@import url('https://fonts.googleapis.com/css2?family=Lexend:wght@400;500;600;700&display=swap');

:root {
    --bg-primary: #0d1117;
    --bg-secondary: #161b22;
    --bg-tertiary: #21262d;
    --primary-accent: #58a6ff;
    --primary-accent-hover: #79c0ff;
    --secondary-accent: #a371f7; /* New accent color: Vibrant Purple */
    --correct-color: #238636;
    --correct-color-glow: rgba(46, 160, 67, 0.4);
    --incorrect-color: #da3633;
    --incorrect-color-glow: rgba(248, 81, 73, 0.4);
    --text-primary: #e6edf3;
    --text-secondary: #8d96a0;
    --border-color: #30363d;
    --shadow-color: rgba(0, 0, 0, 0.4);
    --font-family: 'Lexend', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
}

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

html {
    height: 100%;
}

body {
    font-family: var(--font-family);
    color: var(--text-primary);
    background-color: var(--bg-primary);
    background-image: radial-gradient(circle at top, rgba(33, 38, 45, 0.5) 0%, var(--bg-primary) 60%);
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    min-height: 100%;
    padding: 2rem 1rem;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

.main-content {
    flex: 1 0 auto;
    display: flex;
    justify-content: center;
    align-items: center;
    width: 100%;
}

.container {
    background-color: var(--bg-secondary);
    width: 100%;
    max-width: 800px;
    border-radius: 1rem;
    box-shadow: 0 10px 40px var(--shadow-color), 0 0 0 1px var(--border-color);
    padding: clamp(1.5rem, 5vw, 3rem);
    transition: all 0.3s ease-in-out;
    border: 1px solid var(--border-color);
}

h1 {
    font-size: clamp(2rem, 5vw, 2.75rem);
    font-weight: 700;
    text-align: center;
    margin-bottom: 0.75rem;
    background: linear-gradient(90deg, var(--primary-accent), var(--secondary-accent));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

h2 {
    font-size: clamp(1.5rem, 4vw, 2rem);
    font-weight: 600;
    color: white;
    margin-bottom: 1.5rem;
    border-bottom: 1px solid var(--border-color);
    padding-bottom: 1rem;
    text-align: center;
}

p.subtitle {
    text-align: center;
    color: var(--text-secondary);
    margin-bottom: 3rem;
    font-size: 1.125rem;
    max-width: 550px;
    margin-left: auto;
    margin-right: auto;
    line-height: 1.6;
}

.hidden {
    display: none !important;
}

/* --- Screen & Button Styles --- */
.mode-selection-btn {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.75rem;
    width: 100%;
    padding: 1.1rem 1.5rem;
    margin-bottom: 1rem;
    font-size: 1.2rem;
    font-weight: 600;
    color: white;
    background-color: var(--bg-tertiary);
    border: 1px solid var(--border-color);
    border-radius: 0.75rem;
    cursor: pointer;
    transition: all 0.2s ease-in-out;
}

.mode-selection-btn:hover {
    border-color: var(--secondary-accent);
    transform: translateY(-4px) scale(1.02);
    box-shadow: 0 10px 25px rgba(163, 113, 247, 0.2);
}

/* --- Quiz Setup Styles --- */
.setup-grid {
    display: grid;
    grid-template-columns: 1fr;
    gap: 1.5rem;
    margin-bottom: 2rem;
}

@media (min-width: 640px) {
    .setup-grid {
        grid-template-columns: repeat(2, 1fr);
    }
}

.setup-controls label {
    font-weight: 500;
    color: var(--text-secondary);
    display: block;
    margin-bottom: 0.75rem;
}

.setup-controls select, .setup-controls input {
    width: 100%;
    padding: 0.85rem;
    border: 1px solid var(--border-color);
    border-radius: 0.5rem;
    font-size: 1rem;
    background-color: var(--bg-primary);
    color: var(--text-primary);
    font-family: var(--font-family);
    transition: all 0.2s ease;
}

.setup-controls select:focus, .setup-controls input:focus {
    outline: none;
    border-color: var(--primary-accent);
    box-shadow: 0 0 0 3px rgba(88, 166, 255, 0.3);
}

.section-checkbox-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 1rem;
    margin-bottom: 2.5rem;
}

.checkbox-label {
    display: flex;
    align-items: center;
    padding: 0.75rem 1rem;
    background-color: var(--bg-tertiary);
    border: 1px solid var(--border-color);
    border-radius: 0.5rem;
    cursor: pointer;
    transition: all 0.2s;
    font-weight: 500;
}

.checkbox-label:hover {
    background-color: #30363d;
    border-color: var(--text-secondary);
}

.checkbox-label input {
    margin-right: 0.75rem;
    width: 1.25rem;
    height: 1.25rem;
    accent-color: var(--secondary-accent);
}

.setup-actions {
    display: flex;
    justify-content: space-between;
    gap: 1rem;
    margin-top: 1.5rem;
}

/* --- Practice Mode List --- */
.practice-list button {
    display: block;
    width: 100%;
    text-align: left;
    padding: 1rem 1.25rem;
    margin-bottom: 0.75rem;
    background-color: var(--bg-tertiary);
    border: 1px solid var(--border-color);
    border-radius: 0.5rem;
    cursor: pointer;
    font-weight: 500;
    transition: all 0.2s;
    font-size: 1rem;
    color: var(--text-primary);
}

