/* === Reset & Tokens === */
:root {
  color-scheme: light dark;
  font-family: "SF Pro Display", "Noto Sans TC", system-ui, -apple-system,
    BlinkMacSystemFont, "Segoe UI", sans-serif;

  --c-bg: #f0f0f5;
  --c-surface: rgba(255, 255, 255, 0.82);
  --c-surface-hover: rgba(255, 255, 255, 0.95);
  --c-border: rgba(99, 102, 241, 0.15);
  --c-input-border: #cbd5f5;
  --c-text: #0f172a;
  --c-text-secondary: #475569;
  --c-text-muted: #94a3b8;
  --c-accent: #6366f1;
  --c-accent-light: rgba(99, 102, 241, 0.08);
  --c-accent-glow: rgba(99, 102, 241, 0.35);
  --c-neutral-btn: #e2e8f0;
  --c-neutral-btn-hover: #cbd5e1;
  --c-focus-ring: rgba(124, 58, 237, 0.2);
  --c-footer-bg: transparent;
  --c-footer-text: #94a3b8;
  --c-result-bg: rgba(99, 102, 241, 0.04);
  --shadow-card: 0 20px 60px rgba(15, 23, 42, 0.1);
  --radius: 16px;
}

@media (prefers-color-scheme: dark) {
  :root {
    --c-bg: #0f1117;
    --c-surface: rgba(30, 32, 44, 0.85);
    --c-surface-hover: rgba(38, 40, 56, 0.95);
    --c-border: rgba(99, 102, 241, 0.2);
    --c-input-border: rgba(99, 102, 241, 0.25);
    --c-text: #e2e8f0;
    --c-text-secondary: #94a3b8;
    --c-text-muted: #64748b;
    --c-accent: #818cf8;
    --c-accent-light: rgba(99, 102, 241, 0.12);
    --c-accent-glow: rgba(99, 102, 241, 0.25);
    --c-neutral-btn: rgba(51, 65, 85, 0.7);
    --c-neutral-btn-hover: rgba(71, 85, 105, 0.8);
    --c-focus-ring: rgba(129, 140, 248, 0.25);
    --c-footer-text: #64748b;
    --c-result-bg: rgba(99, 102, 241, 0.06);
    --shadow-card: 0 20px 60px rgba(0, 0, 0, 0.35);
  }
}

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

body {
  margin: 0;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  align-items: center;
  padding: 2.5rem 1rem 0;
  background-color: var(--c-bg);
  background-image:
    radial-gradient(circle at 20% 10%, rgba(99, 102, 241, 0.12), transparent 45%),
    radial-gradient(circle at 80% 90%, rgba(139, 92, 246, 0.08), transparent 40%);
  color: var(--c-text);
}

/* === Card === */
.app {
  width: min(680px, 100%);
  background: var(--c-surface);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border-radius: calc(var(--radius) + 4px);
  padding: 2.5rem;
  box-shadow: var(--shadow-card);
  border: 1px solid var(--c-border);
  animation: fadeUp 0.45s ease-out;
}

@keyframes fadeUp {
  from {
    opacity: 0;
    transform: translateY(12px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

/* === Header === */
.app-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
}

.brand {
  display: flex;
  align-items: center;
  gap: 0.6rem;
}

.brand-icon {
  flex-shrink: 0;
}

h1 {
  margin: 0;
  font-size: 1.75rem;
  font-weight: 700;
  letter-spacing: -0.02em;
}

.subtitle {
  margin: 0.75rem 0 0;
  font-size: 1.1rem;
  font-weight: 500;
  color: var(--c-text);
}

.intro {
  margin: 0.35rem 0 0;
  color: var(--c-text-secondary);
  line-height: 1.65;
  font-size: 0.95rem;
}

/* === GitHub link === */
.github-link {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  text-decoration: none;
  color: var(--c-text);
  background: var(--c-accent-light);
  border: 1px solid var(--c-border);
  border-radius: 999px;
  padding: 0.4rem 0.8rem;
  font-size: 0.85rem;
  font-weight: 600;
  white-space: nowrap;
  transition: background 0.2s, border-color 0.2s;
}

.github-link:hover {
  background: var(--c-accent-light);
  border-color: var(--c-accent);
}

.github-icon {
  flex-shrink: 0;
}

/* === Form === */
label {
  font-weight: 600;
  display: block;
  margin: 1.75rem 0 0.5rem;
  color: var(--c-text);
  font-size: 0.95rem;
}

