/* ============================================
   Web Harmonium - Style Sheet
   Design: Dark theme + Glassmorphism + Amber accent
   Target: South Asian audience, mobile-first
   ============================================ */

/* --- CSS Variables --- */
:root {
    --bg-primary: #0a0a1a;
    --bg-secondary: #1a1a2e;
    --bg-tertiary: #16213e;
    --accent-gold: #f59e0b;
    --accent-gold-light: #fbbf24;
    --accent-red: #ef4444;
    --accent-indigo: #6366f1;
    --text-primary: #f1f5f9;
    --text-secondary: #94a3b8;
    --text-muted: #64748b;
    --glass-bg: rgba(255, 255, 255, 0.06);
    --glass-border: rgba(255, 255, 255, 0.1);
    --glass-blur: 12px;
    --radius-sm: 8px;
    --radius-md: 12px;
    --radius-lg: 16px;
    --key-white: linear-gradient(180deg, #fefefe 0%, #e8e8e0 100%);
    --key-white-active: linear-gradient(180deg, #fbbf24 0%, #f59e0b 100%);
    --key-black: linear-gradient(180deg, #2a2a2a 0%, #111 100%);
    --key-black-active: linear-gradient(180deg, #d97706 0%, #92400e 100%);
    --transition-fast: 0.15s ease;
    --transition-normal: 0.3s ease;
}

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

html {
    scroll-behavior: smooth;
    -webkit-text-size-adjust: 100%;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    background: linear-gradient(135deg, var(--bg-primary) 0%, var(--bg-secondary) 50%, var(--bg-tertiary) 100%);
    background-attachment: fixed;
    color: var(--text-primary);
    line-height: 1.6;
    min-height: 100vh;
    overflow-x: hidden;
}

/* --- Header --- */
.site-header {
    position: sticky;
    top: 0;
    z-index: 100;
    background: rgba(10, 10, 26, 0.85);
    backdrop-filter: blur(var(--glass-blur));
    -webkit-backdrop-filter: blur(var(--glass-blur));
    border-bottom: 1px solid var(--glass-border);
}

.header-inner {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0.75rem 1rem;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.logo {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    text-decoration: none;
    color: var(--text-primary);
}

.logo-icon {
    font-size: 1.5rem;
    color: var(--accent-gold);
}

.logo-text {
    font-size: 1.125rem;
    font-weight: 700;
    letter-spacing: -0.02em;
}

.header-nav {
    display: flex;
    gap: 1.5rem;
}

.header-nav a {
    color: var(--text-secondary);
    text-decoration: none;
    font-size: 0.875rem;
    transition: color var(--transition-fast);
}

.header-nav a:hover {
    color: var(--accent-gold);
}

/* --- Hero --- */
.hero {
    text-align: center;
    padding: 2rem 1rem 1.5rem;
    max-width: 800px;
    margin: 0 auto;
}

.hero h1 {
    font-size: clamp(1.5rem, 5vw, 2.5rem);
    font-weight: 800;
    background: linear-gradient(135deg, var(--accent-gold-light), var(--accent-gold), #d97706);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    line-height: 1.2;
    margin-bottom: 0.75rem;
}

.hero-subtitle {
    color: var(--text-secondary);
    font-size: clamp(0.875rem, 2.5vw, 1.125rem);
    max-width: 600px;
    margin: 0 auto;
}

/* --- Instrument Section --- */
.instrument-section {
    max-width: 960px;
    margin: 0 auto;
    padding: 0 1rem;
    position: relative;
}

/* Load Overlay */
.load-overlay {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: 3rem 1rem;
}

.btn-load {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    padding: 1rem 2.5rem;
    font-size: 1.125rem;
    font-weight: 600;
    color: var(--bg-primary);
    background: linear-gradient(135deg, var(--accent-gold-light), var(--accent-gold));
    border: none;
    border-radius: var(--radius-lg);
    cursor: pointer;
    transition: transform var(--transition-fast), box-shadow var(--transition-fast);
    box-shadow: 0 4px 24px rgba(245, 158, 11, 0.3);
}

.btn-load:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 32px rgba(245, 158, 11, 0.4);
}

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

.btn-load-icon {
    font-size: 1.5rem;
}

.load-hint {
    margin-top: 0.75rem;
    color: var(--text-muted);
    font-size: 0.8125rem;
}

