/* Font imports */
@font-face {
    font-family: 'Volkhov';
    src: url('../fonts/Volkhov/volkhov-v17-latin-regular.woff2') format('woff2'), 
        url('../fonts/Volkhov/volkhov-v17-latin-regular.ttf') format('truetype'); 
}

@font-face {
    font-family: 'Volkhov';
    font-weight: bold;
    src: url('../fonts/Volkhov/volkhov-v17-latin-700.woff2') format('woff2'),
        url('../fonts/Volkhov/volkhov-v17-latin-700.ttf') format('truetype');
}

@font-face {
    font-family: 'Spectral';
    src: url('../fonts/Spectral/spectral-v14-latin-regular.woff2') format('woff2'), 
         url('../fonts/Spectral/spectral-v14-latin-regular.ttf') format('truetype'); 
}

/* Variables */
:root {
    /* Colors */
    --color-background: #f8f9fa;
    --color-text: #212529;
    --color-primary: #0d6efd;
    --color-secondary: #6c757d;
    --color-accent: #fd7e14;
    --color-light: #f8f9fa;
    --color-dark: #212529;
    --color-white: #ffffff;
    --color-card-bg: #ffffff;
    --color-card-shadow: rgba(0, 0, 0, 0.05);
    --color-border: #dee2e6;
    --color-link: #0d6efd;
    --color-link-hover: #0a58ca;
    --color-success: #198754;
    --color-info: #0dcaf0;
    --color-warning: #ffc107;
    --color-danger: #dc3545;
    
    /* Typography */
    --font-heading: 'Volkhov', serif;
    --font-body: 'Spectral', serif;
    --font-size-base: 1rem;
    --font-size-sm: 0.875rem;
    --font-size-lg: 1.25rem;
    --font-size-xl: 1.5rem;
    --font-size-2xl: 2rem;
    --font-size-3xl: 3rem;
    --font-size-4xl: 4rem;
    --line-height-tight: 1.2;
    --line-height-normal: 1.5;
    --line-height-loose: 1.8;
    
    /* Spacing */
    --spacing-0: 0;
    --spacing-1: 0.25rem;
    --spacing-2: 0.5rem;
    --spacing-3: 0.75rem;
    --spacing-4: 1rem;
    --spacing-5: 1.5rem;
    --spacing-6: 2rem;
    --spacing-8: 3rem;
    --spacing-10: 4rem;
    --spacing-12: 5rem;
    
    /* Borders */
    --border-radius-sm: 0.25rem;
    --border-radius: 0.5rem;
    --border-radius-lg: 1rem;
    --border-radius-xl: 1.5rem;
    --border-radius-2xl: 2rem;
    --border-radius-full: 9999px;
    
    /* Transitions */
    --transition-fast: 150ms ease;
    --transition-normal: 300ms ease;
    --transition-slow: 500ms ease;
    
    /* Shadows */
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    --shadow-md: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
    --shadow-lg: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
    --shadow-xl: 0 25px 50px -12px rgba(0, 0, 0, 0.25);
    
    /* Layout */
    --container-max-width: 1200px;
    --header-height: 80px;
    --footer-height: 80px;
}

/* Dark theme */
:root.dark-theme {
    --color-background: #121212;
    --color-text: #e9ecef;
    --color-primary: #3d8bfd;
    --color-secondary: #adb5bd;
    --color-accent: #ff922b;
    --color-light: #343a40;
    --color-dark: #f8f9fa;
    --color-card-bg: #1e1e1e;
    --color-card-shadow: rgba(0, 0, 0, 0.2);
    --color-border: #495057;
    --color-link: #6ea8fe;
    --color-link-hover: #9ec5fe;
}

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

/* Base styles */
html {
    font-size: 16px;
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-body);
    font-size: var(--font-size-base);
    line-height: var(--line-height-normal);
    color: var(--color-text);
    background-color: var(--color-background);
    transition: background-color var(--transition-normal), color var(--transition-normal);
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

h1, h2, h3, h4, h5, h6 {
    font-family: var(--font-heading);
    font-weight: bold;
    line-height: var(--line-height-tight);
    margin-bottom: var(--spacing-4);
}

h1 {
    font-size: var(--font-size-4xl);
}

h2 {
    font-size: var(--font-size-2xl);
}

h3 {
    font-size: var(--font-size-xl);
}

p {
    margin-bottom: var(--spacing-4);
}

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

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

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

button {
    cursor: pointer;
    font-family: inherit;
}

/* Container */
.container {
    width: 100%;
    max-width: var(--container-max-width);
    margin: 0 auto;
    padding: 0 var(--spacing-4);
}

