.field {
    --uiFieldPaddingTop: var(--fieldPaddingTop, 0px);
    --uiFieldPaddingRight: var(--fieldPaddingRight, 0px);
    --uiFieldPaddingBottom: var(--fieldPaddingBottom, 0px);
    --uiFieldPaddingLeft: var(--fieldPaddingLeft, 0px);
    --uiFieldBorderColor: var(--fieldBorderColor, transpatent);
    --uiFieldBorderTop: var(--fieldBorderTop, 0px);
    --uiFieldBorderRight: var(--fieldBorderRight, 0px);
    --uiFieldBorderBottom: var(--fieldBorderBottom, 0px);
    --uiFieldBorderLeft: var(--fieldBorderLeft, 0px);
    --uiFieldBgColor: var(--fieldBgColor, transpatent);
    --uiFieldPlaceholderColor: var(--fieldPlaceholderColor, #767676);
    --uiFieldAnimationDuration: var(--fieldAnimationDuration, .3s);
    --uiFieldFonstSize: var(--fieldFontSize, 16px);
    position: relative;
    margin-top: 100px;
}

.field__input {
    width: 100%;
    box-sizing: border-box;
    background-color: var(--uiFieldBgColor);
    /* for iOS */
    -webkit-appearance: none;
    -moz-appearance: none;
    appearance: none;
    border-radius: 0;
    border-style: solid;
    border-color: var(--uiFieldBorderColor);
    border-top-width: var(--uiFieldBorderTop);
    border-right-width: var(--uiFieldBorderRight);
    border-bottom-width: var(--uiFieldBorderBottom);
    border-left-width: var(--uiFieldBorderLeft);
    padding-top: var(--uiFieldPaddingTop);
    padding-right: var(--uiFieldPaddingRight);
    padding-bottom: var(--uiFieldPaddingBottom);
    padding-left: var(--uiFieldPaddingLeft);
    font-family: inherit;
    font-size: 100%;
    color: inherit;
}

.field__input::-webkit-input-placeholder {
    color: var(--uiFieldPlaceholderColor);
    opacity: 0;
}

.field__input::-moz-placeholder {
    color: var(--uiFieldPlaceholderColor);
    opacity: 0;
}

.field__input:focus {
    outline: none;
}

.field__input:focus::-webkit-input-placeholder {
    -webkit-transition: opacity var(--uiFieldAnimationDuration) ease-out var(--uiFieldAnimationDuration);
    transition: opacity var(--uiFieldAnimationDuration) ease-out var(--uiFieldAnimationDuration);
    opacity: 1;
}

.field__input:focus::-moz-placeholder {
    -webkit-transition: opacity var(--uiFieldAnimationDuration) ease-out var(--uiFieldAnimationDuration);
    transition: opacity var(--uiFieldAnimationDuration) ease-out var(--uiFieldAnimationDuration);
    opacity: 1;
}

.field__label {
    position: absolute;
    top: calc(0px + var(--uiFieldPaddingTop) + var(--uiFieldBorderTop));
    left: calc(0px + var(--uiFieldPaddingLeft) + var(--uiFieldBorderLeft));
    pointer-events: none;
    font-size: .9em;
    -webkit-transition: top var(--uiFieldAnimationDuration) cubic-bezier(0.9, -0.15, 0.1, 1.15), opacity var(--uiFieldAnimationDuration) ease-out;
    transition: top var(--uiFieldAnimationDuration) cubic-bezier(0.9, -0.15, 0.1, 1.15), opacity var(--uiFieldAnimationDuration) ease-out;
    will-change: top, opacity;
}

.field__input:not(:placeholder-shown)~.field__label {
    opacity: 0;
    top: calc(0px + var(--uiFieldPaddingTop) + var(--uiFieldBorderTop));
}

.field__input:focus~.field__label {
    opacity: 1;
    top: calc(-1 * calc(var(--uiFieldPaddingTop) + var(--uiFieldBorderTop) + 15px));
}


/* type 2 */

.field_type2 {
    --uiFieldBorderBottom: var(--fieldBorderBottom, 2px);
    --uiFieldPaddingTop: var(--fieldPaddingTop, 5px);
    --uiFieldPaddingRight: var(--fieldPaddingRight, 15px);
    --uiFieldPaddingBottom: var(--fieldPaddingBottom, 10px);
    --uiFieldPaddingLeft: var(--fieldPaddingLeft, 15px);
}

.field_type2 .field__line {
    width: 0;
    height: var(--uiFieldBorderBottom);
    background-color: var(--fieldBorderColorActive);
    position: absolute;
    bottom: 0;
    left: 0;
    will-change: width;
    -webkit-transition: width var(--uiFieldAnimationDuration) ease-out;
    transition: width var(--uiFieldAnimationDuration) ease-out;
}

.field_type2 .field__input:focus~.field__line {
    width: 100%;
}


/*
  * demo styles
  */

.field {
    --fieldBorderColor: #fff;
    --fieldBorderColorActive: #00b7ff;
    --fieldPlaceholderColor: #fff;
    display: block;
    color: #fff;
}

.field_type1 {}


/*
  * demo page
  */

@media screen and (min-width: 768px) {
    html {
        font-size: 62.5%;
    }
}

@media screen and (max-width: 767px) {
    html {
        font-size: 50%;
    }
}

.page {
    min-height: 100vh;
    display: -webkit-box;
    display: -ms-flexbox;
    display: flex;
    -webkit-box-orient: vertical;
    -webkit-box-direction: normal;
    -ms-flex-direction: column;
    flex-direction: column;
    -ms-flex-pack: distribute;
    justify-content: space-around;
}

.page__demo {
    -webkit-box-flex: 2;
    -ms-flex-positive: 2;
    flex-grow: 2;
    display: -webkit-box;
    display: -ms-flexbox;
    display: flex;
}

.main-container {
    padding-left: 1rem;
    padding-right: 1rem;
}

.page__container {
    width: 80%;
    max-width: 600px;
    padding-top: 5rem;
    padding-bottom: 5rem;
    text-align: center;
    margin: auto;
}

.page__section:not(:first-child) {
    margin-top: 7rem;
}

.inbox {
    display: flex;
    justify-self: center;
    height: 110vh;
    width: 100vw;
}