/* Apple-inspired Portfolio — Jeffrey Lai */

:root {
    --color-bg:              #ffffff;
    --color-bg-alt:          #f5f5f7;
    --color-text:            #1d1d1f;
    --color-text-secondary:  #6e6e73;
    --color-accent:          #0071e3;
    --color-accent-hover:    #0077ed;
    --color-border:          #d2d2d7;
    --font: -apple-system, BlinkMacSystemFont, 'SF Pro Display', 'SF Pro Text',
            'Helvetica Neue', Arial, sans-serif;
    --nav-height: 52px;
    --max-width:  980px;
}

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font);
    color: var(--color-text);
    background: var(--color-bg);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    line-height: 1.6;
}

/* ─── Dark mode ──────────────────────────────────────────────────────────── */

@media (prefers-color-scheme: dark) {
    :root {
        --color-bg:             #000000;
        --color-bg-alt:         #1c1c1e;
        --color-text:           #f5f5f7;
        --color-text-secondary: #a1a1a6;
        --color-accent:         #2997ff;
        --color-accent-hover:   #409cff;
        --color-border:         #3a3a3c;
    }

    #nav {
        background: rgba(0, 0, 0, 0.8) !important;
        border-bottom-color: rgba(255, 255, 255, 0.1) !important;
    }

    .app-card { background: #1c1c1e; }

    .hero-image { box-shadow: 0 20px 60px rgba(0, 0, 0, 0.5); }
}

/* ─── Navigation ───────────────────────────────────────────────────────────── */

#nav {
    position: fixed;
    inset: 0 0 auto;
    z-index: 100;
    height: var(--nav-height);
    background: rgba(255, 255, 255, 0.8);
    backdrop-filter: saturate(180%) blur(20px);
    -webkit-backdrop-filter: saturate(180%) blur(20px);
    border-bottom: 1px solid rgba(0, 0, 0, 0.1);
}

.nav-inner {
    max-width: var(--max-width);
    margin: 0 auto;
    height: 100%;
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0 22px;
}

.nav-name {
    font-size: 17px;
    font-weight: 600;
    color: var(--color-text);
    text-decoration: none;
    letter-spacing: -0.01em;
}

.nav-links {
    display: flex;
    gap: 32px;
    list-style: none;
}

.nav-links a {
    font-size: 13px;
    color: var(--color-text);
    text-decoration: none;
    opacity: 0.75;
    transition: opacity 0.2s;
}

.nav-links a:hover { opacity: 1; }

/* ─── Hero load animations ───────────────────────────────────────────────── */

@keyframes heroFadeUp {
    from { opacity: 0; transform: translateY(24px); }
    to   { opacity: 1; transform: translateY(0);    }
}

@keyframes heroFadeScale {
    from { opacity: 0; transform: scale(0.95); }
    to   { opacity: 1; transform: scale(1);    }
}

.hero-eyebrow { animation: heroFadeUp   0.8s cubic-bezier(0.25,0.46,0.45,0.94) 0.10s both; }
.hero-text h1 { animation: heroFadeUp   0.8s cubic-bezier(0.25,0.46,0.45,0.94) 0.25s both; }
.hero-sub     { animation: heroFadeUp   0.8s cubic-bezier(0.25,0.46,0.45,0.94) 0.40s both; }
.hero-btn     { animation: heroFadeUp   0.8s cubic-bezier(0.25,0.46,0.45,0.94) 0.52s both; }
.hero-image   { animation: heroFadeScale 1.0s cubic-bezier(0.25,0.46,0.45,0.94) 0.15s both; }

/* ─── Hero ──────────────────────────────────────────────────────────────────── */

#hero {
    min-height: 100vh;
    display: flex;
    align-items: center;
    padding: calc(var(--nav-height) + 72px) 22px 80px;
    background: var(--color-bg);
}

.hero-content {
    max-width: var(--max-width);
    margin: 0 auto;
    display: flex;
    align-items: center;
    gap: 72px;
    width: 100%;
}

