:root {
    --color-bg: #f6f7f8;
    --color-card: #ffffff;
    --color-text: #222;
    --color-primary: #009879;
    --color-border: #ccc;
    --color-correct: #94d2bd;
    --color-wrong: #e76f51;
}

[data-theme="dark"] {
    --color-bg: #0f172a;
    --color-card: #1e293b;
    --color-text: #e2e8f0;
    --color-primary: #00ffc4;
    --color-border: #334155;
    --color-correct: #16a34a;
    --color-wrong: #dc2626;
}

* {
    box-sizing: border-box;
    font-family: "Segoe UI", Tahoma, sans-serif;
    transition: background-color 0.3s ease, color 0.3s ease;
}

body {
    background: var(--color-bg);
    color: var(--color-text);
    margin: 0;
    padding: 0;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

.navbar {
    background: var(--color-primary);
    color: white;
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 16px 24px;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.2);
}

.navbar h1 {
    font-size: 1.4rem;
}

.theme-toggle {
    background: transparent;
    border: 2px solid white;
    border-radius: 50%;
    width: 40px;
    height: 40px;
    font-size: 1.2rem;
    cursor: pointer;
    color: white;
    transition: 0.3s;
}

.theme-toggle:hover {
    background: rgba(255, 255, 255, 0.2);
}

.quiz-container {
    display: flex;
    justify-content: center;
    align-items: center;
    flex: 1;
    padding: 20px;
}

.quiz-card {
    background: var(--color-card);
    border: 1px solid var(--color-border);
    border-radius: 12px;
    padding: 24px;
    width: 100%;
    max-width: 600px;
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.1);
    text-align: center;
    animation: fadeIn 0.6s ease;
}

.quiz-card h2 {
    margin-bottom: 20px;
    font-size: 1.4rem;
    line-height: 1.6;
}

.options {
    display: grid;
    gap: 12px;
}

.option {
    border: 2px solid var(--color-primary);
    border-radius: 8px;
    padding: 12px;
    cursor: pointer;
    font-size: 1rem;
    transition: 0.3s;
}

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

.option.correct {
    background: var(--color-correct);
    color: white;
    border-color: var(--color-correct);
}

.option.wrong {
    background: var(--color-wrong);
    color: white;
    border-color: var(--color-wrong);
}

.option.disabled {
    pointer-events: none;
    opacity: 0.6;
}

.next-btn {
    margin-top: 20px;
    background: var(--color-primary);
    color: white;
    border: none;
    border-radius: 8px;
    padding: 10px 24px;
    font-size: 1rem;
    cursor: pointer;
    transition: 0.3s;
}

.next-btn:hover {
    transform: scale(1.05);
    background: var(--color-text);
    color: var(--color-bg);
}

footer {
    text-align: center;
    padding: 10px;
    font-size: 0.9rem;
    opacity: 0.8;
}

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