/* ============================================================
   AB Test Fintech Calculator — Styles
   FinTech dark-blue palette
   ============================================================ */

:root {
  --bg:          #0d1117;
  --bg-card:     #161b22;
  --bg-card2:    #1c2330;
  --border:      #30363d;
  --accent:      #2563eb;
  --accent-hover:#1d4ed8;
  --accent2:     #10b981;
  --warn:        #f59e0b;
  --danger:      #ef4444;
  --text:        #e6edf3;
  --text-muted:  #8b949e;
  --text-dim:    #6e7681;
  --radius:      8px;
  --shadow:      0 4px 24px rgba(0,0,0,0.4);
}

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

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  background: var(--bg);
  color: var(--text);
  min-height: 100vh;
  line-height: 1.5;
  font-size: 14px;
}

/* ── Layout ─────────────────────────────────────────────────── */
.container { max-width: 1060px; margin: 0 auto; padding: 0 20px; }

/* ── Header ─────────────────────────────────────────────────── */
.site-header {
  background: var(--bg-card);
  border-bottom: 1px solid var(--border);
  padding: 14px 0;
  position: sticky;
  top: 0;
  z-index: 100;
}
.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
}
.logo { display: flex; align-items: center; gap: 8px; }
.logo-icon { font-size: 22px; }
.logo-text { font-size: 20px; font-weight: 800; letter-spacing: -0.5px; color: var(--text); }
.logo-accent { color: var(--accent); }
.logo-tag {
  background: rgba(37,99,235,0.15);
  border: 1px solid rgba(37,99,235,0.3);
  color: #93c5fd;
  font-size: 11px;
  padding: 2px 8px;
  border-radius: 20px;
}
.header-meta { color: var(--text-muted); font-size: 13px; }

/* ── Tabs ────────────────────────────────────────────────────── */
.tabs {
  display: flex;
  gap: 4px;
  margin: 24px 0 16px;
  border-bottom: 1px solid var(--border);
  padding-bottom: 0;
}
.tab {
  background: transparent;
  border: none;
  border-bottom: 2px solid transparent;
  color: var(--text-muted);
  cursor: pointer;
  font-size: 14px;
  font-weight: 500;
  padding: 8px 16px;
  transition: all 0.15s;
  margin-bottom: -1px;
}
.tab:hover { color: var(--text); }
.tab.active { color: var(--accent); border-bottom-color: var(--accent); }

/* ── Cards ───────────────────────────────────────────────────── */
.panel-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 20px;
  align-items: start;
}
@media (max-width: 720px) { .panel-grid { grid-template-columns: 1fr; } }

.card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px;
  box-shadow: var(--shadow);
}
.card-title {
  font-size: 15px;
  font-weight: 700;
  color: var(--text);
  margin-bottom: 16px;
  padding-bottom: 10px;
  border-bottom: 1px solid var(--border);
}

/* ── Form fields ─────────────────────────────────────────────── */
.field-row { margin-bottom: 14px; }
.field-row label {
  display: block;
  font-size: 12px;
  font-weight: 600;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.6px;
  margin-bottom: 6px;
}
.field-row .opt { font-weight: 400; text-transform: none; letter-spacing: 0; }
.field-row .hint {
  display: block;
  font-size: 11px;
  font-weight: 400;
  text-transform: none;
  letter-spacing: 0;
  color: var(--text-dim);
  margin-top: 2px;
}
input[type="text"], input[type="number"], input[type="password"], select {
  width: 100%;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 6px;
  color: var(--text);
  font-size: 14px;
  padding: 8px 12px;
  transition: border-color 0.15s;
  outline: none;
}
input:focus, select:focus { border-color: var(--accent); }
input::placeholder { color: var(--text-dim); }
select option { background: var(--bg-card); }

/* ── A/B split ───────────────────────────────────────────────── */
.ab-grid {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  gap: 12px;
  align-items: start;
  margin-bottom: 16px;
}
.ab-label {
  font-size: 11px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.8px;
  margin-bottom: 10px;
}
.ab-col.control .ab-label { color: var(--text-muted); }
.ab-col.variant .ab-label { color: var(--accent); }
.ab-vs {
  align-self: center;
  font-size: 12px;
  font-weight: 800;
  color: var(--text-dim);
  padding-top: 8px;
}
.conv-preview {
  text-align: center;
  font-size: 20px;
  font-weight: 700;
  color: var(--accent2);
  margin-top: 6px;
  letter-spacing: -0.5px;
}

