:root {
  /* Dark Theme Default with Emerald Accents */
  --bg-color: #0d1117;
  --panel-bg: rgba(22, 27, 34, 0.7);
  --border-color: rgba(48, 54, 61, 0.8);
  --text-main: #c9d1d9;
  --text-muted: #8b949e;
  --primary-color: #10b981; /* Emerald */
  --primary-hover: #059669;
  --danger-color: #f85149;
  --danger-hover: #da3633;
  --glass-blur: blur(12px);
  --card-bg: #161b22;
  
  --font-sans: system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --font-mono: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, 'Liberation Mono', monospace;
}

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

body {
  font-family: var(--font-sans);
  background-color: var(--bg-color);
  color: var(--text-main);
  min-height: 100vh;
  margin: 0;
  overflow-x: hidden;
}

.app-container {
  display: flex;
  min-height: 100vh;
}

/* Glass & Base Styles */
.glass-panel {
  background: var(--panel-bg);
  backdrop-filter: var(--glass-blur);
  -webkit-backdrop-filter: var(--glass-blur);
  border: 1px solid var(--border-color);
}

header h1, h2, h3 {
  font-weight: 600;
  color: #fff;
}

/* Sidebar */
.sidebar {
  width: 280px;
  min-width: 280px;
  padding: 1.5rem;
  border-right: 1px solid var(--border-color);
  position: sticky;
  top: 0;
  height: 100vh;
  display: flex;
  flex-direction: column;
  gap: 2rem;
  z-index: 10;
}

.sidebar-header h1 {
  font-size: 1.5rem;
  letter-spacing: -0.03em;
}

.sidebar-header .accent {
  color: var(--primary-color);
}

.sidebar-header .subtitle {
  font-size: 0.875rem;
  color: var(--text-muted);
  margin-top: 0.25rem;
}

/* Controls */
.controls-group {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

.controls-group h3 {
  font-size: 0.875rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--text-muted);
  margin-bottom: 0.5rem;
}

.preset-btn, .action-btn {
  background: transparent;
  border: 1px solid var(--border-color);
  color: var(--text-main);
  padding: 0.6rem 1rem;
  border-radius: 6px;
  font-size: 0.875rem;
  cursor: pointer;
  transition: all 0.2s;
  text-align: left;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.preset-btn:hover {
  border-color: var(--primary-color);
  color: #fff;
  background: rgba(16, 185, 129, 0.1);
}

.preset-btn.danger:hover {
  border-color: var(--danger-color);
  color: #fff;
  background: rgba(248, 81, 73, 0.1);
}

.action-btn {
  justify-content: center;
  font-weight: 500;
  background: var(--card-bg);
}

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

.mt-auto {
  margin-top: auto;
}

/* Switches */
.toggle-switch-wrapper {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 1rem;
  cursor: pointer;
}

.label-text {
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--text-main);
}

.switch {
  position: relative;
  display: inline-block;
  width: 40px;
  height: 22px;
}

.switch input { opacity: 0; width: 0; height: 0; }
.slider.round {
  position: absolute; cursor: pointer;
  top: 0; left: 0; right: 0; bottom: 0;
  background-color: var(--border-color);
  transition: .3s;
  border-radius: 22px;
}
.slider.round:before {
  position: absolute; content: "";
  height: 16px; width: 16px;
  left: 3px; bottom: 3px;
  background-color: var(--text-main);
  transition: .3s;
  border-radius: 50%;
}
input:checked + .slider.round { background-color: var(--primary-color); }
input:checked + .slider.round:before { transform: translateX(18px); background-color: #fff; }

/* Main Content Area */
.content-area {
  flex: 1;
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1.5rem;
  padding: 1.5rem;
  height: 100vh;
  overflow: hidden;
}

@media (max-width: 1024px) {
  .content-area {
    grid-template-columns: 1fr;
    overflow-y: auto;
    height: auto;
  }
}

.editor-section, .preview-section {
  display: flex;
  flex-direction: column;
  border-radius: 12px;
  overflow: hidden;
  height: 100%;
}

.section-header {
  padding: 1rem 1.5rem;
  border-bottom: 1px solid var(--border-color);
  display: flex;
  justify-content: space-between;
  align-items: center;
  background: rgba(0, 0, 0, 0.2);
}

