/* Variables - light theme (default) */
:root {
  --bg: #fafafa;
  --text: #2c3e50;
  --surface: #fff;
  --border: #e1e8ed;
  --muted: #657786;
  --focus-border: #667eea;
  --focus-ring: rgba(102, 126, 234, 0.15);
  --preview-code-bg: #f5f7fa;
  --blockquote-border: #667eea;
  --blockquote-text: #657786;
  --error: #e74c3c;
  --success: #2ecc71;
  --accent: #667eea;
  --accent-hover: #5568d3;
  --header-bg: #ffffff;
  --header-shadow: 0 2px 8px rgba(0, 0, 0, 0.05);
  --header-height: 70px;
}

/* Dark theme */
[data-theme="dark"] {
  --bg: #1a202c;
  --text: #e2e8f0;
  --surface: #2d3748;
  --border: #4a5568;
  --muted: #a0aec0;
  --focus-border: #7c3aed;
  --focus-ring: rgba(124, 58, 237, 0.2);
  --preview-code-bg: #1a202c;
  --blockquote-border: #7c3aed;
  --blockquote-text: #cbd5e0;
  --error: #fc8181;
  --success: #68d391;
  --accent: #7c3aed;
  --accent-hover: #6d28d9;
  --header-bg: #2d3748;
  --header-shadow: 0 2px 8px rgba(0, 0, 0, 0.2);
}

* { box-sizing: border-box; }

html, body {
  height: 100%;
  overflow: hidden;
  margin: 0;
}

body {
  font-family: "Inter", system-ui, sans-serif;
  background: var(--bg);
  color: var(--text);
}

.header {
  height: var(--header-height);
  padding: 1rem 2rem;
  background: var(--header-bg);
  box-shadow: var(--header-shadow);
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 1rem;
}

.header-left, .header-right {
  display: flex;
  align-items: center;
  gap: 1rem;
  flex-wrap: wrap;
}

.logo {
  font-size: 1.35rem;
  font-weight: 700;
  color: var(--text);
  letter-spacing: -0.02em;
}

.file-upload-wrap {
  position: relative;
}

.file-upload-wrap input[type="file"] {
  position: absolute;
  opacity: 0;
  width: 0;
  height: 0;
}

.file-upload-btn {
  display: inline-block;
  font-size: 0.9rem;
  font-weight: 500;
  padding: 0.5rem 1rem;
  border: 2px solid var(--border);
  border-radius: 12px;
  background: var(--surface);
  color: var(--text);
  cursor: pointer;
  transition: all 0.2s ease;
}

.file-upload-btn:hover {
  border-color: var(--accent);
  transform: translateY(-1px);
  box-shadow: 0 4px 12px rgba(102, 126, 234, 0.15);
}

#share-btn {
  font-size: 0.9rem;
  font-weight: 500;
  padding: 0.5rem 1.25rem;
  border: none;
  border-radius: 12px;
  background: var(--accent);
  color: white;
  cursor: pointer;
  transition: all 0.2s ease;
}

#share-btn:hover {
  background: var(--accent-hover);
  transform: translateY(-1px);
  box-shadow: 0 4px 12px rgba(102, 126, 234, 0.3);
}

#share-btn:disabled {
  opacity: 0.5;
  cursor: not-allowed;
  transform: none;
}

.share-feedback {
  font-size: 0.85rem;
  font-weight: 500;
  color: var(--success);
}

.share-feedback.error {
  color: var(--error);
}

select {
  font-size: 0.9rem;
  padding: 0.5rem 0.75rem;
  border: 2px solid var(--border);
  border-radius: 12px;
  background: var(--surface);
  color: var(--text);
  cursor: pointer;
  transition: all 0.2s ease;
}

select:hover {
  border-color: var(--accent);
}

select:focus {
  outline: none;
  border-color: var(--accent);
  box-shadow: 0 0 0 3px var(--focus-ring);
}

.container {
  display: flex;
  flex-wrap: nowrap;
  gap: 0;
  height: calc(100vh - var(--header-height));
  overflow: hidden;
}

