:root {
  --bg: #1a1a1a;
  --bg-card: #242424;
  --bg-input: #2a2a2a;
  --border: #333;
  --text: #f0f0f0;
  --text-muted: #aaa;
  --text-dim: #777;
  --accent: #e07a2f;
  --accent-hover: #c76a28;
  --green: #5cb85c;
  --red: #d45b5b;
  --blue: #5b93d4;
  --r: 6px;
  --font: 'Segoe UI', system-ui, -apple-system, sans-serif;
  --font-mono: 'SF Mono', 'Fira Code', 'Consolas', monospace;
}

* { margin: 0; padding: 0; box-sizing: border-box; }

body {
  font-family: var(--font);
  background: var(--bg);
  color: var(--text);
  min-height: 100vh;
}

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

.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 24px;
}

/* ── Navbar ── */

.navbar {
  background: var(--bg-card);
  border-bottom: 1px solid var(--border);
  padding: 12px 0;
}
.navbar .container {
  display: flex;
  align-items: center;
  gap: 16px;
}
.navbar .logo {
  font-size: 16px;
  font-weight: 700;
  color: var(--accent);
  letter-spacing: -0.5px;
}
.navbar .logo span { color: var(--text-muted); font-weight: 400; }
.navbar nav { display: flex; gap: 16px; margin-left: auto; }
.navbar nav a {
  color: var(--text-muted);
  font-size: 14px;
  padding: 4px 8px;
  border-radius: 4px;
}
.navbar nav a:hover { color: var(--text); background: rgba(255,255,255,0.05); text-decoration: none; }

/* ── Page header ── */

.page-header {
  padding: 32px 0 24px;
}
.page-header h1 {
  font-size: 28px;
  font-weight: 700;
  letter-spacing: -0.5px;
}
.page-header p {
  color: var(--text-muted);
  margin-top: 8px;
  font-size: 15px;
}

/* ── Cards ── */

.card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--r);
  padding: 24px;
  margin-bottom: 20px;
}
.card h2 {
  font-size: 18px;
  margin-bottom: 16px;
  font-weight: 600;
}

/* ── Forms ── */

.form-group {
  margin-bottom: 16px;
}
.form-group label {
  display: block;
  font-size: 13px;
  font-weight: 600;
  color: var(--text-muted);
  margin-bottom: 6px;
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

input[type="file"] {
  display: block;
  width: 100%;
  padding: 12px;
  background: var(--bg-input);
  border: 2px dashed var(--border);
  border-radius: var(--r);
  color: var(--text);
  font-size: 14px;
  cursor: pointer;
}
input[type="file"]:hover { border-color: var(--accent); }
input[type="file"]::file-selector-button {
  background: var(--accent);
  color: #fff;
  border: none;
  padding: 6px 16px;
  border-radius: 4px;
  font-size: 13px;
  font-weight: 600;
  cursor: pointer;
  margin-right: 12px;
}

/* ── Buttons ── */

.btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 10px 20px;
  border: none;
  border-radius: var(--r);
  font-size: 14px;
  font-weight: 600;
  cursor: pointer;
  transition: background 0.15s;
}
.btn-primary { background: var(--accent); color: #fff; }
.btn-primary:hover { background: var(--accent-hover); }
.btn-secondary { background: var(--bg-input); color: var(--text); border: 1px solid var(--border); }
.btn-secondary:hover { background: var(--border); }
.btn-success { background: var(--green); color: #fff; }
.btn-success:hover { background: #4da34d; }
.btn-danger { background: var(--red); color: #fff; }
.btn-danger:hover { background: #c04c4c; }
.btn-sm { padding: 6px 12px; font-size: 13px; }

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

/* ── Flash messages ── */

.flash {
  padding: 10px 16px;
  border-radius: var(--r);
  margin-bottom: 16px;
  font-size: 14px;
}
.flash-success { background: rgba(92,184,92,0.15); color: var(--green); border: 1px solid rgba(92,184,92,0.3); }
.flash-error { background: rgba(212,91,91,0.15); color: var(--red); border: 1px solid rgba(212,91,91,0.3); }

/* ── Sessions list ── */

.sessions-list {
  list-style: none;
}
.sessions-list li {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 12px 0;
  border-bottom: 1px solid var(--border);
}
.sessions-list li:last-child { border-bottom: none; }
.sessions-list .session-name { flex: 1; font-weight: 500; }
.sessions-list .session-status {
  font-size: 12px;
  padding: 2px 10px;
  border-radius: 12px;
  font-weight: 600;
}
.status-done { background: rgba(92,184,92,0.15); color: var(--green); }
.status-tb_ready, .status-editing { background: rgba(91,147,212,0.15); color: var(--blue); }
.status-generating_tb, .status-generating_bpmn { background: rgba(224,122,47,0.15); color: var(--accent); }
.status-error { background: rgba(212,91,91,0.15); color: var(--red); }

/* ── Editor page ── */

.editor-layout {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
  min-height: calc(100vh - 200px);
}
@media (max-width: 900px) {
  .editor-layout { grid-template-columns: 1fr; }
}

.editor-pane, .preview-pane {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--r);
  overflow: hidden;
  display: flex;
  flex-direction: column;
}
.pane-header {
  padding: 8px 14px;
  background: rgba(255,255,255,0.03);
  border-bottom: 1px solid var(--border);
  font-size: 12px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.5px;
  color: var(--text-dim);
}
.editor-pane textarea {
  flex: 1;
  width: 100%;
  min-height: 500px;
  padding: 16px;
  background: var(--bg);
  color: var(--text);
  border: none;
  font-family: var(--font-mono);
  font-size: 13px;
  line-height: 1.6;
  resize: vertical;
}
.editor-pane textarea:focus { outline: none; }

.preview-pane .mermaid-container {
  flex: 1;
  padding: 16px;
  overflow: auto;
  background: var(--bg);
}

/* ── Diagram page ── */

.diagram-frame {
  width: 100%;
  height: calc(100vh - 140px);
  border: 1px solid var(--border);
  border-radius: var(--r);
  background: #212121;
}

.diagram-actions {
  display: flex;
  gap: 8px;
  padding: 16px 0;
}