:root {
  --accent: #008080;
  --accent-dark: #0f5e63;
  --accent-soft: #e8f6f6;
  --text: #2f3941;
  --muted: #5b6b76;
  --line: #d8e1e5;
  --bg-top: #f8fbfc;
  --bg-bottom: #eef3f5;
  --card: rgba(255, 255, 255, 0.96);
  --panel-shadow: 0 12px 28px rgba(21, 45, 54, 0.08);
  --radius: 18px;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-height: 100vh;
  font-family: "Noto Sans JP", "Hiragino Sans", "Yu Gothic", sans-serif;
  color: var(--text);
  line-height: 1.7;
  background:
    radial-gradient(circle at top left, rgba(0, 128, 128, 0.08), transparent 28%),
    linear-gradient(180deg, var(--bg-top) 0%, var(--bg-bottom) 100%);
}

button,
input,
select {
  font: inherit;
}

button {
  cursor: pointer;
}

canvas {
  display: block;
  width: 100%;
  height: auto;
}

.page-shell {
  width: min(1180px, calc(100% - 24px));
  margin: 0 auto;
  padding: 20px 0 40px;
}

.back-link {
  display: inline-flex;
  margin-bottom: 16px;
  color: var(--accent);
  font-weight: 700;
  text-decoration: none;
}

.back-link:hover,
.back-link:focus-visible {
  text-decoration: underline;
}

.card {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  box-shadow: var(--panel-shadow);
}

.hero,
.control-panel,
.preview-header,
.preview-card {
  padding: 24px;
}

.eyebrow {
  display: inline-flex;
  padding: 6px 12px;
  border-radius: 999px;
  background: var(--accent-soft);
  color: var(--accent);
  font-size: 0.82rem;
  font-weight: 700;
  letter-spacing: 0.04em;
}

h1,
h2,
p {
  margin: 0;
}

h1 {
  margin-top: 14px;
  font-size: clamp(1.9rem, 4vw, 2.4rem);
  line-height: 1.3;
}

h2 {
  font-size: 1.08rem;
}

.hero-text,
.section-head p,
.status-text {
  color: var(--muted);
}

.layout {
  display: grid;
  grid-template-columns: 360px minmax(0, 1fr);
  gap: 18px;
  margin-top: 18px;
}

.control-panel {
  align-self: start;
  position: sticky;
  top: 16px;
}

.panel-section + .panel-section {
  margin-top: 22px;
  padding-top: 22px;
  border-top: 1px solid var(--line);
}

.section-head {
  display: grid;
  gap: 6px;
}

.field-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 12px;
  margin-top: 14px;
}

.field {
  display: grid;
  gap: 8px;
}

.field-full {
  grid-column: 1 / -1;
}

.field span {
  font-weight: 700;
  font-size: 0.94rem;
}

.field input[type="text"],
.field input[type="color"],
.field select {
  width: 100%;
  min-width: 0;
}

input[type="text"],
select {
  padding: 12px 14px;
  border: 1px solid #c7d4d9;
  border-radius: 14px;
  background: #fff;
  color: var(--text);
}

input[type="color"] {
  height: 48px;
  padding: 6px;
  border: 1px solid #c7d4d9;
  border-radius: 14px;
  background: #fff;
}

input[type="range"] {
  width: 100%;
  accent-color: var(--accent);
}

input:focus,
select:focus,
button:focus-visible {
  outline: 3px solid rgba(0, 128, 128, 0.15);
  border-color: var(--accent);
}

.range-value {
  color: var(--accent-dark);
  font-size: 0.9rem;
}

.button-row {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-top: 16px;
}

.primary-button,
.secondary-button,
.ghost-button {
  appearance: none;
  border-radius: 14px;
  padding: 12px 16px;
  border: 1px solid transparent;
  font-weight: 700;
  transition: transform 0.15s ease, background 0.15s ease;
}

.primary-button {
  background: linear-gradient(135deg, var(--accent), #0b6770);
  color: #fff;
}

.secondary-button {
  background: #f3f8f8;
  border-color: #d2dfdf;
  color: var(--accent-dark);
}

.ghost-button {
  background: #fff;
  border-color: var(--line);
  color: var(--text);
}

.primary-button:hover,
.secondary-button:hover,
.ghost-button:hover,
.primary-button:focus-visible,
.secondary-button:focus-visible,
.ghost-button:focus-visible {
  transform: translateY(-1px);
}

.status-text {
  margin-top: 14px;
  font-size: 0.92rem;
}

.preview-panel {
  display: grid;
  gap: 18px;
}

.canvas-frame {
  display: grid;
  place-items: center;
  min-height: 520px;
  padding: 18px;
  border: 1px solid var(--line);
  border-radius: 18px;
  background: linear-gradient(180deg, #ffffff 0%, #fafbfc 100%);
}

#previewCanvas {
  width: min(100%, 560px);
  aspect-ratio: 1 / 1;
  background: #ffffff;
  border-radius: 18px;
}

@media (max-width: 980px) {
  .layout {
    grid-template-columns: 1fr;
  }

  .control-panel {
    position: static;
  }
}

@media (max-width: 640px) {
  .page-shell {
    width: min(100% - 14px, 1180px);
    padding: 14px 0 32px;
  }

  .hero,
  .control-panel,
  .preview-header,
  .preview-card {
    padding: 18px;
  }

  .field-grid {
    grid-template-columns: 1fr;
  }

  .button-row {
    flex-direction: column;
  }

  .canvas-frame {
    min-height: auto;
    padding: 12px;
  }

  input[type="text"],
  select,
  button {
    font-size: 16px;
  }
}