/* ==============================================================================
   Y2K Retro-Kawaii Theme Variables
   ============================================================================== */
:root {
    --pink-dark: #ff477e;
    --pink-medium: #ff85a2;
    --pink-light: #fbb1bd;
    --pink-bg: #fff0f3;
    --yellow-accent: #ffeb99;
    --text-color: #5c1d30;
    --border-width: 3px;
    --shadow-offset: 4px;
    --font-heading: 'Press Start 2P', cursive;
    --font-body: 'Fredoka', sans-serif;
}

/* ==============================================================================
   Global Styles
   ============================================================================== */
* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

body {
    background-color: var(--pink-bg);
    /* Y2K Grid Pattern */
    background-image: 
        linear-gradient(to right, rgba(255, 133, 162, 0.1) 1px, transparent 1px),
        linear-gradient(to bottom, rgba(255, 133, 162, 0.1) 1px, transparent 1px);
    background-size: 25px 25px;
    font-family: var(--font-body);
    color: var(--text-color);
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    overflow-x: hidden;
    padding: 20px;
}

/* ==============================================================================
   Floating Sparkles & Particle Effects
   ============================================================================== */
.sparkles-container {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    pointer-events: none;
    z-index: 0;
}

.sparkle-particle {
    position: absolute;
    font-size: 20px;
    pointer-events: none;
    animation: floatUp 1.5s ease-out forwards;
}

@keyframes floatUp {
    0% {
        transform: translateY(0) scale(1) rotate(0deg);
        opacity: 1;
    }
    100% {
        transform: translateY(-80px) scale(0) rotate(180deg);
        opacity: 0;
    }
}

/* ==============================================================================
   Retro Windows & Widgets
   ============================================================================== */
.retro-widget {
    background-color: white;
    border: var(--border-width) solid var(--text-color);
    border-radius: 12px;
    box-shadow: var(--shadow-offset) var(--shadow-offset) 0px var(--text-color);
    overflow: hidden;
    z-index: 10;
}

.widget-header {
    background-color: var(--pink-dark);
    color: white;
    border-bottom: var(--border-width) solid var(--text-color);
    padding: 8px 12px;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.widget-title {
    font-family: var(--font-heading);
    font-size: 8px;
    letter-spacing: 1px;
}

.widget-controls {
    display: flex;
    gap: 6px;
}

.widget-controls .dot {
    width: 10px;
    height: 10px;
    border: 1.5px solid var(--text-color);
    border-radius: 50%;
    background-color: var(--yellow-accent);
}

.widget-body {
    padding: 10px;
    display: flex;
    align-items: center;
    gap: 10px;
    font-weight: 600;
}

.music-widget {
    position: fixed;
    top: 20px;
    right: 20px;
    width: 250px;
    font-size: 14px;
}

.music-widget marquee {
    color: var(--pink-dark);
    font-weight: bold;
}

/* ==============================================================================
   Main Layout & Header
   ============================================================================== */
.main-container {
    max-width: 600px;
    width: 100%;
    display: flex;
    flex-direction: column;
    align-items: center;
    z-index: 5;
}

.retro-header {
    text-align: center;
    margin-bottom: 25px;
}

.retro-header h1 {
    font-family: var(--font-heading);
    font-size: 20px;
    color: var(--pink-dark);
    text-shadow: 3px 3px 0px var(--yellow-accent), 5px 5px 0px var(--text-color);
    margin-bottom: 12px;
    animation: heartbeat 2s infinite;
}

@keyframes heartbeat {
    0%, 100% { transform: scale(1); }
    50% { transform: scale(1.03); }
}

.subtitle {
    font-size: 15px;
    font-weight: 600;
    background-color: white;
    padding: 6px 12px;
    border: 2px solid var(--text-color);
    border-radius: 20px;
    box-shadow: 2px 2px 0px var(--text-color);
}

