/* Color Palette & Variables for Paper Theme */
:root {
    --paper-bg: #f5f0e6;
    --paper-letter: #fdfbf7;
    --env-back: #e3d9c6;
    --env-front: #ebe3d3;
    --env-flap: #e6dfcd;
    --env-shadow: rgba(110, 100, 85, 0.3);
    --ink-color: #2c3e50; /* Fountain pen dark blue/grey */
    --ink-light: #34495e;
    --heart-color: #e07a5f; /* Soft, warm muted red/orange */
}

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

body {
    background-color: var(--paper-bg);
    min-height: 100vh;
    font-family: 'Baskervville', serif;
    font-style: italic;
    color: var(--ink-color);
    overflow-x: hidden;
    overflow-y: auto; /* Fixed: Allow vertical scrolling on small screens */
    position: relative;
    user-select: none;
    -webkit-user-select: none;
    -webkit-tap-highlight-color: transparent;
}

/* Subtle CSS noise texture for real paper feel */
.texture-overlay {
    position: fixed;
    top: 0; left: 0; width: 100%; height: 100%;
    pointer-events: none;
    z-index: 50;
    opacity: 0.35;
    background-image: url("data:image/svg+xml,%3Csvg viewBox='0 0 200 200' xmlns='http://www.w3.org/2000/svg'%3E%3Cfilter id='noiseFilter'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.85' numOctaves='3' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23noiseFilter)'/%3E%3C/svg%3E");
    mix-blend-mode: multiply;
}

/* Hearts Container */
#hearts-container {
    position: absolute;
    top: 0; left: 0; width: 100%; height: 100%;
    pointer-events: none;
    z-index: 5;
    overflow: hidden;
}

.heart-wrapper {
    position: absolute;
    bottom: -50px;
    opacity: 0;
    animation: floatUp 15s linear forwards;
}

.heart {
    position: relative;
    width: 16px; height: 16px;
    background-color: var(--heart-color);
    transform: rotate(-45deg);
    opacity: 0.25;
    border-radius: 2px;
}

.heart::before, .heart::after {
    content: "";
    position: absolute;
    width: 16px; height: 16px;
    background-color: var(--heart-color);
    border-radius: 50%;
}
.heart::before { top: -8px; left: 0; }
.heart::after { top: 0; left: 8px; }

@keyframes floatUp {
    0% { transform: translateY(0) scale(0.6) rotate(-15deg); opacity: 0; }
    15% { opacity: 1; }
    85% { opacity: 1; }
    100% { transform: translateY(-110vh) scale(1.3) rotate(15deg); opacity: 0; }
}

/* Scene */
.scene {
    position: relative;
    width: 100%; 
    min-height: 100vh;
    display: grid; /* Grid superimposes children perfectly without breaking document flow */
    place-items: center;
    perspective: 1400px;
    z-index: 10;
    padding: 40px 0; /* Creates scrollable buffer at top and bottom */
}

/* Tap Hint */
.tap-hint {
    position: absolute;
    top: -60px; width: 100%;
    text-align: center;
    color: var(--heart-color);
    font-size: 2.2rem; font-weight: 600;
    pointer-events: none; transition: opacity 0.2s;
    z-index: 10;
    animation: bounceHint 2s infinite ease-in-out;
}
@keyframes bounceHint {
    0%, 100% { transform: translateY(0); }
    50% { transform: translateY(-8px); }
}

