:root {
  /* Fluent 2 Color Tokens */
  --color-neutral-background: #f7f7f7;
  --color-neutral-background-selected: #e6e6e6;
  --color-neutral-foreground: #242424;
  --color-neutral-foreground-subtle: #616161;
  --color-brand-background: #0078d4;
  --color-brand-background-hover: #106ebe;
  --color-brand-foreground: #0078d4;
  --color-brand-foreground-hover: #004578;
  --color-status-success: #107c10;
  --color-status-warning: #d83b01;
  --color-status-error: #d13438;
  --color-status-info: #0078d4;

  /* Fluent 2 Shadows */
  --shadow-2: 0 0 2px rgba(0,0,0,0.12), 0 2px 4px rgba(0,0,0,0.14);
  --shadow-4: 0 0 2px rgba(0,0,0,0.12), 0 4px 8px rgba(0,0,0,0.14);
  --shadow-8: 0 0 2px rgba(0,0,0,0.12), 0 8px 16px rgba(0,0,0,0.14);

  /* Fluent 2 Typography */
  --font-weight-regular: 400;
  --font-weight-semibold: 600;
  --font-weight-bold: 700;

  /* Spacing */
  --spacing-xs: 4px;
  --spacing-s: 8px;
  --spacing-m: 12px;
  --spacing-l: 16px;
  --spacing-xl: 20px;
  --spacing-xxl: 24px;

  /* Border Radius */
  --border-radius-medium: 4px;
  --border-radius-large: 8px;
}

* {
  box-sizing: border-box;
}

body {
  font-family: "Segoe UI", system-ui, -apple-system, sans-serif;
  margin: 0;
  background-color: var(--color-neutral-background);
  color: var(--color-neutral-foreground);
  line-height: 1.4;
}

/* Header */
header {
  background: white;
  padding: var(--spacing-l) var(--spacing-xl);
  border-bottom: 1px solid #e1e1e1;
  box-shadow: var(--shadow-2);
}

header h2 {
  margin: 0 0 var(--spacing-xs) 0;
  font-weight: var(--font-weight-semibold);
  font-size: 24px;
  color: var(--color-neutral-foreground);
}

.subtitle {
  font-size: 14px;
  color: var(--color-neutral-foreground-subtle);
  margin: 0;
}

/* Main Layout */
main {
  display: flex;
  min-height: calc(100vh - 80px);
}

/* Navigation */
nav {
  width: 260px;
  background: white;
  border-right: 1px solid #e1e1e1;
  padding: var(--spacing-l);
  display: flex;
  flex-direction: column;
  gap: var(--spacing-xs);
}

.nav-button {
  display: flex;
  align-items: center;
  gap: var(--spacing-s);
  padding: var(--spacing-m) var(--spacing-l);
  background: none;
  border: 1px solid transparent;
  border-radius: var(--border-radius-medium);
  font-family: inherit;
  font-size: 14px;
  font-weight: var(--font-weight-regular);
  color: var(--color-neutral-foreground);
  cursor: pointer;
  transition: all 0.1s ease;
  text-align: left;
  text-decoration: none;
}

.nav-button:hover {
  background-color: var(--color-neutral-background);
  border-color: #e1e1e1;
}

.nav-button.active {
  background-color: var(--color-brand-background);
  color: white;
  font-weight: var(--font-weight-semibold);
}

.nav-button.accent {
  background-color: var(--color-brand-background);
  color: white;
  font-weight: var(--font-weight-semibold);
  margin-top: var(--spacing-xl);
}

.nav-button.accent:hover {
  background-color: var(--color-brand-background-hover);
}

.nav-button.warning {
  background-color: var(--color-status-warning);
  color: white;
}

.nav-button.warning:hover {
  background-color: #c13501;
}

/* Content Area */
section {
  flex: 1;
  padding: var(--spacing-xl);
  overflow: auto;
  display: none;
}

section.active {
  display: block;
}

/* Cards/Panels */
.card {
  background: white;
  border-radius: var(--border-radius-large);
  padding: var(--spacing-xl);
  margin-bottom: var(--spacing-l);
  box-shadow: var(--shadow-2);
  border: 1px solid #e1e1e1;
}

.card-header {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  margin-bottom: var(--spacing-l);
}

.card-title {
  margin: 0;
  font-weight: var(--font-weight-semibold);
  font-size: 20px;
  color: var(--color-neutral-foreground);
}

.card-description {
  margin: var(--spacing-xs) 0 0 0;
  font-size: 14px;
  color: var(--color-neutral-foreground-subtle);
}

/* Buttons */
.button {
  display: inline-flex;
  align-items: center;
  gap: var(--spacing-s);
  padding: var(--spacing-m) var(--spacing-l);
  background: var(--color-brand-background);
  color: white;
  border: none;
  border-radius: var(--border-radius-medium);
  font-family: inherit;
  font-size: 14px;
  font-weight: var(--font-weight-semibold);
  cursor: pointer;
  transition: background-color 0.1s ease;
  text-decoration: none;
}

.button:hover {
  background-color: var(--color-brand-background-hover);
}

.button.secondary {
  background: transparent;
  color: var(--color-brand-foreground);
  border: 1px solid var(--color-brand-foreground);
}

