:root {
    --bg-main: #ffffff;
    --bg-side: #f3f2f1;
    --accent: #0078d4;
    --text-primary: #323130;
    --text-secondary: #605e5b;
    --hover: #edebe9;
    --border: #edebe9;
    --button-bg: #efefef;
    --button-hover: #e1e1e1;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
}

body {
    background-color: var(--bg-main);
    color: var(--text-primary);
    overflow: hidden;
    height: 100vh;
    display: flex;
    flex-direction: column;
}

/* Header UI */
header {
    height: 48px;
    background-color: var(--bg-main);
    display: flex;
    align-items: center;
    padding: 0 16px;
    border-bottom: 1px solid #edebe9;
    box-shadow: 0 1px 3px rgba(0,0,0,0.05);
    justify-content: space-between;
    z-index: 10;
}

.header-left {
    display: flex;
    align-items: center;
    gap: 16px;
}

.app-launcher {
    cursor: pointer;
    padding: 8px;
    border-radius: 4px;
}

.app-launcher:hover {
    background-color: var(--hover);
}

.logo-container {
    display: flex;
    align-items: center;
    gap: 8px;
    color: var(--text-primary);
    font-weight: 600;
    font-size: 14px;
}

.logo-container img {
    height: 24px;
    width: 24px;
}

.top-nav-buttons {
    display: flex;
    gap: 4px;
    background: #f3f2f1;
    padding: 2px;
    border-radius: 4px;
    margin-left: 20px;
}

.nav-btn {
    padding: 6px 16px;
    border-radius: 2px;
    font-size: 14px;
    font-weight: 400;
    cursor: pointer;
    transition: background 0.2s;
    color: var(--text-primary);
}

.nav-btn.active {
    background: transparent;
    font-weight: 600;
    border-bottom: 2px solid var(--accent);
    border-radius: 0;
}

.nav-btn:hover:not(.active) {
    background: var(--hover);
}

.search-bar {
    background-color: var(--bg-side);
    border: 1px solid var(--border);
    border-radius: 4px;
    width: 400px;
    height: 32px;
    display: flex;
    align-items: center;
    padding: 0 12px;
    gap: 8px;
    color: var(--text-secondary);
    font-size: 14px;
}

.header-right {
    display: flex;
    align-items: center;
    gap: 20px;
}

.btn-storage {
    background: #ffffff;
    border: 1px solid #d2d0ce;
    padding: 6px 16px;
    border-radius: 2px;
    color: var(--text-primary);
    font-size: 14px;
    font-weight: 400;
    cursor: pointer;
    display: flex;
    align-items: center;
    gap: 8px;
    transition: background 0.2s;
}

.btn-storage:hover {
    background: var(--hover);
}

/* Main Layout */
.main-container {
    display: flex;
    flex: 1;
    overflow: hidden;
}

.sidebar {
    width: 200px;
    background-color: var(--bg-side);
    padding-top: 12px;
    display: flex;
    flex-direction: column;
}

.nav-item {
    display: flex;
    align-items: center;
    padding: 10px 20px;
    gap: 12px;
    font-size: 14px;
    color: var(--text-primary);
    cursor: pointer;
    transition: background 0.2s;
}

.nav-item:hover {
    background-color: var(--hover);
}

.nav-item.active {
    background-color: var(--hover);
    border-left: 3px solid var(--accent);
}

.content-area {
    flex: 1;
    background-color: var(--bg-main);
    display: flex;
    flex-direction: column;
    padding: 24px;
    position: relative;
}

/* File UI Overlay */
.download-msg {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    text-align: center;
}

.file-stack {
    margin-bottom: 24px;
    position: relative;
    width: 120px;
    height: 120px;
    margin: 0 auto 24px;
}

.file-icon {
    width: 80px;
    height: 100px;
    background: #0078d4;
    border-radius: 4px;
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    border: 2px solid #005a9e;
    box-shadow: 0 10px 30px rgba(0,0,0,0.1);
}

.file-icon::before {
    content: '';
    position: absolute;
    top: 0;
    right: 0;
    width: 30px;
    height: 30px;
    background: #ffffff33;
    clip-path: polygon(100% 0, 0 0, 100% 100%);
}

.file-icon-front {
    z-index: 3;
    background: linear-gradient(135deg, #0078d4, #005a9e);
}

.file-icon-mid {
    z-index: 2;
    transform: translate(-40%, -60%) rotate(-5deg);
    opacity: 0.6;
}

.file-icon-back {
    z-index: 1;
    transform: translate(-60%, -40%) rotate(5deg);
    opacity: 0.4;
}

.spinner {
    width: 40px;
    height: 40px;
    border: 3px solid rgba(255, 255, 255, 0.1);
    border-top: 3px solid var(--accent);
    border-radius: 50%;
    margin: 20px auto;
    animation: spin 1s linear infinite;
}

@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}

.status-text {
    font-size: 18px;
    font-weight: 300;
    color: var(--text-secondary);
    margin-top: 20px;
}

.filename {
    color: var(--text-primary);
    font-weight: 600;
    margin-top: 10px;
}

/* Utility */
.hidden {
    display: none;
}

/* Responsive */
@media (max-width: 768px) {
    .sidebar {
        display: none;
    }
    .search-bar {
        width: 150px;
    }
}