:root {
    /* 2005 Skeuomorphic Tokens - INTENSE GLOSS & OVER-DESIGN */
    --desktop-top: #1B447A;
    --desktop-bottom: #528AC4;
    
    /* Plastic/Metallic Window */
    --window-inner: linear-gradient(135deg, #e3ecf5 0%, #bacddf 50%, #9cb3ce 51%, #acc3db 100%);
    --window-border: #526f8d;
    
    /* Strong deep blue/purple gradient matching flashy skins */
    --title-top: #44a5ff;
    --title-mid-light: #1664e3;
    --title-mid-dark: #0747b3;
    --title-bottom: #2b1f87; /* Purple accent introduced */
    --title-border: #041842;
    
    /* Display with slight purplish/cyan vibe */
    --display-bg: linear-gradient(180deg, #091221 0%, #17102b 100%);
    --neon-blue: #00ffff;
    --neon-purple: #c471ff;
    --black: #000000;
    --white: #FFFFFF;
    
    /* Secondary plastic buttons - slightly flatter looking but glossy */
    --btn-base: linear-gradient(180deg, #f7f9fa 0%, #c4d1de 40%, #a4b7cc 41%, #c9d8e6 100%);
    --btn-hover: linear-gradient(180deg, #ffffff 0%, #d8e2ec 40%, #b8c8d9 41%, #e3edf5 100%);
    --btn-press: linear-gradient(180deg, #a4b7cc 0%, #c4d1de 40%, #f7f9fa 100%);
    --btn-border: #587391;
    
    --track-bg: inset 0px 3px 6px rgba(0,0,0,0.6);
    --progress: linear-gradient(180deg, #6fdcff 0%, #158fff 45%, #0d5bb3 46%, #632bd6 100%);
    
    --font-ui: 'Verdana', 'Tahoma', sans-serif;
}

* { box-sizing: border-box; margin: 0; padding: 0; }

body, html {
    width: 100%; height: 100%; overflow: hidden;
    background: linear-gradient(180deg, var(--desktop-top), var(--desktop-bottom));
    font-family: var(--font-ui); font-size: 14px;
    -webkit-font-smoothing: antialiased;
}

/* Background Lively Texture - Abstract Streaks and Digital Energy */
#desktop-bg {
    position: absolute; top: 0; left: 0; width: 100%; height: 100%; z-index: 0;
    /* Chaotic streaks and glowing elements characteristic of early 2000s desktop wallpapers */
    background: 
        radial-gradient(ellipse at 80% 20%, rgba(196, 113, 255, 0.25) 0%, transparent 50%),
        radial-gradient(ellipse at 20% 80%, rgba(0, 255, 255, 0.2) 0%, transparent 50%),
        repeating-linear-gradient(45deg, rgba(255,255,255,0.01) 0%, rgba(255,255,255,0.04) 20px, transparent 20px, transparent 40px),
        url("data:image/svg+xml,%3Csvg viewBox='0 0 200 200' xmlns='http://www.w3.org/2000/svg'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='1.5' numOctaves='2' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23n)' opacity='0.06'/%3E%3C/svg%3E"),
        linear-gradient(135deg, var(--desktop-top) 0%, #2f568a 50%, var(--desktop-bottom) 100%);
    transition: filter 0.5s ease;
}

#desktop { position: relative; width: 100%; height: 100%; z-index: 1; }

#desktop.learn-mode-active ~ #desktop-bg,
body.learn-mode-active #desktop-bg {
    filter: brightness(0.55) blur(1px) desaturate(0.3);
}

/* Era Label - Glossier */
.era-label {
    position: absolute; top: 32px; left: 32px;
    color: var(--white); font-size: 1.8rem; font-weight: bold;
    letter-spacing: -0.5px; text-shadow: 0px 3px 6px rgba(0,0,0,0.8), 0 0 15px rgba(196, 113, 255, 0.8), 0 0 30px rgba(0, 255, 255, 0.4);
}

/* Mode Toggle - Glossy Tabs */
.mode-toggle { position: absolute; top: 32px; right: 32px; display: flex; gap: 4px; z-index: 100; }

