/* CSS Reset and Base Styles */
/* ========================================================================== */

/* CSS Reset */
* {
    box-sizing: border-box;
}

*::before,
*::after {
    box-sizing: inherit;
}

html {
    font-size: 16px;
    scroll-behavior: smooth;
    -webkit-text-size-adjust: 100%;
    -webkit-tap-highlight-color: rgba(0,0,0,0);
}

body {
    margin: 0;
    font-family: system-ui, -apple-system, Segoe UI, Roboto, Ubuntu, Cantarell, Noto Sans, Arial, "Apple Color Emoji", "Segoe UI Emoji";
    line-height: 1.6;
    color: var(--text-primary);
    background: var(--bg-primary);
    transition: background-color 0.3s ease, color 0.3s ease;
}

/* Skip Link for Accessibility */
.skip-link {
    position: absolute;
    top: -40px;
    left: 6px;
    background: var(--accent-primary);
    color: #fff;
    padding: 8px;
    z-index: 100;
    text-decoration: none;
    border-radius: 4px;
    font-weight: 600;
}

.skip-link:focus {
    top: 6px;
}

/* Container */
.container {
    width: min(1200px, 92vw);
    margin-inline: auto;
}

/* Typography */
h1, h2, h3, h4, h5, h6 {
    margin: 0 0 1rem 0;
    line-height: 1.2;
    font-weight: 700;
}

h1 { font-size: clamp(1.8rem, 4vw, 3rem); }
h2 { font-size: clamp(1.4rem, 3vw, 2.2rem); }
h3 { font-size: clamp(1.1rem, 2.5vw, 1.5rem); }
h4 { font-size: 1rem; }

p {
    margin: 0 0 1rem 0;
}

a {
    color: var(--accent-primary);
    text-decoration: none;
    transition: color 0.2s ease, transform 0.1s ease;
}

a:hover, a:focus {
    color: var(--accent-secondary);
    outline: none;
}

a:focus-visible {
    outline: 2px solid var(--focus-color);
    outline-offset: 2px;
    border-radius: 3px;
}

/* Buttons */
.btn {
    display: inline-block;
    padding: 0.75rem 1.25rem;
    border-radius: 8px;
    border: none;
    background: var(--accent-primary);
    color: white;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s ease;
    text-align: center;
    min-width: 120px;
}

.btn:hover {
    background: var(--accent-secondary);
    transform: translateY(-1px);
    box-shadow: 0 4px 12px rgba(0,0,0,0.15);
}

.btn:active {
    transform: translateY(0);
    box-shadow: none;
}

.btn:focus-visible {
    outline: 2px solid var(--focus-color);
    outline-offset: 2px;
}

.btn-primary {
    background: var(--accent-primary);
}

.btn-secondary {
    background: var(--bg-secondary);
    color: var(--text-primary);
    border: 2px solid var(--accent-primary);
}

.btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
    transform: none;
}

/* Forms */
input, select, textarea, button {
    font: inherit;
    color: inherit;
}

input[type="range"] {
    -webkit-appearance: none;
    appearance: none;
    background: transparent;
    width: 100%;
    height: 6px;
    border-radius: 999px;
    outline: none;
}

input[type="range"]::-webkit-slider-runnable-track {
    height: 6px;
    background: var(--bg-secondary);
    border-radius: 999px;
}

input[type="range"]::-webkit-slider-thumb {
    -webkit-appearance: none;
    appearance: none;
    margin-top: -5px;
    height: 16px;
    width: 16px;
    background: var(--accent-primary);
    border-radius: 50%;
    cursor: pointer;
    box-shadow: 0 2px 8px rgba(0,0,0,0.2);
}

input[type="range"]::-moz-range-track {
    height: 6px;
    background: var(--bg-secondary);
    border-radius: 999px;
}

input[type="range"]::-moz-range-thumb {
    height: 16px;
    width: 16px;
    background: var(--accent-primary);
    border: none;
    border-radius: 50%;
    cursor: pointer;
}

input[type="color"] {
    width: 48px;
    height: 40px;
    padding: 0;
    border: none;
    background: transparent;
    cursor: pointer;
}

label.control {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    margin-right: 1rem;
}

.sr-only {
    position: absolute !important;
    width: 1px !important;
    height: 1px !important;
    padding: 0 !important;
    margin: -1px !important;
    overflow: hidden !important;
    clip: rect(0, 0, 0, 0) !important;
    white-space: nowrap !important;
    border: 0 !important;
}

