:root {
    --bg-light: #f6faff;
    --bg-card: #ffffff;
    --accent-blue: #4da3ff;
    --accent-blue-light: #8cc9ff;
    --accent-purple: #a58cff;
    --text-dark: #2c2f33;
    --text-muted: #606b78;
    --correct: #50ff32cc;
    --incorrect: #ff4444cc;
}

html, body {
    height: 100%;
    margin: 0;
}

p {
    font-size: 1.1em;
}

body {
    font-family: 'Segoe UI', Arial, sans-serif;
    background: linear-gradient(135deg, #e6f2ff, #eef4ff, #f9faff);
    color: var(--text-dark);
}
.site_wrapper {
    display: flex;
    flex-direction: column;
    min-height: 100vh;
}

.top_nav {
    position: sticky;
    top: 0;
    z-index: 1000;
    display: flex;
    align-items: center;
    justify-content: space-between;
    background: rgba(255, 255, 255, 0.7);
    padding: 12px 28px;
    border-radius: 16px;
    margin: 10px auto;
    width: 96%;
    max-width: 1300px;
    backdrop-filter: blur(12px);
    box-shadow: 0 4px 16px rgba(0,0,0,0.08);
}
.logo {
    height: 42px;
    width: auto;
    cursor: pointer;
}
.nav_links a {
    color: var(--text-dark);
    text-decoration: none;
    margin-left: 20px;
    font-weight: 500;
    transition: color 0.3s, transform 0.2s;
}
.nav-links a:hover {
    color: var(--accent-blue);
    transform: scale(1.05);
}

.mainsection {
    flex: 1;
    background: var(--bg-card);
    border-radius: 20px;
    margin: 40px auto 20px auto;
    padding: 20px 2%;
    max-width: 900px;
    box-shadow: 0 8px 25px rgba(0,0,0,0.08);
}
.page_title {
    text-align: center;
    margin-bottom: 30px;
}
.page_title h1 {
    margin: 0 0 15px 0;
    font-size: 2rem;
    color: var(--accent-blue);
}
.page_title p {
    font-size: 1.1rem;
    color: var(--text-muted);
    line-height: 1.6;
}

.btn_grid {
    display: grid;
    gap: 0.75rem;
}
.btn {
    background: var(--bg-card);
    color: var(--accent-blue);
    border: 2px solid var(--accent-blue);
    border-radius: 10px;
    box-shadow: 0 3px 8px rgba(0,0,0,0.06);
    padding: 0.75rem;
    cursor: pointer;
    font-size: 1rem;
    font-weight: 500;
    transition: all 0.25s ease;
}
.btn:hover {
    background: var(--accent-blue);
    color: #ffffff;
    transform: translateY(-2px) scale(1.02);
    box-shadow: 0 6px 14px rgba(0,0,0,0.12);
}
.next_btn {
    margin-top: 1rem;
    float: right;
}

.btn.correct {
    background: var(--correct);
    color: #fff;
    border: 2px solid #38c42a;
}
.btn.incorrect {
    background: var(--incorrect);
    color: #fff;
    border: 2px solid #d62828;
}

footer {
    text-align: center;
    padding: 20px;
    font-size: 0.9rem;
    background: var(--bg-card);
    color: var(--text-muted);
    border-top: 2px solid var(--accent-blue-light);
}
.footer_divider {
    width: 80%;
    height: 3px;
    margin: 0 auto 15px auto;
    background: linear-gradient(to right, transparent, var(--accent-blue), transparent);
    animation: glow 2s infinite alternate;
}
@keyframes glow {
    from { opacity: 0.6; }
    to { opacity: 1; }
}