:root {
    --primary-color: #2c3e50;
    --accent-color: #e67e22;
    --text-color: #333;
    --bg-color: #f4f7f6;
    --card-bg: #ffffff;
    --sidebar-width: 260px;
    --header-height: 70px;
    --transition-speed: 0.3s;
    --shadow: 0 4px 6px rgba(0,0,0,0.1);
    --hover-shadow: 0 10px 15px rgba(0,0,0,0.1);
}

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

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background-color: var(--bg-color);
    color: var(--text-color);
    line-height: 1.6;
    display: flex;
    min-height: 100vh;
}

/* Sidebar */
.sidebar {
    width: var(--sidebar-width);
    background-color: var(--primary-color);
    color: white;
    position: fixed;
    height: 100%;
    overflow-y: auto;
    transition: transform var(--transition-speed);
    z-index: 1000;
}

.sidebar-header {
    padding: 20px;
    font-size: 1.5rem;
    font-weight: bold;
    text-align: center;
    border-bottom: 1px solid rgba(255,255,255,0.1);
}

.nav-links {
    list-style: none;
    padding: 20px 0;
}

.nav-links li a {
    display: block;
    padding: 15px 25px;
    color: rgba(255,255,255,0.8);
    text-decoration: none;
    transition: all var(--transition-speed);
    border-left: 4px solid transparent;
}

.nav-links li a:hover, .nav-links li a.active {
    background-color: rgba(255,255,255,0.1);
    color: white;
    border-left-color: var(--accent-color);
}

.nav-links .group-title {
    padding: 10px 25px;
    color: rgba(255,255,255,0.4);
    font-size: 0.8rem;
    text-transform: uppercase;
    letter-spacing: 1px;
    margin-top: 10px;
}

/* Main Content */
.main-content {
    flex: 1;
    margin-left: var(--sidebar-width);
    padding: 20px;
}

.header {
    background: var(--card-bg);
    height: var(--header-height);
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0 30px;
    box-shadow: var(--shadow);
    border-radius: 10px;
    margin-bottom: 30px;
}

.page-title {
    font-size: 1.5rem;
    font-weight: 600;
    color: var(--primary-color);
}

.btn {
    display: inline-block;
    padding: 10px 20px;
    border-radius: 5px;
    text-decoration: none;
    font-weight: 500;
    cursor: pointer;
    border: none;
    transition: background var(--transition-speed);
}

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

.btn-primary:hover {
    background-color: #34495e;
}

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

.btn-accent:hover {
    background-color: #d35400;
}

.btn-danger {
    background-color: #e74c3c;
    color: white;
}

.btn-sm {
    padding: 5px 10px;
    font-size: 0.85rem;
}

/* Cards & Grid */
.grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 20px;
}

.card {
    background: var(--card-bg);
    border-radius: 10px;
    box-shadow: var(--shadow);
    padding: 20px;
    transition: transform var(--transition-speed), box-shadow var(--transition-speed);
}

.card:hover {
    transform: translateY(-5px);
    box-shadow: var(--hover-shadow);
}

.card img {
    width: 100%;
    height: 200px;
    object-fit: cover;
    border-radius: 5px;
    margin-bottom: 15px;
}

.card h3 {
    font-size: 1.2rem;
    margin-bottom: 10px;
}

/* Forms */
.form-group {
    margin-bottom: 20px;
}

.form-group label {
    display: block;
    margin-bottom: 8px;
    font-weight: 500;
}

.form-control {
    width: 100%;
    padding: 12px;
    border: 1px solid #ddd;
    border-radius: 5px;
    font-size: 1rem;
    transition: border-color var(--transition-speed);
}

.form-control:focus {
    outline: none;
    border-color: var(--accent-color);
}

textarea.form-control {
    min-height: 100px;
    resize: vertical;
}

/* Tables */
.table-container {
    background: var(--card-bg);
    border-radius: 10px;
    box-shadow: var(--shadow);
    overflow: hidden;
}

table {
    width: 100%;
    border-collapse: collapse;
}

th, td {
    padding: 15px 20px;
    text-align: left;
    border-bottom: 1px solid #eee;
}

th {
    background-color: #f8f9fa;
    font-weight: 600;
}

tr:last-child td {
    border-bottom: none;
}

.actions {
    display: flex;
    gap: 10px;
}

/* Image select grid */
.image-select-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(100px, 1fr));
    gap: 10px;
    margin-top: 10px;
}

.image-option {
    position: relative;
    cursor: pointer;
    border: 2px solid transparent;
    border-radius: 5px;
    overflow: hidden;
}

.image-option.selected {
    border-color: var(--accent-color);
}

.image-option img {
    width: 100%;
    height: 100px;
    object-fit: cover;
    display: block;
}

.image-option input[type="checkbox"] {
    position: absolute;
    top: 5px;
    right: 5px;
}