:root {
  --red-dark: #780000;
  --red: #c1121f;
  --beige: #fdf0d5;
  --blue-dark: #003049;
  --blue-gray: #669bbc;
  --white: #ffffff;
  --gray: #f5f5f5;
  --text: #1f2933;
}

body {
  margin: 0;
  font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  background: var(--gray);
  color: var(--text);
}

.container {
  max-width: 1150px;
  margin: 0 auto;
  padding: 40px 20px;
}

.hero {
  margin-bottom: 28px;
}

.eyebrow {
  color: var(--red);
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  font-size: 13px;
}

h1 {
  color: var(--blue-dark);
  font-size: 40px;
  margin: 6px 0;
}

.subtitle {
  max-width: 780px;
  line-height: 1.6;
  font-size: 17px;
}

.card,
.method-note {
  background: var(--white);
  border-radius: 18px;
  padding: 26px;
  margin-bottom: 24px;
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.06);
}

h2,
h3 {
  color: var(--blue-dark);
}

.grid {
  display: grid;
  grid-template-columns: repeat(4, minmax(180px, 1fr));
  gap: 16px;
  margin-bottom: 20px;
}

.relation-grid {
  grid-template-columns: repeat(2, minmax(220px, 1fr));
}

label {
  display: flex;
  flex-direction: column;
  font-weight: 600;
  font-size: 14px;
  gap: 6px;
}

select,
input {
  padding: 10px 12px;
  border: 1px solid #d4d4d4;
  border-radius: 10px;
  font-size: 14px;
  background: white;
}

.variable-box {
  display: grid;
  grid-template-columns: repeat(3, minmax(220px, 1fr));
  gap: 16px;
  margin: 18px 0 24px;
}

.variable-card {
  border: 1px solid #e5e7eb;
  border-radius: 14px;
  padding: 16px;
  background: #fafafa;
}

button {
  background: var(--red-dark);
  color: white;
  border: none;
  border-radius: 12px;
  padding: 12px 20px;
  font-weight: 700;
  font-size: 15px;
  cursor: pointer;
}

button:hover {
  background: var(--red);
}

.note,
.status,
.method-note p {
  color: #4b5563;
  line-height: 1.6;
}

#plot {
  width: 100%;
  height: 560px;
}

@media (max-width: 900px) {
  .grid,
  .relation-grid,
  .variable-box {
    grid-template-columns: 1fr;
  }

  h1 {
    font-size: 32px;
  }
}