/* Base Theme Variables */
:root {
    --color-top: var(--theme-top, #3f51b5);
    --color-menu: var(--theme-menu, #2196f3);
    --color-main: var(--theme-main, #fff);
    --color-bottom: var(--theme-bottom, #4caf50);
    --color-text: var(--theme-text, #222);
    --color-link: var(--theme-link, #1565c0);
    --shadow: 0 2px 10px rgba(0,0,0,0.1);
    --menu-width: 250px;
    --transition: 0.3s cubic-bezier(.4,0,.2,1);
}

/* Light Theme */
[data-theme="light"] {
    --theme-top: #3f51b5;
    --theme-menu: #2196f3;
    --theme-main: #fff;
    --theme-bottom: #4caf50;
    --theme-text: #222;
    --theme-link: #1565c0;
}

/* Dark Theme */
[data-theme="dark"] {
    --theme-top: #22223b;
    --theme-menu: #2a2c47;
    --theme-main: #2d3142;
    --theme-bottom: #4a4e69;
    --theme-text: #f2e9e4;
    --theme-link: #b8c1ec;
}

/* Example Custom Theme: Solarized */
[data-theme="solarized"] {
    --theme-top: #268bd2;
    --theme-menu: #2aa198;
    --theme-main: #fdf6e3;
    --theme-bottom: #859900;
    --theme-text: #002b36;
    --theme-link: #d33682;
}

html, body {
    height: 100%;
    margin: 0;
    font-family: 'Segoe UI', Arial, sans-serif;
    color: var(--color-text);
    background: var(--color-main);
    transition: background var(--transition), color var(--transition);
}

/* Grid Layout */
.container {
    display: grid;
    grid-template-areas:
        "top top"
        "menu main"
        "bottom bottom";
    grid-template-columns: var(--menu-width) 1fr;
    grid-template-rows: auto 1fr auto;
    min-height: 100vh;
}

/* Grid Areas */
#top {
    grid-area: top;
    background: var(--color-top);
    color: var(--color-text);
    box-shadow: var(--shadow);
    padding: 1rem;
    transition: background var(--transition), color var(--transition);
}
.menu-area {
    grid-area: menu;
    background: var(--color-menu);
    color: var(--color-text);
    padding: 1rem;
    min-width: 0;
    box-shadow: var(--shadow);
    z-index: 2;
    transition: background var(--transition), color var(--transition);
}
.menu-area ul {
    list-style: none;
    margin: 0; padding: 0;
}
.menu-area a {
    display: block;
    color: var(--color-link);
    padding: 0.5em 0;
    text-decoration: none;
    border-radius: 4px;
    transition: background 0.15s;
}
.menu-area a:hover {
    background: rgba(255,255,255,0.1);
}
#main {
    grid-area: main;
    background: var(--color-main);
    color: var(--color-text);
    padding: 2rem;
    min-width: 0;
    transition: background var(--transition), color var(--transition);
}
#bottom {
    grid-area: bottom;
    background: var(--color-bottom);
    color: var(--color-text);
    box-shadow: var(--shadow);
    padding: 1rem;
    text-align: center;
    transition: background var(--transition), color var(--transition);
}

/* Hamburger Styles */
.hamburger {
    display: none;
    position: absolute;
    top: 1.25rem;
    left: 1.25rem;
    width: 40px;
    height: 40px;
    background: none;
    border: none;
    z-index: 3;
    cursor: pointer;
}
.hamburger span {
    display: block;
    height: 4px;
    margin: 6px 0;
    background: var(--color-menu);
    border-radius: 2px;
    transition: all .2s;
}

/* Hide Menu on Small Screens, Show Hamburger */
@media (max-width: 900px) {
    .container {
        grid-template-areas:
            "top"
            "main"
            "bottom";
        grid-template-columns: 1fr;
    }
    .menu-area {
        display: none;
        position: fixed;
        top: 0; left: 0;
        width: var(--menu-width);
        height: 100vh;
        box-shadow: var(--shadow);
        padding-top: 3rem;
    }
    .menu-area.menu-open {
        display: block;
        animation: slideIn .3s;
    }
    .hamburger {
        display: block;
    }
    #top {
        position: relative;
    }
}
@keyframes slideIn {
    from { transform: translateX(-100%); opacity: 0; }
    to   { transform: translateX(0); opacity: 1; }
}

/* Hamburger "X" when open */
.menu-area.menu-open ~ .hamburger span:nth-child(1) {
    transform: rotate(45deg) translate(7px, 7px);
}
.menu-area.menu-open ~ .hamburger span:nth-child(2) {
    opacity: 0;
}
.menu-area.menu-open ~ .hamburger span:nth-child(3) {
    transform: rotate(-45deg) translate(8px, -8px);
}

/* Theme Switcher Button */
.theme-switcher {
    position: fixed;
    right: 1rem;
    top: 1rem;
    z-index: 99;
}
#theme-toggle {
    background: var(--color-menu);
    color: var(--color-text);
    border: none;
    border-radius: 50%;
    width: 2.5rem;
    height: 2.5rem;
    font-size: 1.25rem;
    cursor: pointer;
    transition: background var(--transition), color var(--transition);
    box-shadow: var(--shadow);
}
#theme-toggle:hover {
    background: var(--color-bottom);
}