.hero-text { flex: 1; }

.hero-eyebrow {
    font-size: 17px;
    font-weight: 500;
    color: var(--color-accent);
    margin-bottom: 12px;
    letter-spacing: -0.01em;
}

.hero-text h1 {
    font-size: clamp(56px, 7vw, 96px);
    font-weight: 700;
    line-height: 1.05;
    letter-spacing: -0.03em;
    color: var(--color-text);
    margin-bottom: 20px;
}

.hero-sub {
    font-size: 21px;
    color: var(--color-text-secondary);
    line-height: 1.55;
    max-width: 460px;
    font-weight: 400;
    margin-bottom: 36px;
}

.hero-btn {
    display: inline-block;
    background: var(--color-accent);
    color: #fff;
    font-size: 15px;
    font-weight: 500;
    padding: 13px 26px;
    border-radius: 980px;
    text-decoration: none;
    transition: background 0.2s, transform 0.15s;
}

.hero-btn:hover {
    background: var(--color-accent-hover);
    transform: scale(1.015);
}

.hero-image {
    flex-shrink: 0;
    width: 300px;
    height: 300px;
    border-radius: 50%;
    overflow: hidden;
    background: var(--color-bg-alt);
    box-shadow: 0 20px 60px rgba(0,0,0,0.10);
}

.hero-image img {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

/* ─── Section shared ─────────────────────────────────────────────────────── */

.section-header {
    text-align: center;
    margin-bottom: 64px;
}

.section-header h2 {
    font-size: clamp(42px, 5vw, 64px);
    font-weight: 700;
    letter-spacing: -0.025em;
    color: var(--color-text);
    margin-bottom: 10px;
}

.section-header p {
    font-size: 19px;
    color: var(--color-text-secondary);
}

/* ─── Portfolio ──────────────────────────────────────────────────────────── */

#portfolio {
    padding: 108px 22px;
    background: var(--color-bg-alt);
}

.app-card {
    max-width: var(--max-width);
    margin: 0 auto 32px;
    background: var(--color-bg);
    border-radius: 20px;
    overflow: hidden;

    /* scroll-fade-in */
    opacity: 0;
    transform: translateY(32px);
    transition: opacity 0.65s ease, transform 0.65s ease;
}

.app-card.visible {
    opacity: 1;
    transform: none;
}

.app-card-inner {
    display: flex;
    align-items: center;
    gap: 64px;
    padding: 64px;
}

.app-card-alt .app-card-inner {
    flex-direction: row-reverse;
}

.app-card-image {
    flex-shrink: 0;
    width: 340px;
}

.app-card-image img {
    width: 100%;
    height: auto;
    display: block;
    border-radius: 12px;
}

.app-card-content { flex: 1; }

.app-category {
    font-size: 12px;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.08em;
    color: var(--color-accent);
    margin-bottom: 8px;
}

.app-card-content h3 {
    font-size: 42px;
    font-weight: 700;
    letter-spacing: -0.025em;
    color: var(--color-text);
    margin-bottom: 4px;
    line-height: 1.1;
}

.app-tagline {
    font-size: 23px;
    color: var(--color-text-secondary);
    font-weight: 400;
    margin-bottom: 20px;
}

.app-description {
    font-size: 18px;
    color: var(--color-text-secondary);
    line-height: 1.7;
    margin-bottom: 16px;
}

.app-tech {
    font-size: 14px;
    color: var(--color-text-secondary);
    margin-bottom: 28px;
}

.app-tech strong { color: var(--color-text); }

.app-store-link img {
    height: 40px;
    width: auto;
    transition: opacity 0.2s, transform 0.15s;
}

.app-store-link:hover img {
    opacity: 0.78;
    transform: scale(1.025);
}

/* ─── Skills ─────────────────────────────────────────────────────────────── */

#skills {
    padding: 108px 22px;
    background: var(--color-bg);
}

.skills-grid {
    display: flex;
    justify-content: center;
    flex-wrap: wrap;
    gap: 40px;
    max-width: var(--max-width);
    margin: 0 auto;
}