/* ── Buttons ─────────────────────────────────────────────────── */
.btn-primary {
  width: 100%;
  background: var(--accent);
  border: none;
  border-radius: 6px;
  color: #fff;
  cursor: pointer;
  font-size: 14px;
  font-weight: 600;
  padding: 10px 20px;
  transition: background 0.15s;
  margin-top: 4px;
}
.btn-primary:hover { background: var(--accent-hover); }
.btn-secondary {
  width: 100%;
  background: rgba(16,185,129,0.1);
  border: 1px solid rgba(16,185,129,0.3);
  border-radius: 6px;
  color: var(--accent2);
  cursor: pointer;
  font-size: 14px;
  font-weight: 600;
  padding: 9px 20px;
  transition: all 0.15s;
  margin-top: 12px;
}
.btn-secondary:hover {
  background: rgba(16,185,129,0.18);
  border-color: var(--accent2);
}
.btn-icon {
  background: var(--bg-card2);
  border: 1px solid var(--border);
  border-radius: 0 6px 6px 0;
  color: var(--text-muted);
  cursor: pointer;
  padding: 8px 12px;
  margin-left: -1px;
}
.key-input-wrap { display: flex; }
.key-input-wrap input { border-radius: 6px 0 0 6px; }

/* ── Verdict banner ──────────────────────────────────────────── */
.verdict-banner {
  border-radius: 6px;
  font-size: 15px;
  font-weight: 700;
  margin-bottom: 16px;
  padding: 10px 14px;
  display: flex;
  justify-content: space-between;
  align-items: center;
}
.verdict-banner.success {
  background: rgba(16,185,129,0.12);
  border: 1px solid rgba(16,185,129,0.3);
  color: #34d399;
}
.verdict-banner.warning {
  background: rgba(245,158,11,0.12);
  border: 1px solid rgba(245,158,11,0.3);
  color: #fbbf24;
}
.verdict-banner span {
  font-size: 12px;
  font-weight: 500;
  opacity: 0.8;
}

/* ── Metrics grid ────────────────────────────────────────────── */
.metrics-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 10px;
  margin-bottom: 16px;
}
.metric {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 10px 12px;
}
.metric.highlight { border-color: rgba(37,99,235,0.4); background: rgba(37,99,235,0.07); }
.metric-label { font-size: 10px; color: var(--text-dim); text-transform: uppercase; letter-spacing: 0.5px; margin-bottom: 4px; }
.metric-value { font-size: 18px; font-weight: 700; color: var(--text); }
.metric-value.positive { color: var(--accent2); }
.metric-value.negative { color: var(--danger); }

/* ── Confidence bar ──────────────────────────────────────────── */
.conf-bar-wrap { margin-bottom: 16px; }
.conf-bar-labels {
  display: flex;
  justify-content: space-between;
  font-size: 10px;
  color: var(--text-dim);
  margin-bottom: 4px;
  position: relative;
}
.conf-threshold {
  position: absolute;
  left: 95%;
  transform: translateX(-50%);
  color: var(--warn);
}
.conf-bar-bg {
  height: 8px;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 4px;
  overflow: hidden;
  position: relative;
}
.conf-bar-fill {
  height: 100%;
  border-radius: 4px;
  transition: width 0.5s ease;
}
.conf-bar-fill.fill-success { background: linear-gradient(90deg, var(--accent), var(--accent2)); }
.conf-bar-fill.fill-warning { background: linear-gradient(90deg, var(--accent), var(--warn)); }
.conf-bar-marker {
  position: absolute;
  left: 95%;
  top: -2px;
  bottom: -2px;
  width: 2px;
  background: var(--warn);
  opacity: 0.6;
}
.conf-bar-caption {
  font-size: 12px;
  color: var(--text-muted);
  margin-top: 6px;
}

/* ── LLM ─────────────────────────────────────────────────────── */
.spinner {
  color: var(--text-muted);
  font-size: 13px;
  padding: 10px 0;
  animation: pulse 1.5s infinite;
}
@keyframes pulse { 0%,100%{ opacity:1 } 50%{ opacity:0.4 } }

.llm-result {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 6px;
  color: var(--text);
  font-size: 13px;
  line-height: 1.7;
  margin-top: 10px;
  padding: 14px;
  white-space: pre-wrap;
}

/* ── Sample size ─────────────────────────────────────────────── */
.ss-main-result {
  text-align: center;
  margin: 8px 0 20px;
}
.ss-number {
  font-size: 48px;
  font-weight: 800;
  color: var(--accent);
  letter-spacing: -2px;
  line-height: 1;
}
.ss-caption { font-size: 13px; color: var(--text-muted); margin-top: 4px; }
.ss-tip {
  background: rgba(37,99,235,0.08);
  border: 1px solid rgba(37,99,235,0.2);
  border-radius: 6px;
  color: #93c5fd;
  font-size: 12px;
  margin-top: 12px;
  padding: 10px 12px;
  line-height: 1.6;
}

/* ── Settings ────────────────────────────────────────────────── */
.settings-desc { color: var(--text-muted); font-size: 13px; line-height: 1.6; margin-bottom: 16px; }
.settings-note {
  color: var(--text-dim);
  font-size: 11px;
  margin-top: 12px;
  border-top: 1px solid var(--border);
  padding-top: 12px;
}

