* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    user-select: none;
    -webkit-user-select: none;
}

body {
    overflow: hidden;
    background: #1a1a2e;
    font-family: "Arial", sans-serif;
    color: #e4e4e7;
}

#gameCanvas {
    display: block;
    position: fixed;
    top: 44px;
    left: 0;
    cursor: default;
}

/* ── HUD ─────────────────────────────────── */
#hud {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    height: 44px;
    background: rgba(0, 0, 0, 0.78);
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0 16px;
    z-index: 20;
    backdrop-filter: blur(6px);
    border-bottom: 1px solid rgba(255, 255, 255, 0.1);
}

#hud-left {
    display: flex;
    align-items: center;
    gap: 20px;
}

#hud-right {
    display: flex;
    align-items: center;
    gap: 12px;
}

.hud-item {
    display: flex;
    align-items: center;
    gap: 6px;
    font-size: 14px;
    font-weight: 600;
}

.hud-icon {
    font-size: 16px;
}

.hud-title {
    font-size: 15px;
    font-weight: 700;
    letter-spacing: 0.04em;
}

.hud-back {
    text-decoration: none;
    color: rgba(255, 255, 255, 0.6);
    font-size: 12px;
    padding: 4px 10px;
    border: 1px solid rgba(255, 255, 255, 0.2);
    border-radius: 4px;
    transition: background 0.2s, color 0.2s;
}

.hud-back:hover {
    background: rgba(255, 255, 255, 0.1);
    color: #fff;
}

/* ── Info panel ──────────────────────────── */
#info-panel {
    position: fixed;
    bottom: 16px;
    left: 50%;
    transform: translateX(-50%);
    background: rgba(0, 0, 0, 0.82);
    border: 1px solid rgba(255, 255, 255, 0.15);
    border-radius: 8px;
    padding: 12px 20px;
    min-width: 200px;
    max-width: 360px;
    z-index: 20;
    backdrop-filter: blur(6px);
    display: none;
    text-align: center;
}

.info-name {
    font-size: 16px;
    font-weight: 700;
    margin-bottom: 6px;
}

.info-stat {
    font-size: 13px;
    color: rgba(255, 255, 255, 0.72);
    margin: 2px 0;
}

.info-hint {
    font-size: 11px;
    color: rgba(255, 255, 255, 0.38);
    margin-top: 6px;
    line-height: 1.5;
}

.info-train-btn {
    margin-top: 8px;
    padding: 6px 16px;
    background: #4caf50;
    color: #fff;
    border: none;
    border-radius: 4px;
    cursor: pointer;
    font-size: 13px;
    font-weight: 600;
    transition: background 0.2s;
}

.info-train-btn:hover:not(:disabled) {
    background: #45a049;
}

.info-train-btn:disabled {
    background: #444;
    cursor: not-allowed;
}

.info-build-btn {
    margin: 3px 0;
    display: block;
    width: 100%;
    text-align: left;
}

/* ── Controls hint ───────────────────────── */
#controls-hint {
    position: fixed;
    top: 52px;
    left: 50%;
    transform: translateX(-50%);
    background: rgba(0, 0, 0, 0.65);
    border-radius: 6px;
    padding: 5px 14px;
    font-size: 11px;
    color: rgba(255, 255, 255, 0.5);
    z-index: 20;
    pointer-events: none;
    white-space: nowrap;
    animation: fadeOutHint 3s 6s forwards;
}

@keyframes fadeOutHint {
    to {
        opacity: 0;
        visibility: hidden;
    }
}

/* ── Light mode ──────────────────────────── */
@media (prefers-color-scheme: light) {
    body {
        background: #3a5a3a;
    }

    #hud {
        background: rgba(255, 255, 255, 0.88);
        border-bottom-color: rgba(0, 0, 0, 0.1);
        color: #1a1a1a;
    }

    .hud-back {
        color: rgba(0, 0, 0, 0.5);
        border-color: rgba(0, 0, 0, 0.2);
    }

    .hud-back:hover {
        background: rgba(0, 0, 0, 0.08);
        color: #000;
    }

    #info-panel {
        background: rgba(255, 255, 255, 0.92);
        border-color: rgba(0, 0, 0, 0.12);
        color: #1a1a1a;
    }

