/* =========================================================================
   WEBSITE STYLING SHEET (CSS)
   =========================================================================
   This file controls the colors, sizes, alignment, and fonts of the page.
   Follow the comments below to easily customize the layout of your site. */

/* Import Google Fonts (Lora for serif heading, Inter for clean body text) */
@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600&family=Lora:ital,wght@0,400;0,500;0,600;1,400&display=swap');

/* Define design colors and settings so they can be changed in one place */
:root {
    --bg-main: #ffffff;         /* Background color of the entire screen */
    --text-title: #18181b;      /* Color of your name and main headers (charcoal/dark gray) */
    --text-subtitle: #6b6687;   /* Color of the subtitle (soft slate purple) */
    --text-body: #4b5563;       /* Color of your bio paragraphs (muted charcoal) */
    --text-muted: #9ca3af;      /* Color for minor symbols and arrow indicators (light gray) */
    --link-color: #18181b;      /* Default color of link text */
    --link-hover: #6b6687;      /* Color of link text when hovered over */
    --border-color: #e5e7eb;    /* Light gray borders (if used anywhere) */
    
    /* Font styles */
    --font-serif: 'Lora', Georgia, serif;
    --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
    
    /* Animation speed for links and transitions */
    --transition-smooth: 0.3s cubic-bezier(0.25, 0.8, 0.25, 1);
}

/* Reset default browser margins and spacings to start with a clean slate */
* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

/* Base styles for the document body */
html, body {
    height: 100%;
    background-color: var(--bg-main);
    color: var(--text-body);
    font-family: var(--font-sans);
    -webkit-font-smoothing: antialiased;
    overflow: hidden; /* Desktop layout: Lock height to prevent page scrolling */
}

/* Custom design for scrollbars (appears only when screen size is small) */
::-webkit-scrollbar {
    width: 6px;
    height: 6px;
}
::-webkit-scrollbar-track {
    background: transparent;
}
::-webkit-scrollbar-thumb {
    background: rgba(0, 0, 0, 0.1);
    border-radius: 3px;
}

/* Wrapper container: Keeps content aligned and adds margins around the screen edge */
.app-wrapper {
    display: flex;
    flex-direction: column;
    height: 100vh;
    padding: 40px 80px;         /* Padding: 40px top/bottom, 80px left/right */
    max-width: 1440px;          /* Maximum width to prevent content stretching on huge screens */
    margin: 0 auto;             /* Centers the website block horizontally */
}

/* --- Navigation Bar (Top) --- */
.navbar {
    display: flex;
    justify-content: flex-end; /* Align the navigation links to the right */
    align-items: center;
    height: 60px;
    margin-bottom: auto; /* Automatically pushes body content to the screen center */
}

/* Logo styling */
.logo {
    font-family: var(--font-sans);
    font-weight: 600;
    font-size: 1.1rem;
    color: var(--text-title);
    letter-spacing: -0.5px;
    text-transform: lowercase;  /* Renders the name in modern lowercase style */
}

/* List holding navigation links */
.nav-links {
    display: flex;
    gap: 32px;
    list-style: none;           /* Removes default bullet points */
}

/* Navigation items link text */
.nav-item a {
    text-decoration: none;
    font-size: 0.9rem;
    color: var(--text-body);
    transition: var(--transition-smooth);
}

.nav-item a:hover {
    color: var(--text-title);
}

.nav-item a.active {
    font-weight: 600;
    color: var(--text-title);
    border-bottom: 1.5px solid var(--text-title);
    padding-bottom: 2px;
}

/* --- Main Layout: Columns split --- */
.main-content {
    display: grid;
    grid-template-columns: 1fr 1fr;    /* Both columns share equal width for maximum image size */
    gap: 80px;                         /* Spacing space between the left and right columns */
    align-items: center;
    margin-bottom: auto;               /* Pushes the footer cleanly to the bottom */
}

/* --- Left Column: Info, Bio & Links --- */
.info-column {
    display: flex;
    flex-direction: column;
    gap: 32px;                         /* Vertical spacing between title, paragraph, and links */
    max-width: 580px;                  /* Prevents lines of text from becoming too wide to read */
}

/* Header layout block */
.heading-group {
    display: flex;
    flex-direction: column;
    gap: 8px;
}

/* Main title: e.g. "Bilal Abbasi" */
.main-title {
    font-family: var(--font-serif);
    font-size: 4rem;                   /* Large text size */
    font-weight: 500;
    line-height: 1.1;
    color: var(--text-title);
    letter-spacing: -1.5px;            /* Tightens letters closer together for clean design */
}