.toggle-btn {
    background: var(--btn-base);
    border: 1px solid var(--btn-border); border-radius: 8px 8px 3px 3px;
    padding: 8px 24px; font-family: var(--font-ui); font-weight: bold; font-size: 1.1rem;
    color: #444; cursor: pointer; text-shadow: 0 1px 0 rgba(255,255,255,0.9);
    box-shadow: inset 0 2px 2px rgba(255,255,255,1), inset 0 -4px 6px rgba(0,0,0,0.1), 0 3px 6px rgba(0,0,0,0.3);
    transition: all 0.15s ease-in-out;
}

.toggle-btn:hover { background: var(--btn-hover); color: #222; transform: translateY(-1px); box-shadow: inset 0 2px 2px rgba(255,255,255,1), inset 0 -4px 6px rgba(0,0,0,0.1), 0 5px 8px rgba(0,0,0,0.4); }

.toggle-btn.active, .toggle-btn:active {
    background: linear-gradient(180deg, #d4e8fc 0%, #82b4ea 40%, #569ae5 41%, #c9e0f7 100%);
    box-shadow: inset 0 3px 8px rgba(0,0,0,0.5), inset 0 1px 1px rgba(255,255,255,0.5);
    color: #0747b3; transform: translateY(2px); border-color: #2b5482; text-shadow: 0 1px 0 rgba(255,255,255,0.5);
}

/* Layout */
#layout-wrapper {
    position: absolute; top: 45%; left: 50%;
    transform: translate(-50%, -50%); width: 100%; max-width: 1100px;
    display: flex; justify-content: center;
}

/* Base Window Style - Over-designed Plastic Gloss */
.window {
    background: var(--window-inner);
    border: 1px solid var(--window-border);
    border-radius: 8px 8px 6px 6px;
    box-shadow: 0 25px 55px rgba(0,0,0,0.5), inset 0 2px 2px rgba(255,255,255,0.9), inset 1px 0 0 rgba(255,255,255,0.5), inset -1px 0 0 rgba(0,0,0,0.3), inset 0 -2px 5px rgba(0,0,0,0.2);
    display: flex; flex-direction: column; padding: 4px;
}

/* OVER-DESIGNED Title Bar */
.title-bar {
    position: relative;
    background: linear-gradient(180deg, var(--title-top) 0%, var(--title-mid-light) 40%, var(--title-mid-dark) 41%, var(--title-bottom) 100%);
    border-radius: 6px 6px 0 0; color: var(--white);
    display: flex; justify-content: space-between; align-items: center;
    padding: 6px 12px; height: 38px; user-select: none;
    box-shadow: inset 0 2px 2px rgba(255,255,255,0.8), inset 0 -1px 3px rgba(0,0,0,0.4), 0 2px 4px rgba(0,0,0,0.3);
    border-bottom: 1px solid var(--title-border);
    overflow: hidden;
}

.title-bar::before {
    content: ''; position: absolute; left:-10%; right:-10%; top: 0; height: 45%;
    background: linear-gradient(180deg, rgba(255,255,255,0.7) 0%, rgba(255,255,255,0.05) 100%);
    pointer-events: none; border-radius: 50% 50% 0 0 / 10px 10px 0 0; /* Classic swoosh reflection */
}

.title-left { display: flex; align-items: center; z-index: 1;}

.title-icon {
    width: 20px; height: 20px; margin-right: 8px;
    background: radial-gradient(circle at 30% 30%, #fff 10%, #db84ff 90%);
    border-radius: 50%; border: 1px solid #002255;
    box-shadow: 0 1px 3px rgba(0,0,0,0.5); display: flex; justify-content: center; align-items: center;
}

.icon-info { color: #0747b3; font-weight: bold; font-size: 13px; text-shadow: 0 1px 0 rgba(255,255,255,0.8); }
.icon-info::after { content: 'i'; }

.title-text {
    font-weight: bold; font-size: 14px;
    text-shadow: 1px 1px 2px rgba(0,0,0,0.9), 0 0 5px rgba(255,255,255,0.3);
}