/* ==============================================================================
   Interactive Card Deck (3D Flip)
   ============================================================================== */
.card-deck-wrapper {
    width: 320px;
    height: 420px;
    perspective: 1000px;
    margin-bottom: 25px;
}

.card-deck {
    width: 100%;
    height: 100%;
    position: relative;
}

.flip-card {
    position: absolute;
    width: 100%;
    height: 100%;
    cursor: pointer;
    visibility: hidden;
    opacity: 0;
    transform: scale(0.9) translateY(20px);
    transition: transform 0.4s ease, opacity 0.4s ease, visibility 0.4s ease;
}

.flip-card.active {
    visibility: visible;
    opacity: 1;
    transform: scale(1) translateY(0);
}

.flip-card-inner {
    position: relative;
    width: 100%;
    height: 100%;
    text-align: center;
    transition: transform 0.8s cubic-bezier(0.175, 0.885, 0.32, 1.275);
    transform-style: preserve-3d;
}

.flip-card.flipped .flip-card-inner {
    transform: rotateY(180deg);
}

.flip-card-front, .flip-card-back {
    position: absolute;
    width: 100%;
    height: 100%;
    backface-visibility: hidden;
    border: var(--border-width) solid var(--text-color);
    border-radius: 24px;
    background-color: white;
    box-shadow: var(--shadow-offset) var(--shadow-offset) 0px var(--text-color);
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: space-between;
    padding: 25px;
    overflow: hidden;
}

.flip-card-front {
    background-image: radial-gradient(var(--pink-light) 10%, transparent 11%);
    background-size: 15px 15px;
}

.flip-card-back {
    background-color: #fff9fa;
    transform: rotateY(180deg);
    border-color: var(--pink-dark);
    box-shadow: var(--shadow-offset) var(--shadow-offset) 0px var(--pink-dark);
}

.card-decor-top, .card-decor-bottom {
    font-size: 18px;
    letter-spacing: 5px;
}

.card-hamster {
    width: 160px;
    height: 160px;
    object-fit: cover;
    border: var(--border-width) solid var(--text-color);
    border-radius: 50%;
    background-color: white;
    padding: 5px;
    box-shadow: 3px 3px 0px var(--text-color);
}

.card-title-text {
    font-family: var(--font-heading);
    font-size: 14px;
    color: var(--pink-dark);
    background-color: var(--yellow-accent);
    padding: 6px 16px;
    border: 2px solid var(--text-color);
    border-radius: 12px;
    transform: rotate(-2deg);
}

.click-hint {
    font-size: 12px;
    font-weight: 700;
    letter-spacing: 1px;
    color: var(--pink-dark);
    animation: flash 1.5s infinite;
}

@keyframes flash {
    0%, 100% { opacity: 0.6; }
    50% { opacity: 1; }
}

/* Back Face Card Styles */
.flip-card-back h2 {
    font-family: var(--font-body);
    font-weight: 800;
    font-size: 22px;
    color: var(--pink-dark);
    border-bottom: 2px dashed var(--pink-light);
    padding-bottom: 6px;
    width: 100%;
}

.card-desc {
    font-size: 15px;
    line-height: 1.6;
    font-weight: 600;
    text-align: center;
    color: var(--text-color);
    margin: 15px 0;
}

/* ==============================================================================
   Button Physics & Controls
   ============================================================================== */
.retro-btn {
    background-color: var(--yellow-accent);
    color: var(--text-color);
    font-family: var(--font-body);
    font-weight: 700;
    font-size: 16px;
    padding: 10px 20px;
    border: var(--border-width) solid var(--text-color);
    border-radius: 12px;
    box-shadow: 3px 3px 0px var(--text-color);
    cursor: pointer;
    outline: none;
    transition: transform 0.1s ease, box-shadow 0.1s ease;
}

.retro-btn:active {
    transform: translate(2px, 2px);
    box-shadow: 1px 1px 0px var(--text-color);
}