/* Layout */
.header {
    position: sticky;
    top: 0;
    z-index: 100;
    background: var(--bg-surface);
    backdrop-filter: saturate(180%) blur(10px);
    border-bottom: 1px solid var(--border-color);
    transition: background-color 0.3s ease, border-color 0.3s ease;
}

.header-inner {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 1rem 0;
    gap: 1rem;
}

.app-title {
    margin: 0;
    font-size: clamp(1.2rem, 2.5vw, 1.6rem);
    color: var(--text-primary);
}

.nav {
    display: flex;
    align-items: center;
    gap: 1rem;
}

.menu-toggle {
    display: none;
    flex-direction: column;
    background: transparent;
    border: none;
    cursor: pointer;
    padding: 0.5rem;
    border-radius: 6px;
}

.menu-toggle:hover {
    background: var(--bg-secondary);
}

.menu-toggle span {
    width: 24px;
    height: 3px;
    background: var(--text-primary);
    margin: 2px 0;
    transition: all 0.3s ease;
    border-radius: 2px;
}

.nav-menu {
    display: flex;
    list-style: none;
    margin: 0;
    padding: 0;
    gap: 0.5rem;
}

.nav-link {
    padding: 0.5rem 0.75rem;
    border-radius: 6px;
    color: var(--text-primary);
    transition: all 0.2s ease;
}

.nav-link:hover {
    background: var(--bg-secondary);
    color: var(--accent-primary);
}

.nav-link.active {
    background: var(--accent-primary);
    color: white;
}

.header-controls {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.theme-toggle, .perf-toggle {
    background: var(--bg-secondary);
    color: var(--text-primary);
    border: 2px solid var(--border-color);
    padding: 0.5rem 0.75rem;
    border-radius: 8px;
    cursor: pointer;
    transition: all 0.2s ease;
    font-size: 1.1rem;
}

.theme-toggle:hover, .perf-toggle:hover {
    background: var(--bg-tertiary);
    border-color: var(--accent-primary);
}

.language-switcher {
    display: flex;
    gap: 0.25rem;
    background: var(--bg-secondary);
    padding: 0.25rem;
    border-radius: 8px;
    border: 1px solid var(--border-color);
}

.lang-btn {
    padding: 0.5rem 0.75rem;
    border: none;
    background: transparent;
    color: var(--text-primary);
    cursor: pointer;
    border-radius: 6px;
    transition: all 0.2s ease;
}

.lang-btn:hover {
    background: var(--bg-tertiary);
}

.lang-btn[aria-pressed="true"] {
    background: var(--accent-primary);
    color: white;
}

.main {
    min-height: calc(100vh - 80px);
}

.section {
    padding: 4rem 0;
    background: var(--bg-primary);
    transition: background-color 0.3s ease;
}

.section:nth-child(even) {
    background: var(--bg-alt);
}

.section-title {
    margin-bottom: 0.5rem;
    color: var(--text-primary);
}

.section-intro {
    color: var(--text-secondary);
    font-size: 1.1rem;
    margin-bottom: 2rem;
}

.demo-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
}

.demo-card {
    background: var(--bg-surface);
    border: 1px solid var(--border-color);
    border-radius: 16px;
    padding: 1.5rem;
    transition: all 0.3s ease;
}

.demo-card:hover {
    transform: translateY(-4px);
    box-shadow: 0 8px 24px rgba(0,0,0,0.1);
}

.demo-visual {
    width: 100%;
    height: 300px;
    position: relative;
    border-radius: 12px;
    overflow: hidden;
    background: var(--bg-tertiary);
    border: 1px solid var(--border-color);
}

.demo-visual canvas {
    width: 100%;
    height: 100%;
    display: block;
}

.game-area, .drawing-area, .grid-area, .chart-area, .synth-area, .visualizer-area, .sequencer-area {
    height: 400px;
}

.demo-controls {
    display: flex;
    align-items: center;
    gap: 1rem;
    margin-top: 1rem;
    flex-wrap: wrap;
}

.score {
    margin-left: auto;
    font-weight: 700;
    color: var(--accent-primary);
}

.game-instructions, .demo-instructions {
    margin-top: 1rem;
    font-size: 0.9rem;
    color: var(--text-secondary);
    font-style: italic;
}

.features-list ul {
    list-style: none;
    padding: 0;
    margin: 1rem 0;
}

.features-list li {
    padding: 0.5rem 0;
    color: var(--text-primary);
    position: relative;
    padding-left: 1.5rem;
}

.features-list li:before {
    content: "✓";
    position: absolute;
    left: 0;
    color: var(--accent-primary);
    font-weight: 700;
}