/* ── Utility ─────────────────────────────────────────────────── */
.hidden { display: none !important; }
.placeholder-text { color: var(--text-dim); font-size: 13px; text-align: center; padding: 24px 0; }
.error-msg {
  background: rgba(239,68,68,0.1);
  border: 1px solid rgba(239,68,68,0.3);
  border-radius: 6px;
  color: #fca5a5;
  font-size: 13px;
  margin-top: 10px;
  padding: 8px 12px;
}
.success-msg {
  color: var(--accent2);
  font-size: 13px;
  margin-top: 8px;
}

/* ── Footer ──────────────────────────────────────────────────── */
.site-footer {
  border-top: 1px solid var(--border);
  color: var(--text-dim);
  font-size: 12px;
  margin-top: 40px;
  padding: 16px 0;
  text-align: center;
}
.site-footer a { color: var(--text-muted); text-decoration: none; }
.site-footer a:hover { color: var(--text); }

/* ── Tab panels ──────────────────────────────────────────────── */
.tab-panel { padding-bottom: 40px; }

/* ── About / sell block ──────────────────────────────────────── */
.about-block {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 20px;
  margin: 24px 0 16px;
  align-items: start;
}
@media (max-width: 780px) { .about-block { grid-template-columns: 1fr; } }

.about-badge {
  display: inline-block;
  background: rgba(37,99,235,0.12);
  border: 1px solid rgba(37,99,235,0.25);
  border-radius: 20px;
  color: #93c5fd;
  font-size: 11px;
  font-weight: 600;
  letter-spacing: 0.5px;
  padding: 3px 12px;
  margin-bottom: 10px;
  text-transform: uppercase;
}
.about-title {
  font-size: 18px;
  font-weight: 800;
  color: var(--text);
  line-height: 1.3;
  margin-bottom: 10px;
}
.about-desc {
  color: var(--text-muted);
  font-size: 13.5px;
  line-height: 1.7;
  margin-bottom: 14px;
}
.about-desc strong { color: var(--text); }

.about-usecases {
  display: flex;
  flex-wrap: wrap;
  gap: 7px;
}
.usecase {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 6px;
  color: var(--text-muted);
  font-size: 12px;
  padding: 5px 10px;
}

/* Method card */
.method-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 16px;
}
.method-title {
  font-size: 12px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 1px;
  color: var(--text-muted);
  margin-bottom: 12px;
  padding-bottom: 8px;
  border-bottom: 1px solid var(--border);
}
.method-item {
  margin-bottom: 12px;
  padding-bottom: 12px;
  border-bottom: 1px solid var(--border);
}
.method-item:last-child { margin-bottom: 0; padding-bottom: 0; border-bottom: none; }
.method-name {
  display: block;
  font-size: 13px;
  font-weight: 700;
  color: var(--text);
  margin-bottom: 4px;
}
.method-desc {
  display: block;
  font-size: 12px;
  color: var(--text-muted);
  line-height: 1.6;
}
.method-desc code {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 3px;
  color: #93c5fd;
  font-size: 11px;
  padding: 1px 5px;
}

/* ── How-to ──────────────────────────────────────────────────── */
.howto {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  margin: 20px 0 0;
  overflow: hidden;
}
.howto summary {
  cursor: pointer;
  font-size: 13px;
  font-weight: 600;
  color: var(--text-muted);
  padding: 12px 16px;
  user-select: none;
  list-style: none;
  display: flex;
  align-items: center;
  gap: 8px;
  transition: color 0.15s;
}
.howto summary::-webkit-details-marker { display: none; }
.howto summary:hover { color: var(--text); }
.howto[open] summary { color: var(--text); border-bottom: 1px solid var(--border); }

.howto-body { padding: 16px; }

.howto-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 14px;
  margin-bottom: 16px;
}
@media (max-width: 640px) { .howto-grid { grid-template-columns: 1fr; } }

.howto-step {
  display: flex;
  gap: 12px;
  align-items: flex-start;
  font-size: 13px;
  color: var(--text-muted);
  line-height: 1.6;
}
.howto-step strong { color: var(--text); display: block; margin-bottom: 3px; }
.howto-step em { color: #93c5fd; font-style: normal; }

.howto-num {
  flex-shrink: 0;
  width: 24px;
  height: 24px;
  background: var(--accent);
  border-radius: 50%;
  color: #fff;
  font-size: 12px;
  font-weight: 700;
  display: flex;
  align-items: center;
  justify-content: center;
  margin-top: 1px;
}

.howto-terms {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  padding-top: 12px;
  border-top: 1px solid var(--border);
}
.howto-terms strong {
  width: 100%;
  font-size: 11px;
  text-transform: uppercase;
  letter-spacing: 0.6px;
  color: var(--text-dim);
}
.howto-terms span {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 4px;
  color: var(--text-muted);
  font-size: 11.5px;
  padding: 4px 10px;
  line-height: 1.5;
}
.howto-terms span b { color: var(--text); }