.skin-label {
    margin-left: 12px; font-size: 10px; font-weight: bold; text-transform: uppercase;
    background: linear-gradient(180deg, rgba(0,0,0,0.6) 0%, rgba(0,0,0,0.2) 100%);
    padding: 2px 6px; border-radius: 3px;
    border: 1px solid rgba(255,255,255,0.1); border-bottom: 1px solid rgba(255,255,255,0.4);
    box-shadow: inset 0 2px 4px rgba(0,0,0,0.6);
    text-shadow: 1px 1px 0 rgba(0,0,0,0.8); color: #fff;
}

.title-right { display: flex; gap: 5px; z-index: 1;}

.window-btn {
    width: 24px; height: 24px;
    background: linear-gradient(180deg, #ff9e9e 0%, #eb4141 40%, #c41e1e 41%, #ed5858 100%);
    border: 1px solid #570c0c; border-radius: 4px;
    font-family: var(--font-ui); font-weight: bold; font-size: 14px; color: white;
    box-shadow: inset 0 2px 2px rgba(255,255,255,0.7), 0 1px 2px rgba(0,0,0,0.4);
    cursor: pointer; display: flex; justify-content: center; align-items: center; text-shadow: 1px 1px 1px rgba(0,0,0,0.5);
}

.window-btn.minimize, .window-btn.maximize {
    background: linear-gradient(180deg, #fefefe 0%, #cbd6e2 40%, #b2c5d8 41%, #d0dfed 100%);
    border-color: #5c728a; color: #111; text-shadow: 0 1px 0 rgba(255,255,255,0.8);
}

.window-btn:active {
    background: linear-gradient(180deg, #b01b1b 0%, #db3333 100%);
    box-shadow: inset 0 3px 6px rgba(0,0,0,0.6); transform: translateY(1px);
}
.window-btn.minimize:active, .window-btn.maximize:active {
    background: var(--btn-press);
    box-shadow: inset 0 3px 6px rgba(0,0,0,0.5);
}

.window-content { padding: 12px; display: flex; flex-direction: column; }

/* --- MUSIC PLAYER --- */
#player-window {
    width: 650px; transition: transform 0.4s cubic-bezier(0.25, 1, 0.5, 1), opacity 0.4s ease; transform-origin: center right; margin: 0 auto; position: relative; z-index: 5;
}

/* Display Panel - Deep Space Contrast */
.display-panel {
    background: var(--display-bg);
    border: 3px solid #667e99; border-radius: 8px;
    box-shadow: inset 0 4px 15px rgba(0,0,0,0.9), 0 2px 3px rgba(255,255,255,0.8), inset 0 0 10px rgba(196, 113, 255, 0.1);
    color: var(--neon-blue); padding: 16px 20px; display: flex; justify-content: space-between; min-height: 120px; margin-bottom: 20px;
    position: relative; overflow: hidden;
}

/* Intense Glare on screen */
.display-panel::after {
    content: ''; position: absolute; top:0; left: 0; right: 0; height: 40%;
    background: linear-gradient(180deg, rgba(255,255,255,0.12) 0%, transparent 100%); pointer-events: none; border-radius: 5px 5px 0 0;
}

.display-main { display: flex; flex-direction: column; justify-content: flex-end; width: 70%; z-index: 1; padding-bottom: 2px;}

.time-display {
    font-size: 3.4rem; line-height: 1; font-weight: bold;
    text-shadow: 0 0 10px rgba(0, 255, 255, 0.6), 0 0 25px rgba(0, 255, 255, 0.4);
    font-variant-numeric: tabular-nums; margin-bottom: 8px;
}

.track-info { display: flex; flex-direction: column; gap: 4px; }

.metadata { font-size: 1.1rem; opacity: 0.9; text-transform: uppercase; letter-spacing: 1px; color: #a4f5ff; }

.song-title { font-size: 1.4rem; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; font-weight: bold; color: #fff; text-shadow: 0 0 8px rgba(196, 113, 255, 0.5); }