    .info-stat {
        color: rgba(0, 0, 0, 0.62);
    }

    .info-hint {
        color: rgba(0, 0, 0, 0.38);
    }

    #controls-hint {
        background: rgba(255, 255, 255, 0.78);
        color: rgba(0, 0, 0, 0.5);
    }
}

/* ── Screen Overlays ────────────────────── */
.screen-overlay {
    position: fixed;
    inset: 0;
    background: rgba(10, 10, 20, 0.95);
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    z-index: 100;
    text-align: center;
}

.screen-title {
    font-size: 46px;
    font-weight: 700;
    letter-spacing: 0.06em;
    margin-bottom: 8px;
    color: #e4e4e7;
}

.screen-subtitle {
    font-size: 16px;
    color: rgba(255, 255, 255, 0.5);
    margin-bottom: 36px;
    max-width: 320px;
    line-height: 1.6;
}

.menu-btn {
    display: block;
    width: 220px;
    margin: 7px auto;
    padding: 13px 0;
    font-size: 18px;
    font-weight: 600;
    background: #4caf50;
    color: #fff;
    border: none;
    border-radius: 8px;
    cursor: pointer;
    transition: background 0.2s, transform 0.1s;
    text-align: center;
    text-decoration: none;
}

.menu-btn:hover {
    background: #43a047;
    transform: scale(1.03);
}

.menu-btn.secondary {
    background: rgba(255, 255, 255, 0.1);
    font-size: 15px;
    padding: 10px 0;
}

.menu-btn.secondary:hover {
    background: rgba(255, 255, 255, 0.18);
}

/* ── Difficulty options ──────────────────── */
.difficulty-group {
    text-align: left;
    margin-bottom: 28px;
}

.difficulty-group-label {
    font-size: 13px;
    font-weight: 600;
    color: rgba(255, 255, 255, 0.55);
    text-transform: uppercase;
    letter-spacing: 0.06em;
    margin-bottom: 14px;
}

.difficulty-option {
    display: flex;
    flex-direction: column;
    margin: 10px 0;
    cursor: pointer;
}

.difficulty-row {
    display: flex;
    align-items: center;
    gap: 8px;
}

.difficulty-row input[type="radio"] {
    accent-color: #4caf50;
    width: 16px;
    height: 16px;
    cursor: pointer;
}

.difficulty-name {
    font-size: 16px;
    font-weight: 600;
    cursor: pointer;
}

.difficulty-desc {
    font-size: 12px;
    color: rgba(255, 255, 255, 0.45);
    margin-left: 24px;
    margin-top: 2px;
}

/* ── Tutorial panel ──────────────────────── */
#tutorial-panel {
    position: fixed;
    top: 56px;
    left: 50%;
    transform: translateX(-50%);
    background: rgba(0, 0, 0, 0.85);
    border: 1px solid rgba(255, 255, 255, 0.18);
    border-radius: 10px;
    padding: 14px 22px;
    max-width: 420px;
    width: 90%;
    z-index: 30;
    text-align: center;
    display: none;
    backdrop-filter: blur(4px);
}

.tutorial-step-label {
    font-size: 11px;
    color: rgba(255, 255, 255, 0.4);
    margin-bottom: 4px;
    text-transform: uppercase;
    letter-spacing: 0.08em;
}

.tutorial-message {
    font-size: 15px;
    font-weight: 500;
    line-height: 1.6;
    color: #e4e4e7;
}

.tutorial-skip-btn {
    margin-top: 10px;
    font-size: 11px;
    color: rgba(255, 255, 255, 0.35);
    background: none;
    border: none;
    cursor: pointer;
    text-decoration: underline;
    padding: 0;
}

.tutorial-skip-btn:hover {
    color: rgba(255, 255, 255, 0.65);
}

/* ── Game Over overlay ───────────────────── */
#game-over {
    position: fixed;
    inset: 0;
    background: rgba(0, 0, 0, 0.78);
    display: none;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    z-index: 50;
    text-align: center;
}

#game-over h1 {
    font-size: 52px;
    margin-bottom: 12px;
}

#game-over p {
    font-size: 18px;
    opacity: 0.75;
    margin-bottom: 24px;
}

#game-over button {
    padding: 10px 28px;
    font-size: 16px;
    font-weight: 600;
    background: #4caf50;
    color: #fff;
    border: none;
    border-radius: 6px;
    cursor: pointer;
}

#game-over button:hover {
    background: #45a049;
}