/* ============================================
   暗色黑客风主题
   ============================================ */
:root {
  --bg:       #0d1117;
  --surface:  #161b22;
  --border:   #30363d;
  --text:     #c9d1d9;
  --muted:    #8b949e;
  --accent:   #58a6ff;
  --green:    #3fb950;
  --red:      #f85149;
  --yellow:   #d29922;
  --mono:     'JetBrains Mono', 'Fira Code', 'Consolas', monospace;
}

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

body {
  background: var(--bg);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Helvetica, Arial, sans-serif;
  min-height: 100vh;
}

/* ---------- Header ---------- */
header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 16px 32px;
  background: var(--surface);
  border-bottom: 1px solid var(--border);
}
.logo {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--accent);
}
.logo .tag {
  font-size: 0.7rem;
  background: var(--border);
  padding: 2px 8px;
  border-radius: 12px;
  color: var(--muted);
  margin-left: 8px;
  font-weight: 400;
}
nav a {
  color: var(--muted);
  text-decoration: none;
  margin-left: 24px;
  font-size: 0.9rem;
  transition: color 0.2s;
}
nav a:hover { color: var(--accent); }
#resetBtn {
  background: transparent;
  border: 1px solid var(--border);
  color: var(--muted);
  padding: 6px 14px;
  border-radius: 6px;
  cursor: pointer;
  margin-left: 16px;
  font-size: 0.85rem;
  transition: all 0.2s;
}
#resetBtn:hover { border-color: var(--red); color: var(--red); }

/* ---------- Hero ---------- */
.hero {
  text-align: center;
  padding: 48px 24px 32px;
}
.hero h1 {
  font-size: 2rem;
  margin-bottom: 8px;
  background: linear-gradient(90deg, var(--accent), var(--green));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}
.hero p { color: var(--muted); margin-bottom: 24px; }

/* Progress bar */
.progress-bar {
  display: inline-flex;
  align-items: center;
  gap: 12px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 24px;
  padding: 8px 20px;
  width: 320px;
}
.progress-fill {
  height: 6px;
  border-radius: 3px;
  background: linear-gradient(90deg, var(--accent), var(--green));
  width: 0%;
  transition: width 0.4s ease;
}
.progress-bar span { font-size: 0.85rem; color: var(--muted); white-space: nowrap; }

/* ---------- Challenge cards ---------- */
.challenges-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 20px;
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 32px 64px;
}
.challenge-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 24px;
  transition: transform 0.2s, border-color 0.2s;
}
.challenge-card:hover:not(.locked) {
  transform: translateY(-2px);
  border-color: var(--accent);
}
.challenge-card.solved { border-color: var(--green); }
.challenge-card.locked { opacity: 0.5; }

.card-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 12px;
}
.difficulty { font-size: 0.9rem; }
.badge-solved, .badge-locked, .badge-unlock {
  font-size: 0.75rem;
  padding: 3px 10px;
  border-radius: 12px;
}
.badge-solved { background: rgba(63,185,80,0.15); color: var(--green); }
.badge-unlock { background: rgba(139,148,158,0.15); color: var(--muted); }

.challenge-card h3 { font-size: 1.15rem; margin-bottom: 8px; color: var(--text); }
.challenge-card .desc { font-size: 0.85rem; color: var(--muted); line-height: 1.5; margin-bottom: 16px; }

.btn-start {
  display: inline-block;
  padding: 8px 20px;
  border-radius: 6px;
  text-decoration: none;
  font-size: 0.9rem;
  font-weight: 600;
  transition: all 0.2s;
}
.btn-start:not([disabled]) {
  background: var(--accent);
  color: #fff;
}
.btn-start:not([disabled]):hover { background: #79c0ff; }
.btn-start[disabled] { background: var(--border); color: var(--muted); cursor: not-allowed; }
.challenge-card.solved .btn-start { background: var(--green); color: #fff; }

/* ---------- Logs page ---------- */
.logs-page { max-width: 1100px; margin: 0 auto; padding: 32px; }
.logs-page h2 { margin-bottom: 16px; color: var(--accent); }
.log-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.82rem;
  font-family: var(--mono);
}
.log-table th {
  background: var(--surface);
  color: var(--muted);
  text-align: left;
  padding: 10px 12px;
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
}
.log-table td {
  padding: 8px 12px;
  border-bottom: 1px solid var(--border);
  color: var(--text);
}
.log-table tr:hover td { background: rgba(88,166,255,0.04); }
.method-GET  { color: var(--accent); }
.method-POST { color: var(--green); }
.method-PUT
.method-DELETE { color: var(--yellow); }
.status-2xx { color: var(--green); }
.status-4xx { color: var(--yellow); }
.status-5xx { color: var(--red); }

/* ---------- Challenge pages ---------- */
.challenge-container {
  max-width: 900px;
  margin: 0 auto;
  padding: 32px;
}
.challenge-container h2 {
  color: var(--accent);
  margin-bottom: 8px;
}
.challenge-container .meta-info {
  color: var(--muted);
  font-size: 0.9rem;
  margin-bottom: 24px;
}
.principle-box {
  background: var(--surface);
  border: 1px solid var(--border);
  border-left: 3px solid var(--yellow);
  border-radius: 8px;
  padding: 16px 20px;
  margin-bottom: 24px;
}
.principle-box h4 { color: var(--yellow); margin-bottom: 8px; }
.principle-box p, .principle-box li {
  color: var(--muted);
  font-size: 0.9rem;
  line-height: 1.7;
}
.principle-box ul { padding-left: 20px; }
.principle-box li { margin-bottom: 4px; }

.hint-box {
  background: rgba(88,166,255,0.06);
  border: 1px solid rgba(88,166,255,0.2);
  border-radius: 8px;
  padding: 12px 16px;
  margin-bottom: 24px;
  font-size: 0.88rem;
  color: var(--accent);
}

/* Form elements */
.input-group { margin-bottom: 16px; }
.input-group label { display: block; color: var(--muted); font-size: 0.85rem; margin-bottom: 6px; }
.input-group input, .input-group textarea {
  width: 100%;
  padding: 10px 14px;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 6px;
  color: var(--text);
  font-size: 0.95rem;
  font-family: var(--mono);
  outline: none;
  transition: border-color 0.2s;
}
.input-group input:focus, .input-group textarea:focus { border-color: var(--accent); }

.btn {
  padding: 10px 24px;
  border: none;
  border-radius: 6px;
  font-size: 0.95rem;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.2s;
}
.btn-primary { background: var(--accent); color: #fff; }
.btn-primary:hover { background: #79c0ff; }
.btn-green  { background: var(--green); color: #fff; }
.btn-green:hover  { background: #56d364; }

.result-box {
  margin-top: 16px;
  padding: 12px 16px;
  border-radius: 6px;
  font-size: 0.9rem;
  display: none;
}
.result-box.success { display: block; background: rgba(63,185,80,0.1); border: 1px solid var(--green); color: var(--green); }
.result-box.error   { display: block; background: rgba(248,81,73,0.1);  border: 1px solid var(--red);   color: var(--red);   }

/* API response display */
.api-response {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 16px;
  font-family: var(--mono);
  font-size: 0.85rem;
  color: var(--green);
  white-space: pre-wrap;
  word-break: break-all;
  margin-top: 12px;
  max-height: 300px;
  overflow-y: auto;
}

/* Back link */
.back-link {
  display: inline-block;
  color: var(--muted);
  text-decoration: none;
  font-size: 0.85rem;
  margin-bottom: 16px;
}
.back-link:hover { color: var(--accent); }