/* ══════════════════════════════════════════════════════════════════
   NAV.CSS — Vertical Sidebar Navigation
   Scientific OS panel aesthetic — left rail
   ══════════════════════════════════════════════════════════════════ */

/* ── Sidebar Container ───────────────────────────────────────── */
.sidebar-nav {
    position: fixed;
    top: 0;
    left: 0;
    bottom: 0;
    width: var(--nav-width);
    z-index: 1000;
    display: flex;
    flex-direction: column;
    align-items: center;
    padding: var(--sp-8) 0;
    background: transparent;
    border-right: var(--border-thin);
    transition: width var(--dur-slow) var(--ease-organic);
}

/* ── Logo / Mark ─────────────────────────────────────────────── */
.nav-logo {
    font-family: var(--font-serif);
    font-size: 1.1rem;
    color: var(--msu-green);
    letter-spacing: -0.02em;
    writing-mode: vertical-rl;
    text-orientation: mixed;
    transform: rotate(180deg);
    margin-bottom: var(--sp-8);
    user-select: none;
}

.nav-logo span {
    font-family: var(--font-mono);
    font-size: var(--fs-xs);
    color: var(--artichoke);
    letter-spacing: 0.1em;
}

/* ── Nav Items ───────────────────────────────────────────────── */
.nav-items {
    list-style: none;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--sp-1);
    flex: 1;
}

.nav-item {
    position: relative;
    width: 100%;
    display: flex;
    justify-content: center;
}

.nav-link {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 6px;
    padding: var(--sp-4) var(--sp-3);
    color: var(--artichoke);
    font-family: var(--font-mono);
    font-size: var(--fs-xs);
    letter-spacing: 0.1em;
    writing-mode: vertical-rl;
    text-orientation: mixed;
    transform: rotate(180deg);
    transition: color var(--dur-base) var(--ease-out);
    position: relative;
    width: 100%;
    text-align: center;
}

/* Index number before each link */
.nav-link::before {
    content: attr(data-index);
    font-size: 0.55rem;
    letter-spacing: 0.05em;
    color: var(--artichoke);
    opacity: 0.5;
    writing-mode: vertical-rl;
    transform: rotate(0deg);
    transition: opacity var(--dur-base) var(--ease-out);
}

/* Active indicator — small horizontal dash */
.nav-link.active {
    color: var(--msu-green);
}

.nav-link.active::after {
    content: '';
    position: absolute;
    right: 0;
    top: 50%;
    transform: translateY(-50%);
    width: 3px;
    height: 24px;
    background: var(--msu-green);
    border-radius: 2px 0 0 2px;
}

/* ── Coordinate Tooltip ──────────────────────────────────────── */
.nav-coord {
    position: absolute;
    left: calc(100% + 12px);
    top: 50%;
    transform: translateY(-50%);
    background: var(--msu-green);
    color: var(--pastel-gray);
    font-family: var(--font-mono);
    font-size: var(--fs-xs);
    padding: 4px 8px;
    white-space: nowrap;
    opacity: 0;
    pointer-events: none;
    transition: opacity var(--dur-base) var(--ease-out), transform var(--dur-base) var(--ease-out);
    transform: translateX(-8px) translateY(-50%);
    z-index: 100;
}

.nav-coord::before {
    content: '';
    position: absolute;
    right: 100%;
    top: 50%;
    transform: translateY(-50%);
    border: 4px solid transparent;
    border-right-color: var(--msu-green);
}

.nav-item:hover .nav-coord,
.nav-link:focus .nav-coord {
    opacity: 1;
    transform: translateX(0) translateY(-50%);
}

/* Hover color change */
.nav-item:hover .nav-link {
    color: var(--msu-green);
}

/* ── Connector Lines Between Nav Items ───────────────────────── */
.nav-connector {
    width: 1px;
    height: 20px;
    background: var(--artichoke-40);
    flex-shrink: 0;
}

/* ── Bottom System Info ──────────────────────────────────────── */
.nav-system-info {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--sp-2);
    font-family: var(--font-mono);
    font-size: 0.55rem;
    color: var(--artichoke);
    opacity: 0.5;
    letter-spacing: 0.05em;
    writing-mode: vertical-rl;
    transform: rotate(180deg);
}

/* ── Mobile Nav ─────────────────────────────────────────────── */
@media (max-width: 768px) {
    .sidebar-nav {
        top: 0;
        left: 0;
        right: 0;
        bottom: auto;
        width: 100%;
        height: 56px;
        flex-direction: row;
        padding: 0 var(--sp-4);
        border-right: none;
        border-bottom: var(--border-thin);
        background: rgba(244, 240, 221, 0.95);
        backdrop-filter: blur(8px);
    }

    .nav-logo {
        writing-mode: horizontal-tb;
        transform: none;
        margin-bottom: 0;
        margin-right: auto;
        font-size: 0.9rem;
    }

    .nav-items {
        flex-direction: row;
        gap: 0;
    }

    .nav-link {
        writing-mode: horizontal-tb;
        transform: none;
        padding: var(--sp-2) var(--sp-3);
        font-size: 0.6rem;
    }

    .nav-link::before {
        display: none;
    }

    .nav-link.active::after {
        top: auto;
        bottom: 0;
        right: auto;
        left: 50%;
        transform: translateX(-50%);
        width: 16px;
        height: 2px;
        border-radius: 2px;
    }

    .nav-connector {
        display: none;
    }

    .nav-system-info {
        display: none;
    }

    .nav-coord {
        display: none;
    }
}