/* ===== FONTS ===== */
@import url('https://fonts.googleapis.com/css2?family=IBM+Plex+Mono:wght@400;500;600&display=swap');

/* ===== CSS VARIABLES ===== */
:root {
    --color-bg-primary: #f5f1e8;
    --color-paper: #ffffff;
    --color-envelope: #d4c4b0;
    --color-text-primary: #2d2420;
    --color-text-muted: #95897d;
    --color-border: #d4c4b0;
    --color-shadow: rgba(45, 36, 32, 0.08);
}

/* ===== BASE STYLES ===== */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'IBM Plex Mono', monospace;
    background: var(--color-bg-primary);
    color: var(--color-text-primary);
    min-height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
    padding: 1.5rem;
    font-size: 18px;
    line-height: 1.6;
}

.container {
    width: 100%;
    max-width: 600px;
}

/* ===== CREATE LETTER FORM ===== */
.create-form {
    background: transparent;
    padding: 0;
    max-width: 600px;
    margin: 0 auto;
}

.create-form h1 {
    margin-bottom: 4rem;
    color: var(--color-text-muted);
    text-align: center;
    font-size: 1.125rem;
    font-weight: 400;
    letter-spacing: 8px;
    opacity: 0.7;
    text-transform: uppercase;
}

/* ===== ENVELOPE CREATION SCENE ===== */
.create-envelope-scene {
    width: 100%;
    max-width: 500px;
    height: 350px;
    margin: 0 auto;
    margin-bottom: 3rem;
    position: relative;
    transform-style: preserve-3d;
    perspective: 2000px;
    overflow: hidden;
}

.create-envelope {
    width: 100%;
    /* make slightly shorter than the scene to avoid flap clipping during 3D flips */
    height: 80%;
    top: 10%;
    bottom: 10%;
    position: absolute;
    transform-style: preserve-3d;
    transition: transform 1s ease-in-out, left 1.2s ease-in-out;
    z-index: 10;
    left: 0;
}

.create-envelope.sliding-out {
    left: 100%;
}

.create-envelope.flipped {
    transform: rotateY(180deg);
}

.slide-wall {
    position: absolute;
    top: 0;
    left: 100%;
    width: 50px;
    height: 100%;
    background: var(--color-envelope);
    z-index: 15;
    pointer-events: none;
}

.create-url-box-wrapper {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 1;
    opacity: 0;
    pointer-events: none;
    transition: opacity 0.5s ease-out;
}

.create-url-box-wrapper.show {
    opacity: 1;
    pointer-events: auto;
}

/* ===== ENVELOPE FRONT & BACK ===== */
.create-front {
    position: absolute;
    width: 100%;
    height: 100%;
    backface-visibility: hidden;
    background: var(--color-envelope);
    border: 1px solid var(--color-border);
    box-shadow: 0 2px 8px var(--color-shadow);
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: 2.5rem;
}

.create-front textarea {
    width: 100%;
    max-width: 350px;
    height: 60px;
    background: transparent;
    border: none;
    font-family: 'IBM Plex Mono', monospace;
    font-size: 1.375rem;
    color: var(--color-text-primary);
    text-align: center;
    resize: none;
    outline: none;
    padding: 0.5rem;
    transition: border-color 0.3s ease;
    line-height: 1.6;
}

.create-front textarea:focus {
    border: none;
}

.create-front textarea::placeholder {
    color: var(--color-text-muted);
    opacity: 0.5;
    font-size: 1.125rem;
    letter-spacing: 1px;
}

.create-back {
    position: absolute;
    width: 100%;
    height: 100%;
    backface-visibility: hidden;
    transform: rotateY(180deg);
    background: var(--color-paper);
    border: 1px solid var(--color-border);
    box-shadow: 0 2px 8px var(--color-shadow);
    overflow: hidden;
}

.create-letter-paper {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: transparent;
    border: none;
    padding: 2.5rem;
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 1;
}

.create-letter-paper textarea {
    width: 100%;
    height: 100%;
    background: transparent;
    border: none;
    font-family: 'IBM Plex Mono', monospace;
    font-size: 1.125rem;
    color: var(--color-text-primary);
    text-align: center;
    resize: none;
    outline: none;
    line-height: 1.8;
}

.create-letter-paper textarea::placeholder {
    color: var(--color-text-muted);
    opacity: 0.5;
    font-size: 1rem;
    letter-spacing: 1px;
}

/* ===== FLAPS FOR CREATION ENVELOPE ===== */
.create-flap {
    position: absolute;
    width: 0;
    height: 0;
    transform-style: preserve-3d;
    z-index: 10;
    transition: transform 0.6s ease-out;
}

