body {
    margin: 0;
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto,
        Oxygen, Ubuntu, Cantarell, 'Open Sans', 'Helvetica Neue', sans-serif;
    min-height: 100vh;
    background: var(--bg);
    color: var(--text);
    display: flex;
    flex-direction: column;
    align-items: center;
    padding: 2rem 1rem 4rem;
    transition: background 0.4s ease, color 0.4s ease;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    background-image:
        radial-gradient(circle at top left, #a5b4fc88 0%, transparent 50%),
        radial-gradient(circle at bottom right, #818cf888 0%, transparent 60%);
    background-repeat: no-repeat;
    background-attachment: fixed;
}

:root {
    --bg: #e0e7ff;
    --text: #1e293b;
    --glass-bg: rgba(255 255 255 / 0.15);
    --glass-border: rgba(255 255 255 / 0.25);
    --accent: #3b82f6;
    --input-bg: rgba(255 255 255 / 0.2);
    --input-border: rgba(0 0 0 / 0.1);
    --button-bg: #3b82f6;
    --button-hover-bg: #2563eb;
    --button-text: #fafafa;
    --shadow: rgba(0 0 0 / 0.07);
    --footer-text: #475569;
    --error-bg: #fee2e2;
    --error-text: #b91c1c;
    --info-bg: #dbeafe;
    --info-text: #1e40af;
}

.dark {
    --bg: #0f172a;
    --text: #e2e8f0;
    --glass-bg: rgba(15 23 42 / 0.4);
    --glass-border: rgba(255 255 255 / 0.15);
    --accent: #60a5fa;
    --input-bg: rgba(255 255 255 / 0.08);
    --input-border: rgba(255 255 255 / 0.16);
    --button-bg: #2563eb;
    --button-hover-bg: #3b82f6;
    --button-text: #f9fafb;
    --shadow: rgba(0 0 0 / 0.25);
    --footer-text: #94a3b8;
    --error-bg: #7f1d1d;
    --error-text: #fee2e2;
    --info-bg: #1e40af;
    --info-text: #dbeafe;
}

header {
    max-width: 700px;
    width: 100%;
    margin-bottom: 2.5rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    color: var(--text);
    user-select: none;
}

header h1 {
    font-weight: 700;
    font-size: 2.5rem;
    line-height: 1.1;
    margin: 0;
}

main {
    max-width: 720px;
    width: 100%;
    background: var(--glass-bg);
    border-radius: 20px;
    padding: 2.5rem 3rem 3rem;
    backdrop-filter: blur(12px) saturate(120%);
    -webkit-backdrop-filter: blur(12px) saturate(120%);
    border: 1.5px solid var(--glass-border);
    box-shadow: 0 8px 22px var(--shadow);
    transition: background 0.4s ease, border-color 0.4s ease;
    display: flex;
    flex-direction: column;
}

form {
    display: flex;
    flex-direction: column;
    gap: 1.4rem;
}

label {
    display: flex;
    flex-direction: column;
    font-weight: 600;
    color: var(--text);
    font-size: 1.05rem;
}

input[type="text"],
textarea,
select {
    margin-top: 0.4rem;
    padding: 0.7rem 1.1rem;
    border-radius: 14px;
    border: 1.5px solid var(--input-border);
    background-color: var(--input-bg);
    color: var(--text);
    font-size: 1rem;
    font-family: 'Inter', sans-serif;
    font-weight: 400;
    transition:
        border-color 0.3s ease,
        background-color 0.3s ease,
        color 0.3s ease;
    resize: vertical;
    min-height: 2.8rem;
    box-shadow: none;
}

input[type="text"]:focus,
textarea:focus,
select:focus {
    outline: none;
    border-color: var(--accent);
    box-shadow: 0 0 8px var(--accent);
    background-color: var(--glass-bg);
}

textarea {
    min-height: 100px;
}

button {
    align-self: flex-start;
    background-color: var(--button-bg);
    color: var(--button-text);
    font-weight: 700;
    border: none;
    border-radius: 15px;
    padding: 1rem 2.8rem;
    font-size: 1.15rem;
    cursor: pointer;
    transition: background-color 0.3s ease, box-shadow 0.3s ease;
    user-select: none;
    box-shadow:
        0 6px 10px var(--shadow);
    margin-top: 0.8rem;
}

button:disabled {
    opacity: 0.55;
    cursor: not-allowed;
    box-shadow: none;
}

button:hover:not(:disabled) {
    background-color: var(--button-hover-bg);
    box-shadow:
        0 8px 16px var(--shadow);
}

/* Message container for errors/info */
#message {
    margin-top: 1.5rem;
    padding: 1rem 1.5rem;
    border-radius: 12px;
    font-weight: 600;
    font-size: 1rem;
    opacity: 0;
    max-height: 0;
    overflow: hidden;
    transition: opacity 0.35s ease, max-height 0.35s ease, padding 0.35s ease;
    user-select: none;
}

#message.show {
    opacity: 1;
    max-height: 120px;
    padding: 1rem 1.5rem;
}

#message.error {
    background-color: var(--error-bg);
    color: var(--error-text);
    border: 1.5px solid var(--error-text);
}

#message.info {
    background-color: var(--info-bg);
    color: var(--info-text);
    border: 1.5px solid var(--info-text);
}

/* Output section */
#result {
    margin-top: 1.8rem;
    padding: 1.8rem 2rem;
    background: var(--glass-bg);
    border-radius: 14px;
    border: 1.3px solid var(--glass-border);
    min-height: 120px;
    font-size: 1rem;
    color: var(--text);
    white-space: pre-wrap;
    line-height: 1.5;
    box-shadow: inset 0 0 8px rgba(0, 0, 0, 0.05);
    opacity: 0;
    transition: opacity 0.5s ease;
    user-select: text;
}

#result.visible {
    opacity: 1;
}

#result.loading {
    color: var(--accent);
    font-style: italic;
}

footer {
    max-width: 100%;
    width: 100%;
    margin-top: 3rem;
    padding-top: 0.8rem;
    border-top: 1px solid var(--glass-border);
    text-align: center;
    color: var(--footer-text);
    font-size: 0.9rem;
    font-weight: 500;
    font-style: italic;
    user-select: none;
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 8px;
}

footer img {
    width: 22px;
    height: 22px;
    filter: var(--footer-filter, none);
    vertical-align: middle;
}

@media (max-width: 600px) {
    main {
        padding: 1.8rem 2rem 2.2rem;
    }

    header h1 {
        font-size: 1.75rem;
    }

    button {
        padding: 0.85rem 2rem;
        font-size: 1rem;
    }

    #result {
        font-size: 0.9rem;
    }
}