/*====================================
    GLOBAL VARIABLES
====================================*/

:root {
    --primary: #17324d;
    --secondary: #4f6b87;
    --accent: #3da5ff;
    --background: #f5f7fa;
    --surface: #ffffff;
    --text: #222222;
    --muted: #666666;
    --hero-overlay: rgba(9,22,41,.65);
    --shadow: 0 5px 15px rgba(0,0,0,.12);
}

/*====================================
    RESET
====================================*/

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

body {
    font-family: Segoe UI, Arial, Helvetica, sans-serif;
    background: var(--background);
    color: var(--text);
    line-height: 1.6;
}

/*====================================
    HEADER
====================================*/

.site-header {
    background: var(--primary);
    color: white;
    padding: 20px 40px;
    box-shadow: var(--shadow);
}

.branding h1 {
    font-size: 2rem;
    font-weight: 700;
}

.branding span {
    color: #cfd9e4;
}

/*====================================
    FOOTER
====================================*/

footer a {
    color: white;
    text-decoration: none;
}

    footer a:hover, footer a:focus {
        color: var(--accent);
        text-decoration: underline;
    }

/*====================================
    SMOOTH SCROLLING
====================================*/

html {
    scroll-behavior: smooth;
}

/*====================================
    NAVIGATION
====================================*/

nav {
    margin-top: 15px;
}

    nav ul {
        list-style: none;
        display: flex;
        flex-wrap: wrap;
        gap: 20px;
    }

    nav a {
        color: white;
        text-decoration: none;
        font-weight: 600;
    }

        nav a:hover {
            color: var(--accent);
        }

/* ====================================
   BIOGRAPHY NAVIGATION
==================================== */

.bio-nav {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: 12px;
    margin-top: 20px;
}

    .bio-nav a {
        display: inline-block;
        padding: 10px 18px;
        background: var(--surface);
        color: var(--primary);
        text-decoration: none;
        font-weight: 600;
        border-radius: 20px;
        box-shadow: var(--shadow);
        transition: all .2s ease;
    }

    .bio-nav a:hover {
        background: var(--accent);
        color: white;
        transform: translateY(-2px);
    }

    .bio-nav a:focus {
        outline: none;
        box-shadow: 0 0 3px rgba(61,165,255,0.5), var(--shadow);
    }
/*====================================
    HERO
====================================*/

.hero {
    min-height: 600px;
    background-size: cover;
    background-position: center center;
    position: relative;
    display: flex;
    justify-content: center;
    align-items: center;
}

    .hero::before {
        content: "";
        position: absolute;
        inset: 0;
        background: var(--hero-overlay);
    }

.hero-content {
    position: relative;
    z-index: 10;
    text-align: center;
    color: white;
    max-width: 900px;
}

.hero h1 {
    font-size: 4rem;
    margin-bottom: 20px;
}

.hero h2 {
    font-size: 2rem;
    margin-bottom: 20px;
}

.hero p {
    font-size: 1.25rem;
}

/*====================================
    BUTTONS
====================================*/

.btn {
    display: inline-block;
    margin: 10px;
    padding: 14px 26px;
    border-radius: 6px;
    text-decoration: none;
    font-weight: 600;
}

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

    .btn-primary:hover {
        opacity: .9;
    }

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

/*====================================
    CONTENT
====================================*/

.container {
    width: 90%;
    max-width: 1400px;
    margin: auto;
    padding: 40px 0;
}

.section {
    background: var(--surface);
    box-shadow: var(--shadow);
    padding: 30px;
    margin-bottom: 30px;
    border-radius: 8px;
}

    .section h2 {
        color: var(--primary);
        margin-bottom: 20px;
    }

/*====================================
    METRIC CARDS
====================================*/

.metrics {
    display: grid;
    grid-template-columns: repeat(auto-fit,minmax(250px,1fr));
    gap: 20px;
}

.metric-card {
    background: white;
    text-align: center;
    padding: 30px;
    border-radius: 8px;
    box-shadow: var(--shadow);
}

.metric-number {
    font-size: 3rem;
    font-weight: bold;
    color: var(--primary);
}

/*====================================
    TIMELINE
====================================*/

.timeline {
    position: relative;
    margin: 50px auto;
    padding: 20px 0;
}

