:root {
    --primary-bg: #F7F7F8;
    --secondary-bg: #FFFFFF;
    --border-color: #E4E4E7;
    --text-color: #18181B;
    --accent-color: #6B7280;
    --hover-accent: #27272A;
    --hover-accent-strong: #000000;
    --card-shadow: 0 1px 2px rgba(0, 0, 0, 0.04);
    --card-hover-shadow: 0 4px 12px rgba(0, 0, 0, 0.08);
    --font-display: 'Inter', sans-serif;
    --font-body: 'Inter', sans-serif;
    --font-mono: 'Inter', sans-serif;
}

[data-theme="dark"] {
    --primary-bg: #121212;
    --secondary-bg: #1C1C1E;
    --border-color: #2E2E32;
    --text-color: #F2F2F2;
    --accent-color: #A1A1AA;
    --hover-accent: #E4E4E7;
    --hover-accent-strong: #FFFFFF;
    --card-shadow: 0 1px 2px rgba(0, 0, 0, 0.3);
    --card-hover-shadow: 0 4px 16px rgba(0, 0, 0, 0.4);
}

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-body);
    background-color: var(--primary-bg);
    color: var(--text-color);
    line-height: 1.6;
    overflow-x: hidden;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    transition: background-color 0.3s ease, color 0.3s ease;
}

h1, h2, h3, h4 {
    font-family: var(--font-display);
}

a {
    text-decoration: none;
    color: var(--accent-color);
    transition: color 0.3s ease, transform 0.3s ease;
}

a:hover {
    color: var(--hover-accent);
}

.container {
    max-width: 1100px;
    margin: 0 auto;
    padding: 0 24px;
}

.sidebar {
    position: fixed;
    top: 0;
    left: 0;
    width: 80px;
    height: 100%;
    background-color: var(--secondary-bg);
    border-right: 1px solid var(--border-color);
    display: flex;
    flex-direction: column;
    align-items: center;
    padding-top: 40px;
    z-index: 1000;
    transition: background-color 0.3s ease, border-color 0.3s ease;
}

.sidebar nav a {
    writing-mode: vertical-rl;
    text-orientation: mixed;
    font-family: var(--font-mono);
    color: var(--text-color);
    font-size: 0.85rem;
    font-weight: 500;
    padding: 10px 10px;
    margin: 10px 0;
    opacity: 0.6;
    transition: transform 0.3s ease, color 0.3s ease, opacity 0.3s ease;
}

.sidebar nav a:hover {
    color: var(--hover-accent);
    opacity: 1;
}

.sidebar nav a.active {
    color: var(--hover-accent);
    opacity: 1;
    border-left: 2px solid var(--hover-accent);
}

.main-content {
    margin-left: 80px;
    padding: 40px 20px;
    min-height: calc(100vh - 80px);
    display: flex;
    flex-direction: column;
}

.hero {
    padding: 100px 0;
    text-align: center;
    background-color: var(--primary-bg);
    animation: fadeIn 1s ease-out;
    transition: background-color 0.3s ease;
}

.hero h1 {
    font-size: 3rem;
    font-weight: 700;
    margin-bottom: 16px;
    color: var(--text-color);
}

.hero p {
    font-size: 1.15rem;
    font-weight: 500;
    color: var(--hover-accent);
    max-width: 600px;
    margin: 0 auto 24px;
    opacity: 0;
    animation: slideUp 0.8s ease-out forwards;
    animation-delay: 0.3s;
}

.hero a.download-cv {
    display: inline-block;
    background-color: var(--hover-accent);
    color: #ffffff;
    padding: 12px 24px;
    border-radius: 8px;
    font-size: 1rem;
    font-weight: 500;
    transition: background-color 0.2s ease;
}

.hero a.download-cv:hover {
    background-color: var(--hover-accent-strong);
}

[data-theme="dark"] .hero a.download-cv {
    background-color: var(--hover-accent);
    color: #121212;
}

[data-theme="dark"] .hero a.download-cv:hover {
    background-color: var(--hover-accent-strong);
}

section {
    padding: 80px 0;
    opacity: 0;
    transform: translateY(20px);
    transition: opacity 0.6s ease-out, transform 0.6s ease-out;
}

section.visible {
    opacity: 1;
    transform: translateY(0);
}

h2 {
    font-size: 2.25rem;
    font-weight: 600;
    margin-bottom: 40px;
    text-align: center;
    position: relative;
}

h2::after {
    content: '';
    width: 40px;
    height: 3px;
    background-color: var(--hover-accent);
    position: absolute;
    bottom: -10px;
    left: 50%;
    transform: translateX(-50%);
    border-radius: 2px;
}

