/* --- CSS VARIABLES & THEMING --- */
:root {
    --bg-color: #0a0a0a;
    --surface-color: #171717;
    --text-primary: #ededed;
    --text-secondary: #a1a1aa;
    --accent-color: #3b82f6;
    --accent-hover: #2563eb;
    --border-color: #27272a;
    --shadow-color: rgba(0, 0, 0, 0.5);
    --nav-bg: rgba(10, 10, 10, 0.8);
}

[data-theme="light"] {
    --bg-color: #ffffff;
    --surface-color: #f4f4f5;
    --text-primary: #18181b;
    --text-secondary: #52525b;
    --accent-color: #2563eb;
    --accent-hover: #1d4ed8;
    --border-color: #e4e4e7;
    --shadow-color: rgba(0, 0, 0, 0.1);
    --nav-bg: rgba(255, 255, 255, 0.8);
}

/* --- RESET & BASE STYLES --- */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: 'Inter', sans-serif;
    background-color: var(--bg-color);
    color: var(--text-primary);
    line-height: 1.6;
    transition: background-color 0.3s ease, color 0.3s ease;
    overflow-x: hidden;
}

a {
    text-decoration: none;
    color: inherit;
}

ul {
    list-style: none;
}

.container {
    max-width: 1100px;
    margin: 0 auto;
    padding: 0 2rem;
}

.section {
    padding: 6rem 0;
}

.section-title {
    font-size: 2rem;
    font-weight: 700;
    margin-bottom: 3rem;
    text-align: center;
    position: relative;
}

.section-title::after {
    content: '';
    position: absolute;
    bottom: -10px;
    left: 50%;
    transform: translateX(-50%);
    width: 60px;
    height: 4px;
    background-color: var(--accent-color);
    border-radius: 2px;
}

/* --- BUTTONS --- */
.btn {
    display: inline-block;
    padding: 0.75rem 1.5rem;
    border-radius: 6px;
    font-weight: 500;
    font-size: 1rem;
    transition: all 0.3s ease;
    cursor: pointer;
    border: 2px solid transparent;
}

.btn-primary {
    background-color: var(--accent-color);
    color: #ffffff;
}

.btn-primary:hover {
    background-color: var(--accent-hover);
    transform: translateY(-2px);
}

.btn-secondary {
    background-color: transparent;
    border-color: var(--border-color);
    color: var(--text-primary);
}

.btn-secondary:hover {
    border-color: var(--text-primary);
    transform: translateY(-2px);
}

.btn-small {
    padding: 0.5rem 1rem;
    font-size: 0.875rem;
}

.btn-outline {
    background-color: transparent;
    border-color: var(--accent-color);
    color: var(--accent-color);
}

.btn-outline:hover {
    background-color: var(--accent-color);
    color: #ffffff;
}

/* --- NAVBAR --- */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    background-color: var(--nav-bg);
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--border-color);
    z-index: 1000;
    transition: background-color 0.3s ease, border-color 0.3s ease;
}

.nav-container {
    max-width: 1100px;
    margin: 0 auto;
    padding: 1rem 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    font-size: 1.5rem;
    font-weight: 700;
    letter-spacing: -0.5px;
    color: var(--text-primary);
}

.nav-links {
    display: none;
    gap: 2rem;
}

.nav-links a {
    font-size: 0.95rem;
    color: var(--text-secondary);
    transition: color 0.3s ease;
}

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

.nav-actions {
    display: flex;
    align-items: center;
    gap: 1rem;
}

#theme-toggle {
    background: none;
    border: none;
    color: var(--text-primary);
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 0.5rem;
    border-radius: 50%;
    transition: background-color 0.3s ease;
}

#theme-toggle:hover {
    background-color: var(--surface-color);
}

.moon-icon {
    display: none;
}

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

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

/* Hamburger Menu */
.hamburger {
    display: flex;
    flex-direction: column;
    gap: 5px;
    background: none;
    border: none;
    cursor: pointer;
    padding: 0.5rem;
}

.hamburger span {
    display: block;
    width: 25px;
    height: 2px;
    background-color: var(--text-primary);
    transition: all 0.3s ease;
}

.hamburger.active span:nth-child(1) {
    transform: translateY(7px) rotate(45deg);
}

.hamburger.active span:nth-child(2) {
    opacity: 0;
}

.hamburger.active span:nth-child(3) {
    transform: translateY(-7px) rotate(-45deg);
}

.nav-links.active {
    display: flex;
    flex-direction: column;
    position: absolute;
    top: 100%;
    left: 0;
    width: 100%;
    background-color: var(--bg-color);
    padding: 2rem;
    border-bottom: 1px solid var(--border-color);
    gap: 1.5rem;
    text-align: center;
}

/* --- HERO SECTION --- */
.hero {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    text-align: center;
    padding: 0 2rem;
    padding-top: 80px;
}

.hero-content {
    max-width: 800px;
}

.hero h1 {
    font-size: 3rem;
    font-weight: 700;
    line-height: 1.2;
    margin-bottom: 1rem;
    letter-spacing: -1px;
}

.hero h2 {
    font-size: 1.5rem;
    color: var(--text-secondary);
    font-weight: 500;
    margin-bottom: 1.5rem;
}

