:root { 
    --primary-color: #007aff; 
    --rss-bg: #ff8300;
    --bg-color: #1c1c1e; 
    --card-bg: #2c2c2e; 
    --text-main: #ffffff; 
    --text-dim: #aeaeae; 
    --border-color: #3a3a3c;
    --btn-bg: #3a3a3c;
}

body.light-mode {
    --bg-color: #f5f5f7;
    --card-bg: #ffffff;
    --text-main: #1d1d1f;
    --text-dim: #86868b;
    --border-color: #ddd;
    --btn-bg: #f9f9f9;
}

body { 
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif; 
    line-height: 1.5; margin: 0 auto;
    background-color: var(--bg-color); color: var(--text-main);
    transition: background-color 0.3s, color 0.3s;
}

select { 
    border: 1px solid var(--border-color);
    background: var(--btn-bg); color: var(--text-main);
    cursor: pointer;
}

#scroll-top-btn { 
    position: fixed; border-radius: 50%; background: var(--text-main); 
    color: var(--bg-color); border: none; cursor: pointer; display: none; z-index: 1000; 
    align-items: center; justify-content: center;
}