:root {
  --bg: #0f172a;
  --panel: #111827;
  --panel-alt: #1f2937;
  --card: #0b1220;
  --accent: #22c55e;
  --accent-strong: #16a34a;
  --text: #e5e7eb;
  --muted: #94a3b8;
  --shadow: rgba(15, 23, 42, 0.45);
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-height: 100vh;
  display: grid;
  place-items: center;
  padding: 24px;
  background: radial-gradient(circle at top, #172554, var(--bg) 45%);
  color: var(--text);
  font-family: Arial, Helvetica, sans-serif;
}

.app {
  width: min(100%, 900px);
  background: rgba(17, 24, 39, 0.9);
  border: 1px solid rgba(148, 163, 184, 0.2);
  border-radius: 22px;
  box-shadow: 0 30px 60px var(--shadow);
  overflow: hidden;
}

.topbar {
  background: linear-gradient(135deg, #111827, #1e293b);
  padding: 28px 28px 18px;
  border-bottom: 1px solid rgba(148, 163, 184, 0.16);
}

.eyebrow {
  margin: 0 0 6px;
  color: var(--accent);
  font-weight: 700;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  font-size: 0.8rem;
}

h1 {
  margin: 0;
  font-size: clamp(2rem, 2.5vw, 3rem);
}

.subtitle {
  margin: 12px 0 0;
  color: var(--muted);
  font-size: 1rem;
}

.content {
  display: grid;
  grid-template-columns: 1.1fr 0.9fr;
  gap: 24px;
  padding: 28px;
}

.panel {
  background: rgba(15, 23, 42, 0.85);
  border: 1px solid rgba(148, 163, 184, 0.18);
  border-radius: 18px;
  padding: 24px;
}

.field-group {
  display: grid;
  gap: 16px;
}

.field {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

label {
  font-weight: 700;
  color: var(--text);
}

input,
select,
button {
  font: inherit;
}

input,
select {
  width: 100%;
  padding: 12px 14px;
  border-radius: 12px;
  border: 1px solid rgba(148, 163, 184, 0.25);
  background: rgba(15, 23, 42, 0.9);
  color: var(--text);
}

button {
  border: none;
  border-radius: 12px;
  background: linear-gradient(135deg, var(--accent), var(--accent-strong));
  color: #06210d;
  font-weight: 800;
  padding: 14px 18px;
  cursor: pointer;
  transition: transform 0.15s ease, filter 0.15s ease;
}

button:hover {
  transform: translateY(-1px);
  filter: brightness(1.03);
}

.result-box {
  background: linear-gradient(160deg, rgba(34, 197, 94, 0.12), rgba(15, 23, 42, 0.9));
}

.result-header {
  margin: 0 0 12px;
  color: var(--muted);
  font-size: 0.8rem;
  text-transform: uppercase;
  letter-spacing: 0.12em;
}

.one-rep-max {
  font-size: clamp(2.4rem, 4vw, 4rem);
  font-weight: 800;
  margin: 0;
}

.percent-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(120px, 1fr));
  gap: 12px;
  margin-top: 22px;
}

.percent-card {
  background: rgba(15, 23, 42, 0.85);
  border: 1px solid rgba(148, 163, 184, 0.15);
  border-radius: 14px;
  padding: 14px 12px;
}

.percent-card .label {
  display: block;
  color: var(--muted);
  font-size: 0.78rem;
  margin-bottom: 8px;
}

.percent-card strong {
  font-size: 1.2rem;
}

.seo-content {
  padding: 0 28px 28px;
  color: var(--muted);
  line-height: 1.65;
}

.seo-content h2 {
  margin: 0 0 10px;
  color: var(--text);
  font-size: 1.35rem;
}

.seo-content p {
  margin: 0;
}

.faq-list {
  display: grid;
  gap: 8px;
  margin-top: 20px;
}

details {
  border-top: 1px solid rgba(148, 163, 184, 0.16);
  padding: 12px 0;
}

summary {
  color: var(--text);
  cursor: pointer;
  font-weight: 700;
}

details p {
  margin-top: 8px;
}

@media (max-width: 720px) {
  .content {
    grid-template-columns: 1fr;
  }
}