.hero p {
    font-size: 1.125rem;
    color: var(--text-secondary);
    margin-bottom: 2.5rem;
    max-width: 600px;
    margin-left: auto;
    margin-right: auto;
}

.highlight {
    color: var(--accent-color);
}

.hero-buttons {
    display: flex;
    gap: 1rem;
    justify-content: center;
    flex-wrap: wrap;
}

/* --- ABOUT SECTION --- */
.about-grid {
    display: grid;
    grid-template-columns: 1fr;
    gap: 3rem;
    align-items: center;
}

.about-image img {
    width: 100%;
    max-width: 350px;
    border-radius: 12px;
    box-shadow: 0 20px 40px var(--shadow-color);
    margin: 0 auto;
    display: block;
}

.about-text p {
    color: var(--text-secondary);
    margin-bottom: 1rem;
    font-size: 1.05rem;
}

/* --- SKILLS SECTION --- */
.skills-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 1.5rem;
}

.skill-card {
    background-color: var(--surface-color);
    padding: 2rem;
    border-radius: 12px;
    text-align: center;
    border: 1px solid var(--border-color);
    transition: transform 0.3s ease, border-color 0.3s ease;
}

.skill-card:hover {
    transform: translateY(-5px);
    border-color: var(--accent-color);
}

.skill-card svg {
    color: var(--accent-color);
    margin-bottom: 1rem;
}

.skill-card h3 {
    font-size: 1.1rem;
    font-weight: 600;
}

/* --- PROJECTS SECTION --- */
.projects-grid {
    display: grid;
    grid-template-columns: 1fr;
    gap: 2rem;
}

.project-card {
    background-color: var(--surface-color);
    border-radius: 12px;
    overflow: hidden;
    border: 1px solid var(--border-color);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.project-card:hover {
    transform: translateY(-8px);
    box-shadow: 0 20px 40px var(--shadow-color);
}

.project-image {
    width: 100%;
    height: 200px;
    overflow: hidden;
}

.project-image img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    transition: transform 0.5s ease;
}

.project-card:hover .project-image img {
    transform: scale(1.05);
}

.project-info {
    padding: 1.5rem;
}

.project-info h3 {
    font-size: 1.25rem;
    margin-bottom: 0.5rem;
}

.project-info p {
    color: var(--text-secondary);
    font-size: 0.95rem;
    margin-bottom: 1.5rem;
}

.project-links {
    display: flex;
    gap: 1rem;
}

/* --- CONTACT SECTION --- */
.contact-grid {
    display: grid;
    grid-template-columns: 1fr;
    gap: 3rem;
}

.contact-info p {
    color: var(--text-secondary);
    margin-bottom: 2rem;
    font-size: 1.05rem;
}

.social-links {
    display: flex;
    gap: 1.5rem;
}

.social-links a {
    color: var(--accent-color);
    font-weight: 500;
    transition: color 0.3s ease;
}

.social-links a:hover {
    color: var(--accent-hover);
    text-decoration: underline;
}

.contact-form {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.form-group {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.form-group label {
    font-size: 0.9rem;
    font-weight: 500;
}

.form-group input,
.form-group textarea {
    padding: 0.75rem;
    border-radius: 6px;
    border: 1px solid var(--border-color);
    background-color: var(--bg-color);
    color: var(--text-primary);
    font-family: inherit;
    font-size: 1rem;
    transition: border-color 0.3s ease;
}

.form-group input:focus,
.form-group textarea:focus {
    outline: none;
    border-color: var(--accent-color);
}

/* --- FOOTER --- */
footer {
    padding: 2rem 0;
    text-align: center;
    border-top: 1px solid var(--border-color);
    color: var(--text-secondary);
    font-size: 0.9rem;
}

/* --- BACK TO TOP BUTTON --- */
#back-to-top {
    position: fixed;
    bottom: 2rem;
    right: 2rem;
    background-color: var(--accent-color);
    color: #ffffff;
    border: none;
    width: 45px;
    height: 45px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    opacity: 0;
    visibility: hidden;
    transition: all 0.3s ease;
    z-index: 999;
}

#back-to-top.visible {
    opacity: 1;
    visibility: visible;
}

#back-to-top:hover {
    background-color: var(--accent-hover);
    transform: translateY(-3px);
}

/* --- ANIMATIONS --- */
.fade-in {
    opacity: 0;
    transform: translateY(20px);
    transition: opacity 0.6s ease-out, transform 0.6s ease-out;
}

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

/* --- MEDIA QUERIES --- */
@media (min-width: 768px) {
    .nav-links {
        display: flex;
    }

    .hamburger {
        display: none;
    }

    .hero h1 {
        font-size: 4rem;
    }

    .hero h2 {
        font-size: 2rem;
    }

    .about-grid {
        grid-template-columns: 1fr 1.5fr;
    }

    .projects-grid {
        grid-template-columns: repeat(2, 1fr);
    }

    .contact-grid {
        grid-template-columns: 1fr 1fr;
    }
}

@media (min-width: 1024px) {
    .projects-grid {
        grid-template-columns: repeat(2, 1fr);
    }
}