Facile Theme Custom CSS

style-1 is nice

/* Dark-themed code block */
.dark-color .post-content pre {
    background: #1f1f1f !important;
    border: 1px solid #333 !important;
    border-radius: 8px !important;

    overflow-x: auto !important;
    overflow-y: hidden !important;

    padding: 12px 16px !important;

    line-height: 1.6 !important;
}

.dark-color .post-content pre code {
    color: #e6edf3 !important;

    font-size: 13px !important;
    line-height: 1.6 !important;

    white-space: pre !important;
    word-break: normal !important;

    font-family: Consolas, Monaco, "Courier New", monospace !important;
}

Style-2 looks pretty good too!

/* ==========================================================
   Will's Blog - Facile Theme Custom CSS
   Optimized for Dark Theme & Technical Blog
   ========================================================== */


/* ==========================================================
   1. Code block optimization (GitHub style)
   ========================================================== */

.dark-color .post-content pre {
    background: #1f1f1f !important;
    border: 1px solid #333 !important;
    border-radius: 10px !important;

    padding: 14px 18px !important;

    overflow-x: auto !important;
    overflow-y: hidden !important;

    line-height: 1.6 !important;
    margin: 1rem 0 !important;
}

.dark-color .post-content pre code {
    color: #e6edf3 !important;

    font-size: 14px !important;
    line-height: 1.6 !important;

    white-space: pre !important;
    word-break: normal !important;

    font-family:
        Consolas,
        Monaco,
        "Courier New",
        monospace !important;
}

/* Inline code */

.dark-color .post-content code:not(pre code) {
    color: #79c0ff !important;
    background: #161b22 !important;
    border-radius: 4px !important;
    padding: 2px 6px !important;
}


/* ==========================================================
   2. Styling for blockquotes（blockquote）
   ========================================================== */

.dark-color .post-content blockquote {
    border-left: 4px solid #58a6ff !important;

    background: #161b22 !important;

    padding: 12px 16px !important;

    border-radius: 6px !important;

    color: #c9d1d9 !important;

    margin: 1rem 0 !important;
}

.dark-color .post-content blockquote p {
    margin-bottom: 0 !important;
}


/* ==========================================================
   3. Table dark theme support
   ========================================================== */

.dark-color .post-content table {
    width: 100%;

    background: #161b22 !important;

    color: #c9d1d9 !important;

    border-collapse: collapse !important;

    margin: 1rem 0 !important;
}

.dark-color .post-content th {
    background: #21262d !important;

    color: #f0f6fc !important;

    font-weight: 600;
}

.dark-color .post-content th,
.dark-color .post-content td {
    border: 1px solid #30363d !important;

    padding: 10px 14px !important;

    text-align: left;
}

.dark-color .post-content tr:nth-child(even) {
    background: #1c2128 !important;
}


/* ==========================================================
   4. Image Enhancement
   ========================================================== */

.post-content img {
    border-radius: 10px !important;

    border: 1px solid #333 !important;

    max-width: 100% !important;

    height: auto !important;

    margin: 1rem auto !important;

    display: block !important;
}


/* ==========================================================
   5. Widen the main content area
   ========================================================== */

@media (min-width: 1200px) {

    .post-page {
        max-width: 900px !important;
    }

}


/* ==========================================================
   Additional optimizations
   ========================================================== */

/* Title space */

.post-content h1,
.post-content h2,
.post-content h3,
.post-content h4 {
    margin-top: 2rem;
    margin-bottom: 1rem;
}

/* Separator line */

.dark-color .post-content hr {
    border-color: #30363d !important;
}

/* Link color */

.dark-color .post-content a {
    color: #58a6ff;
}

.dark-color .post-content a:hover {
    color: #79c0ff;
}

/* Code block scrollbar */

.dark-color .post-content pre::-webkit-scrollbar {
    height: 8px;
}

.dark-color .post-content pre::-webkit-scrollbar-thumb {
    background: #444;
    border-radius: 4px;
}

.dark-color .post-content pre::-webkit-scrollbar-track {
    background: #1f1f1f;
}