:root {
    --bg-color: #ffffff;
    --text-color: #1a1a1a;
    --secondary-text: #555555;
    --accent-color: #000000;
    --border-color: #eaeaea;
    --sidebar-width: 250px;
    --hover-bg: #f8f9fa;
}

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

html {
    scroll-behavior: smooth; 
}

/* Áp dụng font Inter cho phần thân văn bản */
body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    line-height: 1.6;
    color: var(--text-color);
    background-color: var(--bg-color);
}

/* Áp dụng font Poppins cho các tiêu đề chính */
h1, h2, h3, .sidebar-title, .tab-btn {
    font-family: 'Poppins', sans-serif;
}

.layout {
    display: flex;
    max-width: 1050px;
    margin: 0 auto;
    min-height: 100vh;
}

.sidebar {
    width: var(--sidebar-width);
    padding: 50px 20px 40px 0;
    border-right: 1px solid var(--border-color);
    position: sticky;
    top: 0;
    height: 100vh;
    overflow-y: auto;
}

.sidebar-title {
    font-size: 1.05rem;
    color: var(--text-color);
    text-transform: uppercase;
    letter-spacing: 1.2px;
    margin-bottom: 25px;
    padding-left: 15px;
}

.toc {
    display: flex;
    flex-direction: column;
}

.toc a {
    text-decoration: none;
    color: var(--secondary-text);
    padding: 10px 15px;
    border-radius: 6px;
    transition: all 0.2s ease;
    font-size: 0.95rem;
    font-weight: 500;
}

.toc a:hover {
    background-color: var(--hover-bg);
    color: var(--text-color);
    transform: translateX(4px);
}

.main-content {
    flex: 1;
    padding: 50px 0 40px 60px;
    max-width: 750px;
    min-width: 0;
}

.top-bar {
    display: flex;
    justify-content: flex-end;
    align-items: center;
    gap: 20px;
    font-size: 0.85rem;
    color: var(--secondary-text);
    margin-bottom: 40px;
    padding-bottom: 15px;
    border-bottom: 1px solid var(--border-color);
}

.stat-item {
    display: flex;
    align-items: center;
    gap: 6px;
}

.visitor-badge {
    height: 20px;
    margin-left: 5px;
}

header {
    margin-bottom: 40px;
}

h1 {
    font-size: 2.8rem;
    font-weight: 700;
    margin-bottom: 8px;
    letter-spacing: -1px;
    color: var(--text-color);
}

.subtitle {
    font-size: 1.2rem;
    color: var(--secondary-text);
    margin-bottom: 8px;
    font-weight: 500;
}

.location {
    color: var(--secondary-text);
    font-size: 0.95rem;
    margin-bottom: 22px;
}

/* Định dạng màu sắc cho Icons */
.social-links {
    display: flex;
    gap: 20px;
    align-items: center;
    flex-wrap: wrap;
}

.social-links a {
    font-size: 1.6rem;
    transition: all 0.2s ease;
    text-decoration: none;
    display: inline-flex;
    align-items: center;
}

.email-link {
    color: #EA4335;
    font-size: 0.98rem !important;
    font-weight: 600;
    letter-spacing: 0.1px;
    gap: 8px;
}

.icon-linkedin { color: #0A66C2 !important; }
.icon-github { color: #24292e !important; }
.icon-hf { color: #FFD21E !important; }

.icon-hf img {
    width: 24px;
    height: 24px;
    display: block;
}

.social-links a:hover {
    opacity: 0.8;
    transform: translateY(-3px);
}

.ext-link {
    color: var(--text-color);
    text-decoration: none;
    border-bottom: 1px solid transparent;
    display: inline-flex;
    align-items: center;
    gap: 7px;
    transition: color 0.2s ease, border-color 0.2s ease;
}

.ext-link:hover {
    color: #0a66c2;
    border-color: #0a66c2;
}

.link-indicator {
    font-size: 0.72em;
    opacity: 0.75;
    transform: translateY(-1px);
}