/* Subtitle: e.g. "Systems Engineering & Research" */
.main-subtitle {
    font-family: var(--font-serif);
    font-size: 2.75rem;
    font-weight: 400;
    line-height: 1.2;
    color: var(--text-subtitle);
    letter-spacing: -0.5px;
}

/* Bio Paragraph */
.bio-paragraph {
    font-size: 1.05rem;
    line-height: 1.65;                 /* Increases line spacing for easy reading */
    color: var(--text-body);
}

/* Outer wrapper block for the social links row */
.external-links {
    display: flex;
    flex-wrap: wrap;                   /* Wraps links to a new line if screen is narrow */
    gap: 24px;                         /* Spacing between links */
    margin-top: 16px;
}

/* Individual link button styling */
.external-link {
    text-decoration: none;
    font-size: 0.95rem;
    font-weight: 500;
    color: var(--link-color);
    display: inline-flex;
    align-items: center;
    gap: 6px;                          /* Spacing between link label and arrow icon */
    position: relative;
    padding-bottom: 2px;
    transition: var(--transition-smooth);
}

/* Creates a custom line under links that vanishes on hover */
.external-link::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 100%;
    height: 1px;
    background-color: var(--text-title);
    transform: scaleX(1);
    transform-origin: bottom left;
    transition: transform var(--transition-smooth);
}

.external-link:hover {
    color: var(--link-hover);
}

/* Animate the underline to slide away on hover */
.external-link:hover::after {
    transform: scaleX(0);
    transform-origin: bottom right;
}

/* Arrow SVG icon styling next to links */
.external-link svg {
    width: 14px;
    height: 14px;
    stroke-width: 2.5px;
    color: var(--text-muted);
    transition: var(--transition-smooth);
}

/* Animate the arrow icon to point further top-right on hover */
.external-link:hover svg {
    color: var(--link-hover);
    transform: translate(2px, -2px);
}

/* --- Right Column: Image artwork --- */
.visual-column {
    display: flex;
    justify-content: center;
    align-items: center;
}

.sketch-container {
    width: 100%;
    max-width: 100%;                   /* Allow the container to expand fully to fill its grid cell */
    display: flex;
    justify-content: center;
}

.sketch-img {
    width: 100%;
    height: auto;
    max-height: 80vh;                  /* Increased to 80vh for maximum scale within viewport bounds */
    object-fit: contain;               /* Preserves aspect ratio */
    mix-blend-mode: multiply;          /* Blends illustration background cleanly with page background */
    filter: contrast(1.02);
    opacity: 0.9;
    user-select: none;
    pointer-events: none;              /* Prevents mouse dragging/saving issues on clicks */
}

/* --- Footer --- */
.footer {
    height: 40px;
    display: flex;
    align-items: center;
    font-size: 0.8rem;
    color: var(--text-muted);
}

/* =========================================================================
   RESPONSIVE DESIGN RULES (Media Queries)
   =========================================================================
   These rules automatically tweak sizes and change column alignments on
   tablets and mobile screens so the site looks good everywhere. */

/* Tablet Screens (Slightly smaller desktop screens) */
@media (max-width: 1024px) {
    .app-wrapper {
        padding: 40px;
    }
    
    .main-content {
        gap: 40px;
    }
    
    .main-title {
        font-size: 3.2rem;
    }
    
    .main-subtitle {
        font-size: 2.2rem;
    }
}

/* Mobile Portrait & Narrow Viewports */
@media (max-width: 900px) {
    html, body {
        overflow-y: auto;              /* Enable page scrolling on mobile screens */
        height: auto;
    }
    
    .app-wrapper {
        height: auto;
        min-height: 100vh;
        padding: 32px 24px;
    }
    
    .navbar {
        margin-bottom: 60px;
    }
    
    /* Stack the left text and right image vertically instead of side-by-side */
    .main-content {
        grid-template-columns: 1fr;
        gap: 60px;
        margin-bottom: 60px;
    }
    
    .info-column {
        max-width: 100%;
    }
    
    .sketch-container {
        max-width: 400px;
    }
    
    .sketch-img {
        max-height: 45vh;
    }
    
    .footer {
        margin-top: auto;
    }
}

/* Small Smart Phones */
@media (max-width: 480px) {
    .navbar {
        flex-direction: column;
        align-items: flex-start;
        gap: 16px;
        height: auto;
    }
    
    .nav-links {
        gap: 20px;
    }
    
    .main-title {
        font-size: 2.5rem;
    }
    
    .main-subtitle {
        font-size: 1.8rem;
    }
    
    .external-links {
        gap: 16px 20px;
    }
}