:root {
  --primary:        #6366F1;
  --primary-hover:  #4F46E5;
  --neutral:        #9C9C9C;
  --bg:             #FAFAFA;
  --surface:        #FFFFFF;
  --text-primary:   #0A0A0A;
  --text-secondary: #6B6B6B;
  --border:         #E8E8EC;
  --success:        #10B981;
  --error:          #EF4444;
  --think-color:    #8B5CF6;
  --action-color:   #6366F1;
  --result-color:   #10B981;
  --font-display:   'General Sans', system-ui, sans-serif;
  --font-body:      'DM Sans', system-ui, sans-serif;
  --font-mono:      'JetBrains Mono', monospace;
}

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

html, body {
  background: var(--bg);
  color: var(--text-primary);
  font-family: var(--font-body);
  min-height: 100vh;
  font-size: 15px;
  -webkit-font-smoothing: antialiased;
}

main {
  max-width: 1280px;
  margin: 0 auto;
  padding: 32px 24px 80px;
}

/* ── Loading ── */
.loading-screen {
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 80vh;
}

.loading-inner {
  text-align: center;
}

.logo-mark {
  font-family: var(--font-display);
  font-size: 28px;
  font-weight: 700;
  letter-spacing: -0.03em;
  color: var(--text-primary);
  margin-bottom: 32px;
}

.spinner {
  width: 28px;
  height: 28px;
  border: 2px solid var(--border);
  border-top-color: var(--primary);
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
  margin: 0 auto 16px;
}

@keyframes spin { to { transform: rotate(360deg); } }

#loading-msg {
  font-family: var(--font-body);
  font-size: 15px;
  color: var(--text-secondary);
  margin-bottom: 4px;
}

.loading-sub {
  font-size: 13px;
  color: var(--neutral);
}

/* ── Prompt box ── */
.prompt-box {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 20px 24px;
  margin-bottom: 20px;
  display: flex;
  flex-direction: column;
  gap: 8px;
  position: relative;
}

.prompt-meta {
  display: flex;
  align-items: center;
  gap: 12px;
}

.prompt-category {
  font-family: var(--font-body);
  font-size: 11px;
  font-weight: 500;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--primary);
}

.prompt-num {
  font-size: 11px;
  color: var(--neutral);
}

.prompt-text {
  font-family: var(--font-display);
  font-size: 22px;
  font-weight: 600;
  letter-spacing: -0.03em;
  color: var(--text-primary);
  line-height: 1.3;
  padding-right: 120px;
}

.prompt-logo {
  position: absolute;
  right: 24px;
  top: 50%;
  transform: translateY(-50%);
  font-family: var(--font-display);
  font-size: 15px;
  font-weight: 700;
  letter-spacing: -0.03em;
  color: var(--text-primary);
  opacity: 0.2;
  user-select: none;
}

/* ── Battle grid ── */
.battle-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 20px;
  margin-bottom: 16px;
}

.agent-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 12px;
  overflow: hidden;
  transition: box-shadow 0.2s, transform 0.2s, border-color 0.2s;
  display: flex;
  flex-direction: column;
}

.agent-card:hover {
  box-shadow: 0 8px 30px rgba(0,0,0,0.08);
  transform: translateY(-2px);
}

.agent-card.winner {
  border-color: var(--primary);
  box-shadow: 0 0 0 3px rgba(99,102,241,0.12);
}

.agent-card.loser {
  opacity: 0.4;
  transform: none;
  box-shadow: none;
}

/* ── Card header ── */
.card-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 10px 16px;
  border-bottom: 1px solid var(--border);
  background: var(--bg);
  gap: 8px;
}

.model-label {
  font-family: var(--font-body);
  font-size: 12px;
  font-weight: 500;
  color: var(--text-secondary);
  white-space: nowrap;
}

.model-name {
  font-family: var(--font-mono);
  font-size: 11px;
  color: var(--primary);
  flex: 1;
  min-width: 0;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.model-name.hidden { display: none; }

.card-status {
  font-family: var(--font-mono);
  font-size: 11px;
  color: var(--neutral);
  white-space: nowrap;
}

.card-status.done  { color: var(--success); }
.card-status.error { color: var(--error); }

/* ── Trace block ── */
.trace-block {
  flex: 1;
  padding: 12px 16px;
  min-height: 220px;
  max-height: 420px;
  overflow-y: auto;
  border-bottom: 1px solid var(--border);
  background: var(--surface);
}

.trace-placeholder {
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--neutral);
  padding: 8px 0;
}

.trace-error {
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--error);
  padding: 8px 0;
}

/* ── Trace steps ── */
.trace-step {
  margin-bottom: 10px;
  animation: fadeUp 0.25s ease forwards;
  opacity: 0;
}

