:root {
  --ink: #1f1a17;
  --sumi: #2f2a28;
  --paper: #f8f4ea;
  --accent: #b4321b;
  --accent-soft: #e5b88a;
  --accent-muted: #d9c9b1;
  --leaf: #2e665e;
  --shadow: rgba(13, 8, 6, 0.18);
  --radius-large: 24px;
  --radius-medium: 18px;
  --radius-small: 10px;
  --font-sans: "Zen Kaku Gothic New", "Noto Sans JP", "Hiragino Kaku Gothic ProN",
    "Yu Gothic", sans-serif;
  --font-serif: "Noto Serif JP", "Yu Mincho", "Hiragino Mincho ProN", serif;
}

*,
*::before,
*::after {
  box-sizing: border-box;
}

html,
body {
  margin: 0;
  padding: 0;
}

body {
  min-height: 100vh;
  font-family: var(--font-sans);
  color: var(--ink);
  background: radial-gradient(circle at 20% 20%, rgba(255, 255, 255, 0.6), transparent 55%),
    radial-gradient(circle at 80% 10%, rgba(234, 215, 189, 0.35), transparent 60%),
    linear-gradient(135deg, #faf6ef 0%, #f0e6d8 45%, #fdf8ef 100%);
  line-height: 1.7;
  position: relative;
  overflow-x: hidden;
}

.background-texture {
  position: fixed;
  inset: 0;
  pointer-events: none;
  background-image: linear-gradient(
      135deg,
      rgba(180, 50, 27, 0.06) 0,
      rgba(180, 50, 27, 0.06) 1px,
      transparent 1px,
      transparent 8px
    ),
    linear-gradient(
      45deg,
      rgba(46, 102, 94, 0.06) 0,
      rgba(46, 102, 94, 0.06) 1px,
      transparent 1px,
      transparent 8px
    );
  background-size: 18px 18px, 24px 24px;
  opacity: 0.65;
  z-index: 0;
}

.app-shell {
  position: relative;
  z-index: 1;
  padding: 64px 24px;
  max-width: 960px;
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  gap: 36px;
}

.app-header {
  display: flex;
  flex-direction: column;
  gap: 12px;
  text-align: center;
}

.app-title {
  font-family: var(--font-serif);
  font-weight: 600;
  font-size: clamp(28px, 4vw, 40px);
  margin: 0;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--sumi);
}

.app-tagline {
  font-size: 15px;
  letter-spacing: 0.08em;
  color: rgba(31, 26, 23, 0.72);
  margin: 0;
}

.card {
  background: rgba(255, 255, 255, 0.92);
  border-radius: var(--radius-large);
  padding: 32px clamp(20px, 5vw, 48px);
  box-shadow: 0 24px 50px rgba(24, 16, 7, 0.1), 0 12px 24px rgba(24, 16, 7, 0.08);
  backdrop-filter: blur(6px);
  border: 1px solid rgba(233, 224, 205, 0.7);
}

.is-hidden {
  display: none !important;
}

h2 {
  font-family: var(--font-serif);
  font-weight: 600;
  letter-spacing: 0.1em;
  margin-top: 0;
  margin-bottom: 16px;
}

h3 {
  font-family: var(--font-serif);
  font-weight: 600;
  letter-spacing: 0.08em;
  margin-top: 24px;
  margin-bottom: 12px;
}

p {
  margin: 0 0 12px;
}

button {
  font-family: var(--font-sans);
  border: none;
  cursor: pointer;
  background: none;
}

button:disabled {
  cursor: not-allowed;
  opacity: 0.6;
}

@media (max-width: 720px) {
  .app-shell {
    padding: 32px 16px 48px;
  }

  .card {
    border-radius: var(--radius-medium);
    padding: 28px 18px;
  }
}