.create-flap-top {
    top: 0;
    left: 0;
    border-left: 250px solid transparent;
    border-right: 250px solid transparent;
    border-top: 250px solid var(--color-envelope);
    transform-origin: top center;
    transform: rotateX(-180deg);
}

.create-flap-right {
    right: 0;
    top: 0;
    border-top: 175px solid transparent;
    border-bottom: 175px solid transparent;
    border-right: 250px solid var(--color-envelope);
    transform-origin: right center;
    transform: rotateY(180deg);
}

.create-flap-bottom {
    bottom: 0;
    left: 0;
    border-left: 250px solid transparent;
    border-right: 250px solid transparent;
    border-bottom: 250px solid var(--color-envelope);
    transform-origin: bottom center;
    transform: rotateX(180deg);
}

.create-flap-left {
    left: 0;
    top: 0;
    border-top: 175px solid transparent;
    border-bottom: 175px solid transparent;
    border-left: 250px solid var(--color-envelope);
    transform-origin: left center;
    transform: rotateY(-180deg);
}

/* ===== SEALING ANIMATION (SEQUENTIAL) ===== */
.create-envelope.seal-flap-1 .create-flap-top {
    transform: rotateX(0deg);
}

.create-envelope.seal-flap-2 .create-flap-left {
    transform: rotateY(0deg);
}

.create-envelope.seal-flap-3 .create-flap-right {
    transform: rotateY(0deg);
}

.create-envelope.seal-flap-4 .create-flap-bottom {
    transform: rotateX(0deg);
}

/* ===== BUTTONS ===== */
.action-btn {
    display: block;
    width: 100%;
    max-width: 300px;
    margin: 0 auto 1.5rem;
    padding: 1.25rem 2.5rem;
    background: var(--color-envelope);
    color: var(--color-text-primary);
    border: 1px solid var(--color-border);
    font-family: 'IBM Plex Mono', monospace;
    font-size: 0.875rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 4px;
    cursor: pointer;
    transition: all 0.25s ease;
    position: relative;
    z-index: 2;
    box-shadow: 0 1px 3px var(--color-shadow);
}

.action-btn:hover {
    background: #c2b49f;
    border-color: var(--color-text-muted);
    box-shadow: 0 2px 6px var(--color-shadow);
    transform: translateY(-1px);
}

.action-btn:active {
    transform: translateY(0);
    box-shadow: 0 1px 2px var(--color-shadow);
}

.action-btn:disabled {
    opacity: 0.4;
    cursor: not-allowed;
    transform: none;
    box-shadow: 0 1px 3px var(--color-shadow);
}

.button-group {
    display: flex;
    gap: 1.25rem;
    max-width: 615px;
    margin: 0 auto 0;
    justify-content: center;
}

.button-group .action-btn {
    margin: 0;
    flex: 1;
    max-width: 300px;
}

/* ===== URL DISPLAY ===== */
.create-url-display {
    max-width: 420px;
    width: 100%;
    padding: 2rem 1.75rem 1.75rem;
    background: var(--color-paper);
    border: 1px solid var(--color-border);
    box-shadow: 0 4px 12px var(--color-shadow);
}

.create-url-display h3 {
    margin-bottom: 1.5rem;
    color: var(--color-text-muted);
    font-size: 0.875rem;
    text-transform: uppercase;
    letter-spacing: 3px;
    font-weight: 600;
    text-align: center;
}

.create-url-container {
    display: flex;
    gap: 0.75rem;
}

.create-url-input {
    flex: 1;
    padding: 1.125rem;
    border: 1px solid var(--color-border);
    background: var(--color-bg-primary);
    color: var(--color-text-primary);
    font-family: 'IBM Plex Mono', monospace;
    font-size: 0.875rem;
    border-radius: 2px;
    transition: border-color 0.25s ease;
}

.create-url-input:focus {
    outline: none;
    border-color: var(--color-text-muted);
}

.create-copy-btn {
    padding: 1.125rem 2rem;
    background: var(--color-envelope);
    color: var(--color-text-primary);
    border: 1px solid var(--color-border);
    font-family: 'IBM Plex Mono', monospace;
    font-size: 0.875rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 3px;
    cursor: pointer;
    transition: all 0.25s ease;
    white-space: nowrap;
    box-shadow: 0 1px 3px var(--color-shadow);
}

.create-copy-btn:hover {
    background: #c2b49f;
    border-color: var(--color-text-muted);
    box-shadow: 0 2px 6px var(--color-shadow);
    transform: translateY(-1px);
}

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

/* ===== LETTER VIEW MODE ===== */
.letter-container {
    perspective: 2000px;
    display: none;
    min-height: 400px;
}

