:root {
    --bg-color: #f4f6fb;
    --panel-bg-color: #fff;
    --text-color: #212529;
    --heading-color: #000;
    --textarea-bg-color: #f8fafc;
    --textarea-border-color: #d1d5db;
    --result-bg-color: #f8fafc;
    --result-border-color: #e5e7eb;
    --button-bg-color: #2563eb;
    --button-text-color: #fff;
    --button-hover-bg-color: #1d4ed8;
    --shadow-color: rgba(0,0,0,0.07);
    --key-color: #922;
    --string-color: #080;
    --number-color: #00f;
    --boolean-color: #a52a2a;
    --null-color: #b5b5b5;
    --slider-bg: #ccc;
}

body.dark-mode {
    --bg-color: #1a1a1a;
    --panel-bg-color: #2c2c2c;
    --text-color: #e0e0e0;
    --heading-color: #fff;
    --textarea-bg-color: #333;
    --textarea-border-color: #555;
    --result-bg-color: #333;
    --result-border-color: #555;
    --button-bg-color: #3a7bfd;
    --button-text-color: #fff;
    --button-hover-bg-color: #2a6bfd;
    --shadow-color: rgba(0,0,0,0.2);
    --key-color: #f97583;
    --string-color: #a5d6ff;
    --number-color: #79c0ff;
    --boolean-color: #ffab70;
    --null-color: #999;
    --slider-bg: #555;
}

body {
    font-family: 'Inter', 'Segoe UI', Arial, sans-serif;
    background: var(--bg-color);
    color: var(--text-color);
    margin: 0;
    padding: 0;
    transition: background-color 0.3s, color 0.3s;
}

.header-container {
    display: flex;
    justify-content: center;
    align-items: center;
    position: relative;
    max-width: 900px;
    margin: 0 auto;
}

h1 {
    color: var(--heading-color);
    text-align: center;
    font-weight: 700;
    margin-top: 40px;
    margin-bottom: 24px;
    letter-spacing: -1px;
}
.container {
    display: flex;
    gap: 32px;
    max-width: 900px;
    margin: 0 auto;
}
.panel {
    flex: 1;
    background: var(--panel-bg-color);
    box-shadow: 0 4px 24px var(--shadow-color);
    border-radius: 16px;
    padding: 32px 24px;
    display: flex;
    flex-direction: column;
    min-width: 0;
    transition: background-color 0.3s;
}
label {
    font-weight: 600;
    margin-bottom: 8px;
    display: block;
}
textarea {
    width: 100%;
    height: 180px;
    font-size: 16px;
    border-radius: 8px;
    border: 1px solid var(--textarea-border-color);
    padding: 12px;
    margin-bottom: 16px;
    background: var(--textarea-bg-color);
    color: var(--text-color);
    resize: vertical;
    box-sizing: border-box;
    transition: background-color 0.3s, border-color 0.3s;
}
.result {
    white-space: pre-wrap;
    background: var(--result-bg-color);
    padding: 16px;
    border-radius: 10px;
    font-size: 15px;
    border: 1px solid var(--result-border-color);
    margin-bottom: 16px;
    min-height: 60px;
    transition: background-color 0.3s, border-color 0.3s;
}
button {
    margin-top: 10px;
    padding: 10px 24px;
    font-size: 16px;
    background: var(--button-bg-color);
    color: var(--button-text-color);
    border: none;
    border-radius: 8px;
    font-weight: 600;
    cursor: pointer;
    box-shadow: 0 2px 8px rgba(37,99,235,0.08);
    transition: background 0.2s;
}
button:hover {
    background: var(--button-hover-bg-color);
}
.radio-group {
    margin-bottom: 16px;
}
.json-view .key { color: var(--key-color); }
.json-view .string { color: var(--string-color); }
.json-view .number { color: var(--number-color); }
.json-view .boolean { color: var(--boolean-color); }
.json-view .null { color: var(--null-color); }

.tabs {
    display: flex;
    justify-content: center;
    margin-bottom: 24px;
}

.tab-link {
    padding: 10px 20px;
    cursor: pointer;
    border: none;
    background: none;
    font-size: 18px;
    font-weight: 600;
    color: var(--text-color);
    opacity: 0.6;
    transition: opacity 0.3s, border-bottom 0.3s;
    border-bottom: 3px solid transparent;
    position: relative;
}

.tab-link:hover {
    opacity: 1;
}

.tab-link.active {
    opacity: 1;
    border-bottom: 3px solid var(--button-bg-color);
}

.tab-content {
    display: none;
}

.tab-content.active {
    display: block;
}

#payload-kv-pairs .kv-pair {
    display: flex;
    gap: 10px;
    margin-bottom: 10px;
}

#payload-kv-pairs .kv-pair input {
    flex: 1;
    padding: 8px;
    border: 1px solid var(--textarea-border-color);
    border-radius: 6px;
    background: var(--textarea-bg-color);
    color: var(--text-color);
}

.remove-pair-btn, #add-pair-btn {
    padding: 5px 10px;
    border: none;
    border-radius: 6px;
    cursor: pointer;
    font-weight: bold;
}

.remove-pair-btn {
    background-color: #e53e3e;
    color: white;
}

#add-pair-btn {
    background-color: #38a169;
    color: white;
    margin-top: 10px;
}

#secret-key {
    width: 100%;
    padding: 8px;
    border: 1px solid var(--textarea-border-color);
    border-radius: 6px;
    background: var(--textarea-bg-color);
    color: var(--text-color);
    box-sizing: border-box;
}

#generated-jwt {
    width: 100%;
    height: 180px;
    font-size: 16px;
    border-radius: 8px;
    border: 1px solid var(--textarea-border-color);
    padding: 12px;
    margin-bottom: 16px;
    background: var(--textarea-bg-color);
    color: var(--text-color);
    resize: vertical;
    box-sizing: border-box;
}


.theme-switch-wrapper {
    position: absolute;
    right: 20px;
    top: 50%;
    transform: translateY(-50%);
    display: flex;
    align-items: center;
}

.theme-switch-icon {
    cursor: pointer;
    display: flex;
    align-items: center;
    background: none;
    border: none;
    padding: 0;
    outline: none;
    transition: color 0.3s;
}
.theme-switch-icon .icon-sun,
.theme-switch-icon .icon-moon {
    color: #fbbf24;
    font-size: 22px;
    transition: color 0.3s, opacity 0.3s;
}
.theme-switch-icon .icon-moon {
    color: #2563eb;
}
.dark-mode .theme-switch-icon .icon-sun {
    opacity: 0.3;
}
.dark-mode .theme-switch-icon .icon-moon {
    opacity: 1;
}
.theme-switch-icon .icon-sun {
    opacity: 1;
}
.theme-switch-icon .icon-moon {
    opacity: 0.3;
}


@media (max-width: 900px) {
    .header-container {
        padding: 0 16px;
    }
    .container { flex-direction: column; gap: 24px; padding: 0 16px; }
    .theme-switch-wrapper {
        right: 16px;
    }
}