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

:root {
    --primary: #fff;
    --background: #ffebf2;
    --envelope-background: #ffe3ed;
    --flap-background: #ffccd5;
    --body-background: #ffc1d1;
    --shadow: rgba(0, 0, 0, 0.2);
    --text-color: #003049;
    --heart-color: #ff477e;
}

body {
    background: var(--background);
    display: flex;
    align-items: center;
    justify-content: center;
    flex-direction: column;
    height: 100vh;
}

.blinking-title {
    animation: slowBlinkFade 2.5s linear infinite;
    font-family: 'Marck Script', cursive;
    font-size: 46px;
    font-weight: bold;
    color: #4e4b4c;
    letter-spacing: 2px;
    text-shadow: 0 4px 24px #ffb5cd55;
    margin-bottom: 36px;
    text-align: center;
}

.alt-title {
    font-size: 32px;
    font-family: 'Trebuchet MS', Arial, sans-serif;
    color: #b3003c;
    font-weight: 500;
    letter-spacing: 1px;
    opacity: 0.8;
}

@keyframes slowBlinkFade {
    0%, 40% {
        opacity: 1;
    }
    60% {
        opacity: 0.15;
    }
    100% {
        opacity: 1;
    }
}

.container {
    width: 400px;
}

.envelope-wrapper {
    position: relative;
    background-color: var(--envelope-background);
    box-shadow: 0 0 40px var(--shadow);
    border-radius: 15px;
}

.envelope {
    position: relative;
    width: 400px;
    height: 300px;
}

.envelope::before {
    content: "";
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    z-index: 4;
    border-top: 180px solid var(--flap-background);
    border-right: 200px solid transparent;
    border-left: 200px solid transparent;
    transform-origin: top;
    transition: all 0.5s ease-in-out 0.7s;
    border-radius: 10px;
}

.right-flap {
    position: absolute;
    top: 0;
    right: 0;
    width: 100%;
    height: 100%;
    clip-path: polygon(100% 0, 0 100%, 100% 100%);
    background-color: var(--body-background);
    border-bottom-right-radius: 10px;
    border-top-right-radius: 10px;
    border-bottom-left-radius: 10px;
}

.left-flap {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    clip-path: polygon(0 0, 0 100%, 100% 100%);
    background-color: var(--body-background);
    border-top-left-radius: 10px;
    border-bottom-left-radius: 10px;
    border-bottom-right-radius: 10px;
}

.letter {
    position: absolute;
    bottom: 0;
    width: 100%;
    height: 100%;
    background: linear-gradient(135deg, #fff0f5, #ffe4e1);
    border-radius: 10px;
    box-shadow: 0 0 5px var(--shadow);
    text-align: center;
    padding: 20px;
    transition: transform 0.5s ease-in-out;
}

.letter:hover {
    transform: scale(1.02);
}

.content {
    font-family: 'Marck Script', cursive;
    font-size: 24px;
    color: #d6336c;
    line-height: 1.6;
    text-align: center;
    border: 3px dotted var(--text-color);
    padding: 10px;
    height: 100%;
    cursor: pointer;
    overflow-y: scroll;
}

strong {
    font-size: 26px;
    color: #c9184a;
}

.yes-no-animation-wrap {
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 48px;
    min-width: 240px;
    position: relative;
}

.yes-no-container {
    display: flex;
    justify-content: center;
    gap: 14px;
    margin-top: 15px;
    transition: opacity 0.2s;
}

.no-error {
    display: none;
    position: absolute;
    left: 50%;
    top: 50%;
    transform: translate(-50%, -50%);
    font-family: 'Poppins', sans-serif;
    font-size: 12px;
    color: #262223;
    font-weight: bold;
    letter-spacing: 1px;
    background: #fff4f8;
    border: 2px solid #ffb5cd;
    border-radius: 10px;
    box-shadow: 0 2px 10px #ff477e22;
    opacity: 0;
    transition: opacity 0.3s;
    text-align: center;
    padding: 8px 12px;
    min-width: 140px;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
    animation: noBlinkSoft 0.7s linear 0s 3 alternate;
    z-index: 10;
}

@keyframes noBlinkSoft {
    0% {
        opacity: 0.2;
    }
    40% {
        opacity: 0.9;
    }
    70% {
        opacity: 0.15;
    }
    100% {
        opacity: 0.9;
    }
}

.yes-button {
    display: inline-block;
    padding: 7px 16px;
    background-color: var(--heart-color);
    color: white;
    font-weight: bold;
    text-decoration: none;
    border-radius: 18px;
    box-shadow: 0 3px 5px rgba(0, 0, 0, 0.14);
    transition: background 0.3s ease;
    font-family: 'Poppins', sans-serif;
    font-size: 15px;
    min-width: 74px;
    border: none;
    cursor: pointer;
    margin: 0;
}

.yes-button:hover {
    background-color: #e0386b;
}

@media screen and (max-width: 400px) {
    .container {
        width: 300px;
    }

    .envelope {
        width: 300px;
        height: 250px;
    }

    .envelope::before {
        border-top: 150px solid var(--flap-background);
        border-right: 150px solid transparent;
        border-left: 150px solid transparent;
    }

    .yes-no-container {
        gap: 9px;
    }

    .yes-button {
        padding: 5px 11px;
        font-size: 13px;
        min-width: 56px;
    }
}

.heart {
    position: absolute;
    top: 50%;
    left: 50%;
    width: 30px;
    height: 30px;
    background-color: var(--heart-color);
    transform: translate(-50%, 0) rotate(45deg);
    transition: transform 0.5s ease-in-out 1s;
    z-index: 999;
    cursor: pointer;
}

.heart::before,
.heart::after {
    content: "";
    position: absolute;
    width: 30px;
    height: 30px;
    background-color: var(--heart-color);
    border-radius: 100%;
}

.heart::before {
    top: -15px;
}

.heart::after {
    right: 15px;
}

.opened .envelope::before {
    transform: rotateX(180deg);
    z-index: 0;
}

.opened .heart {
    transform: rotate(90deg);
    transition-delay: 0.4s;
}

.letter.show-letter {
    transform: translateY(-290px);
    transition: transform 0.5s ease-in-out;
}

.letter.closing-letter {
    transform: translateY(-290px);
    transition: transform 0.5s ease-in-out;
}

.letter.opened-letter {
    z-index: 10000;
}

.envelope-wrapper.disable-envelope .envelope::before {
    pointer-events: none;
}