/* Custom Properties */
:root {
    --color-primary: #D32F2F; /* Red */
    --color-primary-hover: #B71C1C;
    --color-secondary: #1976D2; /* Blue */
    --color-text: #000000; /* Black */
    --color-text-muted: #4A4A4A;
    --color-bg: #FFFFFF; /* White */
    --color-bg-alt: #F8F9FA;
    
    --font-sans: 'Inter', system-ui, -apple-system, sans-serif;
    
    --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
    --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
    --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);
    
    --transition-fast: 150ms ease-in-out;
    --transition-normal: 250ms ease;
    
    --container-max-width: 1200px;
    --nav-height: 4.5rem;
}

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-sans);
    color: var(--color-text);
    background-color: var(--color-bg);
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

main {
    flex: 1;
    padding-top: var(--nav-height);
}

img {
    max-width: 100%;
    height: auto;
    display: block;
}

a {
    color: var(--color-secondary);
    text-decoration: none;
    transition: color var(--transition-fast);
}

a:hover, a:focus {
    color: var(--color-primary);
}

ul[role="list"] {
    list-style: none;
}

/* Typography */
h1, h2, h3, h4, h5, h6 {
    line-height: 1.2;
    font-weight: 700;
    margin-bottom: 1rem;
    color: var(--color-text);
}

h1 { font-size: clamp(2.5rem, 5vw, 4rem); letter-spacing: -0.02em; }
h2 { font-size: clamp(2rem, 4vw, 3rem); }
h3 { font-size: clamp(1.5rem, 3vw, 2rem); }

p { margin-bottom: 1.5rem; color: var(--color-text-muted); }

/* Layout Components */
.container {
    width: 100%;
    margin-inline: auto;
    padding-inline: 1.5rem;
    max-width: var(--container-max-width);
}

.section {
    padding-block: 5rem;
}

.section-alt {
    background-color: var(--color-bg-alt);
}

/* Header / Navbar */
.navbar {
    position: fixed;
    top: 0;
    width: 100%;
    background-color: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(8px);
    z-index: 100;
    box-shadow: var(--shadow-sm);
    height: var(--nav-height);
    display: flex;
    align-items: center;
}

.nav-container {
    width: 100%;
    max-width: var(--container-max-width);
    margin: 0 auto;
    padding: 0 1.5rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    font-size: 1.5rem;
    font-weight: 800;
    color: var(--color-text);
    letter-spacing: -0.5px;
}

.logo span {
    color: var(--color-primary);
}

.nav-links ul {
    display: flex;
    gap: 2rem;
}

.nav-item {
    font-weight: 500;
    color: var(--color-text);
    position: relative;
    padding: 0.5rem 0;
}

.nav-item::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 0;
    height: 2px;
    background-color: var(--color-primary);
    transition: width var(--transition-normal);
}

.nav-item:hover::after,
.nav-item.active::after {
    width: 100%;
}

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

.mobile-toggle {
    display: none;
    background: transparent;
    border: none;
    cursor: pointer;
    padding: 0.5rem;
}

.mobile-toggle .bar {
    display: block;
    width: 25px;
    height: 2px;
    margin: 5px auto;
    background-color: var(--color-text);
    transition: all 0.3s ease-in-out;
}

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 0.75rem 1.5rem;
    font-weight: 600;
    border-radius: 0.375rem;
    transition: all var(--transition-normal);
    cursor: pointer;
    border: 2px solid transparent;
}

.btn-primary {
    background-color: var(--color-primary);
    color: var(--color-bg);
}

.btn-primary:hover {
    background-color: var(--color-primary-hover);
    color: var(--color-bg);
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

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

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

/* Home Hero Section */
.hero {
    min-height: calc(100vh - var(--nav-height));
    display: flex;
    align-items: center;
    position: relative;
    overflow: hidden;
}

.hero-content {
    max-width: 800px;
    position: relative;
    z-index: 2;
}

.hero-subtitle {
    color: var(--color-secondary);
    font-size: 1.125rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.1em;
    margin-bottom: 1rem;
    display: block;
}