@keyframes fadeUp {
  from { opacity: 0; transform: translateY(4px); }
  to   { opacity: 1; transform: translateY(0); }
}

.step-header {
  display: flex;
  align-items: center;
  gap: 6px;
  margin-bottom: 3px;
}

.step-num {
  font-family: var(--font-mono);
  font-size: 10px;
  background: var(--bg);
  border: 1px solid var(--border);
  color: var(--neutral);
  padding: 1px 5px;
  border-radius: 4px;
}

.step-type {
  font-family: var(--font-mono);
  font-size: 10px;
  font-weight: 500;
  letter-spacing: 0.08em;
}

.step-type.think  { color: var(--think-color); }
.step-type.action { color: var(--action-color); }
.step-type.result { color: var(--result-color); }
.step-type.step-error { color: var(--error); }

.step-content {
  font-family: var(--font-mono);
  font-size: 12px;
  line-height: 1.6;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 6px 10px;
  white-space: pre-wrap;
  word-break: break-word;
  color: var(--text-primary);
}

.step-content.think-content {
  border-left: 2px solid var(--think-color);
  color: var(--text-secondary);
  font-style: italic;
}

/* ── Output box ── */
.output-box {
  padding: 12px 16px;
  background: var(--bg);
  min-height: 60px;
}

.output-label {
  font-family: var(--font-body);
  font-size: 10px;
  font-weight: 500;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--neutral);
  margin-bottom: 6px;
}

.output-text {
  font-family: var(--font-mono);
  font-size: 12.5px;
  color: var(--text-primary);
  white-space: pre-wrap;
  word-break: break-word;
  line-height: 1.55;
}

/* ── Vote area ── */
.vote-area {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  gap: 12px;
  margin-bottom: 16px;
}

.vote-btn {
  padding: 11px 20px;
  background: var(--primary);
  color: #fff;
  border: none;
  border-radius: 6px;
  font-family: var(--font-body);
  font-size: 14px;
  font-weight: 500;
  cursor: pointer;
  transition: background 0.12s, transform 0.08s, box-shadow 0.12s;
}

.vote-btn:hover:not(:disabled) {
  background: var(--primary-hover);
  transform: translateY(-1px);
  box-shadow: 0 4px 12px rgba(99,102,241,0.35);
}

.vote-btn:active:not(:disabled) { transform: translateY(0); }

.vote-btn:disabled {
  opacity: 0.35;
  cursor: not-allowed;
}

.skip-btn {
  background: transparent;
  color: var(--text-secondary);
  border: 1px solid var(--border);
  font-size: 13px;
  font-weight: 400;
  padding: 11px 24px;
}

.skip-btn:hover:not(:disabled) {
  background: var(--bg);
  border-color: #C8C8CE;
  box-shadow: none;
  transform: translateY(-1px);
}

/* ── Next area ── */
.next-area {
  display: flex;
  align-items: center;
  gap: 16px;
  padding: 16px 20px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 12px;
}

.vote-result {
  font-family: var(--font-mono);
  font-size: 13px;
  color: var(--primary);
  flex: 1;
}

.next-btn {
  padding: 9px 20px;
  background: transparent;
  color: var(--text-primary);
  border: 1px solid var(--border);
  border-radius: 6px;
  font-family: var(--font-body);
  font-size: 14px;
  font-weight: 500;
  cursor: pointer;
  transition: border-color 0.12s, transform 0.08s;
  white-space: nowrap;
}

.next-btn:hover {
  border-color: var(--primary);
  color: var(--primary);
  transform: translateY(-1px);
}

/* ── Scrollbar (trace block) ── */
.trace-block::-webkit-scrollbar { width: 4px; }
.trace-block::-webkit-scrollbar-track { background: transparent; }
.trace-block::-webkit-scrollbar-thumb { background: var(--border); border-radius: 2px; }

/* ── Mobile ── */
@media (max-width: 700px) {
  .battle-grid   { grid-template-columns: 1fr; }
  .vote-area     { grid-template-columns: 1fr 1fr; }
  .skip-btn      { grid-column: span 2; order: 3; }
  .prompt-text   { font-size: 18px; padding-right: 0; }
  .prompt-logo   { display: none; }
  main           { padding: 16px 14px 60px; }
  .trace-block   { max-height: 280px; }
}

/* ── Inline spinner (running state) ── */
.inline-spinner {
  display: inline-block;
  width: 10px;
  height: 10px;
  border: 1.5px solid var(--border);
  border-top-color: var(--primary);
  border-radius: 50%;
  animation: spin 0.7s linear infinite;
  margin-right: 6px;
  vertical-align: middle;
  position: relative;
  top: -1px;
}

.card-status.running { color: var(--primary); }