:root {
  --bg: #f5f7fb;
  --surface: #ffffff;
  --border: #e4e8f0;
  --text: #1b2430;
  --muted: #6b7688;
  --primary: #3b82f6;
  --primary-dark: #2563eb;
  --danger: #ef4444;
  --radius: 10px;
  --shadow: 0 1px 3px rgba(16, 24, 40, 0.08);
}

* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  background: var(--bg);
  color: var(--text);
  font-size: 15px;
  line-height: 1.5;
}

.muted { color: var(--muted); }

.topbar {
  display: flex;
  align-items: center;
  gap: 16px;
  padding: 12px 20px;
  background: var(--surface);
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  z-index: 10;
}

.brand { display: flex; align-items: center; gap: 8px; font-weight: 700; font-size: 18px; }
.brand-logo { height: 28px; width: 28px; border-radius: 6px; object-fit: cover; }

.search {
  flex: 1;
  max-width: 520px;
  padding: 9px 14px;
  border: 1px solid var(--border);
  border-radius: 8px;
  font-size: 14px;
  background: var(--bg);
}
.search:focus { outline: 2px solid var(--primary); background: #fff; }

.topbar-right { display: flex; align-items: center; gap: 10px; margin-left: auto; }
.user-select { padding: 8px 10px; border: 1px solid var(--border); border-radius: 8px; background: #fff; }

.btn {
  padding: 8px 14px;
  border: 1px solid var(--border);
  border-radius: 8px;
  background: #fff;
  cursor: pointer;
  font-size: 14px;
  font-weight: 500;
}
.btn:hover { background: #f3f5f9; }
.btn.primary { background: var(--primary); border-color: var(--primary); color: #fff; }
.btn.primary:hover { background: var(--primary-dark); }
.btn.danger { color: var(--danger); border-color: var(--danger); }
.btn.ghost { background: transparent; border-color: transparent; }

.layout {
  display: grid;
  grid-template-columns: 1fr 300px;
  gap: 20px;
  max-width: 1080px;
  margin: 20px auto;
  padding: 0 20px;
}

.col-main h2 { margin-top: 0; font-size: 20px; }
.col-side { background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); padding: 16px; height: fit-content; }
.col-side h3 { margin-top: 0; }

.note-list { list-style: none; margin: 0; padding: 0; display: flex; flex-direction: column; gap: 8px; }
.note-item {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 12px 16px;
  cursor: pointer;
  box-shadow: var(--shadow);
}
.note-item:hover { border-color: var(--primary); }
.note-title { font-weight: 600; }
.note-meta { color: var(--muted); font-size: 12px; margin-top: 2px; }
.note-tags { color: var(--primary); font-size: 12px; margin-top: 4px; }

.tag-cloud { display: flex; flex-wrap: wrap; gap: 6px; }
.tag-chip {
  background: #eef4ff;
  color: var(--primary);
  border: none;
  border-radius: 16px;
  padding: 4px 12px;
  font-size: 13px;
  cursor: pointer;
}
.tag-chip:hover { background: #dbe7ff; }

.editor-wrap { max-width: 900px; margin: 20px auto; padding: 0 20px; }
.editor-topbar { display: flex; align-items: center; gap: 8px; margin-bottom: 10px; }
.spacer { flex: 1; }
.toolbar { display: flex; flex-wrap: wrap; gap: 4px; padding: 8px; background: var(--surface); border: 1px solid var(--border); border-bottom: none; border-radius: var(--radius) var(--radius) 0 0; }
.tool-btn { padding: 6px 10px; border: none; background: transparent; border-radius: 6px; cursor: pointer; font-size: 13px; }
.tool-btn:hover { background: #f3f5f9; }
.sep { width: 1px; background: var(--border); margin: 4px 6px; }

.editor {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 0 0 var(--radius) var(--radius);
  padding: 16px 20px;
  min-height: 60vh;
}
.editor .ProseMirror { min-height: 55vh; outline: none; }
.editor h1, .editor h2, .editor h3 { margin: 0.5em 0 0.25em; }
.editor p { margin: 0.4em 0; }
.editor pre { background: #1e293b; color: #e2e8f0; padding: 12px; border-radius: 8px; overflow-x: auto; }
.editor code { background: #f1f5f9; padding: 1px 4px; border-radius: 4px; font-size: 0.9em; }
.editor pre code { background: none; padding: 0; }
.editor blockquote { border-left: 3px solid var(--primary); margin: 0.5em 0; padding-left: 12px; color: var(--muted); }

.status { margin-top: 10px; color: var(--muted); font-size: 13px; min-height: 20px; }

.login-card {
  display: flex;
  flex-direction: column;
  gap: 12px;
  max-width: 340px;
  margin: 10vh auto;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 28px;
  box-shadow: var(--shadow);
  text-align: center;
}
.login-logo { width: 56px; height: 56px; border-radius: 12px; margin: 0 auto; object-fit: cover; }
.login-card input { padding: 10px 14px; border: 1px solid var(--border); border-radius: 8px; }
.error { color: var(--danger); font-size: 13px; min-height: 18px; }

.overlay { position: fixed; inset: 0; background: rgba(15, 23, 42, 0.4); display: flex; align-items: center; justify-content: center; z-index: 100; }
.modal { background: var(--surface); border-radius: var(--radius); padding: 20px; width: 90%; max-width: 520px; max-height: 80vh; overflow-y: auto; }
.history-list { list-style: none; padding: 0; margin: 0 0 16px; }
.history-list li { padding: 8px 0; border-bottom: 1px solid var(--border); font-size: 13px; }

@media (max-width: 720px) {
  .layout { grid-template-columns: 1fr; }
  .topbar { flex-wrap: wrap; }
  .search { max-width: none; order: 3; flex-basis: 100%; }
}