:root {
    --page-bg: #f5f5f5;
    --text: #333333;
    --muted: #666666;
    --brand: #0078d4;
    --danger: #e74c3c;
    --card-bg: #ffffff;
    --footer-bg: #2c3e50;
    --footer-text: #ecf0f1;
}

* {
    box-sizing: border-box;
}

body {
    min-height: 100vh;
    margin: 0;
    color: var(--text);
    background: var(--page-bg);
    font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;
    line-height: 1.6;
    display: flex;
    flex-direction: column;
}

.page {
    flex: 1;
}

h1 {
    max-width: 1180px;
    margin: 40px auto 20px;
    padding: 0 20px;
    color: var(--text);
    font-size: 40px;
    line-height: 1.25;
    font-weight: 700;
    text-align: center;
}

#sectionTitle {
    margin-top: 26px;
}

.tip {
    max-width: 800px;
    margin: 20px auto;
    padding: 15px;
    color: #ffffff;
    background: var(--danger);
    border-radius: 8px;
    font-size: 18px;
    text-align: center;
}

.tutorial-list {
    width: 100%;
    max-width: 1200px;
    margin: 0 auto 30px;
    padding: 20px;
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: 20px;
}

.tutorial-card {
    width: 300px;
    min-height: 154px;
    padding: 20px;
    color: inherit;
    background: var(--card-bg);
    border-radius: 10px;
    box-shadow: 0 4px 8px rgba(0, 0, 0, 0.10);
    text-align: center;
    text-decoration: none;
    transition: transform 0.25s ease, box-shadow 0.25s ease;
    cursor: pointer;
    display: block;
}

.tutorial-card:hover,
.tutorial-card:focus-visible {
    transform: translateY(-5px);
    box-shadow: 0 8px 16px rgba(0, 0, 0, 0.15);
    outline: none;
}

.tutorial-card h2 {
    margin: 0 0 10px;
    color: var(--brand);
    font-size: 21px;
    line-height: 1.35;
}

.tutorial-card p {
    margin: 0;
    color: var(--muted);
    font-size: 15px;
    line-height: 1.4;
}

footer {
    margin-top: auto;
    padding: 25px 20px;
    color: var(--footer-text);
    background: var(--footer-bg);
    text-align: center;
}

footer p {
    margin: 0;
}

footer a {
    color: #3498db;
    font-weight: 500;
    text-decoration: none;
}

@media (max-width: 768px) {
    h1 {
        margin-top: 30px;
        padding: 0 15px;
        font-size: 32px;
    }

    #sectionTitle {
        margin-top: 18px;
    }

    .tip {
        margin: 20px 15px;
        font-size: 16px;
    }

    .tutorial-card {
        width: 100%;
        max-width: 400px;
        margin: 0 10px;
    }
}

@media (max-width: 420px) {
    h1 {
        font-size: 28px;
    }

    .tutorial-list {
        padding: 15px 10px 24px;
    }

    .tutorial-card {
        margin: 0;
    }
}