:root {
    --primary-color: #28a745;
    --secondary-color: #343a40;
    --background-color: #f4f7f6;
    --text-color: #333;
    --card-background: #FFFFFF;
    --light-gray: #e9ecef;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    line-height: 1.7;
    margin: 0;
    padding: 0;
    background-color: var(--background-color);
    color: var(--text-color);
}

.container {
    width: 90%;
    max-width: 1200px;
    margin: 20px auto;
}

header {
    background-color: var(--card-background);
    box-shadow: 0 2px 5px rgba(0,0,0,0.08);
    position: sticky;
    top: 0;
    z-index: 1000;
}

.logo img{
    display: block;
    width: 60px;
    height: auto;
}

.logo {
    font-size: 1.8em;
    font-weight: 700;
    color: var(--primary-color);
}

nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
    width: 90%;
    max-width: 1200px;
    margin: auto;
    padding: 15px 0;
}


nav ul { list-style: none; display: flex; margin: 0; padding: 0; }
nav ul li { margin-left: 30px; }
nav ul li a { color: var(--secondary-color); text-decoration: none; font-weight: 500; transition: color 0.3s ease; }
nav ul li a:hover { color: var(--primary-color); }
em {
    color: #3d06d3;
}

/* ---- KHUNG AVATAR ---- */
.avatar { background-color: var(--card-background); text-align: center; padding: 80px 20px; }
.profile-picture { width: 150px; height: 150px; border-radius: 50%; border: 5px solid var(--primary-color); object-fit: cover; margin-bottom: 20px; }
.avatar h1 { font-size: 3em; margin-bottom: 10px; color: var(--secondary-color); }
.avatar h1 strong { color: var(--primary-color); }
.subtitle { font-size: 1.3em; color: #6c757d; max-width: 600px; margin: 0 auto 30px; }
.social-links a { color: var(--secondary-color); font-size: 1.8em; margin: 0 15px; transition: color 0.3s ease, transform 0.3s ease; }
.social-links a:hover { color: var(--primary-color); transform: translateY(-5px); }

/* ---- CÁC PHẦN CHUNG ---- */
.section { padding: 70px 0; border-bottom: 1px solid var(--light-gray); }
.section h2 { text-align: center; font-size: 2.5em; color: var(--secondary-color); margin-bottom: 50px; position: relative; }
.section h2::after { content: ''; width: 280px; height: 6px; background: var(--primary-color); position: absolute; bottom: -15px; left: 50%; transform: translateX(-50%); border-radius: 2px; }
.section h2 i { margin-right: 10px; }

/* ---- LƯỚI DỰ ÁN ---- */
.projects-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(340px, 1fr)); gap: 30px; }
.project-card { background: var(--card-background); border-radius: 10px; overflow: hidden; box-shadow: 0 5px 15px rgba(0,0,0,0.07); display: flex; flex-direction: column; }
.project-card:hover { transform: translateY(-10px); box-shadow: 0 10px 20px rgba(0,0,0,0.1); transition: transform 0.3s ease, box-shadow 0.3s ease; }
.project-card img { width: 100%; height: 220px; object-fit: cover; }
.project-info { padding: 25px; flex-grow: 1; display: flex; flex-direction: column; }
.project-info h3 { margin-top: 0; color: var(--primary-color); }
.project-info ul, .project-info ol { padding-left: 20px; }
.project-link { display: inline-block; margin-top: auto; color: var(--primary-color); text-decoration: none; font-weight: bold; }
.caption { font-size: 0.9em; font-style: italic; color: #6c757d; display: block; margin-top: 15px; }

/* ---- BẢNG ---- */
table { width: 100%; border-collapse: collapse; margin-top: 15px; }
th, td { padding: 10px; text-align: left; border: 1px solid var(--light-gray); }
thead { background-color: #e9ecef; font-weight: bold; }
tbody tr:nth-child(even) { background-color: #f8f9fa; }

/* ---- FORM LIÊN HỆ ---- */
.contact-form { max-width: 700px; margin: auto; display: flex; flex-direction: column; gap: 20px; }
.contact-form input, .contact-form textarea { padding: 15px; border: 1px solid #ccc; border-radius: 5px; font-size: 1em; }
.contact-form button { padding: 15px; border: none; border-radius: 5px; background-color: var(--primary-color); color: #fff; font-size: 1.1em; font-weight: bold; cursor: pointer; transition: background-color 0.3s ease; }
.contact-form button:hover { background-color: #218838; }
.center-text {
    text-align: center;
}

/* ---- CHÂN TRANG ---- */
footer { text-align: center; padding: 20px; background-color: var(--secondary-color); color: #fff; }