:root {
    --primary: #4f46e5;
    --primary-hover: #4338ca;
    --success: #10b981;
    --success-bg: #ecfdf5;
    --error: #ef4444;
    --error-bg: #fef2f2;
    --dark: #1f2937;
    --light: #f3f4f6;
    --card-bg: #ffffff;
    --border: #e5e7eb;
}

* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
    font-family: 'Inter', system-ui, -apple-system, sans-serif;
}

body {
    background: linear-gradient(135deg, #f5f7fa 0%, #c3cfe2 100%);
    color: var(--dark);
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    padding: 20px;
}

.quiz-container {
    background-color: var(--card-bg);
    width: 100%;
    max-width: 650px;
    border-radius: 16px;
    box-shadow: 0 10px 25px rgba(0, 0, 0, 0.05), 0 20px 48px rgba(0, 0, 0, 0.05);
    padding: 40px;
    transition: transform 0.2s ease;
}

.screen {
    display: flex;
    flex-direction: column;
    gap: 24px;
}

.hidden {
    display: none !important;
}

h1 {
    font-size: 2rem;
    font-weight: 800;
    text-align: center;
    color: var(--primary);
}

h2 {
    font-size: 1.25rem;
    font-weight: 600;
    line-height: 1.5;
}

p {
    color: #4b5563;
    text-align: center;
}

/* Header & Progress */
.quiz-header {
    display: flex;
    flex-direction: column;
    gap: 10px;
}

#progress-text {
    font-size: 0.875rem;
    font-weight: 600;
    color: #6b7280;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.progress-bar-background {
    background-color: var(--light);
    border-radius: 9999px;
    height: 10px;
    width: 100%;
    overflow: hidden;
}

#progress-bar-fill {
    background: linear-gradient(90deg, var(--primary) 0%, #818cf8 100%);
    height: 100%;
    width: 0%;
    transition: width 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

/* Choices/Options layout */
.options-grid {
    display: flex;
    flex-direction: column;
    gap: 14px;
}

.option-btn {
    background-color: #ffffff;
    border: 2px solid var(--border);
    border-radius: 10px;
    padding: 16px 20px;
    font-size: 1rem;
    text-align: left;
    cursor: pointer;
    transition: all 0.2s ease;
    font-weight: 500;
    color: var(--dark);
}

.option-btn:hover:not(:disabled) {
    border-color: var(--primary);
    background-color: #fcfcff;
    transform: translateY(-1px);
}

.option-btn:disabled {
    cursor: not-allowed;
}

.option-btn.correct {
    background-color: var(--success-bg);
    border-color: var(--success);
    color: #065f46;
    font-weight: 600;
}

.option-btn.incorrect {
    background-color: var(--error-bg);
    border-color: var(--error);
    color: #991b1b;
}

/* Action Control Buttons */
.btn {
    background-color: var(--primary);
    color: white;
    border: none;
    border-radius: 10px;
    padding: 14px 32px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: background-color 0.2s ease, transform 0.1s ease;
    align-self: center;
    box-shadow: 0 4px 12px rgba(79, 70, 229, 0.2);
}

.btn:hover {
    background-color: var(--primary-hover);
}

.btn:active {
    transform: scale(0.98);
}

/* Conditional Feedback block */
.feedback {
    background-color: var(--light);
    border-radius: 12px;
    padding: 20px;
    text-align: center;
    display: flex;
    flex-direction: column;
    gap: 16px;
    border: 1px solid var(--border);
}

#feedback-text {
    font-size: 1.1rem;
    font-weight: 700;
}

.correct-text { color: var(--success); }
.incorrect-text { color: var(--error); }

/* Results Screens view elements */
.score-display {
    font-size: 1.15rem;
}

#final-score {
    font-weight: 700;
    color: var(--primary);
}

.percentage-badge {
    font-size: 3.5rem;
    font-weight: 900;
    text-align: center;
    margin: 12px 0;
    letter-spacing: -0.02em;
}

.status-badge {
    padding: 10px 24px;
    font-size: 1.25rem;
    font-weight: 800;
    border-radius: 9999px;
    width: fit-content;
    margin: 0 auto;
    letter-spacing: 0.05em;
}

.status-badge.passed {
    background-color: var(--success-bg);
    color: var(--success);
    border: 2px solid var(--success);
}

.status-badge.failed {
    background-color: var(--error-bg);
    color: var(--error);
    border: 2px solid var(--error);
}