/* CSS Variables for Theme */
:root {
    --bg-color: #1a1f3a;
    --text-color: #ffffff;
    --card-bg: #2d3561;
    --card-border: #3d4a7a;
    --header-bg: #0f1527;
    --button-bg: #3d4a7a;
    --button-text: #ffffff;
}

/* Light Mode Variables */
body.light-mode {
    --bg-color: #f5f5f5;
    --text-color: #000000;
    --card-bg: #ffffff;
    --card-border: #dddddd;
    --header-bg: #ffffff;
    --button-bg: #007bff;
    --button-text: #ffffff;
}

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

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background-color: var(--bg-color);
    color: var(--text-color);
    transition: background-color 0.3s, color 0.3s;
    height: 100vh;
    overflow: hidden;
}

/* Dashboard Grid Layout */
.dashboard {
    display: grid;
    grid-template-rows: auto 1fr;
    height: 100vh;
}

/* Header */
.header {
    background-color: var(--header-bg);
    padding: 20px 30px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    border-bottom: 1px solid var(--card-border);
}

.header h1 {
    font-size: 28px;
    font-weight: 600;
}

/* Theme Toggle Button */
.theme-toggle {
    background-color: var(--button-bg);
    color: var(--button-text);
    border: none;
    padding: 10px 20px;
    border-radius: 6px;
    cursor: pointer;
    font-size: 16px;
    display: flex;
    align-items: center;
    gap: 8px;
    transition: background-color 0.3s;
}

.theme-toggle:hover {
    opacity: 0.8;
}

/* Main Content Grid */
.main-content {
    display: grid;
    grid-template-columns: 250px 1fr;
    grid-template-rows: 1fr;
    height: 100%;
    gap: 20px;
    padding: 20px;
}

/* Navigation Sidebar */
.navigation {
    background-color: var(--card-bg);
    border: 1px solid var(--card-border);
    border-radius: 8px;
    padding: 30px 20px;
    display: flex;
    flex-direction: column;
    justify-content: flex-start;
}

.navigation h2 {
    font-size: 20px;
    font-weight: 600;
    margin-bottom: 20px;
}

/* Cards Grid */
.cards {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 20px;
    height: fit-content;
}

/* Card Styles */
.card {
    background-color: var(--card-bg);
    border: 1px solid var(--card-border);
    border-radius: 8px;
    padding: 40px 20px;
    display: flex;
    align-items: center;
    justify-content: center;
    min-height: 200px;
    transition: transform 0.3s, box-shadow 0.3s;
}

.card:hover {
    transform: translateY(-5px);
    box-shadow: 0 5px 20px rgba(0, 0, 0, 0.2);
}

.card h3 {
    font-size: 24px;
    font-weight: 600;
    text-align: center;
}

/* Responsive Design - Tablets */
@media (max-width: 768px) {
    .header {
        flex-direction: column;
        gap: 15px;
        text-align: center;
    }

    .main-content {
        grid-template-columns: 1fr;
    }

    .navigation {
        display: none;
    }

    .cards {
        grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    }
}

/* Responsive Design - Mobile */
@media (max-width: 480px) {
    .header h1 {
        font-size: 22px;
    }

    .theme-toggle {
        font-size: 14px;
        padding: 8px 16px;
    }

    .main-content {
        padding: 10px;
        gap: 10px;
    }

    .cards {
        grid-template-columns: 1fr;
        gap: 10px;
    }

    .card {
        padding: 30px 15px;
        min-height: 150px;
    }

    .card h3 {
        font-size: 20px;
    }
}