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

:root {
    --bg-sidebar: #f7f7f8;
    --bg-main: #eeeef0;
    --bg-card: #f7f7f8;
    --bg-hero: #f2f2f4;
    --text-primary: #1a1a1a;
    --text-secondary: #555555;
    --text-muted: #888888;
    --border-color: #dcdce0;
    --border-subtle: #e6e6ea;
    --accent: #1a1a1a;
    --nav-hover: #eaeaee;
    --nav-active-bg: #e2e2e6;
    --nav-active-text: #1a1a1a;
    --shadow-sm: 0 1px 3px rgba(0,0,0,0.05);
    --shadow-md: 0 4px 16px rgba(0,0,0,0.07);
    --shadow-lg: 0 8px 32px rgba(0,0,0,0.09);
    --profile-border: #d0d0d4;
    --toggle-bg: #e4e4e8;
    --toggle-hover: #d8d8dc;
    --transition: 0.3s ease;
    --skill-bg: #f0f0f3;
    --skill-border: #dcdce0;
    --tag-color: #999999;
    --repo-desc: #777777;
    --repo-btn-bg: #1a1a1a;
    --repo-btn-text: #ffffff;
}

[data-theme="dark"] {
    --bg-sidebar: #111111;
    --bg-main: #0a0a0a;
    --bg-card: #161616;
    --bg-hero: #111111;
    --text-primary: #f0f0f0;
    --text-secondary: #a0a0a0;
    --text-muted: #666666;
    --border-color: #222222;
    --border-subtle: #1a1a1a;
    --accent: #ffffff;
    --nav-hover: #1a1a1a;
    --nav-active-bg: #1e1e1e;
    --nav-active-text: #ffffff;
    --shadow-sm: 0 1px 3px rgba(0,0,0,0.2);
    --shadow-md: 0 4px 16px rgba(0,0,0,0.3);
    --shadow-lg: 0 8px 32px rgba(0,0,0,0.4);
    --profile-border: #333333;
    --toggle-bg: #1e1e1e;
    --toggle-hover: #2a2a2a;
    --skill-bg: #161616;
    --skill-border: #252525;
    --tag-color: #666666;
    --repo-desc: #777777;
    --repo-btn-bg: #f0f0f0;
    --repo-btn-text: #111111;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: 'Inter', sans-serif;
    background-color: var(--bg-main);
    color: var(--text-primary);
    line-height: 1.6;
    overflow-x: hidden;
    transition: background-color var(--transition), color var(--transition);
}

::-webkit-scrollbar { width: 5px; }
::-webkit-scrollbar-track { background: var(--bg-main); }
::-webkit-scrollbar-thumb { background: var(--border-color); border-radius: 4px; }

#sidebar {
    position: fixed;
    top: 0;
    left: 0;
    width: 260px;
    height: 100vh;
    background: var(--bg-sidebar);
    border-right: 1px solid var(--border-color);
    display: flex;
    flex-direction: column;
    z-index: 100;
    transition: background var(--transition), border-color var(--transition), transform 0.35s ease;
}

.sidebar-top {
    padding: 36px 24px 24px;
    text-align: center;
    border-bottom: 1px solid var(--border-subtle);
}

.sidebar-profile {
    width: 90px;
    height: 90px;
    margin: 0 auto 16px;
    border-radius: 50%;
    overflow: hidden;
    border: 3px solid var(--profile-border);
    transition: border-color var(--transition), transform 0.3s ease;
}

.sidebar-profile:hover {
    transform: scale(1.05);
    border-color: var(--text-muted);
}

.sidebar-profile img {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.sidebar-name {
    font-size: 1.15rem;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: 4px;
    letter-spacing: -0.3px;
    transition: color var(--transition);
}

.sidebar-title {
    font-size: 0.78rem;
    color: var(--text-muted);
    font-weight: 400;
    letter-spacing: 0.3px;
    text-transform: uppercase;
    transition: color var(--transition);
}

