/* CSS Custom Properties (Variables) for Design System */
:root {
    --primary-sky-blue: #5DADE2;
    --light-sky-blue: #AED6F1;
    --very-light-sky-blue: #EBF5FB;
    --pure-white: #FFFFFF;
    --dark-text: #2C3E50;
    --medium-gray: #7F8C8D;
    --success-green: #58D68D;
    --warning-orange: #F8C471;
    --border-radius: 12px;
    --transition-speed: 0.2s;
}

/* Global Styles & Resets */
* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

body {
    font-family: 'Nunito Sans', sans-serif;
    background-color: var(--very-light-sky-blue);
    color: var(--dark-text);
    line-height: 1.6;
    overflow-x: hidden;
}

/* App Header */
.app-header {
    background-color: var(--pure-white);
    padding: 1rem 1.5rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    box-shadow: 0 2px 4px rgba(0,0,0,0.05);
    position: sticky;
    top: 0;
    z-index: 100;
}

.app-header h1 {
    font-size: 1.5rem;
    font-weight: 600;
    color: var(--primary-sky-blue);
}

/* Utility Classes */
.hidden { display: none !important; }
.icon-btn { background: none; border: none; cursor: pointer; padding: 8px; }

/* Buttons */
.btn {
    padding: 10px 20px;
    border: none;
    border-radius: 8px;
    font-size: 14px;
    font-weight: 600;
    cursor: pointer;
    transition: background-color var(--transition-speed);
    text-decoration: none;
    display: inline-block;
}

.btn-primary {
    background-color: var(--primary-sky-blue);
    color: var(--pure-white);
}
.btn-primary:hover { background-color: var(--light-sky-blue); }

.btn-secondary {
    background-color: transparent;
    color: var(--primary-sky-blue);
    border: 2px solid var(--primary-sky-blue);
}
.btn-secondary:hover { background-color: var(--very-light-sky-blue); }

/* Floating Action Button (FAB) */
.fab {
    position: fixed;
    bottom: 24px;
    right: 24px;
    width: 56px;
    height: 56px;
    border-radius: 50%;
    background-color: var(--primary-sky-blue);
    color: var(--pure-white);
    border: none;
    font-size: 24px;
    cursor: pointer;
    box-shadow: 0 4px 8px rgba(0,0,0,0.2);
    z-index: 1000;
    transition: transform var(--transition-speed), background-color var(--transition-speed);
}
.fab:hover { transform: scale(1.1); background-color: var(--light-sky-blue); }

.fab-menu {
    position: fixed;
    bottom: 90px;
    right: 24px;
    background-color: var(--pure-white);
    border-radius: var(--border-radius);
    box-shadow: 0 4px 12px rgba(0,0,0,0.15);
    display: flex;
    flex-direction: column;
    z-index: 999;
}
.fab-menu-item {
    padding: 12px 24px;
    border: none;
    background: none;
    cursor: pointer;
    white-space: nowrap;
    font-size: 14px;
    color: var(--dark-text);
}
.fab-menu-item:hover { background-color: var(--very-light-sky-blue); }

/* Loading Overlay */
#loading-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(255, 255, 255, 0.8);
    display: flex;
    justify-content: center;
    align-items: center;
    z-index: 2000;
}
.spinner {
    border: 4px solid var(--light-sky-blue);
    border-top: 4px solid var(--primary-sky-blue);
    border-radius: 50%;
    width: 40px;
    height: 40px;
    animation: spin 1s linear infinite;
}
@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}