/* ================================
   CSS-переменные (тема)
   ================================ */
:root {
    /* Цвета бренда */
    --color-bg: #0f1729;
    --color-bg-gradient: linear-gradient(135deg, #0f1729 0%, #1a2342 50%, #0f1729 100%);
    --color-panel: rgba(26, 35, 66, 0.7);
    --color-border: rgba(99, 179, 237, 0.25);
    --color-accent: #63b3ed;
    --color-accent-hover: #4299e1;
    --color-accent-glow: rgba(99, 179, 237, 0.5);
    --color-text: #e2e8f0;
    --color-text-dim: #94a3b8;
    --color-success: #48bb78;
    --color-danger: #f56565;

    /* Игровые цвета */
    --color-snake-head: #48bb78;
    --color-snake-body-1: #38a169;
    --color-snake-body-2: #2f855a;
    --color-food: #f56565;
    --color-food-glow: rgba(245, 101, 101, 0.6);
    --color-grid: rgba(99, 179, 237, 0.06);

    /* Размеры */
    --canvas-size: min(480px, 90vw);
    --cell-size: 24px;
    --grid-size: 20; /* 20x20 клеток */

    /* Отступы */
    --gap-sm: 8px;
    --gap-md: 16px;
    --gap-lg: 24px;
    --radius: 12px;
    --radius-sm: 8px;

    /* Шрифты */
    --font-main: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    --font-mono: 'Consolas', 'Monaco', monospace;
}

/* ================================
   Базовые стили
   ================================ */
* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html, body {
    height: 100%;
    font-family: var(--font-main);
    color: var(--color-text);
    background: var(--color-bg-gradient);
    background-attachment: fixed;
    overflow: hidden;
    -webkit-tap-highlight-color: transparent;
}

body {
    display: flex;
    align-items: center;
    justify-content: center;
    padding: var(--gap-md);
}

#game-container {
    width: 100%;
    max-width: 560px;
    background: var(--color-panel);
    backdrop-filter: blur(10px);
    border: 1px solid var(--color-border);
    border-radius: var(--radius);
    padding: var(--gap-lg);
    box-shadow: 0 20px 60px rgba(0, 0, 0, 0.4);
    display: flex;
    flex-direction: column;
    gap: var(--gap-md);
    max-height: 100vh;
    overflow-y: auto;
}

/* ================================
   Header
   ================================ */
#game-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: var(--gap-md);
    flex-wrap: wrap;
}

.logo {
    display: flex;
    align-items: center;
    gap: var(--gap-sm);
}

.logo-icon {
    font-size: 2rem;
    filter: drop-shadow(0 0 8px var(--color-accent-glow));
}

.logo h1 {
    font-size: 1.75rem;
    font-weight: 700;
    background: linear-gradient(135deg, var(--color-accent) 0%, var(--color-success) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    letter-spacing: -0.5px;
}

.stats {
    display: flex;
    gap: var(--gap-md);
}

.stat {
    display: flex;
    flex-direction: column;
    align-items: center;
    padding: 6px 14px;
    background: rgba(0, 0, 0, 0.25);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-sm);
    min-width: 70px;
}

.stat-label {
    font-size: 0.7rem;
    color: var(--color-text-dim);
    text-transform: uppercase;
    letter-spacing: 1px;
}

.stat-value {
    font-family: var(--font-mono);
    font-size: 1.4rem;
    font-weight: 700;
    color: var(--color-accent);
    line-height: 1.2;
}

.stat-value#highscore {
    color: #fbbf24;
}

/* ================================
   Canvas
   ================================ */
#game-main {
    display: flex;
    justify-content: center;
}

.canvas-wrapper {
    position: relative;
    width: var(--canvas-size);
    height: var(--canvas-size);
    aspect-ratio: 1 / 1;
    border-radius: var(--radius);
    overflow: hidden;
    background: #0a1224;
    box-shadow:
        0 0 0 1px var(--color-border),
        0 0 40px rgba(99, 179, 237, 0.15),
        inset 0 0 60px rgba(0, 0, 0, 0.5);
}

#game-canvas {
    display: block;
    width: 100%;
    height: 100%;
    image-rendering: pixelated;
    image-rendering: crisp-edges;
}

/* ================================
   Overlay (старт/пауза/конец)
   ================================ */
.overlay {
    position: absolute;
    inset: 0;
    display: flex;
    align-items: center;
    justify-content: center;
    background: rgba(10, 18, 36, 0.85);
    backdrop-filter: blur(8px);
    z-index: 10;
    opacity: 0;
    pointer-events: none;
    transition: opacity 0.3s ease;
}

.overlay.active {
    opacity: 1;
    pointer-events: auto;
}

.overlay-content {
    text-align: center;
    padding: var(--gap-lg);
    animation: pop-in 0.4s cubic-bezier(0.34, 1.56, 0.64, 1);
}

@keyframes pop-in {
    from {
        opacity: 0;
        transform: scale(0.8);
    }
    to {
        opacity: 1;
        transform: scale(1);
    }
}

.overlay-icon {
    font-size: 4rem;
    margin-bottom: var(--gap-sm);
    filter: drop-shadow(0 0 20px var(--color-accent-glow));
}

.overlay-content h2 {
    font-size: 1.8rem;
    margin-bottom: var(--gap-sm);
    color: var(--color-accent);
}