.button.secondary:hover {
  background-color: var(--color-neutral-background);
}

.button.warning {
  background: var(--color-status-warning);
}

.button.warning:hover {
  background-color: #c13501;
}

/* Interface Grid */
.interface-grid {
  display: grid;
  gap: var(--spacing-l);
  margin-top: var(--spacing-l);
}

.interface-card {
  background: white;
  border-radius: var(--border-radius-large);
  padding: var(--spacing-xl);
  box-shadow: var(--shadow-2);
  border: 1px solid #e1e1e1;
  border-left: 4px solid var(--color-brand-background);
}

.interface-card.wan {
  border-left-color: var(--color-status-warning);
}

.interface-card.lan {
  border-left-color: var(--color-status-success);
}

.interface-header {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  margin-bottom: var(--spacing-l);
}

.interface-name {
  font-weight: var(--font-weight-semibold);
  font-size: 18px;
  margin: 0;
}

.interface-type {
  display: inline-block;
  padding: var(--spacing-xs) var(--spacing-s);
  background: var(--color-neutral-background);
  border-radius: var(--border-radius-medium);
  font-size: 12px;
  font-weight: var(--font-weight-semibold);
  color: var(--color-neutral-foreground-subtle);
  margin-left: var(--spacing-s);
}

.interface-details {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: var(--spacing-l);
}

.detail-group h4 {
  margin: 0 0 var(--spacing-xs) 0;
  font-size: 14px;
  font-weight: var(--font-weight-semibold);
  color: var(--color-neutral-foreground);
}

.detail-value {
  font-size: 14px;
  color: var(--color-neutral-foreground-subtle);
  line-height: 1.5;
}

.state-badge {
  display: inline-block;
  padding: 2px 8px;
  border-radius: 10px;
  font-size: 12px;
  font-weight: var(--font-weight-semibold);
}

.state-up {
  background: #dff6dd;
  color: var(--color-status-success);
}

.state-down {
  background: #f4d5d5;
  color: var(--color-status-error);
}

/* Forms */
.form-group {
  margin-bottom: var(--spacing-l);
}

.form-label {
  display: block;
  margin-bottom: var(--spacing-s);
  font-weight: var(--font-weight-semibold);
  font-size: 14px;
  color: var(--color-neutral-foreground);
}

.select {
  width: 100%;
  padding: var(--spacing-m);
  border: 1px solid #e1e1e1;
  border-radius: var(--border-radius-medium);
  font-family: inherit;
  font-size: 14px;
  background: white;
  transition: border-color 0.1s ease;
}

.select:focus {
  outline: none;
  border-color: var(--color-brand-background);
}

.textarea {
  width: 100%;
  height: 360px;
  padding: var(--spacing-m);
  border: 1px solid #e1e1e1;
  border-radius: var(--border-radius-medium);
  font-family: 'Consolas', 'Monaco', monospace;
  font-size: 13px;
  line-height: 1.5;
  resize: vertical;
  background: white;
  transition: border-color 0.1s ease;
}

.textarea:focus {
  outline: none;
  border-color: var(--color-brand-background);
}

.checkbox-group {
  display: flex;
  align-items: center;
  gap: var(--spacing-s);
  margin: var(--spacing-l) 0;
}

.checkbox {
  width: 16px;
  height: 16px;
  margin: 0;
}

.checkbox-label {
  font-size: 14px;
  color: var(--color-neutral-foreground);
  margin: 0;
}

/* Validation Results */
.validation-result {
  padding: var(--spacing-m);
  border-radius: var(--border-radius-medium);
  font-size: 14px;
  margin-top: var(--spacing-m);
}

.validation-success {
  background: #dff6dd;
  color: var(--color-status-success);
  border: 1px solid #107c10;
}

.validation-error {
  background: #f4d5d5;
  color: var(--color-status-error);
  border: 1px solid var(--color-status-error);
}

/* Logs */
.logs-container {
  background: #1e1e1e;
  color: #d4d4d4;
  padding: var(--spacing-l);
  border-radius: var(--border-radius-medium);
  font-family: 'Consolas', 'Monaco', monospace;
  font-size: 13px;
  line-height: 1.5;
  overflow: auto;
  max-height: 600px;
  white-space: pre-wrap;
}

/* Command Results */
.command-result {
  padding: var(--spacing-m);
  border-radius: var(--border-radius-medium);
  background: var(--color-neutral-background);
  font-size: 14px;
  margin-top: var(--spacing-m);
}

/* Tips Section */
.tips-section {
  margin-top: auto;
  padding-top: var(--spacing-xl);
  border-top: 1px solid #e1e1e1;
}

.tips-title {
  font-weight: var(--font-weight-semibold);
  font-size: 14px;
  margin-bottom: var(--spacing-s);
  color: var(--color-neutral-foreground);
}

.tips-list {
  margin: 0;
  padding-left: var(--spacing-l);
  font-size: 13px;
  color: var(--color-neutral-foreground-subtle);
  line-height: 1.5;
}

.tips-list li {
  margin-bottom: var(--spacing-xs);
}

/* Responsive */
@media (max-width: 768px) {
  main {
    flex-direction: column;
  }

  nav {
    width: 100%;
    flex-direction: row;
    overflow-x: auto;
    padding: var(--spacing-m);
  }

  .nav-button {
    white-space: nowrap;
  }

  .interface-details {
    grid-template-columns: 1fr;
  }

  .card-header {
    flex-direction: column;
    gap: var(--spacing-m);
  }
}