body {
  font-family: sans-serif;
  background: #fafafa;
  margin: 0;
  padding: 0;
}
header {
  background: #fff;
  padding: 1rem;
  box-shadow: 0 1px 5px rgba(0,0,0,0.1);
  text-align: center;
  font-weight: bold;
  position: sticky;
  top: 0;
  font-size: 2rem;
  padding: 1em;
  z-index: 1000;
  transition: all 0.3s ease;
  box-shadow: none;
}
header.shrink {
  font-size: 1.2rem;
  padding: 0.5em;
  box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
}
.container {
  max-width: 600px;
  margin: 1rem auto;
  padding: 0 1remf;
}
.post-form {
  background: #fff;
  padding: 1rem;
  border: 1px solid #ddd;
  margin-bottom: 2rem;
}
.post-form input[type="text"],
textarea {
  font-size: 16px;
  width: 100%;
  height: 5em;
  padding: 0.5rem;
  margin-bottom: 0.5rem;
  border: 1px solid #ccc;
  border-radius: 4px;
  resize: vertical; /* 横方向に拡大しない */
  box-sizing: border-box; /* padding・border を含めたサイズに */
}
.post-form button {
  background: #0095f6;
  color: white;
  border: none;
  padding: 0.5rem 1rem;
  border-radius: 4px;
  cursor: pointer;
}
.post {
  background: #fff;
  border: 1px solid #ddd;
  margin-bottom: 2rem;
}
.post img {
  width: 100%;
  display: block;
}
.post-content {
  padding: 1rem;
  white-space: pre-wrap;
}
.comments {
  border-top: 1px solid #eee;
  padding: 0.5rem 1rem;
}
.comment {
  margin-bottom: 0.5rem;
  font-size: 0.9em;
}
.add-comment input[type="text"] {
  font-size: 16px;
  width: 80%;
  padding: 0.4rem;
  margin-right: 0.2rem;
}
.add-comment button {
  padding: 0.4rem 0.8rem;
  background: #0095f6;
  color: white;
  border: none;
  border-radius: 4px;
  cursor: pointer;
}
strong {
  display: inline-block;
  margin-right: 0.5em;
}
.time {
  font-size: 85%;
  color: #777;
  margin-left: 1em;
}
a {
  color: gray;
}
footer {
  text-align: center;
  margin: .5em;
}