/* Header */
.site-header {
    height: var(--header-height);
    position: sticky;
    top: 0;
    z-index: 100;
    background-color: var(--color-background);
    box-shadow: var(--shadow-sm);
    transition: background-color var(--transition-normal);
}

.site-header .container {
    height: 100%;
}

nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 100%;
}

.logo {
    font-family: var(--font-heading);
    font-size: var(--font-size-xl);
    font-weight: bold;
    color: var(--color-text);
    transition: color var(--transition-fast);
}

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

.nav-links {
    display: flex;
    align-items: center;
    list-style: none;
    gap: var(--spacing-6);
}

.nav-links a {
    color: var(--color-text);
    font-weight: 500;
    position: relative;
    padding: var(--spacing-2) 0;
}

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

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

.nav-links a.active::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 100%;
    height: 2px;
    background-color: var(--color-primary);
    transform: scaleX(1);
    transform-origin: left;
    transition: transform var(--transition-normal);
}

.nav-links a:not(.active)::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 100%;
    height: 2px;
    background-color: var(--color-primary);
    transform: scaleX(0);
    transform-origin: left;
    transition: transform var(--transition-normal);
}

.nav-links a:not(.active):hover::after {
    transform: scaleX(1);
}

#theme-toggle {
    background: none;
    border: none;
    padding: var(--spacing-1);
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--color-text);
    transition: transform var(--transition-fast);
}

#theme-toggle:hover {
    transform: rotate(15deg);
}

#theme-toggle svg {
    fill: var(--color-text);
    transition: fill var(--transition-fast);
}

.hamburger {
    display: none;
    background: none;
    border: none;
    width: 30px;
    height: 24px;
    position: relative;
    flex-direction: column;
    justify-content: space-between;
}

.hamburger span {
    display: block;
    width: 100%;
    height: 2px;
    background-color: var(--color-text);
    transition: transform var(--transition-normal), opacity var(--transition-normal);
}

/* Hero section */
.hero {
    position: relative;
    height: 60vh;
    min-height: 400px;
    display: flex;
    align-items: center;
    justify-content: center;
    overflow: hidden;
    margin-bottom: var(--spacing-10);
}

.hero-image {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: -1;
}

.hero-image img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    filter: brightness(0.7);
    transition: filter var(--transition-normal), transform var(--transition-slow);
}

.hero:hover .hero-image img {
    filter: brightness(0.75);
    transform: scale(1.05);
}

.image-caption {
    position: absolute;
    bottom: var(--spacing-4);
    left: var(--spacing-4);
    background-color: rgba(0, 0, 0, 0.6);
    color: var(--color-white);
    padding: var(--spacing-2) var(--spacing-4);
    border-radius: var(--border-radius);
    font-size: var(--font-size-sm);
    backdrop-filter: blur(4px);
    opacity: 0.8;
    transition: opacity var(--transition-normal);
}

.hero:hover .image-caption {
    opacity: 1;
}

.hero-content {
    text-align: center;
    color: var(--color-white);
    z-index: 1;
    padding: var(--spacing-6);
    background-color: rgba(0, 0, 0, 0.4);
    backdrop-filter: blur(4px);
    border-radius: var(--border-radius-lg);
    max-width: 80%;
    animation: fadeIn 1s ease-out;
}

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

.hero-content h1 {
    font-size: var(--font-size-4xl);
    margin-bottom: var(--spacing-2);
    text-shadow: 0 2px 4px rgba(0, 0, 0, 0.3);
}

.subtitle {
    font-size: var(--font-size-lg);
    opacity: 0.9;
    margin-bottom: 0;
}

/* Card styles */
.card {
    background-color: var(--color-card-bg);
    border-radius: var(--border-radius-lg);
    padding: var(--spacing-6);
    box-shadow: var(--shadow);
    transition: transform var(--transition-normal), box-shadow var(--transition-normal);
    opacity: 0;
    transform: translateY(20px);
}

.card.show {
    opacity: 1;
    transform: translateY(0);
}

.card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-md);
}

.card-icon {
    width: 48px;
    height: 48px;
    margin-bottom: var(--spacing-4);
    color: var(--color-primary);
}

.card h2, .card h3 {
    margin-bottom: var(--spacing-3);
    position: relative;
    display: inline-block;
}

.card h2::after, .card h3::after {
    content: '';
    position: absolute;
    bottom: -5px;
    left: 0;
    width: 40px;
    height: 3px;
    background-color: var(--color-primary);
}