.sidebar-nav {
    flex: 1;
    padding: 20px 12px;
    display: flex;
    flex-direction: column;
    gap: 4px;
    overflow-y: auto;
}

.nav-link {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 11px 16px;
    border-radius: 10px;
    text-decoration: none;
    color: var(--text-secondary);
    font-size: 0.88rem;
    font-weight: 500;
    transition: all 0.2s ease;
}

.nav-link svg { flex-shrink: 0; opacity: 0.6; transition: opacity 0.2s; }
.nav-link:hover { background: var(--nav-hover); color: var(--text-primary); }
.nav-link:hover svg { opacity: 1; }
.nav-link.active { background: var(--nav-active-bg); color: var(--nav-active-text); font-weight: 600; }
.nav-link.active svg { opacity: 1; }

.sidebar-bottom {
    padding: 16px 12px;
    border-top: 1px solid var(--border-subtle);
}

.theme-toggle {
    display: flex;
    align-items: center;
    gap: 10px;
    width: 100%;
    padding: 10px 16px;
    border-radius: 10px;
    border: none;
    background: var(--toggle-bg);
    color: var(--text-secondary);
    font-family: 'Inter', sans-serif;
    font-size: 0.85rem;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.2s ease;
}

.theme-toggle:hover { background: var(--toggle-hover); color: var(--text-primary); }

.icon-moon { display: none; }
[data-theme="dark"] .icon-sun { display: none; }
[data-theme="dark"] .icon-moon { display: block; }

#mobileHeader {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 56px;
    background: var(--bg-sidebar);
    border-bottom: 1px solid var(--border-color);
    z-index: 200;
    padding: 0 16px;
    align-items: center;
    justify-content: space-between;
    transition: background var(--transition), border-color var(--transition);
}

.mobile-logo {
    font-size: 1.1rem;
    font-weight: 700;
    color: var(--text-primary);
    letter-spacing: -0.3px;
}

.mobile-actions { display: flex; align-items: center; gap: 8px; }

.theme-toggle-mobile {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 36px;
    height: 36px;
    border-radius: 8px;
    border: none;
    background: var(--toggle-bg);
    color: var(--text-secondary);
    cursor: pointer;
    transition: all 0.2s ease;
}

.theme-toggle-mobile:hover { background: var(--toggle-hover); }

.menu-toggle {
    display: flex;
    flex-direction: column;
    justify-content: center;
    gap: 5px;
    width: 36px;
    height: 36px;
    border-radius: 8px;
    border: none;
    background: var(--toggle-bg);
    cursor: pointer;
    padding: 8px;
    transition: background 0.2s;
}

.menu-toggle:hover { background: var(--toggle-hover); }

.menu-toggle span {
    width: 100%;
    height: 2px;
    background: var(--text-primary);
    border-radius: 2px;
    transition: transform 0.3s, opacity 0.3s;
}

.menu-toggle.active span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
.menu-toggle.active span:nth-child(2) { opacity: 0; }
.menu-toggle.active span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }

.mobile-overlay {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.4);
    z-index: 90;
    opacity: 0;
    transition: opacity 0.3s;
}

.mobile-overlay.show { opacity: 1; }

#mainContent {
    margin-left: 260px;
    min-height: 100vh;
    transition: margin-left 0.35s ease;
}

#hero {
    min-height: 100vh;
    display: flex;
    align-items: center;
    background: var(--bg-hero);
    padding: 60px 48px;
    transition: background var(--transition);
}

.hero-inner {
    max-width: 900px;
    width: 100%;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 48px;
}

.hero-text { flex: 1; }

.hero-greeting {
    display: inline-block;
    font-size: 0.9rem;
    font-weight: 500;
    color: var(--text-muted);
    margin-bottom: 12px;
    letter-spacing: 0.5px;
    text-transform: uppercase;
    opacity: 0;
    transform: translateY(16px);
    animation: fadeUp 0.6s ease forwards 0.2s;
}

