/* ---------------------------------------------------------
   Stas Lebedev — Minimalist Portfolio Stylesheet
   Pure B&W Adaptive CSS Design (Light / Dark Mode)
--------------------------------------------------------- */

/* Reset & Base Variables */
:root {
    /* Fonts */
    --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    --font-serif: 'Cormorant Garamond', Georgia, serif;

    /* Transition Speeds */
    --transition-smooth: all 0.4s cubic-bezier(0.16, 1, 0.3, 1);
    --transition-fast: all 0.2s ease;
}

/* Light Theme Variables */
.light-theme {
    --bg-color: #fafafa;
    --bg-card: #ffffff;
    --text-primary: #111111;
    --text-secondary: #555555;
    --text-muted: #888888;
    --border-color: #e5e5e5;
    --border-focus: #111111;
    --btn-primary-bg: #111111;
    --btn-primary-text: #fafafa;
    --btn-secondary-bg: transparent;
    --btn-secondary-text: #111111;
    --btn-secondary-border: #111111;
    --btn-hover-bg: #eaeaea;
    --selection-bg: #111111;
    --selection-text: #fafafa;
}

/* Dark Theme Variables */
.dark-theme {
    --bg-color: #0c0c0c;
    --bg-card: #141414;
    --text-primary: #f5f5f5;
    --text-secondary: #aaaaaa;
    --text-muted: #666666;
    --border-color: #222222;
    --border-focus: #f5f5f5;
    --btn-primary-bg: #f5f5f5;
    --btn-primary-text: #0c0c0c;
    --btn-secondary-bg: transparent;
    --btn-secondary-text: #f5f5f5;
    --btn-secondary-border: #f5f5f5;
    --btn-hover-bg: #1c1c1c;
    --selection-bg: #f5f5f5;
    --selection-text: #0c0c0c;
}

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

html {
    scroll-behavior: smooth;
    font-size: 16px;
    -webkit-text-size-adjust: 100%;
}

body {
    background-color: var(--bg-color);
    color: var(--text-primary);
    font-family: var(--font-sans);
    line-height: 1.6;
    text-rendering: optimizeLegibility;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    transition: var(--transition-smooth);
    overflow-x: hidden;
}

body.home-layout {
    overflow: hidden; /* Prevent scrolling on the clean fullscreen page */
}

::selection {
    background-color: var(--selection-bg);
    color: var(--selection-text);
}

/* Accessibility Skip Link */
.skip-link {
    position: absolute;
    top: -40px;
    left: 0;
    background: var(--text-primary);
    color: var(--bg-color);
    padding: 8px 16px;
    z-index: 100;
    transition: var(--transition-fast);
}

.skip-link:focus {
    top: 0;
}

/* Layout Utilities */
.container {
    max-width: 760px;
    margin: 0 auto;
    padding: 0 2rem;
}

/* Header & Navigation (Used on About page) */
.header {
    position: sticky;
    top: 0;
    z-index: 50;
    background-color: rgba(250, 250, 250, 0.8);
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--border-color);
    transition: var(--transition-smooth);
}

.dark-theme .header {
    background-color: rgba(12, 12, 12, 0.8);
}

.header-container {
    max-width: 760px;
    margin: 0 auto;
    height: 70px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0 2rem;
}

.logo {
    font-family: var(--font-serif);
    font-size: 1.5rem;
    font-weight: 600;
    text-decoration: none;
    color: var(--text-primary);
    letter-spacing: -0.05em;
}

.nav {
    display: flex;
    gap: 1.5rem;
}

.nav-link {
    text-decoration: none;
    color: var(--text-secondary);
    font-size: 0.95rem;
    font-weight: 500;
    transition: var(--transition-fast);
}

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

/* Floating & Normal Theme Toggle Buttons */
.theme-toggle, .theme-toggle-floating {
    background: none;
    border: 1px solid var(--border-color);
    cursor: pointer;
    width: 40px;
    height: 40px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: var(--transition-smooth);
}

.theme-toggle-floating {
    position: fixed;
    top: 2rem;
    right: 2rem;
    z-index: 100;
}

.theme-toggle:hover, .theme-toggle-floating:hover {
    border-color: var(--text-primary);
}

.toggle-icon {
    width: 16px;
    height: 16px;
    border-radius: 50%;
    background-color: var(--text-primary);
    transition: var(--transition-smooth);
    position: relative;
}

/* Morphing toggle animation */
.dark-theme .toggle-icon {
    background-color: transparent;
    box-shadow: inset -5px -5px 0px 0px #f5f5f5;
    border-radius: 50%;
    width: 18px;
    height: 18px;
    transform: rotate(-15deg);
}

/* Fullscreen Centered Home Page Hero */
.fullscreen-hero {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 2rem;
    background-color: var(--bg-color);
    transition: var(--transition-smooth);
    animation: fadeIn 0.8s cubic-bezier(0.16, 1, 0.3, 1) forwards;
}

.hero-center-content {
    display: flex;
    flex-direction: column;
    align-items: center;
    text-align: center;
    max-width: 600px;
    gap: 1.25rem;
}

.profile-container-about {
    width: 240px;
    height: 240px;
    border-radius: 0;
    overflow: hidden;
    border: 1px solid var(--border-color);
    background-color: var(--bg-card);
    transition: var(--transition-smooth);
}

.profile-container-about:hover {
    border-color: var(--text-primary);
    transform: scale(1.01);
}

.profile-avatar {
    width: 100%;
    height: 100%;
    object-fit: cover;
    filter: grayscale(100%);
    transition: var(--transition-smooth);
}

