/* 使用系统字体栈，避免外调 Google Fonts */
body {
    font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto,
                 "Helvetica Neue", Arial, sans-serif;
    background: linear-gradient(135deg, #F1F6F9, #D9E5EC);
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    padding: 0 20px;
    transition: background-color 0.3s, color 0.3s;
    overflow: hidden;
    margin: 0;
    box-sizing: border-box;
}

@media (prefers-color-scheme: dark) {
    body {
        background: linear-gradient(135deg, #212121, #2C2C2C);
        color: #EAEAEA;
    }
}

.container {
    background: #ffffff;
    padding: 40px 60px;
    max-width: 800px;
    width: 100%;
    border-radius: 16px;
    box-shadow: 0 15px 30px rgba(0, 0, 0, 0.1), 0 5px 10px rgba(0, 0, 0, 0.05);
    text-align: center;
    transition: all 0.3s ease;
    opacity: 0;
    transform: translateY(20px);
    animation: fadeInContainer 1s ease-out forwards;
}

@media (prefers-color-scheme: dark) {
    .container {
        background: #333333;
        box-shadow: 0 20px 40px rgba(0, 0, 0, 0.3), 0 10px 20px rgba(0, 0, 0, 0.1);
    }
}

h1 {
    font-size: 3.8rem;
    color: #2C3E50;
    font-weight: 700;
    margin-bottom: 20px;
    letter-spacing: 1.5px;
    line-height: 1.3;
    opacity: 0;
    transform: translateY(30px);
    animation: fadeInTitle 1s ease-out 0.3s forwards;
}

@media (prefers-color-scheme: dark) {
    h1 {
        color: #ECEFF1;
    }
}

p {
    font-size: 1.6rem;
    color: #34495E;
    margin-bottom: 30px;
    line-height: 1.8;
    letter-spacing: 0.5px;
    opacity: 0;
    animation: fadeInParagraph 1s ease-out 0.6s forwards;
}

@media (prefers-color-scheme: dark) {
    p {
        color: #B0BEC5;
    }
}

footer {
    font-size: 1.2rem;
    color: #7F8C8D;
    margin-top: 40px;
    padding-top: 20px;
    opacity: 0.7;
    text-align: center;
    transition: color 0.3s, border-top 0.3s;
}

@media (prefers-color-scheme: dark) {
    footer {
        color: #AAB7B8;
        border-top: 1px solid #444444;
    }
}

@keyframes fadeInContainer {
    0% { opacity: 0; transform: translateY(20px); }
    100% { opacity: 1; transform: translateY(0); }
}

@keyframes fadeInTitle {
    0% { opacity: 0; transform: translateY(30px); }
    100% { opacity: 1; transform: translateY(0); }
}

@keyframes fadeInParagraph {
    0% { opacity: 0; }
    100% { opacity: 1; }
}

.container:hover {
    transform: scale(1.05);
    box-shadow: 0 20px 50px rgba(0, 0, 0, 0.2);
    transition: all 0.3s ease-out;
}

@media (max-width: 1024px) {
    .container {
        padding: 35px 45px;
    }

    h1 {
        font-size: 3.4rem;
    }

    p {
        font-size: 1.4rem;
    }

    footer {
        font-size: 1rem;
    }
}

@media (max-width: 768px) {
    .container {
        padding: 30px;
    }

    h1 {
        font-size: 2.8rem;
    }

    p {
        font-size: 1.3rem;
    }

    footer {
        font-size: 0.95rem;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 20px;
    }

    h1 {
        font-size: 2.4rem;
    }

    p {
        font-size: 1.2rem;
        margin-bottom: 20px;
    }

    footer {
        font-size: 0.9rem;
    }
}