:root {
    --color-bg: #f7f8fa;
    --color-surface: #ffffff;
    --color-text: #0f1724;
    --color-muted: #333a40;
    --color-border: #e6e9ec;
    --color-accent: #2563eb;
    --color-error: #dc2626;

    --toggle-background: rgba(0,0,0,0.04);
    --menu-bg: var(--color-surface);
    --menu-hover: rgba(0,0,0,0.04);

    --space-1: 8px;
    --space-2: 12px;
    --space-3: 24px;
    --space-4: 32px;

    --radius: 8px;
    --max-width: 1100px;
    --container-padding: 24px;

    --text-size-base: 16px;
    --leading: 1.5;
    --h1: 2rem;
    --h2: 1.5rem;
    --h3: 1.125rem;
    --h4: 1rem;
}

[data-theme="dark"] {
    --color-bg: #071020;
    --color-surface: #0b1220;
    --color-text: #e6eef8;
    --color-muted: #94a3b8;
    --color-border: rgba(255,255,255,0.04);
    --color-accent: #2563eb;
    --toggle-background: #0b172c;
    --menu-bg: var(--color-surface);
    --menu-hover: rgba(255,255,255,0.04);
}

*, *::before, *::after { box-sizing: border-box; }
html, body { height: 100%; }
html { font-size: var(--text-size-base); }
body {
    margin: 0;
    font-family: Inter, ui-sans-serif, system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    line-height: var(--leading);
    color: var(--color-text);
    background: var(--color-bg);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    transition: background-color 180ms ease, color 180ms ease;
    scroll-behavior: smooth !important;
}

body a {
    color: var(--color-accent);
    text-decoration: none;
}

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

.container {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: var(--container-padding);
}

.site-header { border-bottom: 1px solid var(--color-border); background: transparent; }
.site-header .container { display: flex; align-items: center; justify-content: space-between; gap: var(--space-3); }
.logo { font-size: 1.125rem; margin: 0; color: var(--color-text); }
.main-nav a { color: var(--color-muted); text-decoration: none; margin-left: 12px; }
.main-nav a:hover, .main-nav a:focus { color: var(--color-text); }

#theme-toggle {
    font-size: 0.9rem;
    padding: 6px 10px;
    background: transparent;
    color: var(--color-muted);
    border: 1px solid transparent;
    border-radius: 6px;
    display: inline-flex;
    align-items: center;
    gap: 8px;
}

#theme-toggle:hover, #theme-toggle:focus {
    background: var(--toggle-background);
    cursor: pointer;
    color: var(--color-text);
}

[data-theme="dark"] #theme-toggle {
    color: var(--color-muted);
}

.theme-icon { width: 18px; height: 18px; display: inline-block; position: relative; }
.theme-icon svg { width: 100%; height: 100%; display: block; }

.theme-icon .sun, .theme-icon .moon {
    transition: transform 220ms cubic-bezier(.2,.9,.2,1), opacity 220ms ease;
    transform-origin: center center;
}

.theme-icon .sun { opacity: 1; transform: scale(1); }
.theme-icon .moon { opacity: 0; transform: scale(0.6) translateY(2px); }

[data-theme="dark"] .theme-icon .sun { opacity: 0; transform: scale(0.6) rotate(20deg); }
[data-theme="dark"] .theme-icon .moon { opacity: 1; transform: scale(1) translateY(0); }

.sr-only { position: absolute !important; width: 1px; height: 1px; padding: 0; margin: -1px; overflow: hidden; clip: rect(0,0,0,0); white-space: nowrap; border: 0; }

.hero { padding: var(--space-4) 0; }
.role { margin: 0 0 var(--space-1) 0; font-size: var(--h2); color: var(--color-accent); font-weight: 600; }
.lead { margin: 0 0 var(--space-2) 0; color: var(--color-muted); max-width: 60ch; }

.about, .projects, .skills, .contact { padding: var(--space-3) 0; border-top: 1px solid var(--color-border); }
h3 { margin-top: 0; font-size: var(--h3); color: var(--color-text); }

.project-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(220px, 1fr)); gap: var(--space-2); margin-top: var(--space-2); }

.project-card {
    background: var(--color-surface);
    padding: var(--space-2);
    border-radius: var(--radius);
    border: 1px solid var(--color-border);
    transition: background-color 180ms ease, border-color 180ms ease, color 180ms ease;
}
.project-card h4 { margin: 0 0 var(--space-1) 0; font-size: var(--h4); }
.project-card p { margin: 0 0 var(--space-2) 0; color: var(--color-text); }

.btn {
    display: inline-block;
    padding: calc(var(--space-1)) calc(var(--space-2));
    background: var(--color-accent);
    color: #fff;
    text-decoration: none;
    border-radius: calc(var(--radius) - 2px);
    font-weight: 600;
    border: none;
    line-height: 1;
    cursor: pointer;
    transition: background-color 140ms ease, color 140ms ease, border-color 140ms ease;
}

.btn--outline {
    background: transparent;
    color: var(--color-accent);
    border: 1px solid var(--color-accent);
}

.skill-list { display: flex; flex-wrap: wrap; gap: var(--space-1); list-style: none; padding: 0; margin: var(--space-2) 0; }
.skill-list li {
    background: transparent;
    padding: 6px 10px;
    border-radius: 6px;
    color: var(--color-muted);
    border: 1px solid var(--color-border);
    font-size: 0.95rem;
}

.site-footer { border-top: 1px solid var(--color-border); padding: var(--space-2) 0; margin-top: var(--space-3); text-align: center; color: var(--color-muted); background: transparent; }

:focus { outline: none; }
:focus-visible {
    outline: 3px solid var(--color-accent);
    outline-offset: 2px;
    border-radius: 6px;
}

.stack { display: grid; gap: var(--space-2); }

@media (max-width: 700px) {
    .site-header .container { flex-direction: column; align-items: flex-start; }
    .main-nav { margin-top: var(--space-2); }
}

@media (prefers-reduced-motion: reduce) {
    * { transition: none !important; animation: none !important; }
}