.card p {
    margin-bottom: 0;
    line-height: var(--line-height-loose);
}

.highlight {
    color: var(--color-primary);
    font-weight: bold;
}

/* Button styles */
.btn {
    display: inline-block;
    font-weight: 500;
    text-align: center;
    white-space: nowrap;
    vertical-align: middle;
    user-select: none;
    border: 1px solid transparent;
    padding: var(--spacing-2) var(--spacing-4);
    font-size: var(--font-size-base);
    line-height: 1.5;
    border-radius: var(--border-radius);
    transition: color var(--transition-fast), background-color var(--transition-fast), border-color var(--transition-fast), box-shadow var(--transition-fast);
}

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

.btn-primary:hover {
    background-color: var(--color-link-hover);
    border-color: var(--color-link-hover);
    color: var(--color-white);
}

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

.btn-secondary:hover {
    background-color: #5a6268;
    border-color: #545b62;
    color: var(--color-white);
}

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

.btn-outline-primary:hover {
    color: var(--color-white);
    background-color: var(--color-primary);
    border-color: var(--color-primary);
}

/* Form styles */
.form-group {
    margin-bottom: var(--spacing-4);
}

.form-label {
    display: block;
    margin-bottom: var(--spacing-2);
    font-weight: 500;
}

.form-control {
    display: block;
    width: 100%;
    padding: var(--spacing-2) var(--spacing-3);
    font-size: var(--font-size-base);
    line-height: 1.5;
    color: var(--color-text);
    background-color: var(--color-card-bg);
    background-clip: padding-box;
    border: 1px solid var(--color-border);
    border-radius: var(--border-radius);
    transition: border-color var(--transition-fast), box-shadow var(--transition-fast);
}

.form-control:focus {
    color: var(--color-text);
    background-color: var(--color-card-bg);
    border-color: var(--color-primary);
    outline: 0;
    box-shadow: 0 0 0 0.2rem rgba(13, 110, 253, 0.25);
}

textarea.form-control {
    min-height: 100px;
    resize: vertical;
}

/* Footer */
footer {
    background-color: var(--color-light);
    padding: var(--spacing-6) 0;
    margin-top: auto;
    border-top: 1px solid var(--color-border);
}

footer .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.github-link {
    font-weight: bold;
}

.copyright {
    margin-bottom: 0;
    font-size: var(--font-size-sm);
    color: var(--color-secondary);
}

/* Grid system */
.row {
    display: flex;
    flex-wrap: wrap;
    margin-right: -15px;
    margin-left: -15px;
}

.col {
    position: relative;
    width: 100%;
    padding-right: 15px;
    padding-left: 15px;
}

.col-12 {
    flex: 0 0 100%;
    max-width: 100%;
}

.col-md-6 {
    flex: 0 0 100%;
    max-width: 100%;
}

.col-lg-4 {
    flex: 0 0 100%;
    max-width: 100%;
}

.col-lg-8 {
    flex: 0 0 100%;
    max-width: 100%;
}

/* Animation for hamburger menu */
.hamburger.active span:nth-child(1) {
    transform: translateY(11px) rotate(45deg);
}

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

.hamburger.active span:nth-child(3) {
    transform: translateY(-11px) rotate(-45deg);
}

/* Responsive styles */
@media (min-width: 768px) {
    .col-md-6 {
        flex: 0 0 50%;
        max-width: 50%;
    }
}

@media (min-width: 992px) {
    .col-lg-4 {
        flex: 0 0 33.333333%;
        max-width: 33.333333%;
    }
    
    .col-lg-8 {
        flex: 0 0 66.666667%;
        max-width: 66.666667%;
    }
}

@media (max-width: 768px) {
    :root {
        --header-height: 70px;
    }
    
    .nav-links {
        position: fixed;
        top: var(--header-height);
        left: 0;
        width: 100%;
        flex-direction: column;
        background-color: var(--color-background);
        padding: var(--spacing-4) 0;
        box-shadow: var(--shadow);
        transform: translateY(-100%);
        opacity: 0;
        pointer-events: none;
        transition: transform var(--transition-normal), opacity var(--transition-normal);
        z-index: 99;
    }
    
    .nav-links.active {
        transform: translateY(0);
        opacity: 1;
        pointer-events: auto;
    }
    
    .hamburger {
        display: flex;
    }
    
    .hero {
        height: 50vh;
    }
    
    .hero-content h1 {
        font-size: var(--font-size-3xl);
    }
    
    footer .container {
        flex-direction: column;
        gap: var(--spacing-4);
        text-align: center;
    }
}

@media (max-width: 480px) {
    :root {
        --header-height: 60px;
    }
    
    .hero {
        height: 40vh;
    }
    
    .hero-content {
        padding: var(--spacing-4);
    }
    
    .hero-content h1 {
        font-size: var(--font-size-2xl);
    }
    
    .subtitle {
        font-size: var(--font-size-base);
    }
    
    .card {
        padding: var(--spacing-4);
    }
}