/* Equalizer */
.equalizer { display: flex; align-items: flex-end; gap: 4px; height: 100%; width: 25%; z-index: 1; padding-bottom: 2px;}

.bar { width: 14%; background: #1a1e26; border-radius: 3px 3px 0 0; box-shadow: inset 0 1px 0 rgba(255,255,255,0.1), inset 0 -1px 6px rgba(0,0,0,0.5); }

.playing .bar {
    background: linear-gradient(180deg, #A4FFFF 0%, #00CCCC 40%, rgba(196, 113, 255, 0.8) 100%);
    box-shadow: 0 0 15px rgba(0, 255, 255, 0.5), inset 0 1px 3px rgba(255,255,255,0.9);
}

@keyframes eqLiquid {
    0% { height: 10%; } 25% { height: 75%; } 50% { height: 95%; } 75% { height: 45%; } 100% { height: 15%; }
}
.playing .bar-1 { animation: eqLiquid 0.5s ease-in-out infinite alternate; }
.playing .bar-2 { animation: eqLiquid 0.65s ease-in-out infinite alternate-reverse; animation-delay: 0.1s;}
.playing .bar-3 { animation: eqLiquid 0.4s ease-in-out infinite alternate; animation-delay: 0.2s;}
.playing .bar-4 { animation: eqLiquid 0.8s ease-in-out infinite alternate-reverse; animation-delay: 0.3s;}
.playing .bar-5 { animation: eqLiquid 0.45s ease-in-out infinite alternate; animation-delay: 0.4s;}
.playing .bar-6 { animation: eqLiquid 0.7s ease-in-out infinite alternate-reverse; animation-delay: 0.5s;}

/* Progress Bar */
.progress-container { margin-bottom: 24px; position: relative; padding: 0 12px;}

.progress-track {
    background: var(--track-bg); border: 1px solid #718DA8; border-radius: 12px;
    box-shadow: inset 0 4px 8px rgba(0,0,0,0.7), 0 1px 1px rgba(255,255,255,0.9);
    height: 18px; width: 100%; overflow: hidden; position: relative;
}

.progress-fill {
    background: var(--progress); height: 100%; width: 0%; border-radius: 12px;
    box-shadow: inset 0 2px 4px rgba(255,255,255,0.8), inset 0 -3px 4px rgba(0,0,0,0.5), 0 0 12px rgba(196, 113, 255, 0.4);
    transition: width 0.2s linear; position: relative;
}

.progress-fill::after {
    content: ''; position: absolute; top:0; left: 0; right: 0; height: 45%;
    background: linear-gradient(rgba(255,255,255,0.7), rgba(255,255,255,0.1)); border-radius: 12px 12px 0 0;
}

/* Feature Clutter: Controls Wrapper */
.controls-wrapper {
    display: flex; justify-content: space-between; align-items: center; padding: 0 6px; margin-bottom: 8px;
}

/* Tiny Secondary Label Buttons */
.mini-controls {
    display: flex; flex-direction: column; gap: 6px; width: 40px;
}

.mini-btn {
    background: var(--btn-base); border: 1px solid var(--btn-border);
    border-radius: 4px; padding: 2px 4px; font-size: 10px; font-weight: bold; color: #444; cursor: pointer;
    box-shadow: inset 0 1px 1px rgba(255,255,255,0.9), 0 2px 4px rgba(0,0,0,0.2);
    text-shadow: 0 1px 0 rgba(255,255,255,0.8); transition: all 0.1s ease;
}
.mini-btn:hover { background: var(--btn-hover); color: #111; }
.mini-btn:active { background: var(--btn-press); box-shadow: inset 0 2px 4px rgba(0,0,0,0.4); transform: translateY(1px); }

/* Main Button Row - Hierarchy! */
.controls-row { display: flex; justify-content: center; align-items: center; gap: 8px; }