/* --- Keyboard --- */
.keyboard-wrapper {
    padding: 1rem 0;
}

.keyboard-container {
    display: flex;
    position: relative;
    max-width: 100%;
    margin: 0 auto;
    height: clamp(140px, 25vw, 220px);
    user-select: none;
    -webkit-user-select: none;
    touch-action: none;
}

/* White Keys */
.key-white {
    position: relative;
    flex: 1;
    background: var(--key-white);
    border: 1px solid #ccc;
    border-radius: 0 0 var(--radius-sm) var(--radius-sm);
    cursor: pointer;
    z-index: 1;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: flex-end;
    padding-bottom: 6px;
    transition: background var(--transition-fast), box-shadow var(--transition-fast);
    box-shadow: 0 2px 4px rgba(0,0,0,0.2), inset 0 -2px 3px rgba(0,0,0,0.05);
}

.key-white:hover {
    background: linear-gradient(180deg, #f5f5ed 0%, #d4d4c8 100%);
}

.key-white.active {
    background: var(--key-white-active);
    box-shadow: 0 1px 2px rgba(0,0,0,0.3), 0 0 20px rgba(245, 158, 11, 0.5);
    transform: translateY(1px);
}

/* Black Keys */
.key-black {
    position: absolute;
    top: 0;
    width: clamp(24px, 4vw, 36px);
    height: 58%;
    background: var(--key-black);
    border: 1px solid #000;
    border-radius: 0 0 4px 4px;
    cursor: pointer;
    z-index: 2;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: flex-end;
    padding-bottom: 4px;
    transition: background var(--transition-fast), box-shadow var(--transition-fast);
    box-shadow: 0 3px 6px rgba(0,0,0,0.5), inset 0 -1px 2px rgba(255,255,255,0.05);
}

.key-black:hover {
    background: linear-gradient(180deg, #383838 0%, #1a1a1a 100%);
}

.key-black.active {
    background: var(--key-black-active);
    box-shadow: 0 1px 3px rgba(0,0,0,0.4), 0 0 16px rgba(217, 119, 6, 0.5);
    height: 56%;
}

/* Key Labels */
.key-label-sargam {
    font-size: clamp(0.5rem, 1.2vw, 0.75rem);
    font-weight: 700;
    color: var(--accent-indigo);
    line-height: 1;
}

.key-label-western {
    font-size: clamp(0.4rem, 1vw, 0.625rem);
    color: #888;
    line-height: 1;
    margin-top: 1px;
}

.key-label-shortcut {
    font-size: clamp(0.4rem, 0.9vw, 0.5625rem);
    color: #aaa;
    font-family: 'Courier New', monospace;
    line-height: 1;
    margin-top: 2px;
}

.key-black .key-label-sargam {
    color: var(--accent-gold-light);
    font-size: clamp(0.4rem, 1vw, 0.625rem);
}

.key-black .key-label-western {
    color: #999;
    font-size: clamp(0.35rem, 0.8vw, 0.5rem);
}

.key-black .key-label-shortcut {
    color: #bbb;
    font-size: clamp(0.35rem, 0.8vw, 0.5rem);
}

.key-white.active .key-label-sargam,
.key-white.active .key-label-western,
.key-white.active .key-label-shortcut {
    color: var(--bg-primary);
}

/* --- Controls Panel --- */
.controls-panel {
    max-width: 960px;
    margin: 1rem auto 0;
    padding: 0 0 1rem;
}

.controls-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
    gap: 0.75rem;
}

.control-card {
    background: var(--glass-bg);
    backdrop-filter: blur(var(--glass-blur));
    -webkit-backdrop-filter: blur(var(--glass-blur));
    border: 1px solid var(--glass-border);
    border-radius: var(--radius-md);
    padding: 0.875rem 1rem;
}

.control-card-wide {
    grid-column: 1 / -1;
}

.control-label {
    display: block;
    font-size: 0.8125rem;
    font-weight: 600;
    color: var(--text-secondary);
    margin-bottom: 0.5rem;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.control-row {
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

.control-row-center {
    justify-content: center;
}

.control-value {
    font-size: 0.875rem;
    color: var(--accent-gold);
    font-weight: 600;
    min-width: 40px;
    text-align: right;
}