/* Envelope */
.envelope-wrapper {
    grid-column: 1;
    grid-row: 1;
    position: relative;
    width: 340px; height: 230px;
    transition: transform 0.1s, filter 1.2s;
    transform-style: preserve-3d;
    z-index: 20;
    filter: drop-shadow(0 15px 25px var(--env-shadow));
    cursor: pointer;
}
.envelope-wrapper.open {
    transform: translateY(120px) scale(0.7) !important;
    opacity: 0; pointer-events: none;
    transition: all 1s cubic-bezier(0.4, 0, 0.2, 1) 1.8s;
}
.envelope { position: relative; width: 100%; height: 100%; transform-style: preserve-3d; }
.envelope-back {
    position: absolute; top: 0; left: 0; width: 100%; height: 100%;
    background: var(--env-back); border-radius: 2px; z-index: 1;
}
.envelope-front {
    position: absolute; bottom: 0; left: 0; width: 0; height: 0;
    border-left: 170px solid var(--env-front);
    border-right: 170px solid var(--env-front);
    border-bottom: 115px solid var(--env-front);
    border-top: 115px solid transparent;
    z-index: 3; border-bottom-left-radius: 2px; border-bottom-right-radius: 2px;
    filter: drop-shadow(0 -1px 2px rgba(0,0,0,0.03));
}
.envelope-flap {
    position: absolute; top: 0; left: 0; width: 0; height: 0;
    border-left: 170px solid transparent;
    border-right: 170px solid transparent;
    border-top: 140px solid var(--env-flap);
    transform-origin: top; transition: transform 0.1s ease-out;
    z-index: 4; filter: drop-shadow(0 4px 6px rgba(0,0,0,0.06));
}
.envelope-wrapper.open .envelope-flap {
    transition: transform 0.8s cubic-bezier(0.4, 0, 0.2, 1);
    transform: rotateX(180deg) !important; z-index: 0;
}
.letter-mini {
    position: absolute; bottom: 10px; left: 50%;
    transform: translateX(-50%); width: 90%; height: 85%;
    background: var(--paper-letter); border-radius: 1px;
    z-index: 2; padding: 20px;
    transition: all 1.2s cubic-bezier(0.4, 0, 0.2, 1) 0.6s;
    box-shadow: 0 4px 10px rgba(0,0,0,0.05), inset 0 0 20px rgba(0,0,0,0.02);
}
.envelope-wrapper.open .letter-mini { transform: translate(-50%, -200px); }
.letter-mini .faux-line {
    height: 2px; background: rgba(44, 62, 80, 0.15); margin-bottom: 16px; border-radius: 2px;
}
.letter-mini .line-1 { width: 40%; }
.letter-mini .line-2 { width: 85%; }
.letter-mini .line-3 { width: 60%; }

/* Full Realistic Paper View for Receiver */
.full-letter-view {
    grid-column: 1;
    grid-row: 1;
    position: relative; /* Fixed: Removed absolute positioning for proper responsive height calculation */
    width: 92%; max-width: 600px;
    background: var(--paper-letter);
    background-image: 
        linear-gradient(to right, rgba(255,255,255,0) 0%, rgba(255,255,255,0.6) 50%, rgba(255,255,255,0) 100%),
        radial-gradient(ellipse at center, rgba(0,0,0,0) 0%, rgba(0,0,0,0.03) 100%);
    border-radius: 3px;
    padding: 60px 70px;
    z-index: 30;
    box-shadow: 
        0 20px 40px -10px rgba(100, 90, 70, 0.25),
        0 0 15px rgba(100, 90, 70, 0.08),
        inset 0 0 40px rgba(0,0,0,0.03);
    transform: translateY(20px);
    opacity: 0; pointer-events: none;
    transition: all 1.2s cubic-bezier(0.4, 0, 0.2, 1) 2s;
}
.envelope-wrapper.open + .full-letter-view {
    opacity: 1; transform: rotate(-1.5deg); pointer-events: auto;
}

/* Handwritten Content Styling */
.content h1 { font-size: 3.8rem; font-weight: 600; margin-bottom: 25px; color: var(--ink-color); text-align: left; opacity: 0; transform: translateY(10px); transition: all 1s ease 2.6s; line-height: 1.1; }
.content p { font-size: 2rem; line-height: 1.4; margin-bottom: 20px; color: var(--ink-light); opacity: 0; transform: translateY(10px); transition: all 1s ease 2.9s; font-weight: 500; }
.content p:nth-of-type(2) { transition-delay: 3.2s; }
.content .signature { font-size: 2.6rem; font-weight: 600; margin-top: 35px; text-align: right; color: var(--ink-color); opacity: 0; transform: translateY(10px); transition: all 1s ease 3.6s; }
.envelope-wrapper.open + .full-letter-view .content h1,
.envelope-wrapper.open + .full-letter-view .content p,
.envelope-wrapper.open + .full-letter-view .content .signature { opacity: 1; transform: translateY(0); }

/* --- Generator View (Sleek Fade) --- */
.generator-view {
    grid-column: 1;
    grid-row: 1;
    position: relative; /* Fixed: Not absolute so it can push container height down on mobile */
    transform: rotate(-1deg);
    width: 92%; max-width: 600px;
    background: var(--paper-letter);
    background-image: 
        linear-gradient(to right, rgba(255,255,255,0) 0%, rgba(255,255,255,0.6) 50%, rgba(255,255,255,0) 100%),
        radial-gradient(ellipse at center, rgba(0,0,0,0) 0%, rgba(0,0,0,0.03) 100%);
    border-radius: 3px;
    padding: 40px 50px;
    box-shadow: 
        0 20px 40px -10px rgba(100, 90, 70, 0.25),
        0 0 15px rgba(100, 90, 70, 0.08),
        inset 0 0 40px rgba(0,0,0,0.03);
    pointer-events: auto;
}

.fade-section {
    opacity: 0;
    transition: opacity 0.4s ease;
}
.fade-section.active {
    opacity: 1;
}

