/* ─── Variables ─────────────────────────────────────── */
:root {
  --brand: #c0392b;
  --brand-light: #fdecea;
  --brand-border: #e8b4b0;

  --color-bg: #ffffff;
  --color-bg-secondary: #f8f8f7;
  --color-bg-tertiary: #f1f0ec;
  --color-border: rgba(0, 0, 0, 0.12);
  --color-border-md: rgba(0, 0, 0, 0.25);
  --color-text: #1a1a1a;
  --color-text-secondary: #6b6b6b;
  --color-text-tertiary: #999;

  --radius-sm: 6px;
  --radius-md: 8px;
  --radius-lg: 12px;

  --font: -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;

  --space-4: 4px;
  --space-8: 8px;
  --space-12: 12px;
  --space-16: 16px;
  --space-20: 20px;
  --space-24: 24px;
}

/* ─── Reset ──────────────────────────────────────────── */
*,
*::before,
*::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}
body {
  font-family: var(--font);
  font-size: 14px;
  color: var(--color-text);
  background: var(--color-bg);
  line-height: 1.5;
}
a {
  color: inherit;
  text-decoration: none;
}
button {
  font-family: var(--font);
  cursor: pointer;
}

/* ─── Layout ─────────────────────────────────────────── */
.app {
  display: flex;
  height: 100vh;
  overflow: hidden;
}
.main {
  flex: 1;
  overflow-y: auto;
  display: flex;
  flex-direction: column;
  min-width: 0;
}

/* ─── Flex utilities ─────────────────────────────────── */
.flex {
  display: flex;
}
.flex-col {
  display: flex;
  flex-direction: column;
}
.items-center {
  align-items: center;
}
.justify-between {
  justify-content: space-between;
}
.flex-1 {
  flex: 1;
}
.flex-shrink-0 {
  flex-shrink: 0;
}
.gap-4 {
  gap: var(--space-4);
}
.gap-8 {
  gap: var(--space-8);
}
.gap-12 {
  gap: var(--space-12);
}
.gap-16 {
  gap: var(--space-16);
}

/* ─── Spacing utilities ──────────────────────────────── */
.p-8 {
  padding: var(--space-8);
}
.p-12 {
  padding: var(--space-12);
}
.p-16 {
  padding: var(--space-16);
}
.p-20 {
  padding: var(--space-20);
}
.px-12 {
  padding-left: var(--space-12);
  padding-right: var(--space-12);
}
.py-8 {
  padding-top: var(--space-8);
  padding-bottom: var(--space-8);
}
.mb-8 {
  margin-bottom: var(--space-8);
}
.mb-12 {
  margin-bottom: var(--space-12);
}
.mb-16 {
  margin-bottom: var(--space-16);
}
.mb-20 {
  margin-bottom: var(--space-20);
}

/* ─── Typography utilities ───────────────────────────── */
.text-xs {
  font-size: 11px;
}
.text-sm {
  font-size: 12px;
}
.text-md {
  font-size: 14px;
}
.text-lg {
  font-size: 18px;
}
.text-xl {
  font-size: 24px;
}
.text-2xl {
  font-size: 32px;
}
.text-3xl {
  font-size: 42px;
}
.font-medium {
  font-weight: 500;
}
.text-primary {
  color: var(--color-text);
}
.text-secondary {
  color: var(--color-text-secondary);
}
.text-tertiary {
  color: var(--color-text-tertiary);
}
.text-brand {
  color: var(--brand);
}
.uppercase {
  text-transform: uppercase;
}
.tracking-wide {
  letter-spacing: 0.05em;
}
.truncate {
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}
.nowrap {
  white-space: nowrap;
}

/* ─── Border utilities ───────────────────────────────── */
.border-b {
  border-bottom: 0.5px solid var(--color-border);
}
.border-l {
  border-left: 2px solid transparent;
}
.border-l-brand {
  border-left: 2px solid var(--brand);
}
.rounded-sm {
  border-radius: var(--radius-sm);
}
.rounded-md {
  border-radius: var(--radius-md);
}
.rounded-lg {
  border-radius: var(--radius-lg);
}

/* ─── Background utilities ───────────────────────────── */
.bg-primary {
  background: var(--color-bg);
}
.bg-secondary {
  background: var(--color-bg-secondary);
}
.bg-tertiary {
  background: var(--color-bg-tertiary);
}
.bg-brand-light {
  background: var(--brand-light);
}

/* ─── Grid utilities ─────────────────────────────────── */
.grid {
  display: grid;
}
.grid-auto {
  grid-template-columns: repeat(auto-fill, minmax(150px, 1fr));
}
.grid-2 {
  grid-template-columns: 1fr 1fr;
}

/* ─── Components — Button ────────────────────────────── */
.btn {
  display: inline-flex;
  align-items: center;
  padding: 6px 16px;
  border-radius: var(--radius-md);
  border: 0.5px solid var(--color-border-md);
  background: var(--color-bg);
  font-size: 13px;
  transition: background 0.15s;
}
.btn:hover {
  background: var(--color-bg-secondary);
}
.btn-brand {
  background: var(--brand-light);
  color: var(--brand);
  border-color: var(--brand-border);
}
.btn-brand:hover {
  background: var(--brand);
  color: #fff;
}
.btn-success {
  color: #2d6a4f;
  background: #d8f3dc;
  border-color: #b7e4c7;
  cursor: default;
}
.btn-success:hover {
  background: #d8f3dc;
  color: #2d6a4f;
}

