:root {
  color-scheme: light;
  --bg: #f6f7f9;
  --panel: #ffffff;
  --ink: #17202a;
  --muted: #667085;
  --line: #d7dce2;
  --accent: #176b87;
  --accent-strong: #0f4d61;
  --soft: #eef6f8;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  line-height: 1.5;
}

a {
  color: var(--accent);
  text-decoration: none;
}

a:hover {
  text-decoration: underline;
}

.topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  min-height: 64px;
  padding: 0 28px;
  background: var(--panel);
  border-bottom: 1px solid var(--line);
}

.brand {
  color: var(--ink);
  font-weight: 700;
}

.nav {
  display: flex;
  align-items: center;
  gap: 14px;
}

.nav form {
  margin: 0;
}

.page {
  width: min(1040px, calc(100% - 32px));
  margin: 28px auto 56px;
}

.toolbar,
.submit-panel,
.post-card,
.post-detail,
.login-panel,
.source-box,
.empty {
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: 8px;
}

.toolbar,
.submit-panel,
.login-panel,
.source-box,
.empty {
  padding: 20px;
}

.toolbar {
  margin-bottom: 16px;
}

.search,
.form {
  display: grid;
  gap: 12px;
}

.search {
  grid-template-columns: 1fr auto;
}

.form p {
  display: grid;
  gap: 6px;
  margin: 0;
}

input,
textarea,
button {
  font: inherit;
}

input,
textarea {
  width: 100%;
  border: 1px solid var(--line);
  border-radius: 6px;
  padding: 10px 12px;
  background: #fff;
  color: var(--ink);
}

button {
  border: 1px solid var(--accent-strong);
  border-radius: 6px;
  padding: 10px 14px;
  background: var(--accent);
  color: #fff;
  cursor: pointer;
}

button:hover {
  background: var(--accent-strong);
}

.submit-panel {
  margin-bottom: 20px;
}

.submit-panel h1,
.login-panel h1 {
  margin: 0 0 16px;
  font-size: 1.25rem;
}

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

.post-card {
  padding: 18px 20px;
}

.post-card h2 {
  margin: 4px 0 8px;
  font-size: 1.3rem;
}

.post-card p {
  margin: 0 0 12px;
  color: #344054;
}

.post-meta {
  color: var(--muted);
  font-size: 0.9rem;
}

.tags {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.tags span {
  display: inline-flex;
  align-items: center;
  min-height: 26px;
  padding: 3px 8px;
  border-radius: 999px;
  background: var(--soft);
  color: var(--accent-strong);
  font-size: 0.85rem;
}

.post-detail {
  padding: 28px;
}

.post-detail h1 {
  margin: 8px 0 10px;
  font-size: clamp(1.8rem, 2.8vw, 2.8rem);
}

.summary {
  color: #344054;
  font-size: 1.05rem;
}

.body-text {
  margin-top: 28px;
}

.body-text p {
  margin: 0 0 16px;
}

.source-box {
  margin-top: 28px;
}

.source-box h2,
.source-box h3 {
  margin: 0 0 10px;
}

.source-box h3 {
  margin-top: 18px;
  font-size: 1rem;
}

.messages {
  display: grid;
  gap: 8px;
  margin-bottom: 16px;
}

.message {
  padding: 10px 12px;
  border-radius: 6px;
  border: 1px solid var(--line);
  background: #fff;
}

.message.success {
  border-color: #91c7a9;
  background: #edf8f1;
}

.message.error {
  border-color: #e4a09b;
  background: #fff1f0;
}

@media (max-width: 680px) {
  .topbar {
    align-items: flex-start;
    flex-direction: column;
    padding: 14px 16px;
  }

  .nav {
    width: 100%;
    flex-wrap: wrap;
  }

  .search {
    grid-template-columns: 1fr;
  }

  .post-detail {
    padding: 20px;
  }
}