:root {
    --primary-color: #4a90e2;
    --secondary-color: #2c3e50;
    --accent-color: #e74c3c;
    --bg-color: #f4f7f6;
    --text-color: #333;
    --white: #ffffff;
    --transition: all 0.3s ease;
}

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

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

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

/* Navbar */
.navbar {
    background: var(--white);
    height: 70px;
    display: flex;
    align-items: center;
    position: sticky;
    top: 0;
    z-index: 1000;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
}

.navbar .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    width: 100%;
}

.logo {
    font-size: 1.5rem;
    font-weight: bold;
    color: var(--primary-color);
    text-decoration: none;
    letter-spacing: 2px;
}

.nav-links {
    display: flex;
    list-style: none;
}

.nav-links li {
    margin-left: 30px;
}

.nav-links a {
    text-decoration: none;
    color: var(--secondary-color);
    font-weight: 500;
    transition: var(--transition);
}

.nav-links a:hover,
.nav-links a.active {
    color: var(--primary-color);
}

/* Hero Section */
.hero {
    background: linear-gradient(135deg, #1a1a1a, #4a0000);
    /* Dán mã màu mới vào đây */
    color: var(--white);
    padding: 100px 0 60px;
    text-align: center;
}


.profile-img-container {
    margin-bottom: 20px;
}

.profile-img {
    width: 180px;
    height: 180px;
    border-radius: 50%;
    border: 5px solid rgba(255, 255, 255, 0.2);
    object-fit: cover;
    transition: transform 0.5s ease;
    box-shadow: 0 0 25px rgba(255, 0, 0, 0.3);
}

.profile-img:hover {
    transform: scale(1.05);
}

.hero h1 {
    font-size: 2.5rem;
    margin-bottom: 10px;
    color: #ffffff;
}

.small-hero {
    padding: 60px 0 40px;
}

.highlight {
    color: #ffce00;
}

.subtitle {
    font-size: 1.2rem;
    color: rgba(255, 255, 255, 0.9);
    margin-bottom: 20px;
}

.social-links a {
    color: #ffffff;
    /* Ép icon sang màu trắng */
    font-size: 1.5rem;
    margin: 0 10px;
    transition: var(--transition);
    opacity: 0.8;
    /* Để hơi mờ một chút */
}

.social-links a:hover {
    color: #ffce00;
    /* Khi di chuột vào vẫn hiện màu vàng kim như cũ */
    opacity: 1;
    /* Hiện rõ lên khi di chuột */
    transform: translateY(-3px);
}


/* Common Sections */
.section-title {
    text-align: center;
    margin: 60px 0 30px;
    font-size: 2rem;
    position: relative;
    padding-bottom: 10px;
}

.section-title::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 50%;
    transform: translateX(-50%);
    width: 60px;
    height: 3px;
    background: var(--primary-color);
}

.card {
    background: var(--white);
    padding: 30px;
    border-radius: 12px;
    box-shadow: 0 5px 15px rgba(0, 0, 0, 0.05);
    margin-bottom: 30px;
}

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

.goal-card {
    background: var(--white);
    padding: 40px 30px;
    border-radius: 12px;
    text-align: center;
    box-shadow: 0 5px 15px rgba(0, 0, 0, 0.05);
    transition: var(--transition);
}

.goal-card:hover {
    transform: translateY(-10px);
    box-shadow: 0 10px 25px rgba(0, 0, 0, 0.1);
}

.goal-card i {
    font-size: 3rem;
    color: var(--primary-color);
    margin-bottom: 20px;
}

.highlight-card ul {
    list-style: none;
}

.highlight-card li {
    margin-bottom: 15px;
    display: flex;
    align-items: center;
}

.highlight-card i {
    color: #27ae60;
    margin-right: 15px;
    font-size: 1.2rem;
}

/* Projects Page */
.projects-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: 30px;
}

.project-card {
    background: var(--white);
    border-radius: 12px;
    overflow: hidden;
    box-shadow: 0 5px 15px rgba(0, 0, 0, 0.05);
    transition: var(--transition);
}

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

.project-header {
    background: var(--secondary-color);
    color: var(--white);
    padding: 20px;
}

.project-body {
    padding: 25px;
}

.project-body h3 {
    margin-bottom: 15px;
}

.project-meta {
    display: block;
    font-size: 0.85rem;
    color: #777;
    margin-bottom: 10px;
}

.project-footer {
    padding: 20px;
    border-top: 1px solid #eee;
    display: flex;
    justify-content: space-between;
}

.btn-link {
    text-decoration: none;
    color: var(--primary-color);
    font-weight: 600;
    display: flex;
    align-items: center;
}

.btn-link i {
    margin-left: 5px;
}

/* Summary Page */
.summary-content {
    max-width: 800px;
    margin: 0 auto;
}

.reflection-item {
    margin-bottom: 40px;
}

.skills-tag-container {
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
    margin-top: 15px;
}

.skill-tag {
    background: var(--primary-color);
    color: var(--white);
    padding: 5px 15px;
    border-radius: 20px;
    font-size: 0.9rem;
}

/* Footer */
.footer {
    text-align: center;
    padding: 40px 0;
    margin-top: 60px;
    background: var(--secondary-color);
    color: var(--white);
}

/* Scroll effects */
.scroll-progress {
    position: fixed;
    top: 0;
    left: 0;
    height: 4px;
    width: 0;
    background: linear-gradient(90deg, var(--primary-color), #ffce00);
    z-index: 2000;
    transition: width 0.12s linear;
}

.back-to-top {
    position: fixed;
    right: 24px;
    bottom: 24px;
    width: 44px;
    height: 44px;
    border: none;
    border-radius: 50%;
    background: var(--primary-color);
    color: #fff;
    font-size: 1rem;
    cursor: pointer;
    opacity: 0;
    visibility: hidden;
    transform: translateY(10px);
    box-shadow: 0 8px 20px rgba(0, 0, 0, 0.25);
    transition: opacity 0.25s ease, transform 0.25s ease, visibility 0.25s ease;
    z-index: 1500;
}

.back-to-top.show {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}

.back-to-top:hover {
    background: #357abd;
}

/* Responsive */
@media (max-width: 768px) {
    .nav-links {
        display: none;
        /* Đơn giản hóa cho bản mẫu */
    }

    .hero h1 {
        font-size: 2rem;
    }

    .back-to-top {
        right: 16px;
        bottom: 16px;
    }
}

/* Nút chuyển đổi */
.theme-btn {
    background: none;
    border: none;
    color: var(--secondary-color);
    cursor: pointer;
    font-size: 1.2rem;
    transition: var(--transition);
}

/* Định nghĩa màu sắc cho chế độ tối */
body.dark-theme {
    --bg-color: #121212;
    --text-color: #e0e0e0;
    --white: #1e1e1e;
    --secondary-color: #ffffff;
}

/* Chỉnh sửa thêm cho các thẻ card trong chế độ tối */
body.dark-theme .card,
body.dark-theme .goal-card,
body.dark-theme .project-card {
    background: #1e1e1e;
    border: 1px solid #333;
    color: #e0e0e0;
}

body.dark-theme .navbar {
    background: #1a1a1a;
}