:root {
--sidebar-width: 250px;
--header-height: 50px;
}

html, body {
height: 100%;
margin: 0;
overflow: hidden;
font-family: Arial, sans-serif;
}

.app {
display: flex;
flex-direction: column;
height: 100%;
}

header {
height: var(--header-height);
background: #333;
color: white;
padding: 0 15px;
display: flex;
align-items: center;
gap: 10px;
flex: 0 0 auto;
z-index: 200;
}

.menu-btn {
font-size: 20px;
cursor: pointer;
display: none;
}

.main {
display: flex;
flex: 1;
min-height: 0;
}

.sidebar {
width: var(--sidebar-width);
background: #444;
color: white;
overflow-y: auto;
transition: width 0.2s ease;
}

.sidebar div {
padding: 10px;
border-bottom: 1px solid #555;
}

.sidebar-footer {
padding: 10px;
font-size: 12px;
opacity: 0.7;
border-top: 1px solid #555;
}

.resizer {
width: 5px;
cursor: col-resize;
}

.resizer:hover {
background: rgba(0,0,0,0.2);
}

.content {
flex: 1;
overflow-y: auto;
padding: 20px;
background: #f5f5f5;
}

.box {
background: white;
padding: 20px;
margin-bottom: 15px;
border-radius: 5px;
}

/* Backdrop */
.backdrop {
position: fixed;
top: var(--header-height);
left: 0;
width: 100%;
height: calc(100% - var(--header-height));
background: rgba(0,0,0,0.4);
opacity: 0;
pointer-events: none;
transition: opacity 0.2s ease;
z-index: 90;
}

.backdrop.open {
opacity: 1;
pointer-events: auto;
}

/* Mobile */
@media (max-width: 768px) {
.menu-btn {
  display: block;
}

.sidebar {
  position: fixed;
  top: var(--header-height);
  left: -260px;
  height: calc(100% - var(--header-height));
  width: 250px;
  z-index: 100;
  transition: left 0.2s ease;
}

.sidebar.open {
  left: 0;
}

.resizer {
  display: none;
}
}