/* 1. CSS Variables for Themes */
:root {
    --bg-color: #f4f4f4;
    --text-color: #333;
    --nav-bg: #1a2a3a; /* Deep blue/slate */
    --card-bg: #ffffff;
    --primary-blue: #007bff;
    --transition-speed: 0.3s;
}

/* 2. Dark Mode Overrides */
[data-theme="dark"] {
    --bg-color: #121212;
    --text-color: #e0e0e0;
    --card-bg: #1e1e1e;
    --nav-bg: #000000;
}

/* 3. Global Styles */
* { box-sizing: border-box; margin: 0; padding: 0; font-family: 'Segoe UI', Arial, sans-serif; }

body { 
    background-color: var(--bg-color); 
    color: var(--text-color);
    line-height: 1.6; 
    transition: background var(--transition-speed), color var(--transition-speed);
}

/* 4. Navigation */
nav {
    background: var(--nav-bg); color: white; padding: 1rem 2rem;
    display: flex; justify-content: space-between; align-items: center;
    position: sticky; top: 0; z-index: 1000;
}
nav ul { display: flex; list-style: none; gap: 20px; align-items: center; }
nav a { color: white; text-decoration: none; font-weight: bold; transition: 0.2s; }
nav a:hover { color: var(--primary-blue); }

/* Theme Button Styling */
#theme-toggle {
    background: #444; color: white; border: none; padding: 5px 10px; 
    border-radius: 5px; cursor: pointer; font-size: 0.8rem;
}

/* 5. Sections & Cards */
section { padding: 4rem 2rem; text-align: center; }
.container { max-width: 900px; margin: 0 auto; }

.project-grid {
    display: grid;
    grid-template-columns: 1fr;
    gap: 20px;
    margin-top: 20px;
}

/* Animation: Modern Card Hover */
.card {
    background: var(--card-bg); padding: 25px; border-radius: 12px;
    box-shadow: 0 4px 6px rgba(0,0,0,0.1);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
    border: 1px solid rgba(0,0,0,0.05);
}

.card:hover {
    transform: translateY(-8px); /* Animation slide-up */
    box-shadow: 0 10px 20px rgba(0,123,255,0.2);
    border-color: var(--primary-blue);
}

/* 6. Form Styling */
form { max-width: 400px; margin: 0 auto; display: flex; flex-direction: column; gap: 15px; }
input, textarea { 
    padding: 12px; border: 1px solid #ccc; border-radius: 8px; 
    background: var(--card-bg); color: var(--text-color);
}
button[type="submit"] { 
    padding: 12px; background: var(--primary-blue); color: white; 
    border: none; border-radius: 8px; cursor: pointer; font-weight: bold;
    transition: 0.3s;
}
button[type="submit"]:hover { background: #0056b3; transform: scale(1.02); }

/* Feedback message styling */
#form-feedback { margin-top: 15px; font-weight: bold; }

/* Desktop Media Query */
@media (min-width: 768px) {
    .project-grid { grid-template-columns: 1fr 1fr; }
}