rgba(255, 255, 255, 0.05);
    backdrop-filter: blur(10px);
    border-radius: 16px;
    padding: 30px;
    box-shadow: 0 8px 32px rgba(0, 0, 0, 0.3);
    border: 1px solid rgba(255, 255, 255, 0.1);
}

.form-group {
    margin-bottom: 25px;
}

label {
    display: block;
    margin-bottom: 10px;
    font-size: 1.1em;
    color: #e0e0e0;
}

select,
input[type="number"] {
    width: 100%;
    padding: 12px;
    border-radius: 8px;
    border: 1px solid rgba(255, 255, 255, 0.2);
    background: rgba(255, 255, 255, 0.1);
    color: #fff;
    font-size: 1em;
    transition: all 0.3s ease;
}

select:focus,
input[type="number"]:focus {
    outline: none;
    border-color: #05131c;
    background: rgba(255, 255, 255, 0.15);
}

select option {
    background: #0a1929;
    color: #fff;
}

.range-inputs {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 15px;
}

.shuffle-questions{
    margin-top: 15px;
}

.btn {
    width: 100%;
    padding: 15px;
    border: none;
    border-radius: 8px;
    font-size: 1.1em;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    margin-top: 10px;
}

.btn-primary {
    background: #05131c;
    color: #fff;
    box-shadow: 0 4px 15px rgba(5, 19, 28, 0.4);
}

.btn-primary:hover:not(:disabled) {
    background: #0a1f2e;
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(5, 19, 28, 0.6);
}

.btn-primary:disabled {
    background: rgba(255, 255, 255, 0.1);
    color: rgba(255, 255, 255, 0.3);
    cursor: not-allowed;
    box-shadow: none;
}

.question-card {
    margin-bottom: 20px;
}

.question-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 20px;
    padding-bottom: 15px;
    border-bottom: 1px solid rgba(255, 255, 255, 0.1);
}

.question-number {
    font-size: 1.2em;
    color: #05131c;
    background: rgba(255, 255, 255, 0.9);
    padding: 5px 15px;
    border-radius: 20px;
    font-weight: 600;
}

.difficulty {
    font-size: 0.9em;
    padding: 5px 12px;
    border-radius: 12px;
    font-weight: 500;
}

.difficulty-1 {
    background: #4caf50;
}

.difficulty-2 {
    background: #ff9800;
}

.difficulty-3 {
    background: #f44336;
}

.question-text {
    font-size: 1.3em;
    margin-bottom: 25px;
    line-height: 1.5;
}

.variants {
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.variant {
    padding: 15px 20px;
    border-radius: 8px;
    background: rgba(255, 255, 255, 0.05);
    border: 2px solid rgba(255, 255, 255, 0.1);
    cursor: pointer;
    transition: all 0.3s ease;
}

.variant:hover:not(.correct):not(.incorrect):not(.correct-answer) {
    background: rgba(255, 255, 255, 0.1);
    border-color: rgba(255, 255, 255, 0.3);
    transform: translateX(5px);
}

.variant.selected {
    background: #05131c;
    border-color: #05131c;
    box-shadow: 0 4px 15px rgba(5, 19, 28, 0.4);
}

.variant.correct {
    background: rgba(76, 175, 80, 0.3);
    border-color: #4caf50;
    box-shadow: 0 4px 15px rgba(76, 175, 80, 0.3);
    cursor: default;
}

.variant.incorrect {
    background: rgba(244, 67, 54, 0.3);
    border-color: #f44336;
    box-shadow: 0 4px 15px rgba(244, 67, 54, 0.3);
    cursor: default;
}

.variant.correct-answer {
    background: rgba(76, 175, 80, 0.2);
    border-color: #4caf50;
    box-shadow: 0 4px 15px rgba(76, 175, 80, 0.2);
    cursor: default;
}

.variant.disabled {
    cursor: default;
    pointer-events: none;
}

.results {
    text-align: center;
}

.score {
    font-size: 4em;
    color: #05131c;
    background: rgba(255, 255, 255, 0.9);
    padding: 30px;
    border-radius: 20px;
    margin: 30px 0;
    font-weight: 700;
}

.score-details {
    font-size: 1.3em;
    margin: 20px 0;
    color: #e0e0e0;
}

.review-section {
    margin-top: 40px;
    text-align: left;
}

.review-title {
    font-size: 1.5em;
    margin-bottom: 20px;
    text-align: center;
    color: #e0e0e0;
}

.review-questions {
    max-height: 500px;
    overflow-y: auto;
    padding-right: 10px;
}

.review-questions::-webkit-scrollbar {
    width: 8px;
}

.review-questions::-webkit-scrollbar-track {
    background: rgba(255, 255, 255, 0.05);
    border-radius: 10px;
}

.review-questions::-webkit-scrollbar-thumb {
    background: rgba(255, 255, 255, 0.2);
    border-radius: 10px;
}

.review-questions::-webkit-scrollbar-thumb:hover {
    background: rgba(255, 255, 255, 0.3);
}

.review-item {
    background: rgba(255, 255, 255, 0.03);
    border-radius: 12px;
    padding: 20px;
    margin-bottom: 15px;
    border-left: 4px solid rgba(255, 255, 255, 0.1);
}

.review-item.correct-review {
    border-left-color: #4caf50;
}

.review-item.incorrect-review {
    border-left-color: #f44336;
}

.review-question-text {
    font-size: 1.1em;
    margin-bottom: 10px;
    font-weight: 600;
}

.review-answer {
    margin: 8px 0;
    padding: 8px 12px;
    border-radius: 6px;
    font-size: 0.95em;
}

.review-answer.user-correct {
    background: rgba(76, 175, 80, 0.2);
    color: #81c784;
}

.review-answer.user-incorrect {
    background: rgba(244, 67, 54, 0.2);
    color: #e57373;
}

.review-answer.correct-answer-show {
    background: rgba(76, 175, 80, 0.15);
    color: #a5d6a7;
    border: 1px #4caf50;
}

.error {
    color: #f44336;
    font-size: 0.9em;
    margin-top: 5px;
    display: none;
}

.error.show {
    display: block;
}

.loading {
    text-align: center;
    padding: 20px;
    color: #e0e0e0;
}