* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
    font-family: Arial, sans-serif;
}

/* ── BASE ── */
body {
    background-color: #f0fff0;
    color: #0a1a00;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    transition: background-color 0.3s, color 0.3s;
}

/* ── DARK MODE ── */
body.dark {
    background-color: #0a1a00;
    color: #f0fff0;
}

/* ── HEADER ── */
.header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    background-color: #e8ffe8;
    padding: 14px 24px;
    border-bottom: 1px solid rgba(127, 255, 0, 0.3);
    transition: background-color 0.3s;
}

body.dark .header {
    background-color: #060f00;
    border-bottom: 1px solid rgba(127, 255, 0, 0.2);
}

.header p {
    font-size: 11px;
    letter-spacing: 2px;
    color: #3a8a00;
    margin-bottom: 3px;
}

body.dark .header p {
    color: #7fff00;
}

.header h1 {
    font-size: 22px;
    color: #0a1a00;
}

body.dark .header h1 {
    color: #f0fff0;
}

#theme-toggle {
    background-color: #0a1a00;
    color: #7fff00;
    border: none;
    padding: 8px 16px;
    border-radius: 100px;
    font-size: 12px;
    font-weight: bold;
    cursor: pointer;
    transition: opacity 0.2s;
}

body.dark #theme-toggle {
    background-color: #7fff00;
    color: #0a1a00;
}

#theme-toggle:hover { opacity: 0.8; }

/* ── MAIN CONTAINER ── */
.container {
    display: flex;
    flex-direction: row;
    flex: 1;
}

/* ── LEFT COLUMN ── */
.input {
    flex: 1;
    padding: 24px;
    border-right: 1px solid rgba(127, 255, 0, 0.3);
}

body.dark .input {
    border-right: 1px solid rgba(127, 255, 0, 0.2);
}

/* ── FORM DIVS ── */
.category-choice,
.value-div,
.convert-div {
    margin-bottom: 18px;
}

.category-choice label,
.value-div label,
.convert-div label {
    display: block;
    color: #3a8a00;
    font-size: 12px;
    margin-bottom: 6px;
    letter-spacing: 0.5px;
}

body.dark .category-choice label,
body.dark .value-div label,
body.dark .convert-div label {
    color: #7fff00;
}

/* ── INPUTS AND SELECT ── */
.category-choice select,
.value-div input {
    background-color: #e8ffe8;
    padding: 10px 12px;
    width: 100%;
    border: 1px solid rgba(127, 255, 0, 0.4);
    border-radius: 8px;
    color: #0a1a00;
    font-size: 14px;
    outline: none;
    transition: border-color 0.2s, background-color 0.3s;
}

body.dark .category-choice select,
body.dark .value-div input {
    background-color: #0f2600;
    color: #f0fff0;
    border: 1px solid rgba(127, 255, 0, 0.2);
}

.category-choice select:focus,
.value-div input:focus {
    border-color: #7fff00;
}

/* ── FROM TO ROW ── */
.from-to-row {
    display: flex;
    align-items: center;
    gap: 8px;
}

.convert-div input {
    flex: 1;
    background-color: #e8ffe8;
    padding: 10px 12px;
    border: 1px solid rgba(127, 255, 0, 0.4);
    border-radius: 8px;
    color: #0a1a00;
    font-size: 14px;
    outline: none;
    transition: border-color 0.2s, background-color 0.3s;
}

body.dark .convert-div input {
    background-color: #0f2600;
    color: #f0fff0;
    border: 1px solid rgba(127, 255, 0, 0.2);
}

.convert-div input:focus {
    border-color: #7fff00;
}

.convert-div input::placeholder,
.value-div input::placeholder {
    color: #888888;
}

.arrow {
    color: #3a8a00;
    font-size: 18px;
    flex-shrink: 0;
}

body.dark .arrow {
    color: #7fff00;
}

/* ── SUBMIT BUTTON ── */
.submit {
    background-color: #7fff00;
    color: #0a1a00;
    padding: 12px 16px;
    border: none;
    border-radius: 8px;
    cursor: pointer;
    width: 100%;
    font-size: 15px;
    font-weight: bold;
    letter-spacing: 0.5px;
    transition: background-color 0.15s, opacity 0.15s;
    margin-top: 4px;
}

.submit:hover { background-color: #5ecc00; }
.submit:active { opacity: 0.6; }

body.dark .submit {
    background-color: #7fff00;
    color: #0a1a00;
}

/* ── RIGHT COLUMN ── */
.output {
    flex: 1;
    padding: 24px;
    display: flex;
    align-items: center;
    justify-content: center;
    background-color: #f8fff8;
    transition: background-color 0.3s;
}

body.dark .output {
    background-color: #0f2600;
}

/* ── RESULT BOX ── */
.result-box,
.error-box,
.empty-box {
    text-align: center;
    width: 100%;
}

.result-emoji,
.error-emoji,
.empty-emoji {
    font-size: 52px;
    margin-bottom: 12px;
}

.result-label {
    font-size: 11px;
    letter-spacing: 2px;
    color: #3a8a00;
    margin-bottom: 6px;
}

body.dark .result-label {
    color: #7fff00;
}

.result-value {
    font-size: 36px;
    font-weight: bold;
    color: #3a8a00;
    margin-bottom: 8px;
    word-break: break-all;
}

body.dark .result-value {
    color: #7fff00;
}

.result-desc {
    font-size: 13px;
    color: #888888;
}

/* ── ERROR BOX ── */
.error-box {
    background-color: rgba(220, 38, 38, 0.05);
    border: 1px solid rgba(220, 38, 38, 0.3);
    border-radius: 12px;
    padding: 20px;
}

.error-msg {
    color: #dc2626;
    font-size: 14px;
    line-height: 1.6;
}

body.dark .error-msg {
    color: #f87171;
}

/* ── EMPTY STATE ── */
.empty-msg {
    color: #888888;
    font-size: 14px;
}

/* ── FOOTER ── */
.footer {
    background-color: #e8ffe8;
    border-top: 1px solid rgba(127, 255, 0, 0.3);
    padding: 12px 24px;
    text-align: center;
    transition: background-color 0.3s;
}

body.dark .footer {
    background-color: #060f00;
    border-top: 1px solid rgba(127, 255, 0, 0.2);
}

.footer p {
    font-size: 11px;
    color: #888888;
    letter-spacing: 0.5px;
}

/* ── RESPONSIVE: TABLET ── */
@media (max-width: 768px) {
    .container {
        flex-direction: column;
    }

    .input {
        border-right: none;
        border-bottom: 1px solid rgba(127, 255, 0, 0.3);
    }

    .output {
        min-height: 220px;
    }
}

/* ── RESPONSIVE: MOBILE ── */
@media (max-width: 480px) {
    .header {
        padding: 12px 16px;
    }

    .header h1 {
        font-size: 18px;
    }

    #theme-toggle {
        font-size: 11px;
        padding: 6px 12px;
    }

    .input {
        padding: 16px;
    }

    .from-to-row {
        flex-direction: column;
        align-items: stretch;
    }

    .arrow {
        text-align: center;
    }

    .result-value {
        font-size: 28px;
    }

    .result-emoji,
    .error-emoji,
    .empty-emoji {
        font-size: 40px;
    }

    .submit {
        width: 100%;
    }
}