:root {
    --bg-color: #f1f5f9;
    /* Slate 100 */
    --card-bg: #ffffff;
    --text-main: #0f172a;
    /* Slate 900 */
    --text-muted: #475569;
    /* Slate 600 */
    --border-color: #e2e8f0;
    /* Slate 200 */

    --radius-md: 16px;
    --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
    --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);

    --font-family: 'Inter', 'Noto Sans JP', sans-serif;
}

* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

body {
    font-family: var(--font-family);
    background-color: var(--bg-color);
    color: var(--text-main);
    line-height: 1.5;
    -webkit-font-smoothing: antialiased;
    padding: 16px;
    padding-bottom: 40px;
}

a {
    text-decoration: none;
    color: inherit;
}

.app-container {
    max-width: 600px;
    margin: 0 auto;
}

/* Header */
.app-header {
    display: flex;
    align-items: center;
    justify-content: flex-start;
    gap: 16px;
    margin-top: 16px;
    margin-bottom: 32px;
    padding: 0 4px;
}

.app-header .header-icon img {
    width: 64px;
    height: 64px;
    border-radius: 16px;
    box-shadow: var(--shadow-sm);
}

.header-title-box h1 {
    font-size: 1.5rem;
    font-weight: 800;
    color: var(--text-main);
    letter-spacing: -0.01em;
    line-height: 1.2;
}

.header-title-box .subtitle {
    font-size: 0.95rem;
    font-weight: 600;
    color: var(--text-muted);
    margin-top: 4px;
}

/* Grid Menu */
.grid-menu {
    display: flex;
    flex-direction: column;
    gap: 16px;
}

.tool-card {
    display: flex;
    align-items: center;
    background-color: var(--card-bg);
    border-radius: var(--radius-md);
    padding: 20px;
    box-shadow: var(--shadow-sm);
    border: 1px solid var(--border-color);
    transition: all 0.2s ease;
    border-left-width: 6px;
}

.tool-card:active {
    transform: scale(0.97);
    box-shadow: none;
    background-color: #f8fafc;
}

.card-icon {
    font-size: 2.2rem;
    width: 56px;
    height: 56px;
    display: flex;
    align-items: center;
    justify-content: center;
    background-color: #f1f5f9;
    border-radius: 12px;
    margin-right: 20px;
    flex-shrink: 0;
}

.card-content h2 {
    font-size: 1.15rem;
    font-weight: 800;
    margin-bottom: 4px;
}

.card-content p {
    font-size: 0.85rem;
    font-weight: 600;
    color: var(--text-muted);
}

/* Theme Colors */
.theme-slate {
    border-left-color: #475569;
}

.theme-slate h2 {
    color: #334155;
}

.theme-indigo {
    border-left-color: #4f46e5;
}

.theme-indigo h2 {
    color: #4338ca;
}

.theme-orange {
    border-left-color: #ea580c;
}

.theme-orange h2 {
    color: #c2410c;
}

.theme-teal {
    border-left-color: #0d9488;
}

.theme-teal h2 {
    color: #0f766e;
}

.theme-green {
    border-left-color: #059669;
}

.theme-green h2 {
    color: #047857;
}

/* Footer */
.app-footer {
    margin-top: 32px;
    text-align: center;
    font-size: 0.8rem;
    font-weight: 600;
    color: var(--text-muted);
}