* {
    box-sizing: border-box;
}

body {
    margin: 0;
    min-height: 100vh;
    display: flex;
    justify-content: center;
    align-items: flex-start;
    padding: 24px 16px;
    background-color: #f4f5f7;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Hiragino Kaku Gothic ProN", "Hiragino Sans", Meiryo, sans-serif;
    color: #1f2328;
}

.card {
    width: 100%;
    max-width: 480px;
    background-color: #ffffff;
    border-radius: 12px;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.08);
    padding: 24px;
}

.form-field {
    display: flex;
    flex-direction: column;
    gap: 8px;
}

textarea {
    width: 100%;
    min-height: 140px;
    padding: 12px;
    font-size: 16px;
    font-family: inherit;
    border: 1px solid #d0d7de;
    border-radius: 8px;
    resize: vertical;
}

textarea:focus {
    outline: none;
    border-color: #4f7cff;
    box-shadow: 0 0 0 3px rgba(79, 124, 255, 0.15);
}

button {
    margin-top: 16px;
    width: 100%;
    padding: 12px;
    font-size: 16px;
    font-weight: 600;
    color: #ffffff;
    background-color: #4f7cff;
    border: none;
    border-radius: 8px;
    cursor: pointer;
}

button:hover {
    background-color: #3d68e8;
}

button:active {
    background-color: #2f56cc;
}

button:disabled {
    background-color: #a9bdf0;
    cursor: default;
}

.spinner {
    width: 32px;
    height: 32px;
    margin: 20px auto 0;
    border: 3px solid #d0d7de;
    border-top-color: #4f7cff;
    border-radius: 50%;
    animation: spin 0.8s linear infinite;
}

@keyframes spin {
    to {
        transform: rotate(360deg);
    }
}

.result-label {
    margin-top: 20px;
    font-size: 13px;
    font-weight: 600;
    color: #6b7280;
}

.result-label + .result-block {
    margin-top: 6px;
}

.result-block {
    display: flex;
    align-items: flex-start;
    gap: 8px;
    margin-top: 20px;
}

.result {
    margin-top: 0;
    flex: 1;
    padding: 12px 16px;
    background-color: #f0f4ff;
    border-left: 4px solid #4f7cff;
    border-radius: 4px;
    white-space: pre-wrap;
    word-break: break-word;
}

.copy-button {
    flex-shrink: 0;
    width: auto;
    margin-top: 0;
    padding: 8px 12px;
    font-size: 13px;
    font-weight: 600;
    color: #4f7cff;
    background-color: #eef1ff;
    border: 1px solid #d0d7de;
    border-radius: 6px;
}

.copy-button:hover {
    background-color: #e0e6ff;
}

.copy-button:active {
    background-color: #d3daff;
}

.result.error {
    background-color: #fff0f0;
    border-left-color: #e5484d;
    color: #8f1f24;
}

@media (max-width: 480px) {
    .card {
        padding: 16px;
        border-radius: 8px;
    }
}