.overlay-content p {
    color: var(--color-text-dim);
    margin-bottom: var(--gap-md);
    line-height: 1.5;
}

.overlay-content p strong {
    color: var(--color-success);
    font-size: 1.2rem;
}

/* ================================
   Кнопки
   ================================ */
.btn-primary,
.btn-control {
    cursor: pointer;
    border: none;
    border-radius: var(--radius-sm);
    font-family: var(--font-main);
    font-weight: 600;
    transition: all 0.2s ease;
    user-select: none;
}

.btn-primary {
    background: linear-gradient(135deg, var(--color-accent) 0%, var(--color-accent-hover) 100%);
    color: white;
    padding: 12px 32px;
    font-size: 1.1rem;
    box-shadow: 0 4px 12px var(--color-accent-glow);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px var(--color-accent-glow);
}

.btn-primary:active {
    transform: translateY(0);
}

.btn-control {
    flex: 1;
    background: rgba(99, 179, 237, 0.1);
    color: var(--color-text);
    border: 1px solid var(--color-border);
    padding: 10px 14px;
    font-size: 0.95rem;
}

.btn-control:hover {
    background: rgba(99, 179, 237, 0.2);
    border-color: var(--color-accent);
    transform: translateY(-1px);
}

.btn-control:active {
    transform: translateY(0);
}

.btn-control:disabled {
    opacity: 0.4;
    cursor: not-allowed;
    transform: none;
}

.btn-control.active {
    background: var(--color-accent);
    color: var(--color-bg);
}

/* ================================
   Controls (кнопки + слайдер)
   ================================ */
#controls {
    display: flex;
    flex-direction: column;
    gap: var(--gap-sm);
}

.btn-row {
    display: flex;
    gap: var(--gap-sm);
}

.speed-control {
    display: flex;
    align-items: center;
    gap: var(--gap-sm);
    padding: 8px 12px;
    background: rgba(0, 0, 0, 0.2);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-sm);
    font-size: 0.9rem;
    color: var(--color-text-dim);
}

.speed-control label {
    white-space: nowrap;
}

#speed-slider {
    flex: 1;
    -webkit-appearance: none;
    appearance: none;
    height: 4px;
    background: var(--color-border);
    border-radius: 2px;
    outline: none;
}

#speed-slider::-webkit-slider-thumb {
    -webkit-appearance: none;
    appearance: none;
    width: 16px;
    height: 16px;
    background: var(--color-accent);
    border-radius: 50%;
    cursor: pointer;
    box-shadow: 0 0 8px var(--color-accent-glow);
}

#speed-slider::-moz-range-thumb {
    width: 16px;
    height: 16px;
    background: var(--color-accent);
    border-radius: 50%;
    cursor: pointer;
    border: none;
}

#speed-label {
    font-family: var(--font-mono);
    color: var(--color-accent);
    font-weight: 700;
    min-width: 20px;
    text-align: center;
}

/* ================================
   Mobile pad (D-pad)
   ================================ */
.mobile-pad {
    display: none;
    flex-direction: column;
    align-items: center;
    gap: 4px;
    margin: 0 auto;
    user-select: none;
}

.pad-row {
    display: flex;
    gap: 4px;
}

.pad-btn {
    width: 56px;
    height: 56px;
    border: 1px solid var(--color-border);
    background: rgba(99, 179, 237, 0.1);
    color: var(--color-text);
    border-radius: var(--radius-sm);
    font-size: 1.3rem;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: background 0.1s;
    -webkit-tap-highlight-color: transparent;
    touch-action: manipulation;
}

.pad-btn:active {
    background: var(--color-accent);
    color: var(--color-bg);
}

/* ================================
   Footer
   ================================ */
#game-footer {
    text-align: center;
    color: var(--color-text-dim);
    font-size: 0.8rem;
    padding-top: var(--gap-sm);
    border-top: 1px solid var(--color-border);
}

#game-footer p {
    margin: 4px 0;
}

#game-footer kbd {
    display: inline-block;
    padding: 2px 6px;
    background: rgba(99, 179, 237, 0.15);
    border: 1px solid var(--color-border);
    border-radius: 4px;
    font-family: var(--font-mono);
    font-size: 0.75rem;
    color: var(--color-accent);
    margin: 0 2px;
}

.hint {
    font-size: 0.75rem;
    opacity: 0.7;
}

/* ================================
   Адаптивность
   ================================ */
@media (max-width: 520px) {
    :root {
        --canvas-size: min(360px, 85vw);
        --gap-lg: 16px;
    }

    .logo h1 {
        font-size: 1.4rem;
    }

    .stat {
        padding: 4px 10px;
        min-width: 60px;
    }

    .stat-value {
        font-size: 1.1rem;
    }

    #game-container {
        padding: var(--gap-md);
    }

    .mobile-pad {
        display: flex;
    }
}

@media (hover: none) and (pointer: coarse) {
    .mobile-pad {
        display: flex;
    }
}

/* ================================
   Анимация Game Over
   ================================ */
@keyframes shake {
    0%, 100% { transform: translateX(0); }
    10%, 30%, 50%, 70%, 90% { transform: translateX(-6px); }
    20%, 40%, 60%, 80% { transform: translateX(6px); }
}

.canvas-wrapper.shake {
    animation: shake 0.4s ease;
}