:root {
    /* Theme Colors: Warm Yellow / Light Orange */
    --primary-color: #FFA726; /* Orange 400 */
    --primary-light: #FFCC80; /* Orange 200 */
    --primary-dark: #F57C00; /* Orange 700 */
    
    --secondary-color: #FFECB3; /* Amber 100 */
    --accent-color: #FF7043; /* Deep Orange 400 */
    
    --bg-color: #FFF8E1; /* Main background - very light amber */
    --sidebar-bg: #FFFFFF;
    --card-bg: #FFFFFF;
    
    --text-main: #4E342E; /* Dark Brown for text instead of harsh black */
    --text-secondary: #8D6E63;
    
    --border-color: #FFE0B2;
    
    /* Spacing */
    --spacing-sm: 8px;
    --spacing-md: 16px;
    --spacing-lg: 24px;
    
    /* Border Radius */
    --radius-md: 8px;
    --radius-lg: 16px;
}

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

body {
    font-family: 'Segoe UI', "Microsoft JhengHei", sans-serif;
    background-color: var(--bg-color);
    color: var(--text-main);
    height: 100vh;
    overflow: hidden;
}

/* Layout */
#app {
    display: flex;
    height: 100vh;
}

/* Sidebar */
.sidebar {
    width: 250px;
    background-color: var(--sidebar-bg);
    border-right: 1px solid var(--border-color);
    display: flex;
    flex-direction: column;
    padding: var(--spacing-md);
    box-shadow: 2px 0 5px rgba(0,0,0,0.05);
}

.logo {
    margin-bottom: var(--spacing-lg);
    text-align: center;
}

.logo h2 {
    color: var(--primary-dark);
}

.user-info {
    font-size: 0.9em;
    color: var(--text-secondary);
    margin-top: var(--spacing-sm);
}

#nav-links {
    list-style: none;
}

#nav-links li {
    padding: var(--spacing-md);
    margin-bottom: var(--spacing-sm);
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: background-color 0.2s;
    color: var(--text-main);
    font-weight: 500;
}

#nav-links li:hover {
    background-color: var(--secondary-color);
}

#nav-links li.active {
    background-color: var(--primary-light);
    color: var(--primary-dark);
}

/* Main Content */
.main-content {
    flex: 1;
    display: flex;
    flex-direction: column;
    overflow: hidden;
}

.top-bar {
    height: 60px;
    background-color: var(--card-bg);
    border-bottom: 1px solid var(--border-color);
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0 var(--spacing-lg);
}

#content-area {
    flex: 1;
    padding: var(--spacing-lg);
    overflow-y: auto;
}

/* Buttons */
.btn {
    padding: 8px 16px;
    border: none;
    border-radius: var(--radius-md);
    cursor: pointer;
    font-weight: bold;
    transition: all 0.2s;
}

.btn-primary {
    background-color: var(--primary-color);
    color: white;
}

.btn-primary:hover {
    background-color: var(--primary-dark);
}

.btn-secondary {
    background-color: transparent;
    border: 1px solid var(--primary-dark);
    color: var(--primary-dark);
}

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

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

label {
    display: block;
    margin-bottom: var(--spacing-sm);
    font-weight: bold;
}

input, select, textarea {
    width: 100%;
    padding: 10px;
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    background-color: #FFF;
}

input:focus, select:focus, textarea:focus {
    outline: 2px solid var(--primary-color);
    border-color: transparent;
}

/* Cards & Tables */
.card {
    background-color: var(--card-bg);
    padding: var(--spacing-md);
    border-radius: var(--radius-md);
    box-shadow: 0 2px 4px rgba(0,0,0,0.05);
    margin-bottom: var(--spacing-md);
}

table {
    width: 100%;
    border-collapse: collapse;
    margin-top: var(--spacing-md);
}

th, td {
    padding: 12px;
    text-align: left;
    border-bottom: 1px solid var(--border-color);
}

th {
    background-color: var(--secondary-color);
    color: var(--primary-dark);
}

/* Utilities */
.hidden {
    display: none !important;
}

.view-section {
    display: none;
}

.view-section.active {
    display: block;
    animation: fadeIn 0.3s;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(10px); }
    to { opacity: 1; transform: translateY(0); }
}