.retro-btn:disabled {
    background-color: #e0e0e0;
    color: #999;
    box-shadow: none;
    cursor: not-allowed;
    transform: none;
}

.open-letter-btn {
    background-color: var(--pink-medium);
    color: white;
    border-color: var(--pink-dark);
    box-shadow: 3px 3px 0px var(--pink-dark);
}

.open-letter-btn:active {
    transform: translate(2px, 2px);
    box-shadow: 1px 1px 0px var(--pink-dark);
}

/* Deck Control Panel */
.deck-controls {
    display: flex;
    align-items: center;
    gap: 20px;
}

.nav-btn {
    width: 100px;
}

.progress-indicator {
    display: flex;
    gap: 8px;
}

.progress-indicator .heart {
    font-size: 18px;
    filter: grayscale(1);
    opacity: 0.3;
    transition: filter 0.3s ease, opacity 0.3s ease, transform 0.3s ease;
}

.progress-indicator .heart.active {
    filter: none;
    opacity: 1;
    transform: scale(1.2);
}

/* ==============================================================================
   Retro Letter Overlay / Modal (Lined Paper Vibe)
   ============================================================================== */
.letter-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100vw;
    height: 100vh;
    background-color: rgba(254, 197, 217, 0.6);
    backdrop-filter: blur(5px);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 100;
    opacity: 0;
    pointer-events: none;
    transition: opacity 0.4s ease;
}

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

.letter-window {
    width: 90%;
    max-width: 500px;
    height: 80vh;
    max-height: 600px;
    display: flex;
    flex-direction: column;
}

.letter-window .close-btn {
    background: none;
    border: none;
    color: white;
    font-family: var(--font-heading);
    font-size: 14px;
    cursor: pointer;
    padding: 0 4px;
}

.letter-body {
    flex-grow: 1;
    background-color: white;
    overflow-y: auto;
    padding: 15px;
}

.letter-paper {
    background-color: #fffdec;
    border: 1px solid #e0dbb8;
    border-radius: 8px;
    padding: 25px;
    min-height: 100%;
    box-shadow: inset 0 0 20px rgba(0, 0, 0, 0.05);
    position: relative;
    /* Red margins and blue lined-paper styling */
    background-image: 
        linear-gradient(rgba(173, 216, 230, 0.5) 1px, transparent 1px),
        linear-gradient(90deg, rgba(255, 0, 0, 0.15) 1px, transparent 1px);
    background-size: 100% 24px, 100% 100%;
    background-position: 0 10px, 40px 0;
    padding-left: 55px; /* offset for red margin line */
}

.letter-paper h3 {
    font-weight: 800;
    font-size: 20px;
    margin-bottom: 20px;
    color: var(--pink-dark);
}

.letter-paper p {
    font-size: 15px;
    line-height: 24px; /* Align text to the blue notebook lines! */
    font-weight: 600;
    margin-bottom: 24px;
    color: var(--text-color);
}

.letter-hamster {
    width: 90px;
    height: 90px;
    border: 2px solid var(--text-color);
    border-radius: 50%;
    background-color: white;
    padding: 3px;
    float: right;
    margin-left: 15px;
    margin-bottom: 15px;
    box-shadow: 2px 2px 0px var(--text-color);
}

.letter-signature {
    text-align: right;
    font-weight: bold;
    font-size: 16px;
    margin-top: 30px;
}

/* Play Button Styling */
.music-play-btn {
    background-color: var(--yellow-accent);
    color: var(--text-color);
    border: 2px solid var(--text-color);
    border-radius: 50%;
    width: 28px;
    height: 28px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 11px;
    cursor: pointer;
    box-shadow: 2px 2px 0px var(--text-color);
    outline: none;
    transition: transform 0.1s, box-shadow 0.1s;
    flex-shrink: 0;
}

.music-play-btn:active {
    transform: translate(1px, 1px);
    box-shadow: 1px 1px 0px var(--text-color);
}