:root {
    --content-padding: 48px 24px 64px;
    --content-padding-mobile: 28px 16px 40px;
    --section-gap: 32px;
    --label-gap: 10px;
    --button-gap: 18px;
    --button-gap-mobile: 12px;
    --modal-radius: 12px;
    --text-primary: #202124;
    --text-secondary: #5f6368;
    --border-subtle: #dadce0;
    --surface: #ffffff;
    --surface-soft: #f8f9fa;
    --button-bg: #f8f9fa;
    --button-bg-hover: #f1f3f4;
    --button-shadow: 0 1px 1px rgba(60, 64, 67, 0.1);
}

* {
    box-sizing: border-box;
}

body, html {
    margin: 0;
    padding: 0;
    width: 100%;
    min-height: 100%;
    display: flex;
    justify-content: center;
    align-items: flex-start;
    font-family: "Roboto", "Arial", sans-serif;
    color: var(--text-primary);
    background: var(--surface-soft);
}

#content {
    text-align: center;
    padding: var(--content-padding);
    max-width: 960px;
    width: 100%;
    background: var(--surface);
    border-top: 1px solid var(--border-subtle);
    box-shadow: 0 1px 6px rgba(60, 64, 67, 0.08);
}

h1 {
    margin: 8px 0 20px 0;
    font-size: 34px;
    font-weight: 400;
    letter-spacing: -0.2px;
}

button {
    padding: 10px 22px;
    font-size: 14px;
    font-weight: 500;
    border-radius: 20px;
    border: 1px solid var(--border-subtle);
    background: var(--button-bg);
    color: var(--text-primary);
    box-shadow: var(--button-shadow);
    transition: box-shadow 0.2s ease, background 0.2s ease, border-color 0.2s ease;
    cursor: pointer;
}

button:hover:not(:disabled) {
    background: var(--button-bg-hover);
    border-color: #c8ccd1;
    box-shadow: 0 2px 4px rgba(60, 64, 67, 0.15);
}

button:active:not(:disabled) {
    box-shadow: none;
}

button:disabled {
    cursor: not-allowed;
    opacity: 0.6;
}

#browseButton,
#resetButton,
#saveButton {
    display: block;
    margin: var(--button-gap) auto 0 auto;
}

#loginButton {
    display: block;
    margin: var(--button-gap) auto 0 auto;
}

#uploadSection,
#sourceSection,
#statusSection,
#correctedSection {
    margin-top: var(--section-gap);
}

#sourceLabel,
#correctedLabel,
#statusText {
    margin-bottom: var(--label-gap);
    font-size: 15px;
    font-weight: 500;
    color: var(--text-secondary);
}

#correctedHint {
    margin-bottom: 12px;
    font-size: 13px;
    color: var(--text-secondary);
}

#sourceImage,
#correctedImage {
    display: block;
    max-width: 100%;
    height: auto;
    margin: 0 auto;
}

#statusText {
    animation: blink 1s step-start 0s infinite;
}

#actionButtons {
    display: flex;
    justify-content: center;
    gap: 16px;
    margin-top: var(--button-gap);
    flex-wrap: wrap;
}

#resetButton,
#saveButton {
    margin: 0;
}

#errorModal {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 999;
}

#errorModalBackdrop {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0, 0, 0, 0.5);
}

#errorModalContent {
    position: relative;
    background: #fff;
    padding: 24px;
    border-radius: var(--modal-radius);
    width: 90%;
    max-width: 480px;
    box-shadow: 0 10px 30px rgba(60, 64, 67, 0.2);
    text-align: center;
    z-index: 1;
}

#errorModalTitle {
    font-size: 18px;
    font-weight: 500;
    margin-bottom: 12px;
}

#errorModalMessage {
    margin-bottom: 20px;
    word-break: break-word;
}

@keyframes blink {
    0%, 50% { opacity: 1; }
    51%, 100% { opacity: 0; }
}

@media (max-width: 600px) {
    #content {
        padding: var(--content-padding-mobile);
    }

    #sourceLabel,
    #correctedLabel,
    #statusText {
        font-size: 14px;
    }

    #correctedHint {
        font-size: 12px;
    }

    button {
        width: 100%;
        max-width: 320px;
    }

    #actionButtons {
        flex-direction: column;
        align-items: center;
        gap: var(--button-gap-mobile);
    }
}