:root {
  --color-bg: #f6f8fa;
  --color-surface: #ffffff;
  --color-text: #1f2933;
  --color-muted: #64707d;
  --color-line: #d8e0e8;
  --color-primary: #1f6f8b;
  --color-primary-dark: #185a72;
  --color-primary-soft: #e7f2f6;
  --shadow-card: 0 12px 32px rgba(31, 41, 51, 0.08);
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  background: var(--color-bg);
  color: var(--color-text);
  font-family: "Yu Gothic", "Hiragino Kaku Gothic ProN", Meiryo, system-ui, sans-serif;
  font-size: 16px;
  line-height: 1.75;
}

button,
textarea {
  font: inherit;
}

.page-shell {
  width: min(100% - 32px, 820px);
  margin: 0 auto;
  padding: 56px 0 96px;
}

.page-header {
  margin-bottom: 24px;
}

.eyebrow {
  margin: 0 0 8px;
  color: var(--color-primary);
  font-size: 0.92rem;
  font-weight: 700;
}

h1,
h2,
p {
  margin-top: 0;
}

h1 {
  margin-bottom: 10px;
  font-size: clamp(2rem, 6vw, 2.8rem);
  line-height: 1.25;
  letter-spacing: 0;
}

h2 {
  margin-bottom: 16px;
  font-size: clamp(1.35rem, 4vw, 1.8rem);
  line-height: 1.45;
  letter-spacing: 0;
}

.lead {
  margin-bottom: 26px;
  color: var(--color-muted);
}

.progress {
  padding: 18px 20px;
  border: 1px solid var(--color-line);
  border-radius: 8px;
  background: var(--color-surface);
}

.progress__meta {
  display: flex;
  justify-content: space-between;
  gap: 16px;
  margin-bottom: 12px;
  color: var(--color-muted);
  font-size: 0.94rem;
  font-weight: 700;
}

.progress__track {
  height: 10px;
  overflow: hidden;
  border-radius: 8px;
  background: #e8edf2;
}

.progress__bar {
  width: 25%;
  height: 100%;
  border-radius: 8px;
  background: var(--color-primary);
  transition: width 180ms ease;
}

.step-card {
  padding: clamp(24px, 5vw, 40px);
  border: 1px solid var(--color-line);
  border-radius: 8px;
  background: var(--color-surface);
  box-shadow: var(--shadow-card);
}

.step-card.is-active {
  animation: fadeIn 160ms ease-out;
}

.step-card__body {
  max-width: 700px;
}

.step-label {
  margin-bottom: 8px;
  color: var(--color-primary);
  font-size: 0.9rem;
  font-weight: 700;
}

.note {
  color: var(--color-muted);
  font-size: 0.95rem;
}

.instruction-figure {
  width: min(100%, 680px);
  margin: 22px 0 18px;
}

.instruction-figure + .instruction-figure {
  margin-top: 28px;
}

.instruction-figure a {
  display: block;
}

.instruction-figure img {
  display: block;
  width: 100%;
  height: auto;
  max-height: 420px;
  object-fit: contain;
  border: 1px solid var(--color-line);
  border-radius: 8px;
  background: #f8fafc;
}

.instruction-figure figcaption {
  margin-top: 8px;
  color: var(--color-muted);
  font-size: 0.92rem;
  line-height: 1.6;
}

.copy-box {
  display: flex;
  align-items: center;
  min-height: 56px;
  margin: 22px 0 12px;
  padding: 14px 16px;
  border: 1px solid var(--color-line);
  border-radius: 8px;
  background: #fbfcfd;
  font-weight: 700;
  word-break: break-word;
}

.examples {
  margin-bottom: 18px;
  color: var(--color-muted);
  font-size: 0.92rem;
}

.examples p {
  margin-bottom: 2px;
}

.textarea-label {
  display: block;
  margin: 22px 0 8px;
  font-weight: 700;
}

.prompt-area {
  width: 100%;
  min-height: 260px;
  padding: 16px;
  border: 1px solid var(--color-line);
  border-radius: 8px;
  background: #fbfcfd;
  color: var(--color-text);
  resize: vertical;
  white-space: pre-wrap;
}

.prompt-area:focus,
.button:focus-visible {
  outline: 3px solid rgba(31, 111, 139, 0.28);
  outline-offset: 3px;
}

.step-image {
  margin-top: 22px;
}

.step-image.is-empty {
  display: none;
}

.step-image img {
  display: block;
  width: 100%;
  height: auto;
  border: 1px solid var(--color-line);
  border-radius: 8px;
}

.finish-list {
  margin: 22px 0 0;
  padding-left: 1.35em;
  color: var(--color-muted);
}

.actions {
  display: flex;
  gap: 12px;
  margin-top: 32px;
}

.actions--wrap {
  flex-wrap: wrap;
}

.button {
  min-height: 48px;
  padding: 12px 18px;
  border: 1px solid transparent;
  border-radius: 8px;
  cursor: pointer;
  font-weight: 700;
  line-height: 1.4;
  transition: background-color 120ms ease, border-color 120ms ease, color 120ms ease;
}

.button--primary {
  background: var(--color-primary);
  color: #ffffff;
}

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

.button--secondary {
  border-color: var(--color-primary);
  background: var(--color-surface);
  color: var(--color-primary);
}

.button--secondary:hover {
  background: var(--color-primary-soft);
}

.button--light {
  border-color: var(--color-line);
  background: #f8fafc;
  color: var(--color-text);
}

.button--light:hover {
  background: #eef3f7;
}

.toast {
  position: fixed;
  right: 24px;
  bottom: 24px;
  z-index: 10;
  max-width: min(320px, calc(100% - 32px));
  padding: 12px 16px;
  border-radius: 8px;
  background: var(--color-text);
  color: #ffffff;
  box-shadow: 0 10px 26px rgba(31, 41, 51, 0.18);
  opacity: 0;
  pointer-events: none;
  transform: translateY(8px);
  transition: opacity 140ms ease, transform 140ms ease;
}

.toast.is-visible {
  opacity: 1;
  transform: translateY(0);
}

@keyframes fadeIn {
  from {
    opacity: 0;
    transform: translateY(6px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@media (max-width: 640px) {
  .page-shell {
    width: min(100% - 24px, 820px);
    padding-top: 32px;
  }

  .progress__meta,
  .actions {
    flex-direction: column;
  }

  .progress__meta {
    gap: 4px;
  }

  .button {
    width: 100%;
  }
}