.tech-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(120px, 1fr));
    gap: 0.75rem;
    margin-top: 1rem;
}

.tech-item {
    padding: 0.5rem 0.75rem;
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    text-align: center;
    font-weight: 600;
    color: var(--text-primary);
}

.footer {
    background: var(--bg-surface);
    border-top: 1px solid var(--border-color);
    padding: 2rem 0;
    transition: background-color 0.3s ease, border-color 0.3s ease;
}

.footer-links {
    display: flex;
    gap: 1rem;
    margin-top: 1rem;
}

.footer-links a {
    color: var(--text-secondary);
}

.footer-links a:hover {
    color: var(--accent-primary);
}

/* Modal */
.modal {
    position: fixed;
    inset: 0;
    background: rgba(0,0,0,0.5);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 1000;
    padding: 1rem;
}

.modal-content {
    background: var(--bg-surface);
    border: 1px solid var(--border-color);
    border-radius: 16px;
    width: min(500px, 95vw);
    max-height: 80vh;
    overflow: auto;
    box-shadow: 0 20px 60px rgba(0,0,0,0.3);
}

.modal-close {
    position: absolute;
    top: 1rem;
    right: 1rem;
    background: transparent;
    border: none;
    font-size: 2rem;
    cursor: pointer;
    color: var(--text-primary);
    padding: 0.5rem;
    border-radius: 8px;
}

.modal-close:hover {
    background: var(--bg-secondary);
}

.modal-body {
    padding: 2rem;
}

.setting-group {
    margin-bottom: 2rem;
}

.setting-group h3 {
    margin-bottom: 1rem;
    color: var(--text-primary);
}

.setting {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    margin-bottom: 1rem;
    cursor: pointer;
}

.setting-group .language-options {
    display: flex;
    gap: 1rem;
    flex-wrap: wrap;
}

.setting-group .language-options label {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.5rem 1rem;
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    cursor: pointer;
}

/* Loading */
.loading {
    position: fixed;
    inset: 0;
    background: var(--bg-primary);
    display: grid;
    place-items: center;
    z-index: 2000;
    transition: opacity 0.5s ease, visibility 0.5s ease;
}

.loading.hidden {
    opacity: 0;
    visibility: hidden;
}

.spinner {
    width: 50px;
    height: 50px;
    border: 4px solid var(--bg-secondary);
    border-top-color: var(--accent-primary);
    border-radius: 50%;
    animation: spin 1s linear infinite;
}

@keyframes spin {
    to { transform: rotate(360deg); }
}

/* Stats */
.stat {
    display: inline-block;
    padding: 0.35rem 0.75rem;
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: 999px;
    font-weight: 600;
    margin-right: 0.5rem;
    color: var(--text-primary);
}

.low-spec-indicator {
    background: #ff6b6b;
    color: white;
    border-color: #ff6b6b;
}

/* Utility Classes */
.hidden { display: none !important; }
.sr-only { position: absolute !important; width: 1px !important; height: 1px !important; padding: 0 !important; margin: -1px !important; overflow: hidden !important; clip: rect(0, 0, 0, 0) !important; white-space: nowrap !important; border: 0 !important; }

/* Responsive */
@media (max-width: 768px) {
    .menu-toggle {
        display: flex;
    }

    .nav-menu {
        position: fixed;
        inset: 0 0 auto 0;
        top: 70px;
        flex-direction: column;
        background: var(--bg-surface);
        border-top: 1px solid var(--border-color);
        padding: 1rem;
        gap: 1rem;
        transform: translateX(-100%);
        transition: transform 0.3s ease;
        z-index: 90;
    }

    .nav-menu[aria-hidden="false"] {
        transform: translateX(0);
    }

    .demo-visual, .game-area, .drawing-area, .grid-area, .chart-area, .synth-area, .visualizer-area, .sequencer-area {
        height: 250px;
    }

    .demo-grid {
        grid-template-columns: 1fr;
    }

    .section {
        padding: 2rem 0;
    }

    .header-controls {
        gap: 0.25rem;
    }

    .theme-toggle, .perf-toggle {
        padding: 0.4rem 0.6rem;
        font-size: 1rem;
    }

    .language-switcher {
        gap: 0.125rem;
    }

    .lang-btn {
        padding: 0.4rem 0.6rem;
        font-size: 0.9rem;
    }
}

@media (max-width: 480px) {
    .btn {
        min-width: 100px;
        padding: 0.6rem 1rem;
    }

    .demo-controls {
        flex-direction: column;
        align-items: flex-start;
    }

    .score {
        margin-left: 0;
    }
}