#hero h1 {
    font-size: 3.5rem;
    font-weight: 800;
    color: var(--text-primary);
    letter-spacing: -2px;
    line-height: 1.1;
    margin-bottom: 16px;
    opacity: 0;
    transform: translateY(20px);
    animation: fadeUp 0.6s ease forwards 0.35s;
    transition: color var(--transition);
}

.hero-desc {
    font-size: 1.15rem;
    color: var(--text-secondary);
    font-weight: 400;
    max-width: 480px;
    line-height: 1.7;
    opacity: 0;
    transform: translateY(16px);
    animation: fadeUp 0.6s ease forwards 0.5s;
    transition: color var(--transition);
}

.hero-avatar {
    width: 200px;
    height: 200px;
    border-radius: 50%;
    overflow: hidden;
    border: 4px solid var(--border-color);
    flex-shrink: 0;
    opacity: 0;
    transform: scale(0.9);
    animation: fadeScale 0.7s ease forwards 0.4s;
    transition: border-color var(--transition), transform 0.3s ease;
}

.hero-avatar:hover {
    transform: scale(1.04);
    border-color: var(--text-muted);
}

.hero-avatar img {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

@keyframes fadeScale {
    to { opacity: 1; transform: scale(1); }
}

section:not(#hero) {
    padding: 80px 48px;
    transition: background var(--transition);
}

#skills { background: var(--bg-main); }
#repos { background: var(--bg-hero); }
#certificates { background: var(--bg-main); }
#contact { background: var(--bg-hero); }

.section-container { max-width: 700px; }
.section-wide { max-width: 900px; }
.section-header { margin-bottom: 36px; }

.section-tag {
    display: block;
    font-size: 0.72rem;
    font-weight: 600;
    letter-spacing: 2px;
    color: var(--tag-color);
    margin-bottom: 8px;
    transition: color var(--transition);
}

.section-header h2 {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--text-primary);
    letter-spacing: -0.5px;
    margin-bottom: 10px;
    transition: color var(--transition);
}

.header-line {
    width: 40px;
    height: 3px;
    background: var(--accent);
    border-radius: 2px;
    transition: background var(--transition);
}

.skills-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(130px, 1fr));
    gap: 16px;
}

.skill-card {
    background: var(--skill-bg);
    border: 1px solid var(--skill-border);
    border-radius: 14px;
    padding: 24px 16px;
    text-align: center;
    transition: transform 0.3s ease, box-shadow 0.3s ease, background var(--transition), border-color var(--transition);
}

.skill-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-md);
}

.skill-icon {
    margin-bottom: 12px;
}

.skill-icon svg {
    display: block;
    margin: 0 auto;
}

.skill-name {
    font-size: 0.82rem;
    font-weight: 600;
    color: var(--text-primary);
    transition: color var(--transition);
}

.repos-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
    gap: 16px;
}

.repo-card {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: 14px;
    padding: 22px 24px;
    display: flex;
    flex-direction: column;
    gap: 12px;
    transition: transform 0.3s ease, box-shadow 0.3s ease, background var(--transition), border-color var(--transition);
}

.repo-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
}

.repo-name {
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 0.95rem;
    font-weight: 700;
    color: var(--text-primary);
    transition: color var(--transition);
}

.repo-name svg {
    flex-shrink: 0;
    opacity: 0.5;
    color: var(--text-secondary);
}

.repo-desc {
    font-size: 0.82rem;
    color: var(--repo-desc);
    line-height: 1.6;
    flex: 1;
    transition: color var(--transition);
}

.repo-link {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    font-size: 0.78rem;
    font-weight: 600;
    color: var(--repo-btn-text);
    background: var(--repo-btn-bg);
    padding: 7px 14px;
    border-radius: 8px;
    text-decoration: none;
    align-self: flex-start;
    transition: opacity 0.2s, background var(--transition), color var(--transition);
}