.control-display {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--text-primary);
    min-width: 48px;
    text-align: center;
}

/* Slider */
.slider {
    -webkit-appearance: none;
    appearance: none;
    flex: 1;
    height: 6px;
    background: rgba(255, 255, 255, 0.1);
    border-radius: 3px;
    outline: none;
}

.slider::-webkit-slider-thumb {
    -webkit-appearance: none;
    appearance: none;
    width: 20px;
    height: 20px;
    background: var(--accent-gold);
    border-radius: 50%;
    cursor: pointer;
    box-shadow: 0 2px 8px rgba(245, 158, 11, 0.4);
}

.slider::-moz-range-thumb {
    width: 20px;
    height: 20px;
    background: var(--accent-gold);
    border-radius: 50%;
    cursor: pointer;
    border: none;
}

/* Buttons */
.btn-control {
    width: 40px;
    height: 40px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--text-primary);
    background: var(--glass-bg);
    border: 1px solid var(--glass-border);
    border-radius: var(--radius-sm);
    cursor: pointer;
    transition: background var(--transition-fast), border-color var(--transition-fast);
    min-width: 40px;
    min-height: 40px;
}

.btn-control:hover {
    background: rgba(255, 255, 255, 0.12);
    border-color: var(--accent-gold);
}

.btn-control:active {
    background: rgba(245, 158, 11, 0.2);
}

.btn-refresh {
    font-size: 1.125rem;
}

/* Switch / Toggle */
.switch {
    position: relative;
    display: inline-block;
    width: 52px;
    height: 28px;
}

.switch input {
    opacity: 0;
    width: 0;
    height: 0;
}

.switch-slider {
    position: absolute;
    cursor: pointer;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(255, 255, 255, 0.1);
    border-radius: 28px;
    transition: background var(--transition-normal);
}

.switch-slider::before {
    content: '';
    position: absolute;
    height: 22px;
    width: 22px;
    left: 3px;
    bottom: 3px;
    background: white;
    border-radius: 50%;
    transition: transform var(--transition-normal);
}

.switch input:checked + .switch-slider {
    background: var(--accent-gold);
}

.switch input:checked + .switch-slider::before {
    transform: translateX(24px);
}

/* MIDI Select */
.midi-select {
    flex: 1;
    padding: 0.5rem 0.75rem;
    font-size: 0.875rem;
    color: var(--text-primary);
    background: var(--glass-bg);
    border: 1px solid var(--glass-border);
    border-radius: var(--radius-sm);
    outline: none;
    cursor: pointer;
}

.midi-select option {
    background: var(--bg-secondary);
    color: var(--text-primary);
}

.midi-status {
    display: block;
    font-size: 0.75rem;
    color: var(--text-muted);
    margin-top: 0.25rem;
}

/* --- Ad Container --- */
.ad-container {
    max-width: 960px;
    margin: 1.5rem auto;
    padding: 0 1rem;
    text-align: center;
}

.ad-placeholder {
    background: var(--glass-bg);
    border: 1px dashed var(--glass-border);
    border-radius: var(--radius-sm);
    padding: 1.5rem;
    color: var(--text-muted);
    font-size: 0.75rem;
    text-transform: uppercase;
    letter-spacing: 0.1em;
}

/* --- Content Sections --- */
.content-section {
    max-width: 960px;
    margin: 0 auto;
    padding: 2rem 1rem;
}

.content-section {
    scroll-margin-top: 4rem;
}

.content-section h2 {
    font-size: clamp(1.25rem, 3vw, 1.75rem);
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: 1.5rem;
    text-align: center;
}

.content-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 1rem;
    margin-bottom: 2rem;
}

.content-card {
    background: var(--glass-bg);
    backdrop-filter: blur(var(--glass-blur));
    -webkit-backdrop-filter: blur(var(--glass-blur));
    border: 1px solid var(--glass-border);
    border-radius: var(--radius-md);
    padding: 1.5rem;
}

.content-card h3 {
    font-size: 1.125rem;
    font-weight: 600;
    color: var(--accent-gold);
    margin-bottom: 0.75rem;
}