.practice-list button:hover {
    background-color: var(--secondary-accent);
    border-color: var(--secondary-accent);
    color: white;
    transform: translateX(5px);
}

/* --- Quiz Area Styles --- */
#progress-info {
    font-weight: 500;
    color: var(--text-secondary);
    text-align: center;
    margin-bottom: 1rem;
    font-size: 1.1rem;
}

#question-text {
    font-size: clamp(1.25rem, 3vw, 1.6rem);
    font-weight: 600;
    min-height: 100px;
    margin-bottom: 2rem;
    text-align: center;
    line-height: 1.6;
    color: white;
}

#answer-options {
    display: grid;
    grid-template-columns: 1fr;
    gap: 0.85rem;
}

@media (min-width: 768px) {
    #answer-options.mcq {
        grid-template-columns: 1fr 1fr;
    }
}

#answer-options button.answer-btn {
    width: 100%;
    padding: 1rem;
    text-align: left;
    background-color: var(--bg-tertiary);
    border: 1px solid var(--border-color);
    border-radius: 0.75rem;
    cursor: pointer;
    transition: all 0.2s;
    font-size: 1rem;
    color: var(--text-primary);
    line-height: 1.5;
}

#answer-options button.answer-btn:hover:not(:disabled) {
    border-color: var(--primary-accent);
    background-color: #30363d;
}

#answer-options button.answer-btn:disabled {
    cursor: not-allowed;
    opacity: 0.8;
}

#answer-input {
    width: 100%;
    padding: 1rem;
    font-size: 1.1rem;
    border: 1px solid var(--border-color);
    border-radius: 0.75rem;
    margin-bottom: 1rem;
    background-color: var(--bg-primary);
    color: var(--text-primary);
    font-family: var(--font-family);
}
#answer-input:focus {
    outline: none;
    border-color: var(--primary-accent);
    box-shadow: 0 0 0 3px rgba(88, 166, 255, 0.3);
}

.answer-btn.correct {
    background-color: var(--bg-secondary) !important;
    border-color: var(--correct-color) !important;
    color: white !important;
    box-shadow: 0 0 15px var(--correct-color-glow);
    transform: scale(1.02);
}

.answer-btn.incorrect {
    background-color: var(--bg-secondary) !important;
    border-color: var(--incorrect-color) !important;
    color: white !important;
    box-shadow: 0 0 15px var(--incorrect-color-glow);
}

#feedback-area {
    margin-top: 1.5rem;
    padding: 1rem;
    border-radius: 0.75rem;
    font-weight: 600;
    text-align: center;
    line-height: 1.5;
}

.feedback-correct {
    background-color: rgba(35, 134, 54, 0.15);
    color: #3fb950;
    border: 1px solid var(--correct-color);
}

.feedback-incorrect {
    background-color: rgba(218, 54, 51, 0.15);
    color: #ff7b72;
    border: 1px solid var(--incorrect-color);
}

/* --- Controls & Footer --- */
.quiz-footer {
    display: flex;
    flex-wrap: wrap;
    justify-content: space-between;
    align-items: center;
    gap: 1rem;
    margin-top: 2.5rem;
    padding-top: 1.5rem;
    border-top: 1px solid var(--border-color);
}

.btn {
    padding: 0.75rem 1.5rem;
    font-weight: 600;
    border: none;
    border-radius: 0.5rem;
    cursor: pointer;
    transition: all 0.2s;
    font-size: 1rem;
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    justify-content: center;
    font-family: var(--font-family);
}
.btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 10px rgba(0,0,0,0.2);
}
.btn:focus-visible {
    outline: none;
    box-shadow: 0 0 0 3px var(--bg-primary), 0 0 0 5px var(--primary-accent);
}

.primary-btn {
    background-image: linear-gradient(90deg, var(--primary-accent), var(--secondary-accent));
    color: white;
    background-size: 200% auto;
}
.primary-btn:hover {
    background-position: right center;
    box-shadow: 0 6px 15px rgba(121, 120, 255, 0.2);
}

.secondary-btn {
    background-color: var(--bg-tertiary);
    color: var(--text-primary);
    border: 1px solid var(--border-color);
}
.secondary-btn:hover {
    background-color: #30363d;
    border-color: #8b949e;
}

/* --- Score Screen --- */
#score-display {
    font-size: clamp(3rem, 10vw, 4.5rem);
    font-weight: 700;
    margin-bottom: 2rem;
    text-align: center;
    background: linear-gradient(90deg, var(--primary-accent), var(--secondary-accent));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}
.final-score-actions {
    display: flex;
    justify-content: center;
    gap: 1rem;
    flex-wrap: wrap;
}

/* --- Footer --- */
.footer {
    flex-shrink: 0;
    width: 100%;
    text-align: center;
    padding: 2rem 1rem 1rem 1rem;
    color: var(--text-secondary);
    font-size: 0.9rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    max-width: 800px;
    margin: 0 auto;
}

.footer-stats {
    font-weight: 500;
}

.footer a {
    color: var(--primary-accent);
    text-decoration: none;
    font-weight: 500;
    transition: color 0.2s;
}

.footer a:hover {
    color: var(--primary-accent-hover);
    text-decoration: underline;
}