/* Flatter, smaller secondary buttons */
.control-btn {
    width: 48px; height: 48px; border-radius: 10px;
    background: var(--btn-base); border: 1px solid var(--btn-border);
    box-shadow: 0 3px 6px rgba(0,0,0,0.3), inset 0 2px 3px rgba(255,255,255,1), inset 0 -2px 5px rgba(0,0,0,0.1);
    font-size: 1.4rem; cursor: pointer; display: flex; justify-content: center; align-items: center;
    color: #3f556d; text-shadow: 0 1px 0 rgba(255,255,255,0.8);
    transition: all 0.1s ease;
}

.control-btn:hover { background: var(--btn-hover); color: #16437c; box-shadow: 0 4px 8px rgba(0,0,0,0.3), inset 0 2px 3px rgba(255,255,255,1); transform: translateY(-1px); }
.control-btn:active, .control-btn.active.pressed {
    background: var(--btn-press); box-shadow: inset 0 4px 8px rgba(0,0,0,0.5), 0 1px 1px rgba(0,0,0,0.1);
    transform: translateY(2px); border-color: #556B82; color: #11284a; text-shadow: none;
}

/* DRAMATIC PLAY BUTTON */
#ctrl-play {
    width: 85px; height: 85px; border-radius: 50%;
    background: linear-gradient(180deg, #fefefe 0%, #cbd6e2 40%, #a4c4e5 41%, #d0eefc 100%);
    font-size: 2.8rem; margin: 0 10px; color: #1646a3;
    border: 2px solid #8baac9;
    box-shadow: 0 8px 16px rgba(0,0,0,0.4), inset 0 3px 6px rgba(255,255,255,1), inset 0 -4px 8px rgba(0,0,0,0.2);
}

#ctrl-play:hover {
    background: linear-gradient(180deg, #ffffff 0%, #d8e2ec 40%, #bacbe2 41%, #e5f4ff 100%);
    box-shadow: 0 10px 20px rgba(0,0,0,0.5), inset 0 3px 6px rgba(255,255,255,1), inset 0 -4px 8px rgba(0,0,0,0.2);
    color: #0747b3;
}

#ctrl-play:active, #ctrl-play.active.pressed {
    background: linear-gradient(180deg, #ebf4fc 0%, #90badb 40%, #6da1ce 41%, #c9e8fb 100%);
    box-shadow: inset 0 6px 15px rgba(0,0,0,0.7), inset 0 1px 3px rgba(255,255,255,0.5); 
    transform: translateY(4px); color: #022d7a;
    border-color: #6a8cba;
}

/* Micro Volume Slider Clutter */
.vol-container {
    display: flex; flex-direction: column; align-items: center; gap: 4px; width: 60px;
}

.vol-label { font-size: 10px; font-weight: bold; color: #333; text-shadow: 0 1px 0 rgba(255,255,255,0.8); }

.vol-track {
    width: 100%; height: 8px; background: inset 0 2px 4px rgba(0,0,0,0.6);
    background: #111e2b; border-bottom: 1px solid rgba(255,255,255,0.6);
    border-radius: 4px; display: flex; align-items: center; padding: 0 2px;
    box-shadow: inset 0 2px 4px rgba(0,0,0,0.9);
}

.vol-thumb {
    width: 14px; height: 14px; border-radius: 50%;
    background: linear-gradient(180deg, #fff 0%, #cbd6e2 50%, #9cb3ce 100%);
    border: 1px solid #587391; box-shadow: 0 2px 4px rgba(0,0,0,0.5), inset 0 1px 2px rgba(255,255,255,1);
    margin-left: 60%; /* Aesthetic positioning */
    cursor: pointer;
}

/* Status Bar */
.status-bar {
    background: inset 0 1px 2px rgba(0,0,0,0.1); border: 1px solid #8fa9c2; border-radius: 4px; padding: 4px 8px;
    margin-top: 10px; font-size: 13px; color: #22374d; text-shadow: 0 1px 0 rgba(255,255,255,0.8); box-shadow: 0 1px 0 rgba(255,255,255,0.8); background: #d7e2ed;
}