/* Theme Selector */
.theme-options {
    display: flex;
    gap: 10px;
    margin-bottom: 15px;
}
.theme-option {
    flex: 1;
    cursor: pointer;
}
.theme-option input {
    display: none;
}
.theme-card {
    background: rgba(0,0,0,0.02);
    border: 2px solid rgba(44, 62, 80, 0.1);
    border-radius: 4px;
    padding: 10px 5px;
    text-align: center;
    transition: all 0.2s;
    height: 100%;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
}
.theme-option input:checked + .theme-card {
    border-color: var(--heart-color);
    background: rgba(224, 122, 95, 0.05); /* very light heart color */
    transform: translateY(-2px);
    box-shadow: 0 4px 10px rgba(224, 122, 95, 0.15);
}
.theme-icon {
    font-size: 2.5rem;
    margin-bottom: 5px;
    display: block;
}
.theme-name {
    font-family: 'Baskervville', serif;
    font-style: italic;
    font-size: 1.2rem;
    color: var(--ink-color);
    line-height: 1.1;
}

.form-group { margin-bottom: 15px; }
.form-group label { display: block; font-size: 1.6rem; color: var(--ink-light); margin-bottom: 5px; }
.form-group input, .form-group textarea {
    width: 100%; background: transparent; border: 1px solid rgba(44, 62, 80, 0.2); border-radius: 2px;
    padding: 6px 10px; font-family: 'Baskervville', serif; font-style: italic; font-size: 1.4rem; color: var(--ink-color);
    outline: none; transition: border-color 0.3s, background 0.3s;
}
.form-group input:focus, .form-group textarea:focus { border-color: var(--ink-color); background: rgba(255, 255, 255, 0.5); }
.btn {
    display: block; width: 100%; background: var(--ink-color); color: var(--paper-letter); border: none;
    padding: 10px; font-family: 'Baskervville', serif; font-style: italic; font-size: 2rem; border-radius: 2px; cursor: pointer;
    transition: transform 0.1s, background 0.2s; margin-top: 25px; text-align: center; text-decoration: none;
}
.btn:active { transform: scale(0.98); }
.btn:hover { background: var(--ink-light); }
.result-box p { font-size: 1.8rem; margin-bottom: 10px; color: var(--ink-color); text-align: center; }

/* Error pages reuse generator styling */
.error-view { grid-column: 1; grid-row: 1; position: relative; transform: rotate(-1deg); width: 92%; max-width: 500px; text-align: center; pointer-events: auto; }
.error-view h1 { font-size: 6rem; margin-bottom: 10px; color: var(--heart-color); }
.error-view p { font-size: 2.2rem; margin-bottom: 30px; }

@media (max-width: 768px) {
    .full-letter-view, .generator-view { padding: 35px 25px; width: 88%; }
    .content h1 { font-size: 3.2rem; } .content p { font-size: 1.6rem; } .content .signature { font-size: 2.2rem; }
}
@media (max-width: 480px) {
    .envelope-wrapper { width: 280px; height: 190px; }
    .envelope-front { border-left-width: 140px; border-right-width: 140px; border-bottom-width: 95px; border-top-width: 95px; }
    .envelope-flap { border-left-width: 140px; border-right-width: 140px; border-top-width: 120px; }
    
    .generator-view { padding: 20px 15px; width: 85%; }
    .cute-final-message { 
        padding: 20px 15px; 
        width: 85%; 
        max-height: 45vh; 
    }
    .pop-board { 
        padding: 20px 15px; 
        width: 80%; 
        max-height: 60vh; 
    }
    .cute-final-message h1, .pop-board h1 { font-size: 2.0rem; margin-bottom: 15px; }
    .pop-msg-container, .board-msg-container { font-size: 1.4rem; margin: 10px 0; }
    .cute-sig, .pop-sig { font-size: 1.5rem; margin-top: 15px; }
    
    .form-group label { font-size: 1.4rem; margin-bottom: 3px; }
    .form-group input, .form-group textarea { font-size: 1.4rem; padding: 6px 10px; }
    .btn { font-size: 1.6rem; padding: 8px; margin-top: 15px; }
    .theme-icon { font-size: 2rem; }
    .theme-name { font-size: 1.2rem; }
}