.profile-avatar:hover {
    filter: grayscale(0%);
}

.hero-name-center {
    font-family: var(--font-serif);
    font-size: 3.5rem;
    font-weight: 400;
    line-height: 1.1;
    letter-spacing: -0.02em;
}

.hero-subtitle-center {
    font-size: 0.9rem;
    font-weight: 500;
    text-transform: uppercase;
    letter-spacing: 0.12em;
    color: var(--text-muted);
    margin-bottom: 0.5rem;
}

.hero-bio {
    font-size: 1.15rem;
    line-height: 1.6;
    color: var(--text-secondary);
    font-weight: 300;
    max-width: 500px;
    margin-bottom: 0.5rem;
}

.hero-nav-center {
    display: flex;
    flex-direction: column;
    gap: 1rem;
    align-items: center;
}

.hero-nav-link {
    text-decoration: none;
    color: var(--text-primary);
    font-size: 1.05rem;
    font-weight: 500;
    position: relative;
    padding-bottom: 4px;
    transition: var(--transition-fast);
}

.hero-nav-link::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 0;
    height: 1px;
    background-color: var(--text-primary);
    transition: var(--transition-fast);
}

.hero-nav-link:hover::after {
    width: 100%;
}

.hero-links {
    display: flex;
    gap: 1rem;
    margin-top: 0.5rem;
}

/* About Page Specific Styles */
.about-hero {
    padding: 6rem 0 3.5rem 0;
    animation: fadeIn 0.8s cubic-bezier(0.16, 1, 0.3, 1) forwards;
}

.about-hero-grid {
    display: grid;
    grid-template-columns: 1fr 240px;
    gap: 3.5rem;
    align-items: center;
}

.page-title {
    font-family: var(--font-serif);
    font-size: 3rem;
    font-weight: 400;
    margin-bottom: 1.25rem;
    letter-spacing: -0.02em;
}

.about-lead {
    font-size: 1.25rem;
    line-height: 1.6;
    color: var(--text-secondary);
    font-weight: 300;
}

.about-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 2.5rem;
}

.grid-col h3 {
    font-size: 1.1rem;
    font-weight: 600;
    margin-bottom: 0.75rem;
    color: var(--text-primary);
}

.grid-col p {
    font-size: 0.95rem;
    color: var(--text-secondary);
    line-height: 1.6;
}

/* Timeline (Things I Did) */
.timeline {
    display: flex;
    flex-direction: column;
    gap: 3rem;
}

.timeline-item {
    position: relative;
    padding-left: 1.5rem;
    border-left: 1px solid var(--border-color);
}

.timeline-role {
    font-size: 1.2rem;
    font-weight: 600;
    margin-bottom: 0.25rem;
}

.timeline-date {
    display: inline-block;
    font-size: 0.85rem;
    color: var(--text-muted);
    font-weight: 500;
    letter-spacing: 0.05em;
    margin-bottom: 0.75rem;
}

.timeline-item p {
    font-size: 0.975rem;
    color: var(--text-secondary);
    line-height: 1.65;
}

/* General Section Styling */
.section {
    padding: 5rem 0;
    border-top: 1px solid var(--border-color);
    animation: fadeIn 1s cubic-bezier(0.16, 1, 0.3, 1) forwards;
}

.section-title {
    font-family: var(--font-serif);
    font-size: 2rem;
    font-weight: 400;
    margin-bottom: 2.5rem;
    letter-spacing: -0.01em;
}

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 0.8rem 1.8rem;
    font-family: var(--font-sans);
    font-size: 0.9rem;
    font-weight: 500;
    text-decoration: none;
    border-radius: 4px;
    cursor: pointer;
    transition: var(--transition-fast);
}

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

.btn-primary:hover {
    opacity: 0.9;
    transform: translateY(-1px);
}

.btn-secondary {
    background-color: var(--btn-secondary-bg);
    color: var(--btn-secondary-text);
    border: 1px solid var(--btn-secondary-border);
}

.btn-secondary:hover {
    background-color: var(--btn-hover-bg);
    transform: translateY(-1px);
}

/* Contact / Connect Elements */
.contact-links {
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.contact-link {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem 0;
    border-bottom: 1px solid var(--border-color);
    text-decoration: none;
    color: var(--text-primary);
    transition: var(--transition-fast);
}

.contact-link:hover {
    border-color: var(--text-primary);
    padding-left: 0.5rem;
    padding-right: 0.5rem;
}

.contact-detail {
    color: var(--text-secondary);
    font-weight: 500;
}

/* Footer (Detail Pages) */
.footer {
    padding: 4rem 0;
    border-top: 1px solid var(--border-color);
    font-size: 0.85rem;
    color: var(--text-muted);
}

.footer-container {
    max-width: 760px;
    margin: 0 auto;
    padding: 0 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

/* Animations */
@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(10px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* Responsive Layouts */
@media (max-width: 768px) {
    .fullscreen-hero {
        padding: 1.5rem;
    }

    .hero-name-center {
        font-size: 2.75rem;
    }

    .hero-nav-center {
        gap: 1.5rem;
    }

    .page-title {
        font-size: 2.5rem;
    }

    .about-hero-grid {
        grid-template-columns: 1fr;
        gap: 2rem;
        text-align: center;
    }

    .profile-container-about {
        margin: 0 auto;
        width: 200px;
        height: 200px;
        grid-row: 1;
    }

    .footer-container {
        flex-direction: column;
        gap: 1rem;
        align-items: flex-start;
    }

    .theme-toggle-floating {
        top: 1.5rem;
        right: 1.5rem;
    }
}