/* ─── Components — Badge ─────────────────────────────── */
.badge {
  display: inline-flex;
  align-items: center;
  font-size: 11px;
  padding: 2px 8px;
  border-radius: var(--radius-md);
  border: 0.5px solid var(--color-border);
  background: var(--color-bg-secondary);
  color: var(--color-text-secondary);
}
.badge-brand {
  background: var(--brand-light);
  color: var(--brand);
  border-color: var(--brand-border);
}
.badge-success {
  background: #d8f3dc;
  color: #2d6a4f;
  border-color: #b7e4c7;
}

/* ─── Components — Progress bar ──────────────────────── */
.progress-bar {
  height: 4px;
  background: var(--color-border);
  border-radius: 2px;
  overflow: hidden;
}
.progress-fill {
  height: 100%;
  border-radius: 2px;
  transition: width 0.3s ease;
}
.progress-fill-brand {
  background: var(--brand);
}
.progress-fill-gray {
  background: var(--color-text-tertiary);
}

/* ─── Components — Card ──────────────────────────────── */
.card {
  background: var(--color-bg-secondary);
  border: 0.5px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: var(--space-12);
}
.card:hover {
  border-color: var(--brand-border);
  background: var(--brand-light);
}
.card-static {
  background: var(--color-bg-secondary);
  border: 0.5px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: var(--space-12);
}

/* ─── Components — Toggle switch ─────────────────────── */
.toggle-wrap {
  display: flex;
  align-items: center;
  gap: var(--space-8);
  cursor: pointer;
  user-select: none;
}
.toggle {
  width: 28px;
  height: 16px;
  background: var(--color-border-md);
  border-radius: 8px;
  position: relative;
  transition: background 0.2s;
  flex-shrink: 0;
}
.toggle.on {
  background: var(--brand);
}
.toggle-knob {
  width: 12px;
  height: 12px;
  background: #fff;
  border-radius: 50%;
  position: absolute;
  top: 2px;
  left: 2px;
  transition: left 0.2s;
}
.toggle.on .toggle-knob {
  left: 14px;
}

/* ─── Components — Sidebar ───────────────────────────── */
.sidebar {
  width: 260px;
  min-width: 260px;
  background: var(--color-bg);
  border-right: 0.5px solid var(--color-border);
  display: flex;
  flex-direction: column;
  transition:
    width 0.2s ease,
    min-width 0.2s ease;
  overflow: hidden;
  flex-shrink: 0;
}
.sidebar.collapsed {
  width: 0;
  min-width: 0;
  border-right: none;
}
.sidebar-tree {
  flex: 1;
  overflow-y: auto;
  padding: 8px 0;
}

/* ─── Components — Tree ──────────────────────────────── */
.tree-cat {
  padding: 6px 12px;
  font-size: 11px;
  font-weight: 500;
  color: var(--color-text-secondary);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  display: flex;
  align-items: center;
  gap: 6px;
  cursor: pointer;
  user-select: none;
  white-space: nowrap;
}
.tree-cat:hover {
  color: var(--color-text);
}
.tree-arrow {
  font-size: 9px;
  transition: transform 0.15s;
  flex-shrink: 0;
}
.tree-arrow.open {
  transform: rotate(90deg);
}
.tree-topic {
  padding: 5px 12px 5px 24px;
  font-size: 12px;
  color: var(--color-text-secondary);
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 8px;
  white-space: nowrap;
  border-left: 2px solid transparent;
}
.tree-topic:hover {
  color: var(--color-text);
  background: var(--color-bg-secondary);
}
.tree-topic.active {
  color: var(--brand);
  border-left-color: var(--brand);
  background: var(--brand-light);
}
.topic-dot {
  width: 6px;
  height: 6px;
  border-radius: 50%;
  border: 1px solid var(--color-border-md);
  flex-shrink: 0;
}
.topic-dot.done {
  background: var(--brand);
  border-color: var(--brand);
}
.tag-m {
  font-size: 9px;
  padding: 1px 5px;
  border-radius: 3px;
  background: var(--color-bg-secondary);
  color: var(--color-text-tertiary);
  border: 0.5px solid var(--color-border);
  margin-left: auto;
  flex-shrink: 0;
}

/* ─── Components — Header ────────────────────────────── */
.main-header {
  padding: 0 16px;
  border-bottom: 0.5px solid var(--color-border);
  display: flex;
  align-items: center;
  gap: 10px;
  min-height: 49px;
  flex-shrink: 0;
}
.header-divider {
  width: 0.5px;
  height: 20px;
  background: var(--color-border);
  flex-shrink: 0;
}
.collapse-btn {
  width: 28px;
  height: 28px;
  border: 0.5px solid var(--color-border-md);
  border-radius: var(--radius-md);
  background: none;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--color-text-secondary);
  font-size: 14px;
  flex-shrink: 0;
}
.collapse-btn:hover {
  background: var(--color-bg-secondary);
}

/* ─── Utilities ──────────────────────────────────────── */
.hidden {
  display: none;
}
.cursor-pointer {
  cursor: pointer;
}
.w-full {
  width: 100%;
}
.min-w-0 {
  min-width: 0;
}
.overflow-hidden {
  overflow: hidden;
}
.overflow-y-auto {
  overflow-y: auto;
}