.skills-grid {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: 10px;
    margin-top: 24px;
}

.skill-tag {
    display: inline-block;
    padding: 8px 16px;
    font-size: 0.9rem;
    font-weight: 500;
    color: var(--text-color);
    background-color: var(--secondary-bg);
    border: 1px solid var(--border-color);
    border-radius: 6px;
    transition: border-color 0.2s ease, color 0.2s ease;
}

.skill-tag:hover {
    border-color: var(--hover-accent);
    color: var(--hover-accent);
}

.about-content {
    max-width: 800px;
    margin: 0 auto;
    text-align: center;
    background-color: var(--secondary-bg);
    border: 1px solid var(--border-color);
    padding: 32px;
    border-radius: 12px;
    transition: border-color 0.3s ease, background-color 0.3s ease;
}

.about-content:hover {
    border-color: var(--hover-accent);
}

.projects-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: 24px;
    min-height: auto;
    overflow: visible;
    width: 100%;
}

.project-card {
    background-color: var(--secondary-bg);
    border: 1px solid var(--border-color);
    padding: 24px;
    border-radius: 10px;
    transition: transform 0.2s ease, border-color 0.2s ease;
    width: 100%;
    max-width: 100%;
    margin: 0 auto;
    visibility: visible;
}

.project-card:hover {
    transform: translateY(-4px);
    border-color: var(--hover-accent);
}

.project-card h4 {
    font-size: 1.4rem;
    font-weight: 600;
    margin-bottom: 12px;
    color: var(--text-color);
}

.job-meta {
    font-family: var(--font-mono);
    font-size: 0.85rem;
    font-weight: 500;
    color: var(--hover-accent);
    margin: -8px 0 12px;
}

.card-tag {
    display: inline-block;
    font-size: 0.72rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.04em;
    color: var(--accent-color);
    border: 1px solid var(--border-color);
    padding: 3px 9px;
    border-radius: 4px;
    margin-bottom: 10px;
}

.project-card ul {
    list-style: none;
    margin: 12px 0;
}

.project-card li {
    font-size: 0.95rem;
    color: var(--accent-color);
    margin-bottom: 8px;
    position: relative;
    padding-left: 20px;
}

.project-card li::before {
    content: '•';
    position: absolute;
    left: 0;
    color: var(--hover-accent);
    font-size: 1.2rem;
}

.certifications-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 24px;
    margin-top: 32px;
}

.certification-card {
    background-color: var(--secondary-bg);
    border: 1px solid var(--border-color);
    padding: 24px;
    border-radius: 10px;
    transition: border-color 0.2s ease;
    position: relative;
    display: flex;
    align-items: center;
    gap: 16px;
}

.certification-card:hover {
    border-color: var(--hover-accent);
}

.certification-card::before {
    content: '';
    width: 8px;
    height: 8px;
    border-radius: 50%;
    background-color: var(--hover-accent);
    flex-shrink: 0;
}

.certification-card p {
    font-size: 1.05rem;
    font-weight: 500;
    color: var(--text-color);
}

.contact-content {
    text-align: center;
    max-width: 600px;
    margin: 0 auto;
}

.contact-content p {
    margin-bottom: 16px;
}

.contact-links {
    margin-bottom: 32px;
}

.contact-links a {
    display: inline-block;
    margin: 8px 12px;
    font-weight: 500;
    padding: 8px 16px;
    border-radius: 6px;
    background-color: var(--secondary-bg);
    border: 1px solid var(--border-color);
    transition: border-color 0.2s ease, color 0.2s ease;
}

.contact-links a:hover {
    border-color: var(--hover-accent);
    color: var(--hover-accent);
}

.contact-form {
    background-color: var(--secondary-bg);
    border: 1px solid var(--border-color);
    padding: 32px;
    border-radius: 12px;
    margin-top: 24px;
    max-width: 500px;
    margin-left: auto;
    margin-right: auto;
    transition: border-color 0.3s ease;
}