/* --- Cute Parade Theme --- */
.cute-stage {
    position: absolute; top: 0; left: 0; width: 100%; height: 100%;
    z-index: 50;
}
.cute-character {
    position: absolute;
    transform: scale(0);
    opacity: 0;
    transition: all 0.4s cubic-bezier(0.68, -0.55, 0.265, 1.55);
    cursor: pointer;
    text-align: center;
    user-select: none;
    -webkit-tap-highlight-color: transparent;
}
.cute-character.visible {
    transform: scale(1);
    opacity: 1;
}
.cute-hat {
    width: 55px;
    height: 55px;
    position: absolute;
    top: -25px;
    left: 50%;
    transform: translateX(-50%) rotate(15deg);
    z-index: 2;
    filter: drop-shadow(0 2px 4px rgba(0,0,0,0.2));
}
.cute-bounce-wrapper {
    position: relative;
    animation: bounce 0.8s infinite alternate;
}
.cute-face {
    font-size: 6rem;
    filter: drop-shadow(0 10px 10px rgba(0,0,0,0.1));
}
.cute-sign {
    background: white;
    border: 2px solid var(--ink-color);
    border-radius: 4px;
    padding: 10px 15px;
    font-size: 2.2rem;
    color: var(--ink-color);
    margin-bottom: 10px;
    box-shadow: 2px 4px 0 var(--ink-color);
    display: inline-block;
}
@keyframes bounce {
    0% { transform: translateY(0); }
    100% { transform: translateY(-20px); }
}
.cute-final-message {
    background: var(--paper-letter);
    border-radius: 4px;
    border: 2px dashed var(--heart-color);
    box-shadow: 0 20px 40px rgba(0,0,0,0.15);
    opacity: 0; 
    pointer-events: none; 
    transition: opacity 1s; 
    padding: 40px; 
    text-align: center; 
    position: absolute; 
    top: 10%; left: 50%; 
    transform: translateX(-50%); 
    width: 90%; max-width: 600px;
    max-height: 80vh;
    overflow-y: auto;
    margin-bottom: 50px;
    z-index: 10;
}
.cute-final-message.active {
    opacity: 1;
    pointer-events: auto;
}
.cute-final-message h1 { font-size: 2.6rem; color: var(--heart-color); margin-bottom: 20px; }
.cute-final-message p { font-size: 1.6rem; color: var(--ink-color); margin-bottom: 15px; }
.cute-sig { font-size: 1.8rem; color: var(--ink-color); font-weight: 600; text-align: right; margin-top: 30px; }

/* --- Balloon Pop Theme --- */
.balloon-stage {
    position: absolute; top: 0; left: 0; width: 100%; height: 100%; overflow: hidden;
}
.balloon {
    position: absolute;
    bottom: -150px;
    width: 60px;
    height: 75px;
    border-radius: 50% 50% 50% 50% / 40% 40% 60% 60%;
    cursor: crosshair;
    animation: floatBalloon linear infinite;
    transition: transform 0.1s, opacity 0.2s;
    box-shadow: inset -10px -10px 15px rgba(0,0,0,0.15);
    user-select: none;
    -webkit-tap-highlight-color: transparent;
}
.balloon::before {
    content: "";
    position: absolute;
    bottom: -8px; left: 50%;
    transform: translateX(-50%);
    width: 0; height: 0;
    border-left: 5px solid transparent;
    border-right: 5px solid transparent;
    border-bottom: 8px solid inherit;
}
.balloon::after {
    content: "";
    position: absolute;
    bottom: -50px; left: 50%;
    width: 1px; height: 50px;
    background: rgba(44, 62, 80, 0.4);
}
@keyframes floatBalloon {
    0% { transform: translateY(0) translateX(0); }
    33% { transform: translateY(-40vh) translateX(30px); }
    66% { transform: translateY(-80vh) translateX(-30px); }
    100% { transform: translateY(-130vh) translateX(0); }
}
.pop-board {
    position: absolute; 
    top: 10%; left: 50%; 
    transform: translateX(-50%); 
    width: 90%; max-width: 600px; 
    max-height: 60vh;
    overflow-y: auto;
    margin-bottom: 50px;
    text-align: center;
    background: rgba(253, 251, 247, 0.95);
    padding: 30px;
    border-radius: 8px;
    box-shadow: 0 10px 30px rgba(0,0,0,0.1);
    z-index: 10;
    border: 1px solid rgba(0,0,0,0.05);
}
.pop-board h1 { font-size: 2.6rem; color: var(--ink-color); opacity: 0; transition: opacity 0.5s; }
.pop-board.active h1 { opacity: 1; }
.pop-msg-container, .board-msg-container {
    display: block; 
    font-size: 1.6rem; 
    color: var(--ink-color); 
    margin: 20px 0;
}
.board-paragraph {
    margin-bottom: 15px; 
    line-height: 1.4;
}
.dropped-chunk {
    opacity: 0;
    display: inline;
    filter: blur(4px);
    transition: all 0.6s ease;
}
.dropped-chunk.visible {
    opacity: 1;
    filter: blur(0);
}
.pop-sig { font-size: 1.8rem; color: var(--ink-color); font-weight: 600; text-align: right; opacity: 0; transition: opacity 0.5s; }
.pop-board.active .pop-sig { opacity: 1; }