.ext-link:hover .link-indicator,
.email-link:hover .link-indicator {
    opacity: 1;
}

.tabs {
    display: flex;
    border-bottom: 2px solid var(--border-color);
    margin-bottom: 35px;
}

.tab-btn {
    background: none;
    border: none;
    padding: 12px 25px;
    font-size: 1.1rem;
    cursor: pointer;
    color: var(--secondary-text);
    position: relative;
    top: 2px;
    transition: color 0.2s;
}

.tab-btn:hover {
    color: var(--text-color);
}

.tab-btn.active {
    color: var(--text-color);
    border-bottom: 2px solid var(--text-color);
}

.tab-content {
    display: none;
    animation: fadeIn 0.4s ease;
}

.tab-content.active-tab {
    display: block;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(8px); }
    to { opacity: 1; transform: translateY(0); }
}

section {
    margin-bottom: 45px;
    padding-top: 15px; 
}

h2 {
    font-size: 1.4rem;
    margin-bottom: 25px;
    border-bottom: 1px dashed var(--border-color);
    padding-bottom: 10px;
    color: var(--text-color);
}

.item {
    margin-bottom: 28px;
}

.item-header {
    display: flex;
    justify-content: space-between;
    align-items: baseline;
    margin-bottom: 10px;
}

.item-title {
    font-weight: 600;
    font-size: 1.05rem;
}

.item-meta {
    color: var(--secondary-text);
    font-size: 0.9rem;
    white-space: nowrap;
}

ul {
    list-style-type: disc;
    margin-left: 20px;
    color: var(--secondary-text);
}

li {
    margin-bottom: 8px;
}

p {
    color: var(--secondary-text);
}

.skills-grid {
    display: grid;
    grid-template-columns: 180px 1fr;
    gap: 10px;
    margin-bottom: 15px;
    color: var(--secondary-text);
}

.skill-category {
    font-weight: 600;
    color: var(--text-color);
}

footer {
    margin-top: 70px;
    padding-top: 25px;
    border-top: 1px solid var(--border-color);
    text-align: center;
    color: var(--secondary-text);
    font-size: 0.9rem;
}

.go-top-btn {
    position: fixed;
    right: 14px;
    bottom: 16px;
    width: 42px;
    height: 42px;
    border: none;
    border-radius: 999px;
    background: #1a1a1a;
    color: #ffffff;
    box-shadow: 0 8px 20px rgba(0, 0, 0, 0.22);
    display: none;
    align-items: center;
    justify-content: center;
    font-size: 0.95rem;
    cursor: pointer;
    z-index: 40;
}

.go-top-btn.show {
    display: inline-flex;
}

.go-top-btn:hover {
    background: #333333;
}

@media (max-width: 1100px) {
    .sidebar {
        display: none;
    }
    .main-content {
        max-width: 900px;
        margin: 0 auto;
        padding: 40px 22px;
    }
}

@media (max-width: 850px) {
    .layout {
        flex-direction: column;
    }
    .main-content {
        padding: 30px 20px;
        max-width: 100%;
    }
    .item-header {
        flex-direction: column;
        gap: 4px;
    }
    .skills-grid {
        grid-template-columns: 1fr;
        gap: 4px;
        margin-bottom: 18px;
    }
    .top-bar {
        flex-direction: column;
        align-items: flex-start;
        gap: 10px;
    }
    h1 {
        font-size: 2.2rem;
    }
    .subtitle {
        font-size: 1.08rem;
    }
    .social-links {
        gap: 14px;
    }
    .email-link {
        font-size: 0.9rem !important;
    }
}

@media (min-width: 851px) {
    .go-top-btn {
        display: none !important;
    }
}

@media (max-width: 480px) {
    .main-content {
        padding: 24px 14px;
    }
    .tabs {
        overflow-x: auto;
        scrollbar-width: thin;
    }
    .tab-btn {
        padding: 10px 18px;
        font-size: 1rem;
        white-space: nowrap;
    }
    h2 {
        font-size: 1.25rem;
    }
}