:root {
    --primary-color: #4CAF50;
    --primary-dark: #45a049;
    --secondary-color: #2196F3;
    --danger-color: #f44336;
    --danger-dark: #d32f2f;
    --text-color: #333;
    --text-light: #666;
    --text-lighter: #999;
    --bg-color: #f5f5f5;
    --card-bg: #fff;
    --border-color: #ddd;
    --success-bg: #e8f5e9;
    --error-bg: #ffebee;
}

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

body {
    font-family: 'Roboto', sans-serif;
    line-height: 1.6;
    color: var(--text-color);
    background-color: var(--bg-color);
}

a {
    text-decoration: none;
    color: var(--primary-color);
    transition: color 0.3s;
}

a:hover {
    color: var(--primary-dark);
}

img {
    max-width: 100%;
    height: auto;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 20px;
}

/* Header */
header {
    background-color: var(--primary-color);
    color: white;
    padding: 15px 0;
    box-shadow: 0 2px 5px rgba(0,0,0,0.1);
    position: sticky;
    top: 0;
    z-index: 100;
}

header .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    display: flex;
    align-items: center;
    gap: 15px;
    font-size: 24px;
    font-weight: 700;
}

.logo img {
    max-height: 50px;
}

nav ul {
    display: flex;
    list-style: none;
    gap: 20px;
}

nav a {
    color: white;
    font-weight: 500;
    padding: 5px 0;
    position: relative;
}

nav a:hover {
    color: white;
    opacity: 0.8;
}

nav a::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 0;
    height: 2px;
    background-color: white;
    transition: width 0.3s;
}

nav a:hover::after {
    width: 100%;
}

/* Main Content */
.main-content {
    min-height: calc(100vh - 150px);
}

.current-date {
    text-align: center;
    color: var(--text-light);
    margin-bottom: 30px;
    font-size: 18px;
}

/* Price Chart */
.price-chart-container {
    text-align: center;
    margin-bottom: 40px;
    padding: 20px;
    background: var(--card-bg);
    border-radius: 8px;
    box-shadow: 0 0 15px rgba(0,0,0,0.1);
}

.price-chart {
    max-width: 100%;
    border: 1px solid var(--border-color);
    margin: 20px 0;
    border-radius: 4px;
}

/* Categories & Items */
.category-section {
    margin-bottom: 30px;
    padding: 20px;
    background: var(--card-bg);
    border-radius: 8px;