diff --git a/theme/components/Author.tsx b/theme/components/Author.tsx
index 6b0b5a2..fa00a1d 100644
--- a/theme/components/Author.tsx
+++ b/theme/components/Author.tsx
@@ -1,19 +1,17 @@
 import { useFrontmatter } from "@rspress/core/runtime"
 
-// SHA-256 — self-contained, works in any JS environment
-function sha256Hex(message: string): string {
-  const K = [
-    0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5, 0x3956c25b, 0x59f111f1, 0x923f82a4, 0xab1c5ed5,
-    0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3, 0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174,
-    0xe49b69c1, 0xefbe4786, 0x0fc19dc6, 0x240ca1cc, 0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da,
-    0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7, 0xc6e00bf3, 0xd5a79147, 0x06ca6351, 0x14292967,
-    0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13, 0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85,
-    0xa2bfe8a1, 0xa81a664b, 0xc24b8b70, 0xc76c51a3, 0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070,
-    0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5, 0x391c0cb3, 0x4ed8aa4a, 0x5b9cca4f, 0x682e6ff3,
-    0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208, 0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2,
-  ]
+// MD5 — self-contained, works in any JS environment
+function md5Hex(message: string): string {
+  const S = [7, 12, 17, 22, 7, 12, 17, 22, 7, 12, 17, 22, 7, 12, 17, 22,
+             5, 9, 14, 20, 5, 9, 14, 20, 5, 9, 14, 20, 5, 9, 14, 20,
+             4, 11, 16, 23, 4, 11, 16, 23, 4, 11, 16, 23, 4, 11, 16, 23,
+             6, 10, 15, 21, 6, 10, 15, 21, 6, 10, 15, 21, 6, 10, 15, 21]
+
+  const T: number[] = []
+  for (let i = 0; i < 64; i++) {
+    T[i] = (Math.floor(Math.abs(Math.sin(i + 1)) * 0x100000000)) | 0
+  }
 
-  // UTF-8 encode
   const bytes: number[] = []
   for (let i = 0; i < message.length; i++) {
     const c = message.charCodeAt(i)
@@ -22,54 +20,50 @@ function sha256Hex(message: string): string {
     else { bytes.push(0xe0 | (c >> 12)); bytes.push(0x80 | ((c >> 6) & 0x3f)); bytes.push(0x80 | (c & 0x3f)) }
   }
 
-  // Padding
   const bitLen = bytes.length * 8
   bytes.push(0x80)
   while ((bytes.length + 8) % 64 !== 0) bytes.push(0)
-  for (let i = 0; i < 4; i++) bytes.push(0) // high 32 bits of length (always 0 for our use)
-  for (let i = 3; i >= 0; i--) bytes.push((bitLen >>> (i * 8)) & 0xff)
+  for (let i = 0; i < 4; i++) bytes.push((bitLen >>> (i * 8)) & 0xff)
+  for (let i = 0; i < 4; i++) bytes.push(0)
 
-  const H = [0x6a09e667, 0xbb67ae85, 0x3c6ef372, 0xa54ff53a, 0x510e527f, 0x9b05688c, 0x1f83d9ab, 0x5be0cd19]
+  let a0 = 0x67452301, b0 = 0xefcdab89, c0 = 0x98badcfe, d0 = 0x10325476
 
   for (let offset = 0; offset < bytes.length; offset += 64) {
-    const w = new Array(64)
-    for (let t = 0; t < 16; t++) {
-      w[t] = (bytes[offset + t * 4] << 24) | (bytes[offset + t * 4 + 1] << 16) | (bytes[offset + t * 4 + 2] << 8) | bytes[offset + t * 4 + 3]
+    const M = new Array(16)
+    for (let i = 0; i < 16; i++) {
+      M[i] = bytes[offset + i * 4] | (bytes[offset + i * 4 + 1] << 8) |
+             (bytes[offset + i * 4 + 2] << 16) | (bytes[offset + i * 4 + 3] << 24)
     }
-    for (let t = 16; t < 64; t++) {
-      const s0 = (rotateRight(w[t - 15], 7) ^ rotateRight(w[t - 15], 18) ^ (w[t - 15] >>> 3))
-      const s1 = (rotateRight(w[t - 2], 17) ^ rotateRight(w[t - 2], 19) ^ (w[t - 2] >>> 10))
-      w[t] = (w[t - 16] + s0 + w[t - 7] + s1) | 0
+
+    let A = a0, B = b0, C = c0, D = d0
+
+    for (let i = 0; i < 64; i++) {
+      let F: number, g: number
+      if (i < 16) { F = (B & C) | (~B & D); g = i }
+      else if (i < 32) { F = (D & B) | (~D & C); g = (5 * i + 1) % 16 }
+      else if (i < 48) { F = B ^ C ^ D; g = (3 * i + 5) % 16 }
+      else { F = C ^ (B | ~D); g = (7 * i) % 16 }
+
+      F = (F + A + T[i] + M[g]) | 0
+      A = D; D = C; C = B
+      B = (B + ((F << S[i]) | (F >>> (32 - S[i])))) | 0
     }
-    let [a, b, c, d, e, f, g, h] = H
-    for (let t = 0; t < 64; t++) {
-      const S1 = rotateRight(e, 6) ^ rotateRight(e, 11) ^ rotateRight(e, 25)
-      const ch = (e & f) ^ (~e & g)
-      const temp1 = (h + S1 + ch + K[t] + w[t]) | 0
-      const S0 = rotateRight(a, 2) ^ rotateRight(a, 13) ^ rotateRight(a, 22)
-      const maj = (a & b) ^ (a & c) ^ (b & c)
-      const temp2 = (S0 + maj) | 0
-      h = g; g = f; f = e; e = (d + temp1) | 0
-      d = c; c = b; b = a; a = (temp1 + temp2) | 0
-    }
-    H[0] = (H[0] + a) | 0; H[1] = (H[1] + b) | 0; H[2] = (H[2] + c) | 0; H[3] = (H[3] + d) | 0
-    H[4] = (H[4] + e) | 0; H[5] = (H[5] + f) | 0; H[6] = (H[6] + g) | 0; H[7] = (H[7] + h) | 0
+
+    a0 = (a0 + A) | 0; b0 = (b0 + B) | 0
+    c0 = (c0 + C) | 0; d0 = (d0 + D) | 0
   }
 
-  let result = ""
-  for (let i = 0; i < 8; i++) {
-    result += (H[i] >>> 0).toString(16).padStart(8, "0")
-  }
-  return result
-}
-
-function rotateRight(x: number, n: number): number {
-  return (x >>> n) | (x << (32 - n))
+  return [a0, b0, c0, d0].map(x =>
+    ((x >>> 0) & 0xff).toString(16).padStart(2, "0") +
+    ((x >>> 8) & 0xff).toString(16).padStart(2, "0") +
+    ((x >>> 16) & 0xff).toString(16).padStart(2, "0") +
+    ((x >>> 24) & 0xff).toString(16).padStart(2, "0")
+  ).join("")
 }
 
 function gravatarUrl(email: string, size = 80): string {
   const normalized = email.trim().toLowerCase()
-  const hash = sha256Hex(normalized)
+  const hash = md5Hex(normalized)
   return `https://cravatar.cn/avatar/${hash}?s=${size}&d=robohash&r=g`
 }