/* ============================================================
   DEV TOOLBOX — Dark Theme Chung
   Dùng CSS Variables để dễ dàng tuỳ chỉnh toàn bộ giao diện
   ============================================================ */

/* --- Google Fonts --- */
@import url('https://fonts.googleapis.com/css2?family=JetBrains+Mono:wght@400;600&family=Be+Vietnam+Pro:wght@300;400;500;600;700&display=swap');

/* === CSS Variables === */
:root {
    /* Nền */
    --bg-body: #06080f;
    --bg-surface: #0d1117;
    --bg-card: #131922;
    --bg-card-hover: #1a2233;
    --bg-input: #0d1117;

    /* Viền */
    --border-color: #1e2d3d;
    --border-hover: #30a14e;

    /* Text */
    --text-primary: #e6edf3;
    --text-secondary: #8b949e;
    --text-muted: #525c67;

    /* Accent / màu nhấn */
    --accent: #58a6ff;
    --accent-hover: #79c0ff;
    --accent-glow: rgba(88, 166, 255, 0.15);
    --accent-green: #3fb950;
    --accent-orange: #f0883e;
    --accent-red: #f85149;
    --accent-purple: #bc8cff;

    /* Font */
    --font-body: 'Be Vietnam Pro', sans-serif;
    --font-mono: 'JetBrains Mono', monospace;

    /* Border radius */
    --radius-sm: 8px;
    --radius-md: 12px;
    --radius-lg: 16px;
    --radius-xl: 20px;

    /* Shadow */
    --shadow-card: 0 2px 12px rgba(0,0,0,0.4);
    --shadow-glow: 0 0 20px rgba(88, 166, 255, 0.08);

    /* Transition */
    --transition: 0.25s cubic-bezier(0.4, 0, 0.2, 1);
}

/* === Reset & Base === */
*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-body);
    background: var(--bg-body);
    color: var(--text-primary);
    line-height: 1.6;
    min-height: 100vh;
    -webkit-font-smoothing: antialiased;
}

/* === Scrollbar === */
::-webkit-scrollbar {
    width: 6px;
}
::-webkit-scrollbar-track {
    background: var(--bg-surface);
}
::-webkit-scrollbar-thumb {
    background: var(--border-color);
    border-radius: 3px;
}
::-webkit-scrollbar-thumb:hover {
    background: var(--text-muted);
}

/* === Typography === */
h1, h2, h3, h4, h5, h6 {
    font-weight: 600;
    line-height: 1.3;
    color: var(--text-primary);
}

a {
    color: var(--accent);
    text-decoration: none;
    transition: color var(--transition);
}
a:hover {
    color: var(--accent-hover);
}

code, .mono {
    font-family: var(--font-mono);
}

/* === Shared Layout === */
.toolbox-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 2rem 1.5rem;
}

/* === Header chung cho mỗi tool === */
.tool-header {
    display: flex;
    align-items: center;
    gap: 1rem;
    margin-bottom: 2rem;
    padding-bottom: 1rem;
    border-bottom: 1px solid var(--border-color);
}

.tool-header .back-btn {
    display: inline-flex;
    align-items: center;
    gap: 0.4rem;
    padding: 0.5rem 1rem;
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    color: var(--text-secondary);
    font-size: 0.85rem;
    cursor: pointer;
    transition: all var(--transition);
}
.tool-header .back-btn:hover {
    color: var(--accent);
    border-color: var(--accent);
    background: var(--accent-glow);
}

.tool-header h1 {
    font-size: 1.4rem;
    font-weight: 700;
}

/* === Card chung === */
.card-dark {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    padding: 1.5rem;
    box-shadow: var(--shadow-card);
}

/* === Form elements === */
.input-dark {
    width: 100%;
    padding: 0.75rem 1rem;
    background: var(--bg-input);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    color: var(--text-primary);
    font-family: var(--font-body);
    font-size: 0.95rem;
    transition: all var(--transition);
    outline: none;
}
.input-dark:focus {
    border-color: var(--accent);
    box-shadow: 0 0 0 3px var(--accent-glow);
}
.input-dark::placeholder {
    color: var(--text-muted);
}

textarea.input-dark {
    resize: vertical;
    min-height: 100px;
}

select.input-dark {
    cursor: pointer;
    appearance: none;
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' fill='%238b949e' viewBox='0 0 16 16'%3E%3Cpath d='M7.247 11.14 2.451 5.658C1.885 5.013 2.345 4 3.204 4h9.592a1 1 0 0 1 .753 1.659l-4.796 5.48a1 1 0 0 1-1.506 0z'/%3E%3C/svg%3E");
    background-repeat: no-repeat;
    background-position: right 1rem center;
    padding-right: 2.5rem;
}

/* === Buttons === */
.btn-primary-dark {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    padding: 0.75rem 1.5rem;
    background: var(--accent);
    color: #ffffff;
    border: none;
    border-radius: var(--radius-sm);
    font-family: var(--font-body);
    font-size: 0.95rem;
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition);
    width: 100%;
}
.btn-primary-dark:hover {
    background: var(--accent-hover);
    box-shadow: 0 4px 16px rgba(88, 166, 255, 0.3);
    transform: translateY(-1px);
}
.btn-primary-dark:active {
    transform: translateY(0);
}

.btn-danger-dark {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    padding: 0.75rem 1.5rem;
    background: var(--accent-red);
    color: #ffffff;
    border: none;
    border-radius: var(--radius-sm);
    font-family: var(--font-body);
    font-size: 0.95rem;
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition);
    width: 100%;
}
.btn-danger-dark:hover {
    background: #da3633;
    box-shadow: 0 4px 16px rgba(248, 81, 73, 0.3);
}

.btn-secondary-dark {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    padding: 0.6rem 1.2rem;
    background: var(--bg-card);
    color: var(--text-secondary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    font-family: var(--font-body);
    font-size: 0.85rem;
    font-weight: 500;
    cursor: pointer;
    transition: all var(--transition);
}
.btn-secondary-dark:hover {
    color: var(--text-primary);
    border-color: var(--text-muted);
    background: var(--bg-card-hover);
}

/* === Label === */
.label-dark {
    display: block;
    margin-bottom: 0.4rem;
    font-size: 0.85rem;
    font-weight: 500;
    color: var(--text-secondary);
}

/* === Hint text === */
.hint-text {
    font-size: 0.8rem;
    color: var(--accent-orange);
    margin-top: 0.35rem;
}

/* === Loading Overlay === */
.loading-overlay {
    position: fixed;
    top: 0; left: 0;
    width: 100%; height: 100%;
    background: rgba(6, 8, 15, 0.85);
    backdrop-filter: blur(6px);
    z-index: 9999;
    display: none;
    flex-direction: column;
    align-items: center;
    justify-content: center;
}
.loading-overlay.active {
    display: flex;
}
.loading-spinner {
    width: 40px; height: 40px;
    border: 3px solid var(--border-color);
    border-top-color: var(--accent);
    border-radius: 50%;
    animation: spin 0.8s linear infinite;
}
@keyframes spin {
    to { transform: rotate(360deg); }
}
.loading-text {
    margin-top: 1rem;
    color: var(--text-secondary);
    font-size: 0.9rem;
}

/* === Responsive === */
@media (max-width: 768px) {
    .toolbox-container {
        padding: 1rem;
    }
    .tool-header h1 {
        font-size: 1.1rem;
    }
}