* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

[hidden] {
  display: none !important;
}

:root {
  --bg-primary: #ffffff;
  --bg-secondary: #f8f9fa;
  --bg-tertiary: #f1f3f4;
  --bg-card: #ffffff;
  --text-primary: #1a1a2e;
  --text-secondary: #4a4a68;
  --text-tertiary: #8e8ea0;
  --border-color: #e4e4e7;
  --accent: #6366f1;
  --accent-hover: #4f46e5;
  --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.05);
  --shadow-lg: 0 8px 30px rgba(0, 0, 0, 0.08);
  --transition: 0.2s cubic-bezier(0.4, 0, 0.2, 1);
}

[data-theme='dark'] {
  color-scheme: dark;
  --bg-primary: #0a0a0f;
  --bg-secondary: #12121a;
  --bg-tertiary: #1a1a24;
  --bg-card: #16161e;
  --text-primary: #f4f4f5;
  --text-secondary: #a1a1aa;
  --text-tertiary: #71717a;
  --border-color: #27272a;
  --accent: #818cf8;
  --accent-hover: #6366f1;
  --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.3);
  --shadow-lg: 0 8px 30px rgba(0, 0, 0, 0.4);
}

body {
  font-family:
    'Inter',
    -apple-system,
    BlinkMacSystemFont,
    'Segoe UI',
    'Hiragino Sans',
    'Noto Sans JP',
    sans-serif;
  background: var(--bg-secondary);
  color: var(--text-primary);
  min-height: 100vh;
  display: flex;
  justify-content: center;
  align-items: flex-start;
  padding: 24px;
  transition:
    background var(--transition),
    color var(--transition);
}

@media (min-width: 481px) {
  body {
    align-items: center;
  }
}

.app {
  width: 100%;
  max-width: 560px;
  background: var(--bg-card);
  border-radius: 24px;
  padding: 40px;
  box-shadow: var(--shadow-lg);
  border: 1px solid var(--border-color);
  transition:
    background-color var(--transition),
    border-color var(--transition);
}

.header {
  position: relative;
  text-align: center;
  margin-bottom: 32px;
}

.theme-toggle {
  position: absolute;
  top: 0;
  right: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
  background: var(--bg-tertiary);
  border: 1px solid var(--border-color);
  border-radius: 10px;
  cursor: pointer;
  color: var(--text-secondary);
  font-size: 1.1rem;
  transition:
    background-color var(--transition),
    border-color var(--transition),
    transform var(--transition);
}

.theme-toggle:hover {
  background: var(--bg-secondary);
  border-color: var(--accent);
  transform: scale(1.05);
}

.theme-toggle:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}

.logo {
  font-size: 1.8rem;
  font-weight: 700;
  color: var(--text-primary);
  letter-spacing: -0.03em;
}

.tagline {
  margin-top: 8px;
  font-size: 0.9rem;
  color: var(--text-tertiary);
}

.main {
  display: flex;
  flex-direction: column;
  gap: 20px;
}

.input-wrapper {
  position: relative;
}

.input {
  width: 100%;
  padding: 16px 52px 16px 20px;
  font-size: 1rem;
  background: var(--bg-tertiary);
  border: 2px solid transparent;
  border-radius: 14px;
  color: var(--text-primary);
  resize: none;
  font-family: inherit;
  line-height: 1.6;
  transition:
    border-color var(--transition),
    background-color var(--transition);
}

.input:focus-visible {
  outline: none;
  border-color: var(--accent);
  background: var(--bg-primary);
}

.input::placeholder {
  color: var(--text-tertiary);
}

.input-action-btn {
  position: absolute;
  top: 12px;
  right: 12px;
  width: 32px;
  height: 32px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: 8px;
  cursor: pointer;
  color: var(--text-tertiary);
  padding: 0;
  transition:
    background-color var(--transition),
    color var(--transition);
}

.input-action-btn:hover {
  background: var(--bg-tertiary);
  color: var(--text-secondary);
}

.char-count {
  text-align: right;
  font-size: 0.8rem;
  color: var(--text-tertiary);
  margin-top: 6px;
}

.char-count.warning {
  color: #ca8a04;
}

.char-count.danger {
  color: #dc2626;
}

.output-section {
  display: flex;
  flex-direction: column;
  gap: 14px;
}

.url-box {
  padding: 14px 16px;
  background: var(--bg-tertiary);
  border: 1px solid var(--border-color);
  border-radius: 12px;
  font-family: ui-monospace, SFMono-Regular, Menlo, monospace;
  font-size: 0.8rem;
  color: var(--text-secondary);
  word-break: break-all;
  line-height: 1.5;
  max-height: 120px;
  overflow-y: auto;
}

.actions {
  display: flex;
  gap: 12px;
}

.action-btn {
  flex: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 13px 16px;
  background: var(--bg-tertiary);
  border: 1px solid var(--border-color);
  border-radius: 12px;
  color: var(--text-secondary);
  font-size: 0.95rem;
  font-weight: 500;
  font-family: inherit;
  cursor: pointer;
  text-decoration: none;
  transition:
    background-color var(--transition),
    border-color var(--transition),
    color var(--transition);
}

.action-btn:hover {
  background: var(--bg-secondary);
  border-color: var(--accent);
  color: var(--accent);
}

.action-btn:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}

.action-btn.primary {
  background: var(--accent);
  border-color: var(--accent);
  color: #ffffff;
}

.action-btn.primary:hover {
  background: var(--accent-hover);
  border-color: var(--accent-hover);
  color: #ffffff;
}

.action-btn.copied {
  border-color: #16a34a;
  color: #16a34a;
}

.footer {
  text-align: center;
  margin-top: 28px;
  font-size: 0.8rem;
}

.footer-privacy {
  color: var(--text-tertiary);
}

@media (max-width: 480px) {
  .app {
    padding: 28px 24px;
    border-radius: 20px;
  }

  .logo {
    font-size: 1.5rem;
  }

  .actions {
    flex-direction: column;
  }
}