.hero-description {
    font-size: 1.25rem;
    max-width: 600px;
    margin-bottom: 2rem;
}

.hero-actions {
    display: flex;
    gap: 1rem;
    flex-wrap: wrap;
}

.hero-bg-accent {
    position: absolute;
    right: -10%;
    top: -20%;
    width: 800px;
    height: 800px;
    background-color: rgba(25, 118, 210, 0.05); /* very light blue */
    border-radius: 50%;
    z-index: 1;
}

/* Skills Cards (Home & About) */
.skills-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 2rem;
    margin-top: 3rem;
}

.skill-card {
    background-color: var(--color-bg);
    padding: 2rem;
    border-radius: 0.5rem;
    box-shadow: var(--shadow-sm);
    border: 1px solid rgba(0,0,0,0.05);
    transition: transform var(--transition-normal), box-shadow var(--transition-normal);
    border-top: 4px solid var(--color-secondary);
}

.skill-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
    border-top-color: var(--color-primary);
}

.skill-card h3 {
    margin-bottom: 1rem;
    font-size: 1.25rem;
}

/* Footer */
.footer {
    background-color: #111;
    color: #fff;
    padding-top: 4rem;
}

.footer-container {
    max-width: var(--container-max-width);
    margin: 0 auto;
    padding: 0 1.5rem;
    display: flex;
    justify-content: space-between;
    flex-wrap: wrap;
    gap: 2rem;
    margin-bottom: 2rem;
}

.footer-info h3 {
    color: #fff;
}

.footer-info p {
    color: #999;
    max-width: 300px;
}

.footer-socials {
    display: flex;
    gap: 1.5rem;
}

.footer-socials a {
    color: #fff;
    font-weight: 500;
}

.footer-socials a:hover {
    color: var(--color-primary);
}

.footer-bottom {
    background-color: #000;
    text-align: center;
    padding: 1.5rem;
    color: #666;
    font-size: 0.875rem;
}

/* Contact Page Form */
.contact-form {
    max-width: 600px;
    margin: 0 auto;
    background: var(--color-bg);
    padding: 2.5rem;
    border-radius: 0.5rem;
    box-shadow: var(--shadow-md);
}

.form-group {
    margin-bottom: 1.5rem;
}

.form-label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: 600;
}

.form-input {
    width: 100%;
    padding: 0.75rem 1rem;
    border: 1px solid #ddd;
    border-radius: 0.375rem;
    font-family: inherit;
    font-size: 1rem;
    transition: border-color var(--transition-fast), box-shadow var(--transition-fast);
}

.form-input:focus {
    outline: none;
    border-color: var(--color-secondary);
    box-shadow: 0 0 0 3px rgba(25, 118, 210, 0.1);
}

textarea.form-input {
    min-height: 15rem;
    resize: vertical;
}

/* Mobile Responsiveness */
@media (max-width: 768px) {
    .mobile-toggle {
        display: block;
    }

    .nav-links {
        position: absolute;
        top: var(--nav-height);
        left: 0;
        width: 100%;
        background-color: var(--color-bg);
        border-top: 1px solid #eaeaea;
        box-shadow: var(--shadow-md);
        transform: translateY(-100%);
        opacity: 0;
        visibility: hidden;
        transition: all var(--transition-normal);
        z-index: 99;
    }

    .nav-links.nav-links-open {
        transform: translateY(0);
        opacity: 1;
        visibility: visible;
    }

    .nav-links ul {
        flex-direction: column;
        padding: 1.5rem;
        gap: 1.5rem;
        text-align: center;
    }

    .mobile-toggle.is-active .bar:nth-child(2) {
        opacity: 0;
    }

    .mobile-toggle.is-active .bar:nth-child(1) {
        transform: translateY(7px) rotate(45deg);
    }

    .mobile-toggle.is-active .bar:nth-child(3) {
        transform: translateY(-7px) rotate(-45deg);
    }
    
    .hero {
        text-align: center;
    }
    
    .hero-actions {
        justify-content: center;
    }
    
    .hero-bg-accent {
        display: none;
    }
}