.panel {
  flex: 1 1 50%;
  min-width: 0;
  min-height: 0;
  display: flex;
  flex-direction: column;
  padding: 1.5rem;
  overflow: hidden;
}

.input-area {
  display: flex;
  flex-direction: column;
  flex: 1;
  overflow: hidden;
  min-height: 0;
}

.input-area textarea {
  flex: 1;
  min-height: 0;
  padding: 1.25rem;
  font-family: ui-monospace, "SF Mono", "Cascadia Code", "Source Code Pro", monospace;
  font-size: 0.95rem;
  line-height: 1.6;
  border: 2px solid var(--border);
  border-radius: 16px;
  resize: none;
  background: var(--surface);
  color: var(--text);
  overflow: auto;
  transition: all 0.2s ease;
}

.input-area textarea:focus {
  outline: none;
  border-color: var(--focus-border);
  box-shadow: 0 0 0 4px var(--focus-ring);
}

.input-area textarea::placeholder {
  color: var(--muted);
  font-style: italic;
}

.preview-pane {
  flex: 1;
  min-height: 0;
  padding: 1.5rem;
  background: var(--surface);
  border: 2px solid var(--border);
  border-radius: 16px;
  overflow: auto;
  color: var(--text);
  line-height: 1.7;
}

.preview-pane:empty::before {
  content: "Your preview will appear here ✨";
  color: var(--muted);
  font-style: italic;
  display: block;
  text-align: center;
  margin-top: 3rem;
}

.preview-pane h1 {
  font-size: 2rem;
  margin-top: 0;
  margin-bottom: 1rem;
  font-weight: 700;
  color: var(--text);
}

.preview-pane h2 {
  font-size: 1.5rem;
  margin-top: 1.5rem;
  margin-bottom: 0.75rem;
  font-weight: 600;
}

.preview-pane h3 {
  font-size: 1.25rem;
  margin-top: 1.25rem;
  margin-bottom: 0.5rem;
  font-weight: 600;
}

.preview-pane pre {
  background: var(--preview-code-bg);
  padding: 1rem;
  border-radius: 12px;
  overflow-x: auto;
  font-size: 0.9rem;
  border: 1px solid var(--border);
}

.preview-pane code {
  font-family: ui-monospace, "SF Mono", "Cascadia Code", monospace;
  font-size: 0.9em;
  background: var(--preview-code-bg);
  padding: 0.2em 0.4em;
  border-radius: 4px;
}

.preview-pane pre code {
  background: none;
  padding: 0;
}

.preview-pane blockquote {
  border-left: 4px solid var(--blockquote-border);
  margin: 1rem 0;
  padding-left: 1.25rem;
  padding-top: 0.25rem;
  padding-bottom: 0.25rem;
  color: var(--blockquote-text);
  font-style: italic;
}

.preview-pane p {
  margin: 0.75rem 0;
}

.preview-pane ul, .preview-pane ol {
  margin: 0.75rem 0;
  padding-left: 1.75rem;
}

.preview-pane li {
  margin: 0.35rem 0;
}

.preview-pane a {
  color: var(--accent);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: border-color 0.2s ease;
}

.preview-pane a:hover {
  border-bottom-color: var(--accent);
}

/* Responsive: stack panels on narrow screens */
@media (max-width: 768px) {
  :root {
    --header-height: auto;
  }

  html, body {
    height: auto;
    overflow: auto;
  }

  .header {
    height: auto;
    padding: 1rem;
  }

  .header-left, .header-right {
    gap: 0.75rem;
  }

  .logo {
    font-size: 1.1rem;
  }

  #share-btn, .file-upload-btn, select {
    font-size: 0.85rem;
    padding: 0.4rem 0.9rem;
  }

  .container {
    flex-wrap: wrap;
    height: auto;
    min-height: calc(100vh - 120px);
    overflow: visible;
  }

  .panel {
    flex: 1 1 100%;
    min-width: 100%;
    min-height: 50vh;
    padding: 1rem;
  }

  .input-area textarea {
    min-height: 300px;
    resize: vertical;
    padding: 1rem;
    font-size: 0.9rem;
  }

  .preview-pane {
    min-height: 300px;
    padding: 1rem;
  }
}