.content-card p,
.content-card ol,
.content-card ul {
    color: var(--text-secondary);
    font-size: 0.9375rem;
    margin-bottom: 0.75rem;
}

.content-card ol,
.content-card ul {
    padding-left: 1.25rem;
}

.content-card li {
    margin-bottom: 0.5rem;
}

/* Shortcuts Table */
.shortcuts-section {
    margin-top: 1.5rem;
}

.shortcuts-section h3 {
    font-size: 1.125rem;
    font-weight: 600;
    color: var(--accent-gold);
    margin-bottom: 1rem;
    text-align: center;
}

.table-responsive {
    overflow-x: auto;
    -webkit-overflow-scrolling: touch;
}

.shortcuts-table {
    width: 100%;
    border-collapse: collapse;
    background: var(--glass-bg);
    border-radius: var(--radius-md);
    overflow: hidden;
}

.shortcuts-table th,
.shortcuts-table td {
    padding: 0.625rem 1rem;
    text-align: left;
    font-size: 0.875rem;
    border-bottom: 1px solid var(--glass-border);
}

.shortcuts-table th {
    background: rgba(255, 255, 255, 0.04);
    color: var(--text-secondary);
    font-weight: 600;
    text-transform: uppercase;
    font-size: 0.75rem;
    letter-spacing: 0.05em;
}

.shortcuts-table td {
    color: var(--text-primary);
}

kbd {
    display: inline-block;
    padding: 0.125rem 0.5rem;
    font-family: 'Courier New', monospace;
    font-size: 0.8125rem;
    background: rgba(255, 255, 255, 0.1);
    border: 1px solid var(--glass-border);
    border-radius: 4px;
    color: var(--accent-gold);
}

/* --- FAQ --- */
.faq-list {
    max-width: 720px;
    margin: 0 auto;
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
}

.faq-item {
    background: var(--glass-bg);
    backdrop-filter: blur(var(--glass-blur));
    -webkit-backdrop-filter: blur(var(--glass-blur));
    border: 1px solid var(--glass-border);
    border-radius: var(--radius-md);
    overflow: hidden;
}

.faq-item summary {
    padding: 1rem 1.25rem;
    font-weight: 600;
    font-size: 0.9375rem;
    cursor: pointer;
    color: var(--text-primary);
    list-style: none;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.faq-item summary::-webkit-details-marker {
    display: none;
}

.faq-item summary::after {
    content: '+';
    font-size: 1.25rem;
    color: var(--accent-gold);
    font-weight: 300;
    transition: transform var(--transition-normal);
}

.faq-item[open] summary::after {
    content: '−';
}

.faq-item p {
    padding: 0 1.25rem 1rem;
    color: var(--text-secondary);
    font-size: 0.9375rem;
    line-height: 1.7;
}

/* --- Footer --- */
.site-footer {
    margin-top: 2rem;
    border-top: 1px solid var(--glass-border);
    background: rgba(10, 10, 26, 0.6);
}

.footer-inner {
    max-width: 1200px;
    margin: 0 auto;
    padding: 1.5rem 1rem;
    display: flex;
    align-items: center;
    justify-content: space-between;
    flex-wrap: wrap;
    gap: 0.75rem;
}

.footer-inner p {
    color: var(--text-muted);
    font-size: 0.8125rem;
}

.footer-nav {
    display: flex;
    gap: 1.5rem;
}

.footer-nav a {
    color: var(--text-muted);
    text-decoration: none;
    font-size: 0.8125rem;
    transition: color var(--transition-fast);
}

.footer-nav a:hover {
    color: var(--accent-gold);
}

/* --- Responsive --- */
@media (max-width: 640px) {
    .header-nav {
        gap: 1rem;
    }

    .hero {
        padding: 1.5rem 1rem 1rem;
    }

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

    .control-card-wide {
        grid-column: 1 / -1;
    }

    .footer-inner {
        flex-direction: column;
        text-align: center;
    }

    .key-label-western,
    .key-label-shortcut {
        display: none;
    }

    .keyboard-container {
        height: 160px;
    }
}

@media (max-width: 380px) {
    .controls-grid {
        grid-template-columns: 1fr;
    }
}

/* --- Print --- */
@media print {
    .instrument-section,
    .ad-container,
    .site-header {
        display: none;
    }
}