/* ===== Reset & Base ===== */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

:root {
  --color-primary: #4a7c59;
  --color-primary-dark: #365c42;
  --color-primary-light: #e8f3eb;
  --color-accent: #7ab893;
  --color-text: #1e2a1f;
  --color-text-muted: #5a6b5b;
  --color-border: #c8ddc9;
  --color-bg: #f5faf6;
  --color-white: #ffffff;
  --color-error: #c0392b;
  --color-error-bg: #fdf0ee;
  --color-result-bg: #f0f7f1;
  --radius: 10px;
  --shadow: 0 2px 8px rgba(0, 0, 0, 0.08);
}

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Helvetica Neue', sans-serif;
  background-color: var(--color-bg);
  color: var(--color-text);
  font-size: 16px;
  line-height: 1.6;
  min-height: 100vh;
}

/* ===== Layout ===== */
.container {
  max-width: 640px;
  margin: 0 auto;
  padding: 16px;
}

/* ===== Header ===== */
.app-header {
  text-align: center;
  padding: 24px 0 16px;
  border-bottom: 2px solid var(--color-border);
  margin-bottom: 24px;
}

.app-header h1 {
  font-size: 1.6rem;
  font-weight: 700;
  color: var(--color-primary-dark);
  letter-spacing: -0.02em;
}

.app-header p {
  margin-top: 6px;
  font-size: 0.9rem;
  color: var(--color-text-muted);
}

/* ===== Section ===== */
.section {
  background: var(--color-white);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 20px;
  margin-bottom: 16px;
}

.section-title {
  font-size: 0.85rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--color-primary);
  margin-bottom: 14px;
}

/* ===== Shape Selector ===== */
.shape-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 10px;
}

.shape-card {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 8px;
  padding: 14px 8px;
  border: 2px solid var(--color-border);
  border-radius: var(--radius);
  background: var(--color-white);
  cursor: pointer;
  transition: border-color 0.2s, background 0.2s;
  user-select: none;
  -webkit-tap-highlight-color: transparent;
}

.shape-card:hover {
  border-color: var(--color-accent);
  background: var(--color-primary-light);
}

.shape-card.selected {
  border-color: var(--color-primary);
  background: var(--color-primary-light);
}

.shape-card svg {
  display: block;
}

.shape-label {
  font-size: 0.82rem;
  font-weight: 600;
  color: var(--color-text-muted);
  text-align: center;
}

.shape-card.selected .shape-label {
  color: var(--color-primary-dark);
}

/* ===== Forms ===== */
.form-fields {
  display: flex;
  flex-direction: column;
  gap: 14px;
}

.field-group {
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.field-label {
  font-size: 0.88rem;
  font-weight: 600;
  color: var(--color-text-muted);
}

.input-wrapper {
  display: flex;
  align-items: center;
  gap: 6px;
}

input[type="number"] {
  flex: 1;
  padding: 10px 12px;
  border: 1.5px solid var(--color-border);
  border-radius: 8px;
  font-size: 1rem;
  color: var(--color-text);
  background: var(--color-bg);
  transition: border-color 0.2s, box-shadow 0.2s;
  -webkit-appearance: none;
  appearance: none;
  width: 100%;
}

input[type="number"]:focus {
  outline: none;
  border-color: var(--color-primary);
  box-shadow: 0 0 0 3px rgba(74, 124, 89, 0.15);
}

input[type="number"].input-error {
  border-color: var(--color-error);
  background: var(--color-error-bg);
}

.input-unit {
  font-size: 0.88rem;
  color: var(--color-text-muted);
  white-space: nowrap;
  min-width: 2.5em;
}

.error-msg {
  font-size: 0.8rem;
  color: var(--color-error);
  min-height: 1em;
}

/* ===== Stone Height (common) ===== */
.stone-section {
  border-top: 1px dashed var(--color-border);
  padding-top: 14px;
  margin-top: 4px;
}

/* ===== Calculate Button ===== */
.calc-btn {
  display: block;
  width: 100%;
  padding: 14px;
  background: var(--color-primary);
  color: var(--color-white);
  border: none;
  border-radius: var(--radius);
  font-size: 1.05rem;
  font-weight: 700;
  cursor: pointer;
  transition: background 0.2s;
  -webkit-tap-highlight-color: transparent;
}

.calc-btn:hover {
  background: var(--color-primary-dark);
}

.calc-btn:active {
  background: var(--color-primary-dark);
  transform: translateY(1px);
}

/* ===== Result ===== */
.result-section {
  background: var(--color-result-bg);
  border: 2px solid var(--color-accent);
  border-radius: var(--radius);
  padding: 20px;
  margin-bottom: 16px;
}

.result-section .section-title {
  color: var(--color-primary-dark);
}

.result-cards {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 12px;
}

.result-card {
  background: var(--color-white);
  border-radius: 8px;
  padding: 16px 12px;
  text-align: center;
  box-shadow: var(--shadow);
}

.result-card-label {
  font-size: 0.82rem;
  font-weight: 600;
  color: var(--color-text-muted);
  margin-bottom: 6px;
}

.result-card-value {
  font-size: 2rem;
  font-weight: 800;
  color: var(--color-primary-dark);
  line-height: 1;
}

.result-card-unit {
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--color-primary);
  margin-left: 2px;
}

.result-note {
  font-size: 0.78rem;
  color: var(--color-text-muted);
  margin-top: 12px;
  text-align: center;
}

/* ===== Footer ===== */
.app-footer {
  text-align: center;
  padding: 16px 0 24px;
  font-size: 0.78rem;
  color: var(--color-text-muted);
}

/* ===== PC Media Query ===== */
@media (min-width: 768px) {
  .container {
    max-width: 900px;
    padding: 24px;
  }

  .app-header {
    padding: 32px 0 20px;
  }

  .app-header h1 {
    font-size: 1.9rem;
  }

  .main-layout {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 20px;
    align-items: start;
  }

  .shape-section {
    grid-column: 1 / -1;
  }

  .result-section {
    grid-column: 1 / -1;
  }

  .calc-btn-wrapper {
    grid-column: 1 / -1;
  }

  .shape-grid {
    grid-template-columns: repeat(4, 1fr);
  }
}