.contact-form:hover {
    border-color: var(--hover-accent);
}

.contact-form label {
    display: block;
    font-size: 1rem;
    font-weight: 500;
    margin-bottom: 8px;
    color: var(--text-color);
    text-align: left;
}

.contact-form input,
.contact-form textarea {
    width: 100%;
    padding: 12px 16px;
    margin-bottom: 20px;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    background-color: var(--primary-bg);
    color: var(--text-color);
    font-family: var(--font-body);
    font-size: 0.95rem;
    transition: border-color 0.3s ease, background-color 0.3s ease, box-shadow 0.3s ease;
}

[data-theme="dark"] .contact-form input,
[data-theme="dark"] .contact-form textarea {
    border-color: var(--border-color);
    background-color: var(--primary-bg);
}

.contact-form input:focus,
.contact-form textarea:focus {
    outline: none;
    border-color: var(--hover-accent);
    box-shadow: 0 0 0 3px rgba(92, 58, 82, 0.15);
}

.contact-form textarea {
    resize: vertical;
    min-height: 120px;
    max-height: 300px;
}

.contact-form button {
    display: block;
    width: 100%;
    background-color: var(--hover-accent);
    color: #ffffff;
    padding: 12px 24px;
    border: none;
    border-radius: 8px;
    font-size: 1rem;
    font-weight: 500;
    cursor: pointer;
    transition: background-color 0.2s ease;
}

.contact-form button:hover {
    background-color: var(--hover-accent-strong);
}

[data-theme="dark"] .contact-form button {
    background-color: var(--hover-accent);
    color: #121212;
}

[data-theme="dark"] .contact-form button:hover {
    background-color: var(--hover-accent-strong);
}

.form-message {
    margin-top: 16px;
    padding: 12px;
    border-radius: 8px;
    text-align: center;
    font-size: 0.95rem;
    transition: opacity 0.3s ease;
}

.form-message.success {
    background-color: var(--primary-bg);
    color: var(--text-color);
    border: 1px solid var(--border-color);
}

.form-message.error {
    background-color: var(--primary-bg);
    color: var(--text-color);
    border: 1px solid var(--hover-accent);
}

footer {
    background-color: var(--secondary-bg);
    padding: 20px 0;
    text-align: center;
    font-size: 0.9rem;
    font-family: var(--font-mono);
    color: var(--accent-color);
    border-top: 1px solid var(--border-color);
    margin-top: auto;
    transition: background-color 0.3s ease, color 0.3s ease, border-color 0.3s ease;
}

.theme-toggle {
    position: fixed;
    top: 20px;
    right: 20px;
    z-index: 1001;
    background-color: var(--secondary-bg);
    border: 1px solid var(--border-color);
    border-radius: 50%;
    width: 40px;
    height: 40px;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: border-color 0.2s ease;
}

.theme-toggle:hover {
    border-color: var(--hover-accent);
}

.theme-toggle svg {
    width: 20px;
    height: 20px;
    fill: none;
    stroke: var(--text-color);
    stroke-width: 2;
    stroke-linecap: round;
    stroke-linejoin: round;
    transition: stroke 0.3s ease;
}

.light-icon {
    display: block;
}

.dark-icon {
    display: none;
}

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

[data-theme="dark"] .dark-icon {
    display: block;
}

@keyframes fadeIn {
    from { opacity: 0; }
    to { opacity: 1; }
}

@keyframes slideUp {
    from { opacity: 0; transform: translateY(20px); }
    to { opacity: 1; transform: translateY(0); }
}

#projects {
    min-height: 100vh;
    overflow: visible;
}

.main-content,
#projects,
.projects-grid {
    overflow: visible !important;
    width: 100%;
    height: auto;
}

@media (max-width: 768px) {
    .sidebar {
        position: fixed;
        top: 0;
        left: 0;
        width: 100%;
        height: auto;
        padding: 10px 0;
        display: flex;
        flex-direction: row;
        justify-content: center;
        align-items: center;
        background-color: var(--secondary-bg);
        box-shadow: 0 2px 4px rgba(0, 0, 0, 0.05);
        z-index: 1000;
        flex-wrap: wrap;
    }

    .sidebar nav {
        display: flex;
        flex-direction: row;
        flex-wrap: wrap;
        justify-content: center;
    }

