/* ══════════ Reset & base ══════════ */
*, *::before, *::after { margin: 0; padding: 0; box-sizing: border-box; }

:root {
    --hdr-h: 52px;
    --c-bg: #f4f6f9;
    --c-surface: #ffffff;
    --c-primary: #3b82f6;
    --c-primary-dark: #2563eb;
    --c-text: #1e293b;
    --c-text-muted: #64748b;
    --c-border: #e2e8f0;
    --c-success: #16a34a;
    --c-danger: #dc2626;
    --c-warning: #d97706;
    --shadow-sm: 0 1px 3px rgba(0,0,0,.06);
    --shadow-md: 0 4px 12px rgba(0,0,0,.08);
    --radius: 8px;
}

body {
    font-family: 'Segoe UI', system-ui, -apple-system, sans-serif;
    background: var(--c-bg);
    color: var(--c-text);
    min-height: 100vh;
}

/* ══════════ Header bar ══════════ */
.site-header {
    height: var(--hdr-h);
    background: linear-gradient(135deg, #4facfe 0%, #00f2fe 100%);
    display: flex;
    align-items: center;
    padding: 0 24px;
    gap: 24px;
    position: sticky;
    top: 0;
    z-index: 200;
    box-shadow: 0 2px 8px rgba(0,0,0,.12);
}

.site-header .brand {
    font-size: 1.1em;
    font-weight: 700;
    color: white;
    text-decoration: none;
    white-space: nowrap;
    letter-spacing: -.02em;
}

/* Hamburger toggle (hidden on desktop) */
.hamburger {
    display: none;
    background: none;
    border: none;
    cursor: pointer;
    padding: 4px;
    margin-left: auto;
    -webkit-tap-highlight-color: transparent;
}
.hamburger svg {
    width: 24px;
    height: 24px;
    stroke: white;
    stroke-width: 2;
    stroke-linecap: round;
}
.hamburger .line {
    transition: transform .25s, opacity .2s;
    transform-origin: center;
}
.hamburger.open .line1 { transform: translateY(6px) rotate(45deg); }
.hamburger.open .line2 { opacity: 0; }
.hamburger.open .line3 { transform: translateY(-6px) rotate(-45deg); }

.site-header nav {
    display: flex;
    gap: 2px;
    margin-left: 8px;
}

.site-header nav a {
    padding: 6px 14px;
    border-radius: 6px;
    font-size: .875em;
    font-weight: 500;
    color: rgba(255,255,255,.75);
    text-decoration: none;
    transition: all .15s;
}
.site-header nav a:hover {
    background: rgba(255,255,255,.2);
    color: white;
}
.site-header nav a.active {
    background: rgba(255,255,255,.25);
    color: white;
    font-weight: 600;
}

.header-right {
    margin-left: auto;
    display: flex;
    align-items: center;
    gap: 12px;
    font-size: .85em;
    color: rgba(255,255,255,.85);
}

/* ══════════ Shared utility classes ══════════ */
.card {
    background: var(--c-surface);
    border: 1px solid var(--c-border);
    border-radius: var(--radius);
    box-shadow: var(--shadow-sm);
}

.btn {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    padding: 8px 16px;
    border: none;
    border-radius: 6px;
    font-size: .875em;
    font-weight: 600;
    cursor: pointer;
    transition: all .15s;
    text-decoration: none;
    line-height: 1.4;
}
.btn-primary { background: var(--c-primary); color: white; }
.btn-primary:hover { background: var(--c-primary-dark); }
.btn-primary:disabled { opacity: .5; cursor: not-allowed; }
.btn-danger  { background: var(--c-danger); color: white; }
.btn-danger:hover  { background: #b91c1c; }
.btn-outline {
    background: var(--c-surface);
    color: var(--c-text-muted);
    border: 1px solid var(--c-border);
}
.btn-outline:hover { background: #f8fafc; color: var(--c-text); }
.btn-success { background: var(--c-success); color: white; }
.btn-success:hover { background: #15803d; }
.btn-warning { background: var(--c-warning); color: white; }
.btn-warning:hover { background: #b45309; }

.badge {
    display: inline-block;
    padding: 2px 8px;
    border-radius: 10px;
    font-size: .8em;
    font-weight: 600;
}
.badge-pos { background: #fee2e2; color: #dc2626; }
.badge-neg { background: #dcfce7; color: #16a34a; }
.badge-null { background: #f1f5f9; color: #94a3b8; }

/* ══════════ Toast (shared) ══════════ */
.toast {
    position: fixed;
    bottom: 24px;
    right: 24px;
    padding: 12px 22px;
    border-radius: var(--radius);
    color: white;
    font-size: .875em;
    font-weight: 600;
    z-index: 2000;
    opacity: 0;
    transform: translateY(10px);
    transition: all .25s;
    pointer-events: none;
}
.toast.show { opacity: 1; transform: none; }
.toast-success { background: var(--c-success); }
.toast-error { background: var(--c-danger); }

/* ══════════ Responsive ══════════ */
@media (max-width: 768px) {
    .site-header {
        padding: 0 14px;
        gap: 0;
        flex-wrap: wrap;
        height: auto;
        min-height: var(--hdr-h);
    }

    .hamburger { display: block; }

    .nav-collapse {
        display: none;
        width: 100%;
        flex-direction: column;
        padding: 6px 0 14px;
        order: 10; /* push below header row */
    }
    .nav-collapse.open { display: flex; }

    .site-header nav {
        flex-direction: column;
        gap: 0;
        margin-left: 0;
        width: 100%;
    }
    .site-header nav a {
        padding: 10px 14px;
        border-radius: 6px;
        font-size: .92em;
    }
    .site-header nav a:hover,
    .site-header nav a.active {
        background: rgba(255,255,255,.18);
    }

    .header-right {
        width: 100%;
        padding: 10px 14px 4px;
        margin-left: 0;
        border-top: 1px solid rgba(255,255,255,.15);
        gap: 14px;
    }
}