.input-wrap {
  position: relative;
}

textarea {
  width: 100%;
  border-radius: var(--radius);
  border: 1.5px solid var(--c-input-border);
  padding: 1rem 3rem 1rem 1.1rem;
  font-size: 1rem;
  font-family: inherit;
  color: var(--c-text);
  background: var(--c-surface-hover);
  transition: border-color 0.2s, box-shadow 0.2s;
  outline: none;
  min-height: 130px;
  resize: vertical;
}

textarea:focus {
  border-color: var(--c-accent);
  box-shadow: 0 0 0 3px var(--c-focus-ring);
}

textarea::placeholder {
  color: var(--c-text-muted);
}

.paste-btn {
  position: absolute;
  top: 0.65rem;
  right: 0.65rem;
  display: flex;
  align-items: center;
  justify-content: center;
  width: 34px;
  height: 34px;
  border-radius: 10px;
  border: 1px solid var(--c-input-border);
  background: var(--c-surface);
  color: var(--c-text-muted);
  cursor: pointer;
  transition: color 0.2s, border-color 0.2s, background 0.2s;
  padding: 0;
  flex: none;
  min-width: 0;
}

.paste-btn:hover {
  color: var(--c-accent);
  border-color: var(--c-accent);
  background: var(--c-accent-light);
}

/* === Buttons === */
.buttons {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  margin-top: 1.5rem;
}

button {
  flex: 1;
  min-width: 130px;
  border: none;
  border-radius: var(--radius);
  padding: 0.85rem 1.1rem;
  font-size: 0.95rem;
  font-weight: 600;
  font-family: inherit;
  cursor: pointer;
  transition: transform 0.12s, box-shadow 0.15s, background 0.2s;
}

button:active {
  transform: translateY(1px);
}

.primary {
  background: linear-gradient(135deg, #6366f1, #8b5cf6);
  color: white;
  box-shadow: 0 8px 24px var(--c-accent-glow);
}

.primary:hover {
  box-shadow: 0 12px 32px var(--c-accent-glow);
}

.primary:active {
  box-shadow: 0 4px 12px var(--c-accent-glow);
}

.neutral {
  background: var(--c-neutral-btn);
  color: var(--c-text);
}

.neutral:hover {
  background: var(--c-neutral-btn-hover);
}

/* === Result === */
.result {
  margin-top: 1.25rem;
  border-radius: var(--radius);
  border: 1.5px dashed var(--c-input-border);
  padding: 1rem 1.1rem;
  background: var(--c-result-bg);
  min-height: 3.2rem;
  color: var(--c-text);
  font-size: 0.95rem;
  word-break: break-all;
  transition: border-color 0.3s, background 0.3s;
}

.result.empty {
  color: var(--c-text-muted);
}

.result.has-result {
  border-style: solid;
  border-color: var(--c-accent);
  background: var(--c-accent-light);
  animation: resultIn 0.3s ease-out;
}

@keyframes resultIn {
  from {
    opacity: 0.5;
    transform: scale(0.99);
  }
  to {
    opacity: 1;
    transform: scale(1);
  }
}

.status {
  margin-top: 0.5rem;
  font-size: 0.88rem;
  color: var(--c-text-secondary);
  min-height: 1.4em;
}

.removed-tag {
  display: inline-block;
  background: var(--c-accent-light);
  color: var(--c-accent);
  border-radius: 6px;
  padding: 0.1em 0.45em;
  font-size: 0.82rem;
  font-weight: 600;
  margin: 0.15em 0.2em;
}

/* === Footer === */
.site-footer {
  margin-top: auto;
  padding: 2rem 1rem 1.5rem;
  text-align: center;
  font-size: 0.82rem;
  color: var(--c-footer-text);
}

.site-footer p {
  margin: 0.25rem 0;
  color: inherit;
}

.site-footer a {
  color: var(--c-text-muted);
  text-decoration: none;
  transition: color 0.2s;
}

.site-footer a:hover {
  color: var(--c-accent);
}

/* === Responsive === */
@media (max-width: 640px) {
  body {
    padding: 1rem 0.75rem 0;
  }

  .app {
    padding: 1.5rem 1.25rem;
    border-radius: var(--radius);
  }

  .app-header {
    flex-direction: column;
    align-items: flex-start;
  }

  h1 {
    font-size: 1.5rem;
  }

  .buttons {
    flex-direction: column;
  }

  button {
    min-width: 0;
  }
}