@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700;800&display=swap');

:root {
    --app-font: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
    --nav-bg: #ffffff;
    --nav-border: rgba(0, 0, 0, 0.06);
    --nav-text: #1d1d1f;
    --nav-muted: #6e6e73;
    --nav-hover: #1d1d1f;
    --nav-shadow: none;
    --nav-backdrop: saturate(180%) blur(20px);
    --nav-max-width: 1150px;
    --nav-padding-x: 22px;
    --nav-height: 64px;
    --nav-menu-top: var(--nav-height);
    --nav-menu-width: 260px;
}

@media (prefers-color-scheme: dark) {
    :root:not([data-theme]) {
        --nav-bg: #1d1d1f;
        --nav-border: rgba(255, 255, 255, 0.08);
        --nav-text: #f5f5f7;
        --nav-muted: #a1a1a6;
        --nav-hover: #f5f5f7;
        --nav-backdrop: saturate(180%) blur(20px);
    }
}

:root[data-theme="dark"] {
    --nav-bg: #1d1d1f;
    --nav-border: rgba(255, 255, 255, 0.08);
    --nav-text: #f5f5f7;
    --nav-muted: #a1a1a6;
    --nav-hover: #f5f5f7;
    --nav-backdrop: saturate(180%) blur(20px);
}

.topbar {
    background: var(--nav-bg);
    border-bottom: 1px solid var(--nav-border);
    padding: 0;
    position: sticky;
    top: 0;
    z-index: 1000;
    backdrop-filter: var(--nav-backdrop);
    box-shadow: var(--nav-shadow);
    font-family: var(--app-font);
}
.topbar-inner {
    max-width: var(--nav-max-width);
    margin: 0 auto;
    padding: 0 var(--nav-padding-x);
    min-height: var(--nav-height);
    display: flex;
    justify-content: flex-start;
    align-items: center;
    gap: 16px;
}
.logo {
    font-family: var(--app-font);
    font-size: 1.3rem;
    font-weight: 800;
    color: var(--nav-text);
    letter-spacing: -0.03em;
    text-decoration: none;
    white-space: nowrap;
    max-width: min(70vw, 520px);
    overflow: hidden;
    text-overflow: ellipsis;
}
.nav-links {
    display: flex;
    gap: 24px;
    align-items: center;
    margin-left: auto;
}
.nav-links a {
    color: var(--nav-muted);
    text-decoration: none;
    font-size: 14px;
    font-weight: 500;
    transition: color 0.2s;
    white-space: nowrap;
}
.nav-links a:hover { color: var(--nav-hover); }

.theme-toggle {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    border: 1px solid var(--nav-border);
    background: var(--nav-bg);
    color: var(--nav-text);
    padding: 6px 10px;
    border-radius: 999px;
    cursor: pointer;
    font-size: 12px;
    font-weight: 600;
    letter-spacing: 0.01em;
    transition: background 0.2s ease, border-color 0.2s ease, color 0.2s ease;
    margin-left: 8px;
}
.theme-toggle:hover {
    border-color: var(--nav-hover);
}
.theme-toggle-icon {
    width: 34px;
    height: 18px;
    border-radius: 999px;
    border: 1px solid var(--nav-border);
    background: rgba(148, 163, 184, 0.25);
    position: relative;
    transition: background 0.2s ease, border-color 0.2s ease;
}
.theme-toggle-icon::after {
    content: "";
    position: absolute;
    top: 2px;
    left: 2px;
    width: 12px;
    height: 12px;
    border-radius: 50%;
    background: var(--nav-text);
    transition: transform 0.2s ease, background 0.2s ease;
}
.theme-toggle.is-dark .theme-toggle-icon {
    background: rgba(59, 130, 246, 0.3);
    border-color: rgba(59, 130, 246, 0.6);
}
.theme-toggle.is-dark .theme-toggle-icon::after {
    transform: translateX(16px);
    background: #fbbf24;
}
.theme-toggle-text { font-size: 12px; }

.hamburger {
    display: none;
    flex-direction: column;
    gap: 5px;
    background: none;
    border: none;
    cursor: pointer;
    padding: 10px;
    margin-left: 8px;
}
.hamburger span {
    width: 25px;
    height: 3px;
    background: var(--nav-text);
    border-radius: 2px;
    transition: 0.3s;
}

@media (max-width: 768px) {
    .hamburger { display: flex; order: 2; }
    .logo { order: 1; }
    .theme-toggle { order: 3; }
    .theme-toggle-text { display: none; }
    .logo { font-size: 1.05rem; max-width: calc(100vw - 110px); }
    .nav-links { margin-left: 0; }

    .nav-links {
        position: fixed;
        right: -120%;
        top: var(--nav-menu-top);
        flex-direction: column;
        align-items: flex-start;
        background: var(--nav-bg);
        width: min(82vw, var(--nav-menu-width));
        height: calc(100vh - var(--nav-menu-top));
        padding: 32px 22px;
        box-shadow: -10px 0 30px rgba(0,0,0,0.08);
        border-left: 1px solid var(--nav-border);
        transition: right 0.3s ease;
        gap: 18px;
        overflow-y: auto;
    }
    .nav-links.active { right: 0; }
    .hamburger.active span:nth-child(1) { transform: translateY(8px) rotate(45deg); }
    .hamburger.active span:nth-child(2) { opacity: 0; }
    .hamburger.active span:nth-child(3) { transform: translateY(-8px) rotate(-45deg); }
}

body.nav-open { overflow: hidden; }

@media (max-width: 420px) {
    .logo { font-size: 0.95rem; max-width: calc(100vw - 96px); }
}

.site-footer {
    border-top: 1px solid var(--nav-border);
    padding: 28px 0 36px;
    color: var(--nav-muted);
    font-size: 12px;
    text-align: center;
}
.site-footer-inner {
    max-width: var(--nav-max-width);
    margin: 0 auto;
    padding: 0 var(--nav-padding-x);
    line-height: 1.5;
}

@media print { .topbar, .hamburger, .nav-links { display: none !important; } }