* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  background: #f7f7f7;
  color: #222;
  line-height: 1.8;
}

a {
  color: inherit;
  text-decoration: none;
}

.topbar {
  background: #fff;
  border-bottom: 1px solid #e5e5e5;
  position: sticky;
  top: 0;
  z-index: 10;
}

.topbar-inner {
  max-width: 820px;
  margin: 0 auto;
  padding: 14px 18px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.logo {
  font-weight: 800;
  font-size: 18px;
}

.nav a {
  color: #555;
  font-size: 14px;
  margin-left: 14px;
}

.container {
  max-width: 820px;
  margin: 0 auto;
  padding: 28px 18px 60px;
}

.hero {
  background: #fff;
  border: 1px solid #e8e8e8;
  border-radius: 18px;
  padding: 28px;
  margin-bottom: 22px;
}

.hero h1 {
  margin: 0 0 8px;
  font-size: 32px;
  line-height: 1.3;
}

.hero p {
  margin: 0;
  color: #666;
}

.post-list {
  display: grid;
  gap: 14px;
}

.post-card {
  display: block;
  background: #fff;
  border: 1px solid #e8e8e8;
  border-radius: 18px;
  padding: 22px;
  transition: 0.15s ease;
}

.post-card:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 24px rgba(0,0,0,.08);
}

.date {
  color: #888;
  font-size: 13px;
  margin-bottom: 8px;
}

.post-card h2 {
  margin: 0 0 10px;
  font-size: 22px;
  line-height: 1.45;
}

.post-card p {
  margin: 0;
  color: #555;
  line-height: 1.75;
}

.article {
  background: #fff;
  border: 1px solid #e8e8e8;
  border-radius: 18px;
  padding: 30px;
}

.article h1 {
  margin: 0 0 18px;
  font-size: 32px;
  line-height: 1.4;
}

.body {
  font-size: 16px;
}

.back {
  display: inline-block;
  margin-top: 20px;
  color: #555;
}

.panel {
  background: #fff;
  border: 1px solid #e8e8e8;
  border-radius: 18px;
  padding: 24px;
}

.form {
  display: grid;
  gap: 16px;
}

.form label {
  display: grid;
  gap: 6px;
  font-weight: 700;
}

input,
textarea,
select {
  width: 100%;
  border: 1px solid #dcdcdc;
  border-radius: 12px;
  padding: 12px;
  font: inherit;
  background: #fff;
}

textarea {
  resize: vertical;
}

button,
.btn {
  border: 0;
  background: #111;
  color: #fff;
  border-radius: 999px;
  padding: 11px 18px;
  font-weight: 700;
  cursor: pointer;
}

.btn-light {
  background: #f0f0f0;
  color: #222;
}

.error {
  color: #d33;
}

.empty {
  color: #777;
  text-align: center;
  padding: 40px 0;
}

.markdown-body {
  line-height: 1.95;
  word-break: break-word;
}

.markdown-body h1,
.markdown-body h2,
.markdown-body h3,
.markdown-body h4 {
  margin: 1.4em 0 .6em;
  line-height: 1.35;
}

.markdown-body h1 {
  font-size: 1.8rem;
  border-bottom: 1px solid #e5e7eb;
  padding-bottom: .35em;
}

.markdown-body h2 {
  font-size: 1.5rem;
  border-bottom: 1px solid #e5e7eb;
  padding-bottom: .3em;
}

.markdown-body h3 {
  font-size: 1.25rem;
}

.markdown-body p {
  margin: 1em 0;
}

.markdown-body ul,
.markdown-body ol {
  padding-left: 1.4em;
  margin: 1em 0;
}

.markdown-body blockquote {
  margin: 1.2em 0;
  padding: .6em 1em;
  border-left: 4px solid #d1d5db;
  background: #f9fafb;
  color: #4b5563;
  border-radius: 10px;
}

.markdown-body code {
  background: #f3f4f6;
  padding: .15em .35em;
  border-radius: 6px;
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
}

.markdown-body pre {
  background: #111827;
  color: #f9fafb;
  padding: 14px;
  border-radius: 14px;
  overflow-x: auto;
}

.markdown-body pre code {
  background: transparent;
  padding: 0;
  color: inherit;
}

.markdown-body a {
  color: #2563eb;
  text-decoration: underline;
}

.markdown-help {
  background: #f9fafb;
  border: 1px solid #e5e7eb;
  color: #4b5563;
  border-radius: 14px;
  padding: 12px;
  font-size: 14px;
}

@media (max-width: 640px) {
  .container {
    padding: 18px 12px 50px;
  }

  .hero,
  .article,
  .panel,
  .post-card {
    border-radius: 14px;
    padding: 18px;
  }

  .hero h1,
  .article h1 {
    font-size: 26px;
  }

  .post-card h2 {
    font-size: 20px;
  }
}