:root {
    --primary-color: #2c3e50;
    --secondary-color: #3498db;
    --accent-color: #e74c3c;
    --bg-color: #f4f4f4;
    --card-bg: #ffffff;
    --text-color: #333;
}

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

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

.container {
    max-width: 1100px;
    margin: 0 auto;
    padding: 0 20px;
}

header {
    background-color: var(--primary-color);
    color: white;
    padding: 2rem 0;
    text-align: center;
    margin-bottom: 2rem;
}

header h1 {
    font-size: 2.5rem;
    margin-bottom: 0.5rem;
}

section {
    margin-bottom: 3rem;
}

h2 {
    color: var(--primary-color);
    border-bottom: 2px solid var(--secondary-color);
    padding-bottom: 0.5rem;
    margin-bottom: 1.5rem;
    display: inline-block;
}

/* Tip Section */
#tip-section {
    background-color: var(--card-bg);
    padding: 1.5rem;
    border-radius: 8px;
    box-shadow: 0 2px 5px rgba(0,0,0,0.1);
    border-left: 5px solid var(--accent-color);
}

#new-tip-btn {
    background-color: var(--secondary-color);
    color: white;
    border: none;
    padding: 8px 16px;
    border-radius: 4px;
    cursor: pointer;
    margin-top: 1rem;
    transition: background 0.3s;
}

#new-tip-btn:hover {
    background-color: #2980b9;
}

/* Filter Controls */
.filter-controls {
    margin-bottom: 1.5rem;
    display: flex;
    gap: 10px;
    flex-wrap: wrap;
}

.filter-btn {
    background: transparent;
    border: 2px solid var(--secondary-color);
    color: var(--secondary-color);
    padding: 6px 12px;
    border-radius: 20px;
    cursor: pointer;
    font-weight: bold;
    transition: all 0.3s;
}

.filter-btn:hover, .filter-btn.active {
    background-color: var(--secondary-color);
    color: white;
}

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

.card {
    background-color: var(--card-bg);
    padding: 1.5rem;
    border-radius: 8px;
    box-shadow: 0 2px 5px rgba(0,0,0,0.1);
    transition: transform 0.2s;
    display: flex;
    flex-direction: column;
}

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

.card h3 {
    margin-bottom: 0.5rem;
    color: var(--primary-color);
}

.card p {
    flex-grow: 1;
    margin-bottom: 1rem;
    color: #666;
}

.card a {
    display: inline-block;
    text-decoration: none;
    color: var(--secondary-color);
    font-weight: bold;
}

.card a:hover {
    text-decoration: underline;
}

footer {
    text-align: center;
    padding: 2rem 0;
    margin-top: 2rem;
    color: #777;
    border-top: 1px solid #ddd;
}

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

@media (max-width: 600px) {
    header h1 {
        font-size: 2rem;
    }
    
    .resource-grid {
        grid-template-columns: 1fr;
    }
}