:root {
  --bg-top: #fff8ef;
  --bg-bottom: #eef6ff;
  --surface: #ffffff;
  --surface-soft: #fffcf7;
  --text: #1f2430;
  --muted: #5b6272;
  --line: #ddd7cf;
  --line-strong: #bfb3a4;
  --primary: #165d8a;
  --primary-strong: #0f4565;
  --accent: #d68f30;
  --shadow-soft: 0 12px 30px rgba(25, 38, 56, 0.08);
  --radius-lg: 20px;
  --radius-md: 14px;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: "Hiragino Kaku Gothic ProN", "Yu Gothic", "Noto Sans JP", sans-serif;
  color: var(--text);
  background:
    radial-gradient(860px 380px at -8% -12%, rgba(214, 143, 48, 0.16) 0%, rgba(214, 143, 48, 0) 72%),
    radial-gradient(920px 380px at 108% 8%, rgba(22, 93, 138, 0.16) 0%, rgba(22, 93, 138, 0) 70%),
    linear-gradient(155deg, var(--bg-top) 0%, var(--bg-bottom) 100%);
  min-height: 100vh;
}

.container {
  max-width: 1100px;
  margin: 0 auto;
  padding: 26px 16px 44px;
}

.hero {
  display: grid;
  gap: 16px;
  background: linear-gradient(140deg, rgba(255, 255, 255, 0.9) 0%, rgba(255, 250, 242, 0.98) 58%);
  border: 1px solid rgba(191, 179, 164, 0.68);
  border-radius: 24px;
  padding: 22px;
  box-shadow: var(--shadow-soft);
}

.hero h1 {
  margin: 0;
  font-size: clamp(1.6rem, 1.15rem + 1.4vw, 2.3rem);
}

.hero p {
  margin: 8px 0 0;
  color: var(--muted);
  line-height: 1.65;
}

.hero-badges {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}

.hero-badges span {
  display: inline-flex;
  align-items: center;
  min-height: 34px;
  padding: 0 12px;
  border-radius: 999px;
  border: 1px solid rgba(15, 69, 101, 0.12);
  background: rgba(255, 255, 255, 0.82);
  color: var(--primary-strong);
  font-weight: 700;
  font-size: 0.94rem;
}

.panel {
  margin-top: 16px;
  border-radius: var(--radius-lg);
  border: 1px solid var(--line);
  background: linear-gradient(180deg, var(--surface) 0%, var(--surface-soft) 100%);
  box-shadow: var(--shadow-soft);
  padding: 18px;
}

.tool-grid {
  display: grid;
  grid-template-columns: minmax(0, 1.15fr) minmax(320px, 0.85fr);
  gap: 16px;
}

.card {
  background: #fff;
  border: 1px solid var(--line);
  border-radius: var(--radius-md);
  padding: 16px;
}

.card h2 {
  margin: 0;
  color: var(--primary-strong);
  font-size: 1.16rem;
}

.field {
  display: grid;
  gap: 8px;
  margin-top: 14px;
}

.field span,
.size-fieldset legend {
  font-weight: 700;
  color: #5e4732;
}

textarea,
button {
  font: inherit;
}

textarea {
  width: 100%;
  resize: vertical;
  min-height: 170px;
  padding: 12px 13px;
  border: 1px solid var(--line-strong);
  border-radius: 12px;
  background: #fffdfa;
  color: var(--text);
  line-height: 1.6;
}

.size-fieldset {
  margin: 16px 0 0;
  padding: 12px;
  border: 1px solid var(--line);
  border-radius: 12px;
  display: grid;
  gap: 10px;
}

.size-option {
  display: flex;
  align-items: center;
  gap: 10px;
  font-weight: 700;
  color: var(--text);
}

.alpha-control {
  display: grid;
  gap: 8px;
  margin-top: 14px;
}

.alpha-control span {
  font-weight: 700;
  color: var(--text);
}

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

button {
  border: 0;
  border-radius: 12px;
  padding: 11px 14px;
  font-weight: 700;
  cursor: pointer;
  color: #fff;
  background: linear-gradient(180deg, #1b78af 0%, #11577f 100%);
  box-shadow: 0 8px 18px rgba(17, 87, 127, 0.18);
}

button.secondary-button {
  color: var(--primary-strong);
  background: linear-gradient(180deg, #fff4df 0%, #f6e3bf 100%);
  box-shadow: 0 8px 18px rgba(214, 143, 48, 0.16);
}

button:disabled {
  cursor: not-allowed;
  opacity: 0.6;
  box-shadow: none;
}

.status-text {
  margin: 12px 0 0;
  color: var(--muted);
  line-height: 1.6;
  min-height: 1.6em;
}

.status-text.is-error {
  color: #b24a2b;
}

.status-text.is-emphasis {
  padding: 10px 12px;
  border: 1px solid rgba(214, 143, 48, 0.4);
  border-radius: 12px;
  background: linear-gradient(180deg, rgba(255, 243, 214, 0.95), rgba(255, 232, 186, 0.95));
  color: #7a4a07;
  font-weight: 700;
  box-shadow: 0 8px 18px rgba(214, 143, 48, 0.14);
}

.preview-card {
  display: grid;
  gap: 16px;
}

.preview-shell {
  display: grid;
  place-items: center;
  min-height: 360px;
  padding: 12px;
  border: 1px solid var(--line);
  border-radius: 14px;
  background: linear-gradient(180deg, rgba(247, 248, 250, 0.92), rgba(255, 255, 255, 0.98));
}

.checker {
  background:
    linear-gradient(45deg, #eef0f5 25%, transparent 25%, transparent 75%, #eef0f5 75%, #eef0f5 100%),
    linear-gradient(45deg, #eef0f5 25%, #fff 25%, #fff 75%, #eef0f5 75%, #eef0f5 100%);
  background-size: 24px 24px;
  background-position: 0 0, 12px 12px;
}

.preview-stage {
  display: grid;
  place-items: center;
  width: min(100%, 440px);
  aspect-ratio: 1 / 1;
  padding: 20px;
  border-radius: 18px;
  border: 1px solid rgba(17, 87, 127, 0.12);
}

#previewCanvas {
  display: block;
  width: 100%;
  aspect-ratio: 1 / 1;
  max-width: 100%;
  height: auto;
  image-rendering: pixelated;
  background: #fff;
}

#previewCanvas.is-transparent {
  background: transparent;
}

.meta-list {
  margin: 0;
  display: grid;
  gap: 10px;
}

.meta-list div {
  display: grid;
  grid-template-columns: 84px 1fr;
  gap: 12px;
}

.meta-list dt {
  font-weight: 700;
  color: #5e4732;
}

.meta-list dd {
  margin: 0;
  color: var(--text);
  font-family: "SFMono-Regular", "Consolas", "Menlo", monospace;
  word-break: break-all;
}

.guide-content ul {
  margin: 10px 0 0;
  padding-left: 20px;
  color: var(--text);
  line-height: 1.7;
}

@media (max-width: 860px) {
  .tool-grid {
    grid-template-columns: 1fr;
  }

  .preview-shell {
    min-height: 300px;
  }
}

@media (max-width: 560px) {
  .container {
    padding-inline: 12px;
  }

  .panel,
  .hero,
  .card {
    padding: 14px;
  }

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

  .action-row button {
    width: 100%;
  }

  .meta-list div {
    grid-template-columns: 1fr;
    gap: 4px;
  }
}

.annotation {
  color: #333333;
  margin-top: 8px;
  font-size: 14px;
}