/* --- LEARN PANEL --- */
#learn-panel {
    position: absolute; left: 0; width: 580px; height: 100%; min-height: 500px;
    transform: translateX(-60px); opacity: 0; visibility: hidden;
    transition: all 0.4s cubic-bezier(0.25, 1, 0.5, 1); z-index: 10;
}

#layout-wrapper.learn-mode #learn-panel { transform: translateX(0); opacity: 1; visibility: visible; }
#layout-wrapper.learn-mode #player-window { transform: scale(0.8) translateX(360px); }

.learn-content {
    background: var(--window-inner); flex-grow: 1; overflow-y: auto; padding: 24px; color: #1c2a38; display: flex; flex-direction: column;
}

.learn-header { border-bottom: 2px groove #aebdd1; margin-bottom: 16px; padding-bottom: 6px; }

.learn-header h3 { font-size: 1.2rem; color: #0747b3; letter-spacing: 0.5px; text-shadow: 0 1px 0 rgba(255,255,255,0.8); }

.principles-list { list-style: none; margin-bottom: 24px; }
.principles-list li { display: flex; align-items: center; margin-bottom: 16px; font-size: 1.1rem; line-height: 1.5; }
.bullet { color: #0747b3; font-size: 1.4rem; margin-right: 12px; }
.context-text { font-size: 1.1rem; line-height: 1.6; margin-bottom: 24px; }

.highlight-box {
    background: linear-gradient(135deg, #FFFCE8, #FFE285); padding: 18px; border: 1px solid #D6A800; border-radius: 8px;
    box-shadow: inset 0 2px 5px rgba(255,255,255,1), 0 4px 8px rgba(0,0,0,0.15); margin-bottom: 30px;
}

.highlight-label { font-size: 0.9rem; color: #997800; font-weight: bold; margin-bottom: 8px; text-transform: uppercase; }
.highlight-text { font-size: 1.2rem; color: #332800; font-weight: bold; }

.learn-footer { display: flex; justify-content: space-between; margin-top: auto; }
a.nav-lesson-link { text-decoration: none; }

.prev-btn, .next-btn {
    background: var(--btn-base); border: 1px solid var(--btn-border); border-radius: 6px;
    padding: 10px 18px; font-size: 1.1rem; font-weight: bold; font-family: var(--font-ui); color: #333;
    cursor: pointer; box-shadow: 0 4px 8px rgba(0,0,0,0.2), inset 0 2px 2px rgba(255,255,255,1); transition: all 0.2s ease;
}

.prev-btn:hover, .next-btn:hover { background: var(--btn-hover); color: #111; box-shadow: 0 5px 10px rgba(0,0,0,0.3), inset 0 2px 2px rgba(255,255,255,1); transform: translateY(-1px); }
.prev-btn:active, .next-btn:active { background: var(--btn-press); box-shadow: inset 0 4px 8px rgba(0,0,0,0.4); transform: translateY(2px); border-color: #6a829e;}

/* External Navigation */
.navigation-panel { position: absolute; bottom: 32px; right: 32px; display: flex; flex-direction: column; align-items: flex-end; gap: 12px; }
.nav-buttons { display: flex; gap: 14px; }

.nav-btn {
    width: 52px; height: 52px; border-radius: 50%; background: var(--btn-base); border: 1px solid var(--btn-border);
    box-shadow: 0 6px 12px rgba(0,0,0,0.3), inset 0 2px 2px rgba(255,255,255,1); font-size: 1.4rem; color: #444; cursor: pointer;
    display: flex; justify-content: center; align-items: center; transition: all 0.2s ease;
}

.nav-btn:hover { background: var(--btn-hover); color: #0747b3; box-shadow: 0 8px 16px rgba(7, 71, 179, 0.4), inset 0 2px 2px rgba(255,255,255,1); transform: translateY(-1px); }
.nav-btn:active { background: var(--btn-press); box-shadow: inset 0 5px 10px rgba(0,0,0,0.5); transform: translateY(3px); }

.nav-text { color: var(--white); font-size: 1.1rem; text-shadow: 0 2px 5px rgba(0,0,0,0.8); }