.letter-container.show {
    display: block;
}

.letter-container h1 {
    margin-bottom: 4rem;
    color: var(--color-text-muted);
    text-align: center;
    font-size: 1.125rem;
    font-weight: 400;
    letter-spacing: 8px;
    opacity: 0.7;
    text-transform: uppercase;
}

.envelope-scene {
    width: 100%;
    max-width: 500px;
    height: 350px;
    position: relative;
    transform-style: preserve-3d;
    margin: 0 auto;
    margin-bottom: 3rem;
}

.envelope {
    width: 100%;
    /* reduce height slightly so top/bottom borders don't get clipped by the scene */
    height: 80%;
    top: 10%;
    bottom: 10%;
    position: absolute;
    transform-style: preserve-3d;
    transition: transform 1s ease-in-out;
    cursor: pointer;
}

.envelope.flipped {
    transform: rotateY(180deg);
}

.envelope-front {
    position: absolute;
    width: 100%;
    height: 100%;
    backface-visibility: hidden;
    background: var(--color-envelope);
    border: 1px solid var(--color-border);
    box-shadow: 0 2px 8px var(--color-shadow);
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 2.5rem;
}

.envelope-text {
    font-size: 1.5rem;
    color: var(--color-text-primary);
    line-height: 1.7;
    text-align: center;
    word-wrap: break-word;
}

.envelope-back {
    position: absolute;
    width: 100%;
    height: 100%;
    backface-visibility: hidden;
    transform: rotateY(180deg);
    background: var(--color-paper);
    border: 1px solid var(--color-border);
    box-shadow: 0 2px 8px var(--color-shadow);
    display: flex;
    align-items: center;
    justify-content: center;
    overflow: hidden;
}

.letter-paper {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: transparent;
    border: none;
    padding: 2.5rem;
    display: flex;
    align-items: center;
    justify-content: center;
    overflow: auto;
    z-index: 1;
}

.letter-text {
    font-size: 1.25rem;
    line-height: 2;
    color: var(--color-text-primary);
    white-space: pre-wrap;
    word-wrap: break-word;
    text-align: center;
}

/* ===== VIEW MODE FLAPS ===== */
.flap {
    position: absolute;
    width: 0;
    height: 0;
    transition: transform 0.6s ease-out;
    transform-style: preserve-3d;
    z-index: 10;
}

.flap-top {
    top: 0;
    left: 0;
    border-left: 250px solid transparent;
    border-right: 250px solid transparent;
    border-top: 250px solid var(--color-envelope);
    transform-origin: top center;
}

.flap-right {
    right: 0;
    top: 0;
    border-top: 175px solid transparent;
    border-bottom: 175px solid transparent;
    border-right: 250px solid var(--color-envelope);
    transform-origin: right center;
}

.flap-bottom {
    bottom: 0;
    left: 0;
    border-left: 250px solid transparent;
    border-right: 250px solid transparent;
    border-bottom: 250px solid var(--color-envelope);
    transform-origin: bottom center;
}

.flap-left {
    left: 0;
    top: 0;
    border-top: 175px solid transparent;
    border-bottom: 175px solid transparent;
    border-left: 250px solid var(--color-envelope);
    transform-origin: left center;
}

.envelope.open-flap-1 .flap-top {
    transform: rotateX(-180deg);
}

.envelope.open-flap-2 .flap-left {
    transform: rotateY(-180deg);
}

.envelope.open-flap-3 .flap-right {
    transform: rotateY(180deg);
}

.envelope.open-flap-4 .flap-bottom {
    transform: rotateX(180deg);
}

/* ===== HINTS & UTILITIES ===== */
.create-hint {
    margin-top: 1.5rem;
    color: var(--color-text-muted);
    font-size: 0.875rem;
    text-transform: uppercase;
    letter-spacing: 4px;
    text-align: center;
    animation: pulse 2s infinite;
    white-space: nowrap;
    opacity: 0.6;
}

.click-hint {
    position: absolute;
    bottom: -3rem;
    left: 50%;
    transform: translateX(-50%);
    color: var(--color-text-muted);
    font-size: 0.875rem;
    text-transform: uppercase;
    letter-spacing: 4px;
    animation: pulse 2s infinite;
    white-space: nowrap;
    opacity: 0.6;
}

@keyframes pulse {
    0%, 100% { opacity: 0.6; }
    50% { opacity: 0.35; }
}

.hidden {
    display: none !important;
}

/* ===== RESPONSIVE DESIGN ===== */
@media (max-width: 600px) {
    body {
        padding: 1rem;
    }