    .sidebar nav a {
        writing-mode: horizontal-tb;
        font-size: 0.85rem;
        padding: 8px 12px;
        margin: 5px;
        opacity: 1;
        transition: transform 0.3s ease, color 0.3s ease;
    }

    .sidebar nav a:hover {
        color: var(--hover-accent);
        transform: scale(1.1);
    }

    .sidebar nav a.active {
        border-left: none;
        border-bottom: 2px solid var(--hover-accent);
    }

    .main-content {
        margin-left: 0;
        margin-top: 100px;
        padding: 20px 10px;
        min-height: 100vh;
        width: 100%;
        max-width: 100%;
        box-sizing: border-box;
        overflow: visible;
        z-index: 500;
        position: relative;
    }

    .container {
        padding: 0 16px;
        width: 100%;
        max-width: 100%;
        box-sizing: border-box;
        overflow: visible;
    }

    .hero {
        padding: 80px 0;
    }

    .hero h1 {
        font-size: 2.25rem;
    }

    .hero p {
        font-size: 1.1rem;
        padding: 0 20px;
    }

    .hero a.download-cv {
        padding: 10px 20px;
        font-size: 0.9rem;
    }

    .skills-grid {
        gap: 8px;
    }

    .skill-tag {
        font-size: 0.8rem;
        padding: 6px 12px;
    }

    .projects-grid {
        display: block;
        display: grid;
        grid-template-columns: 1fr;
        gap: 16px;
        min-height: auto;
        overflow: visible !important;
        width: 100%;
        max-width: 100%;
        padding: 0;
        margin: 0 auto;
    }

    .project-card {
        width: 100%;
        max-width: 100%;
        margin: 0 auto;
        margin-bottom: 16px;
        padding: 20px;
        box-sizing: border-box;
        visibility: visible !important;
        opacity: 1 !important;
        min-height: 150px;
    }

    #projects {
        opacity: 1 !important;
        transform: translateY(0) !important;
        min-height: auto;
        padding: 40px 0;
    }

    h2 {
        font-size: 2rem;
    }

    .about-content {
        padding: 24px;
    }

    .contact-links {
        margin-bottom: 24px;
    }

    .contact-links a {
        margin: 6px 8px;
        padding: 6px 12px;
        font-size: 0.9rem;
    }

    .contact-form {
        padding: 24px;
        max-width: 100%;
    }

    .contact-form input,
    .contact-form textarea {
        padding: 10px 14px;
        font-size: 0.9rem;
        margin-bottom: 16px;
    }

    .contact-form button {
        padding: 10px 20px;
        font-size: 0.9rem;
    }

    .form-message {
        font-size: 0.9rem;
        padding: 10px;
    }

    footer {
        width: 100%;
        margin-left: 0;
        padding: 16px 0;
    }

    .theme-toggle {
        top: 75px;
        right: 10px;
        width: 36px;
        height: 36px;
    }

    .theme-toggle svg {
        width: 18px;
        height: 18px;
    }
}

@media (max-width: 480px) {
    .hero {
        padding: 60px 0;
    }

    .hero h1 {
        font-size: 1.75rem;
    }

    .hero p {
        font-size: 1rem;
    }

    .hero a.download-cv {
        padding: 8px 16px;
        font-size: 0.85rem;
    }

    .sidebar nav a {
        font-size: 0.75rem;
        padding: 6px 8px;
        margin: 3px;
    }

    .main-content {
        margin-top: 120px;
        padding: 16px 8px;
    }

    .container {
        padding: 0 12px;
    }

    .skill-tag {
        font-size: 0.75rem;
        padding: 5px 10px;
    }

    .projects-grid {
        gap: 12px;
    }

    .project-card {
        padding: 16px;
        min-height: 120px;
        margin-bottom: 12px;
    }

    #projects {
        opacity: 1 !important;
        transform: translateY(0) !important;
        min-height: auto;
        padding: 20px 0;
    }

    h2 {
        font-size: 1.75rem;
    }

    .project-card h4 {
        font-size: 1.3rem;
    }

    .contact-content {
        padding: 0 16px;
    }

    .contact-form {
        padding: 20px;
    }

    .contact-form input,
    .contact-form textarea {
        padding: 8px 12px;
        font-size: 0.85rem;
    }

    .form-message {
        font-size: 0.85rem;
        padding: 8px;
    }
}