.repo-link:hover { opacity: 0.8; }
.repo-link svg { flex-shrink: 0; }

.repos-loading {
    grid-column: 1 / -1;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 12px;
    padding: 48px 0;
    color: var(--text-muted);
    font-size: 0.88rem;
}

.spinner {
    width: 20px;
    height: 20px;
    border: 2px solid var(--border-color);
    border-top-color: var(--text-primary);
    border-radius: 50%;
    animation: spin 0.7s linear infinite;
}

@keyframes spin { to { transform: rotate(360deg); } }

.cert-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 20px;
}

.cert-card {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: 14px;
    overflow: hidden;
    transition: transform 0.3s ease, box-shadow 0.3s ease, background var(--transition), border-color var(--transition);
}

.cert-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
}

.cert-img-wrap {
    overflow: hidden;
    border-bottom: 1px solid var(--border-color);
}

.cert-img-wrap img {
    width: 100%;
    display: block;
    transition: transform 0.4s ease;
}

.cert-card:hover .cert-img-wrap img { transform: scale(1.03); }

.cert-info { padding: 16px 20px; }

.cert-info h3 {
    font-size: 0.92rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 4px;
    transition: color var(--transition);
}

.cert-date {
    font-size: 0.78rem;
    color: var(--text-muted);
    font-weight: 400;
    transition: color var(--transition);
}

.contact-buttons {
    display: flex;
    gap: 14px;
    flex-wrap: wrap;
}

.contact-btn {
    display: inline-flex;
    align-items: center;
    gap: 10px;
    padding: 14px 28px;
    border-radius: 12px;
    text-decoration: none;
    font-size: 0.92rem;
    font-weight: 600;
    color: #ffffff;
    transition: transform 0.2s ease, box-shadow 0.2s ease, opacity 0.2s;
}

.contact-btn:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.contact-btn:active { transform: translateY(0); }

.discord-btn { background: #5865F2; }
.github-btn { background: #333333; }
[data-theme="dark"] .github-btn { background: #f0f0f0; color: #111111; }

.contact-btn svg { flex-shrink: 0; }

#footer {
    padding: 28px 48px;
    border-top: 1px solid var(--border-subtle);
    background: var(--bg-main);
    transition: background var(--transition), border-color var(--transition);
}

#footer p {
    font-size: 0.8rem;
    color: var(--text-muted);
    transition: color var(--transition);
}

@keyframes fadeUp { to { opacity: 1; transform: translateY(0); } }

.fade-in {
    opacity: 0;
    transform: translateY(18px);
    transition: opacity 0.5s ease, transform 0.5s ease;
}

.fade-in.visible {
    opacity: 1;
    transform: translateY(0);
}

@media (max-width: 900px) {
    #sidebar {
        transform: translateX(-100%);
        width: 270px;
        box-shadow: none;
    }

    #sidebar.open {
        transform: translateX(0);
        box-shadow: var(--shadow-lg);
    }

    #mobileHeader { display: flex; }
    .mobile-overlay.show { display: block; }

    #mainContent {
        margin-left: 0;
        padding-top: 56px;
    }

    #hero {
        min-height: calc(100vh - 56px);
        padding: 40px 24px;
    }

    .hero-inner {
        flex-direction: column-reverse;
        text-align: center;
        gap: 32px;
    }

    .hero-avatar { width: 140px; height: 140px; }
    #hero h1 { font-size: 2.4rem; }

    section:not(#hero) { padding: 60px 24px; }
    #footer { padding: 24px; }

    .cert-grid { grid-template-columns: 1fr; }
    .repos-grid { grid-template-columns: 1fr; }
    .skills-grid { grid-template-columns: repeat(3, 1fr); }
}

@media (max-width: 480px) {
    #hero h1 { font-size: 2rem; }
    .hero-desc { font-size: 1rem; }
    .hero-avatar { width: 120px; height: 120px; }
    .skills-grid { grid-template-columns: repeat(2, 1fr); }
    .contact-buttons { flex-direction: column; }
    .contact-btn { justify-content: center; }
}