    .create-form {
        padding: 0;
    }

    .create-form h1 {
        font-size: 0.875rem;
        letter-spacing: 4px;
        margin-bottom: 2rem;
    }

    .letter-container h1 {
        font-size: 0.875rem;
        letter-spacing: 4px;
        margin-bottom: 2rem;
    }

    .envelope-scene,
    .create-envelope-scene {
        max-width: 350px;
        height: 245px;
        margin-bottom: 2.5rem;
    }

    .create-front,
    .envelope-front {
        padding: 1.5rem;
    }

    .create-front textarea {
        font-size: 1.125rem;
        max-width: 280px;
    }

    .create-letter-paper,
    .letter-paper {
        padding: 1.25rem;
    }

    .create-letter-paper textarea {
        font-size: 1rem;
    }

    .envelope-text {
        font-size: 1.125rem;
    }

    .letter-text {
        font-size: 1rem;
    }

    .action-btn {
        padding: 1rem 1.5rem;
        font-size: 0.75rem;
        letter-spacing: 2px;
    }

    .button-group {
        gap: 0.75rem;
        margin: 0 auto 0;
    }

    .create-url-display {
        padding: 1.5rem 1.125rem 1.25rem;
    }

    .create-url-input,
    .create-copy-btn {
        font-size: 0.75rem;
        padding: 0.875rem;
    }

    .create-copy-btn {
        padding: 0.875rem 1.25rem;
        letter-spacing: 1.5px;
    }

    .click-hint {
        font-size: 0.75rem;
        letter-spacing: 2px;
        bottom: -2rem;
    }

    .create-hint {
        font-size: 0.75rem;
        letter-spacing: 2px;
        margin-top: 1.25rem;
    }

    /* Flap adjustments for mobile */
    .create-flap-top {
        border-left: 175px solid transparent;
        border-right: 175px solid transparent;
        border-top: 175px solid var(--color-envelope);
    }

    .create-flap-right {
        border-top: 98px solid transparent;
        border-bottom: 98px solid transparent;
        border-right: 175px solid var(--color-envelope);
    }

    .create-flap-bottom {
        border-left: 175px solid transparent;
        border-right: 175px solid transparent;
        border-bottom: 175px solid var(--color-envelope);
    }

    .create-flap-left {
        border-top: 98px solid transparent;
        border-bottom: 98px solid transparent;
        border-left: 175px solid var(--color-envelope);
    }

    .flap-top {
        border-left: 175px solid transparent;
        border-right: 175px solid transparent;
        border-top: 175px solid var(--color-envelope);
    }

    .flap-right {
        border-top: 98px solid transparent;
        border-bottom: 98px solid transparent;
        border-right: 175px solid var(--color-envelope);
    }

    .flap-bottom {
        border-left: 175px solid transparent;
        border-right: 175px solid transparent;
        border-bottom: 175px solid var(--color-envelope);
    }

    .flap-left {
        border-top: 98px solid transparent;
        border-bottom: 98px solid transparent;
        border-left: 175px solid var(--color-envelope);
    }
}

@media (max-width: 400px) {
    body {
        padding: 0.75rem;
    }

    .create-envelope-scene,
    .envelope-scene {
        max-width: 300px;
        height: 210px;
        margin-bottom: 2rem;
    }

    .create-front textarea {
        max-width: 240px;
        font-size: 1rem;
    }

    .create-url-display {
        max-width: 320px;
        padding: 1.25rem 1rem;
    }

    .button-group {
        margin: 0 auto 0;
    }

    /* Flap adjustments for smaller mobile */
    .create-flap-top {
        border-left: 150px solid transparent;
        border-right: 150px solid transparent;
        border-top: 150px solid var(--color-envelope);
    }

    .create-flap-right {
        border-top: 84px solid transparent;
        border-bottom: 84px solid transparent;
        border-right: 150px solid var(--color-envelope);
    }

    .create-flap-bottom {
        border-left: 150px solid transparent;
        border-right: 150px solid transparent;
        border-bottom: 150px solid var(--color-envelope);
    }

    .create-flap-left {
        border-top: 84px solid transparent;
        border-bottom: 84px solid transparent;
        border-left: 150px solid var(--color-envelope);
    }

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

    .flap-right {
        border-top: 84px solid transparent;
        border-bottom: 84px solid transparent;
        border-right: 150px solid var(--color-envelope);
    }

    .flap-bottom {
        border-left: 150px solid transparent;
        border-right: 150px solid transparent;
        border-bottom: 150px solid var(--color-envelope);
    }

    .flap-left {
        border-top: 84px solid transparent;
        border-bottom: 84px solid transparent;
        border-left: 150px solid var(--color-envelope);
    }
}