    .timeline::before {
        content: "";
        position: absolute;
        left: 50%;
        width: 4px;
        top: 0;
        bottom: 0;
        background: var(--primary);
    }

.timeline-item {
    width: 50%;
    padding: 20px 40px;
    position: relative;
}

.timeline-card {
    background: white;
    border-radius: 8px;
    padding: 20px;
    box-shadow: var(--shadow);
}

.timeline-year {
    font-weight: bold;
    color: var(--accent);
    font-size: 1.3rem;
}

/*====================================
    FOOTER
====================================*/

footer {
    background: var(--primary);
    color: white;
    margin-top: 50px;
}

.footer-content {
    max-width: 1400px;
    margin: auto;
    padding: 25px;
    display: flex;
    justify-content: space-between;
    flex-wrap: wrap;
}

/*====================================
    MOBILE
====================================*/

@media screen and (max-width:768px) {

    .hero h1 {
        font-size: 2.5rem;
    }

    .hero h2 {
        font-size: 1.4rem;
    }

    nav ul {
        flex-direction: column;
        gap: 10px;
    }

    .timeline::before {
        left: 20px;
    }

    .timeline-item {
        width: 100%;
        padding-left: 60px;
    }

    .footer-content {
        flex-direction: column;
        gap: 10px;
    }

    .nav-toggle {
        display: block;
        margin-bottom: 15px;
    }

    .nav-menu {
        display:none;
        flex-direction: column;
        width: 100%;
        gap: 8px;
    }

    .nav-menu.show {
        display: flex;
    }

    .nav-menu a {
        width: 100%;
        padding: 14px;
    }
}

.timeline-detail {
    background: white;
    border-radius: 8px;
    margin-bottom: 20px;
    box-shadow: var(--shadow);
    overflow: hidden;
}

    .timeline-detail summary {
        cursor: pointer;
        padding: 20px;
        font-weight: 600;
        list-style: none;
        background: white;
    }

        .timeline-detail summary:hover {
            background: #f8fafc;
        }

    .timeline-detail[open] summary {
        border-bottom: 1px solid #e5e7eb;
    }

.timeline-expanded {
    padding: 20px;
}

    .timeline-expanded ul {
        margin-left: 20px;
    }

@media screen and (max-width:768px) {

    .timeline::before {
        display: none;
    }

    .timeline-item {
        width: 100%;
        margin: 0 !important;
        padding: 0;
    }
}

.site-nav {
    margin-top: 20px;
}

.nav-menu {
    list-style: none;
    display: flex;
    flex-wrap: wrap;
    gap: 20px;
}

    .nav-menu li {
        margin: 0;
    }

    .nav-menu a {
        display: block;
        padding: 10px 14px;
        border-radius: 6px;
        color: white;
        text-decoration: none;
        font-weight: 600;
        transition: all .2s ease;
    }

        .nav-menu a:hover,
        .nav-menu a:focus {
            background: rgba(255,255,255,.12);
            outline: none;
        }

        .nav-menu a:focus-visible {
            box-shadow: 0 0 0 3px white;
        }

.nav-toggle {
    display: none;
    background: transparent;
    color: white;
    border: 1px solid rgba(255,255,255,.4);
    border-radius: 6px;
    padding: 10px 14px;
    font-size: 1rem;
    cursor: pointer;
}

/*====================================
    ACCESSIBILITY
====================================*/

.skip-link {
    position: absolute;
    left: -9999px;
    top: auto;
    width: 1px;
    height: 1px;
    overflow: hidden;
}

    .skip-link:focus {
        left: 20px;
        top: 20px;
        width: auto;
        height: auto;
        padding: 12px 20px;
        background: white;
        color: black;
        border-radius: 6px;
        z-index: 9999;
        box-shadow: 0 4px 12px rgba(0,0,0,.25);
    }

/* ====================================
            FLOATING BACK TO TOP
   ==================================== */

.floating-top {
    position: fixed;
    bottom: 30px;
    right: 30px;
    width: 48px;
    height: 48px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--accent);
    color: white;
    text-decoration: none;
    font-size: 1.5rem;
    font-weight: bold;
    border-radius: 50%;
    box-shadow: var(--shadow);
    z-index: 1000;
}

.floating-top:hover {
    background: var(--primary);
}