:root {
  --bg: linear-gradient(135deg, #f5efe6 0%, #dfe7dd 45%, #c9d7dd 100%);
  --panel: rgba(255, 252, 247, 0.92);
  --panel-border: rgba(52, 78, 65, 0.16);
  --text: #1f2a1f;
  --muted: #5e6f63;
  --accent: #cf6a32;
  --accent-soft: #f5dfcf;
  --shadow: 0 18px 40px rgba(59, 78, 68, 0.14);
  --radius: 24px;
  --radius-sm: 18px;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-height: 100vh;
  font-family: "Segoe UI", "PingFang SC", "Hiragino Sans GB", sans-serif;
  color: var(--text);
  background: var(--bg);
}

body::before {
  content: "";
  position: fixed;
  inset: 0;
  background:
    radial-gradient(circle at top left, rgba(255, 255, 255, 0.55), transparent 30%),
    radial-gradient(circle at bottom right, rgba(207, 106, 50, 0.14), transparent 24%);
  pointer-events: none;
}

.app-shell {
  position: relative;
  max-width: 980px;
  margin: 0 auto;
  padding: 40px 20px 56px;
}

.hero {
  margin-bottom: 24px;
}

.eyebrow {
  margin: 0 0 10px;
  font-size: 0.84rem;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--accent);
  font-weight: 700;
}

.hero h1 {
  margin: 0;
  font-size: clamp(2rem, 4vw, 3.4rem);
  line-height: 1.1;
}

.subtitle {
  max-width: 760px;
  margin: 14px 0 0;
  font-size: 1rem;
  line-height: 1.7;
  color: var(--muted);
}

.panel,
.result-card {
  backdrop-filter: blur(10px);
  background: var(--panel);
  border: 1px solid var(--panel-border);
  box-shadow: var(--shadow);
}

.panel {
  border-radius: var(--radius);
  padding: 24px;
}

.panel-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  margin-bottom: 22px;
}

.panel-head h2,
.explanation h2 {
  margin: 0;
  font-size: 1.2rem;
}

.ghost-button {
  border: 1px solid rgba(207, 106, 50, 0.28);
  background: rgba(255, 255, 255, 0.75);
  color: var(--accent);
  border-radius: 999px;
  padding: 10px 16px;
  font-size: 0.95rem;
  font-weight: 700;
  cursor: pointer;
  transition: transform 160ms ease, box-shadow 160ms ease, background 160ms ease;
}

.ghost-button:hover {
  transform: translateY(-1px);
  box-shadow: 0 10px 20px rgba(207, 106, 50, 0.12);
  background: #fffaf6;
}

.form-grid,
.results-grid,
.formula-grid {
  display: grid;
  gap: 18px;
}

.form-grid {
  grid-template-columns: repeat(2, minmax(0, 1fr));
}

.field {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.field span {
  font-weight: 700;
  color: #344e41;
}

.field input {
  width: 100%;
  border: 1px solid rgba(52, 78, 65, 0.16);
  border-radius: var(--radius-sm);
  padding: 16px 18px;
  font-size: 1.15rem;
  color: var(--text);
  background: rgba(255, 255, 255, 0.9);
  transition: border-color 160ms ease, box-shadow 160ms ease, transform 160ms ease;
}

.field input:focus {
  outline: none;
  border-color: rgba(207, 106, 50, 0.65);
  box-shadow: 0 0 0 4px rgba(207, 106, 50, 0.12);
  transform: translateY(-1px);
}

.results-grid {
  grid-template-columns: repeat(2, minmax(0, 1fr));
  margin: 24px 0;
}

.result-card {
  border-radius: var(--radius);
  padding: 24px;
}

.result-card.accent {
  background:
    linear-gradient(135deg, rgba(207, 106, 50, 0.12), rgba(255, 255, 255, 0.95)),
    var(--panel);
}

.result-label {
  margin: 0;
  font-size: 0.95rem;
  font-weight: 700;
  color: var(--muted);
}

.result-value {
  margin: 12px 0 8px;
  font-size: clamp(2.3rem, 6vw, 3.6rem);
  font-weight: 800;
  letter-spacing: -0.04em;
}

.result-detail,
.sample-note {
  margin: 0;
  font-size: 0.96rem;
  line-height: 1.7;
  color: var(--muted);
}

.explanation {
  margin-top: 24px;
}

.formula-grid {
  grid-template-columns: repeat(2, minmax(0, 1fr));
  margin: 18px 0 14px;
}

.formula-title {
  margin: 0 0 8px;
  font-size: 0.95rem;
  font-weight: 700;
  color: var(--accent);
}

.formula-body {
  margin: 0;
  line-height: 1.8;
}

@media (max-width: 720px) {
  .app-shell {
    padding: 28px 14px 42px;
  }

  .panel,
  .result-card {
    border-radius: 20px;
    padding: 18px;
  }

  .form-grid,
  .results-grid,
  .formula-grid {
    grid-template-columns: 1fr;
  }

  .panel-head {
    align-items: flex-start;
    flex-direction: column;
  }
}