.skill-item {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 14px;
    width: 120px;

    opacity: 0;
    transform: translateY(20px);
    transition: opacity 0.5s ease, transform 0.5s ease;
}

.skill-item.visible {
    opacity: 1;
    transform: none;
}

.skill-item i {
    font-size: 34px;
    color: var(--color-text);
}

.skill-item p {
    font-size: 13px;
    font-weight: 500;
    color: var(--color-text-secondary);
    text-align: center;
    line-height: 1.4;
}

/* ─── About ──────────────────────────────────────────────────────────────── */

#about {
    padding: 108px 22px;
    background: var(--color-bg-alt);
}

.about-inner {
    max-width: 680px;
    margin: 0 auto;
    text-align: center;

    opacity: 0;
    transform: translateY(32px);
    transition: opacity 0.65s ease, transform 0.65s ease;
}

.about-inner.visible {
    opacity: 1;
    transform: none;
}

.about-inner h2 {
    font-size: clamp(42px, 5vw, 64px);
    font-weight: 700;
    letter-spacing: -0.025em;
    color: var(--color-text);
    margin-bottom: 24px;
}

.about-inner p {
    font-size: 19px;
    color: var(--color-text-secondary);
    line-height: 1.75;
    margin-bottom: 16px;
}

.resume-btn {
    display: inline-block;
    margin-top: 20px;
    font-size: 15px;
    font-weight: 500;
    color: var(--color-accent);
    text-decoration: none;
    border: 1.5px solid var(--color-accent);
    padding: 11px 24px;
    border-radius: 980px;
    transition: background 0.2s, color 0.2s;
}

.resume-btn:hover {
    background: var(--color-accent);
    color: #fff;
}

/* ─── Footer ─────────────────────────────────────────────────────────────── */

#footer {
    padding: 40px 22px;
    background: var(--color-bg);
    border-top: 1px solid var(--color-border);
}

.footer-inner {
    max-width: var(--max-width);
    margin: 0 auto;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 16px;
}

.footer-name {
    font-size: 17px;
    font-weight: 600;
    color: var(--color-text);
}

.footer-links {
    display: flex;
    gap: 28px;
    list-style: none;
}

.footer-links a {
    font-size: 22px;
    color: var(--color-text-secondary);
    text-decoration: none;
    transition: color 0.2s;
}

.footer-links a:hover { color: var(--color-text); }

.footer-copy {
    font-size: 12px;
    color: var(--color-text-secondary);
}

/* ─── Sticky section label ───────────────────────────────────────────────── */

#section-label {
    position: fixed;
    top: calc(var(--nav-height) + 14px);
    right: 22px;
    font-size: 11px;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.09em;
    color: var(--color-text-secondary);
    background: var(--color-bg-alt);
    padding: 5px 13px;
    border-radius: 980px;
    border: 1px solid var(--color-border);
    opacity: 0;
    transform: translateY(-6px);
    transition: opacity 0.25s ease, transform 0.25s ease;
    z-index: 99;
    pointer-events: none;
}

#section-label.visible {
    opacity: 1;
    transform: none;
}

/* ─── Responsive ─────────────────────────────────────────────────────────── */

@media (max-width: 768px) {
    .nav-links { display: none; }

    .hero-content {
        flex-direction: column-reverse;
        text-align: center;
        gap: 36px;
    }

    .hero-image {
        width: 180px;
        height: 180px;
    }

    .hero-sub {
        margin-left: auto;
        margin-right: auto;
    }

    .app-card-inner,
    .app-card-alt .app-card-inner {
        flex-direction: column;
        padding: 40px 28px;
        gap: 32px;
    }

    .app-card-image {
        width: 260px;
        margin: 0 auto;
    }

    .app-card-content { text-align: center; }
}