.section-header h2 {
  font-size: 1.125rem;
}

.tabs {
  display: flex;
  gap: 0.5rem;
}

.tab-btn {
  background: transparent;
  border: 1px solid transparent;
  color: var(--text-muted);
  font-size: 0.75rem;
  padding: 0.25rem 0.75rem;
  border-radius: 20px;
  cursor: pointer;
}
.tab-btn.active {
  background: var(--card-bg);
  border-color: var(--border-color);
  color: #fff;
}

/* Editor Form */
.add-header-form {
  display: flex;
  gap: 0.5rem;
  padding: 1.5rem;
  border-bottom: 1px solid var(--border-color);
  background: rgba(255, 255, 255, 0.02);
}

.add-header-form input {
  background: var(--bg-color);
  border: 1px solid var(--border-color);
  color: var(--text-main);
  padding: 0.75rem;
  border-radius: 6px;
  font-family: var(--font-mono);
  font-size: 0.875rem;
}
.add-header-form input:focus {
  outline: none;
  border-color: var(--primary-color);
}
#newHeaderKey { flex: 1; min-width: 150px; }
#newHeaderValue { flex: 2; }

.primary-btn {
  background: var(--primary-color);
  color: #000;
  border: none;
  padding: 0 1.5rem;
  border-radius: 6px;
  font-weight: 600;
  cursor: pointer;
  transition: background 0.2s;
}
.primary-btn:hover {
  background: var(--primary-hover);
}

/* Headers List */
.headers-list {
  flex: 1;
  overflow-y: auto;
  padding: 0;
  list-style: none;
}

.header-row {
  display: flex;
  gap: 0.5rem;
  padding: 0.75rem 1.5rem;
  border-bottom: 1px solid var(--border-color);
  align-items: center;
  transition: background 0.2s;
  cursor: pointer;
}
.header-row:hover {
  background: rgba(255,255,255,0.03);
}
.header-row.active-explain {
  background: rgba(16, 185, 129, 0.1);
  border-left: 3px solid var(--primary-color);
  padding-left: calc(1.5rem - 3px);
}

.header-row input {
  background: transparent;
  border: 1px solid transparent;
  color: var(--text-main);
  font-family: var(--font-mono);
  font-size: 0.875rem;
  padding: 0.4rem;
  width: 100%;
}
.header-row input:focus {
  outline: none;
  background: var(--bg-color);
  border-color: var(--border-color);
  border-radius: 4px;
}
.header-key-col { flex: 1; }
.header-val-col { flex: 2; }

.remove-btn {
  background: transparent;
  border: none;
  color: var(--text-muted);
  cursor: pointer;
  padding: 0.4rem;
  border-radius: 4px;
  display: flex;
  align-items: center;
  justify-content: center;
}
.remove-btn:hover {
  color: var(--danger-color);
  background: rgba(248, 81, 73, 0.1);
}

/* Preview / Explanation Area */
.preview-container {
  padding: 1.5rem;
  flex: 1;
  overflow-y: auto;
  font-family: var(--font-mono);
  font-size: 0.875rem;
  line-height: 1.5;
  white-space: pre-wrap;
  word-break: break-all;
}

.token-method { color: #79c0ff; font-weight: 600; }
.token-url { color: #a5d6ff; }
.token-protocol { color: #8b949e; }
.token-key { color: var(--primary-color); }
.token-colon { color: var(--text-muted); }
.token-value { color: #c9d1d9; }
.token-status { color: #79c0ff; font-weight: 600; }

.explanation-panel {
  border-top: 1px solid var(--border-color);
  padding: 1.5rem;
  background: var(--card-bg);
  min-height: 120px;
}
.explanation-panel.hidden { display: none; }
.explanation-panel h4 {
  font-family: var(--font-mono);
  color: var(--primary-color);
  margin-bottom: 0.5rem;
}
.explanation-panel p {
  font-size: 0.875rem;
  color: var(--text-muted);
  line-height: 1.5;
}

/* Toast */
.toast {
  position: fixed;
  bottom: 2rem;
  left: 50%;
  transform: translateX(-50%);
  background: #fff;
  color: #000;
  padding: 0.75rem 1.5rem;
  border-radius: 20px;
  font-size: 0.875rem;
  font-weight: 600;
  z-index: 100;
  box-shadow: 0 4px 12px rgba(0,0,0,0.5);
  opacity: 0;
  transition: opacity 0.3s, transform 0.3s;
}

.toast.show {
  opacity: 1;
  transform: translate(-50%, -20px);
}